CROSS-REFERENCE TO RELATED APPLICATIONS This application claims benefit of U.S. provisional patent application Ser. No. 62/222,535 filed Sep. 23, 2015, and entitled “Impact Attenuating Media,” which is hereby incorporated herein by reference in its entirety for all purposes.
BACKGROUND Field of the Disclosure This disclosure relates generally to safety devices for handling piping and other tubulars during drilling operations. More particularly, it relates to apparatus and systems for capturing piping, other tubulars, and other equipment that can fit inside a borehole and that may be accidentally dropped while being repositioned on an oil platform or other drilling rig.
Background to the Disclosure Work around off-shore oil platforms, including drilling and production equipment, involves lifting, assembling, and dissembling heavy strings of tubular members, e.g. multiple sections of individual pipes, which may be called pipe joints, and other objects connectable to the drill pipe, such as drill bits. During this work, various strings and pipe sections must be grasped, transported to a new location and then rotated, released, and re-grasped. Often times this work is done over a hole in the drilling floor, commonly called a mouse hole, which includes the hole/opening and a staging or storage area below the opening. A mouse hole is configured to receive one or more pipe joints so that multiple pipe joints can be connected together end-to-end before being moved as a unit and placed in the well bore. There is a risk that strings and pipe sections may be accidentally dropped while being handled above or within the mouse hole. A dropped stand of pipe has the potential of falling to the sea floor below the rig and causing severe damage to the well-head, pipelines or other equipment that is positioned below. Such a fall has potential to injure rig personnel and also to cause environmental and economic damage. Equipment and methods for mitigating the effect of a falling tubulars on a drilling system would be beneficial to the industry.
BRIEF SUMMARY OF THE DISCLOSURE These and other needs in the art are addressed in one embodiment by an impact attenuating device. In an embodiment, the device includes an elongate housing comprising first and second housing ends, an internal chamber, and a housing base spaced-apart from the first housing end. In addition, the device includes an attenuator base disposed in the housing and spaced-apart from the first housing end. Further, the device includes a first stack of impact attenuating media disposed in the chamber at a location between the first housing end and the attenuator base, the stack comprising a plurality of resilient members.
In another embodiment, a drilling apparatus includes a drilling floor with a mousehole. In addition, the apparatus includes an elongate housing supported in a position below the drilling floor and comprising an internal chamber positioned beneath the mouse hole. Further, the apparatus includes at least a first impact attenuating stack disposed in the chamber and comprising a plurality of resilient members disposed along an elongate guide member. The resilient members include an alignment aperture that receives the guide member therethrough.
In another embodiment, an impact attenuating device comprises a longitudinal axis and an elongate housing. The housing includes first and second housing ends spaced-apart along the axis, an internal chamber, and a housing base axially spaced from the first housing end. In addition, the device includes an impact attenuating media assembly in the housing. The media assembly includes: a receiver; an attenuator base axially spaced-apart from the receiver and having an alignment hole; at least a first stack of impact attenuating media disposed between the receiver and the attenuator base, the stack comprising a plurality of resilient members; and a guide member extending from the receiver to the attenuator base, through the stack.
Thus, embodiments described herein include a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The various features and characteristics described above, as well as others, will be readily apparent to those of ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS For a detailed description of the disclosed embodiments, reference will now be made to the accompanying drawings:
FIG. 1 shows a perspective front view of an embodiment of an off-shore drilling system including an impact attenuating device in accordance with principles described herein, the impact attenuating device comprising an impact attenuating media assembly with three guide rods;
FIG. 2 shows a close-up side view of the impact attenuating device of FIG. 1 along a cross-section 2-2, having an impact attenuating media assembly installed in a housing;
FIG. 3 shows an upper end view of the impact attenuating device of FIG. 2;
FIG. 4 shows a lower end view of the impact attenuating device of FIG. 2;
FIG. 5 shows an end view of the base of the impact attenuating media assembly of FIG. 2;
FIG. 6A shows an end view of a resilient member (a “donut”) of the impact attenuating media assembly within FIG. 2;
FIG. 6B shows a side view of the resilient member within FIG. 6A along the section 6B-6B;
FIG. 7 shows an end view and a cross-sectional side view of a spacer of the impact attenuating media assembly within FIG. 2; the spacer configured to couple three resilient members on each side and to receive three guide rods;
FIG. 8 shows an end view of the housing base of the impact attenuating device of FIG. 2;
FIG. 9 shows cross-sectional side view of the impact attenuating media assembly of the device of FIG. 2 as it may be arranged during make-up/assembly;
FIG. 10 shows a full side view, in cross-section, of the impact attenuating device of FIG. 2 having the impact attenuating media assembly installed in the housing;
FIG. 11 shows a cross-sectional view of the impact attenuating device of FIG. 10 with the impact attenuating media assembly fully-compressed under load;
FIG. 12 shows an end view and a cross-sectional view side view of another spacer that may be used to form the impact attenuating media assembly of FIG. 9 in accordance with principles described herein; the spacer is configured to couple one resilient member on each side and to receive one guide rod;
FIG. 13 shows an upper end view and a lower end view of another impact attenuating device compatible with the impact attenuating device of FIG. 1 in accordance with principles described herein.
FIG. 14 shows a side view of the impact attenuating device of FIG. 13 along a cross-section 14-14;
FIG. 15 shows an end view of a spacer of the impact attenuating media assembly of FIG. 14, the spacer configured to couple four resilient members on each side and to receive four guide rods;
FIG. 16 shows an end view of another spacer compatible with an impact attenuating media device similar to the devices of FIG. 2 and FIG. 14 in accordance with principles described herein, the spacer being square and configured to couple four resilient members on each side and to receive four guide rods;
FIG. 17 shows components of an impact attenuating media assembly, including a receiver, a base, and a billow hose in accordance with principles described herein;
FIG. 18 shows a side view in cross-section of another impact attenuating device in accordance with principles described herein, the impact attenuating device comprising having an impact attenuating media assembly installed in a housing and being compatible with the drilling system of FIG. 1;
FIG. 19 shows an isometric, exterior view of the impact attenuating device of FIG. 18;
FIG. 20 shows a close-up view of the end of the impact attenuating media stack of the impact attenuating device of FIG. 18;
FIG. 21 shows a stabilizer of the impact attenuating device of FIG. 18;
FIG. 22 shows an end view in cross-section of the impact attenuating device of FIG. 18 along a section 22-22;
FIG. 23 shows an end view of an impact attenuating media element of the impact attenuating device of FIG. 18 and FIG. 22, the media element having a star-shaped hole for receiving a guide member; and
FIG. 24 shows an impact attenuating media element in accordance with principles described herein, suitable for use with any of the attenuating devices disclosed herein.
NOTATION AND NOMENCLATURE The following description is exemplary of certain embodiments of the disclosure. One of ordinary skill in the art will understand that the following description has broad application, and the discussion of any embodiment is meant to be exemplary of that embodiment, and is not intended to suggest in any way that the scope of the disclosure, including the claims, is limited to that embodiment.
The drawing figures are not necessarily to scale. Certain features and components disclosed herein may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. In some of the figures, in order to improve clarity and conciseness, one or more components or aspects of a component may be omitted or may not have reference numerals identifying the features or components that are identified elsewhere. In addition, within the specification, including the drawings, like or identical reference numerals may be used to identify common or similar elements.
As used herein, including in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” In addition, the term “couple” or “couples” means either an indirect or direct connection. Thus, if a first component couples or is coupled to a second component, the connection between the components may be through a direct engagement of the two components, or through an indirect connection that is accomplished via other intermediate components, devices and/or connections. The recitation “based on” means “based at least in part on.” Therefore, if X is based on Y, X may be based on Y and any number of other factors. The word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.”
In addition, the terms “axial” and “axially” generally mean along or parallel to a given axis, while the term “axially aligned” more specifically means along a given axis. The terms “radial” and “radially” generally mean perpendicular to an axis. For instance, an axial distance refers to a distance measured along or parallel to a given axis, and a radial distance means a distance measured perpendicular to the axis.
Furthermore, any reference to a relative direction or relative position is made for purpose of clarity, with examples including “top,” “bottom,” “up,” “upper,” “upward,” “left,” “leftward,” “right,” “right-hand,” “down,” “lower,” “clockwise,” and the like. For example, a relative direction or a relative position of an object or feature may pertain to the orientation as shown in a figure or as described. If the object or feature were viewed from another orientation or were positioned differently, it may be appropriate to describe the direction or position using an alternate term.
DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS This disclosure presents embodiments of an apparatus and a related system for handling strings and individual sections of pipe and other tubulars on or around an oil platform or oil rig, including off-shore oil systems. The apparatus and a related system include an impact attenuating device for capturing a falling tubular. During impact, the kinetic energy of the falling tubular is converted and stored as potential energy in multiple resilient members that experience displacement or expansion perpendicular to the direction of impact. In at least some embodiments, after the captured member is removed, the resilient members recover at least a portion of their original size and shape and at least a portion of their original impact-absorbing capacity.
Referring now to FIG. 1, an embodiment of an offshore drilling system 10 is shown. In this embodiment, drilling system 10 includes a rig structure 12 having a drilling deck 14 and a mast or derrick 15 coupled to deck 14. Vertically-extending derrick 15 supports a drill string 16 suspended within a drilling riser defining a drilling centerline 18. In particular, the upper portion of the derrick 15 includes a top drive system 25 and pipe elevator 26 that support drill string 16, which extends through the drilling deck 14, a drilling riser, and into a subsea borehole.
One or more storage areas are provided for individual pipe joints 20 and pipe stands 22. In this embodiment, a first storage unit 21 temporarily stores a plurality of pipe joints 20 in a horizontal orientation on deck 14, and a second storage unit 23 temporarily stores a plurality of pipe stands 22 in a vertical orientation. Storage unit 23 includes a racking or finger board 30 extending horizontally from derrick 15 above drilling deck 14. As shown, storage units 21, 23 are offset or spaced away from centerline 18. Pipe joints 20 in storage unit 21 are used to assembly pipe stands 22, which may then be added to drill string 16. In this embodiment, each pipe stand 22 is made of four individual pipe joints 20 connected together end-to-end. In other examples, a pipe stand 22 is made of more or fewer individual pipe joints 20, such as two or three individual pipe joints 20 connected together end-to-end.
Referring still to FIG. 1, an embodiment of a mouse hole 90 is offset from centerline 18, and extends vertically downward from drilling deck 14. Mouse hole 90 includes a rotary interface 92 disposed adjacent and coupled to drilling deck 14 below a hole 17, a plurality of receiving tubes or guide tubes 94, and an impact attenuating device 100, all connected in series along a vertical, mouse hole axis 95 and extending below drilling deck 14. Mouse hole 90 or portions of it may also be called a rotary sock. Mouse hole 90 may be used to assemble and disassemble a plurality of pipe joints 20 into pipe stands 22.
In general, any suitable pipe handling device or system may be used to engage individual pipe joints 20, as well as individual pipe stands 22, to manipulate and move joints 20 and stands 22 between storage units 21, 23, mouse hole 90, and centerline 18. The combined operation of the pipe handling system and mouse hole 90 may be by manual or robotic means, which can include automated or remote control. Examples of suitable pipe handling systems are disclosed in U.S. Pat. Nos. 7,841,415; 7,228,919; 6,976,540; 7,736,119; 7,083,007; and U.S. Patent Application Publication Nos. 2007/0251728 and 2008/0164064, each of which is hereby incorporated herein by reference in its entirety for all purposes.
Drilling system 10 is an example of a well operation that employs the impact attenuating device 100, also referred to herein as an impact attenuator. In some embodiments, impact attenuator may be attached to another advantageous location, such as, for example, being directly coupled to drilling deck 14 without a rotary interface 92 or a guide tubes 94 therebetween. A portion or all of impact attenuator 100 may be submerged in sea water in some installations.
Referring now to FIG. 2, FIG. 3, and FIG. 4, impact attenuator 100 includes impact attenuating media assembly 105 installed in an elongate housing 200. Assembly 105 includes a receiver 110, an attenuator base 130 spaced-apart from receiver 110 by a distance D along an attenuation axis 145, a plurality of parallel, elongate guide members 150 extending between the receiver 110 and the base 130, and a plurality of stacks 160 of impact attenuating media. In the exemplary embodiment shown in FIGS. 2-4, guide members 150 are solid rods, and, therefore, will also be called guide rods 150. Each stack 160 is slidingly disposed along one of the guide rods 150 parallel to the attenuation axis 145 between the receiver 110 and the base 130. Thus, receiver 110 and base 130 are end members of assembly 105, and attenuation axis 145 extends through receiver 110 and base 130. Each stack 160 of impact attenuating media includes a plurality of impact attenuating media elements, which will also be called resilient members 162, with adjacent resilient members 162 separated by a spacer 180. One of a plurality of fasteners 159 attaches to each guide rod 150 and is positioned against or adjacent base 130, helping to hold media assembly 105 together. As shown in FIG. 2, assembly 105 includes three impact attenuating media stacks 160 held on or coupled to three rods 150. Some other embodiments include fewer than or more than three pair of rods 150 coupled to media stacks 160. For example, some other embodiments may include one, two, four, five, six, or any practical number of pair of media stacks 160 and coupled rods 150. When impact attenuator 100 is installed in drilling system 10, attenuation axis 145 is aligned along mouse hole axis 95 (FIG. 1).
Referring to FIG. 2 and FIG. 3, receiver 110, one of the end members of assembly 105, includes a central axis 111 aligned with attenuation axis 145 and a round receiver plate 115 centered on axis 111. Receiver plate 115 includes an upper surface 116 opposite a lower surface 118, a counter-sunk through-hole 117 extending from upper surface 116 through lower surface 118 for fluid communication, perimeter surface 119 extending between upper and lower surfaces 116, 118, and a plurality of alignment apertures or holes 124 evenly-spaced around the through-hole 117. As shown, holes 124 may be through-holes and may have a counter-sunk portion, i.e. an enlarged portion, at upper surface 116. Each hole 124 is sized to receive slidingly one of the guide rods 150. FIG. 2 shows that receiver plate 115 includes one hole 124 for each rod 150 of media assembly 105, therefore having three holes 124. This receiver 110 also includes a guide tube 120 extending from the upper surface 116 to aid in receiving and directing the impact of a moving object, of which the motion and impact energy is to be absorbed by impact attenuator 100. Guide tube 120 includes an outside diameter than matches the diameter of perimeter surface 119 of receiver plate 115. In the assembly of impact attenuator 100, guide tube 120 is located on the opposite side of receiver plate 115 as are media stacks 160 and therefore extends axially away from the stacks 160. Receiver 110 transfers or distributes the dynamic load of an impacting object among the stacks 160. Guide tube 120 assists in keeping receiver plate 115 oriented perpendicular to attenuation axis 145 and traveling smoothly within housing 200 when absorbing an impact from a falling object. In this embodiment, receiver plate 115 and surfaces 116, 118 are flat and through-hole 117 is aligned on attenuation axis 145 through the center of surfaces 115, 116. Some embodiments include a resilient disc or a resilient conical insert member located within guide tube 120 and adjacent upper surface 116 of receiver plate 115 to aid in absorbing the impact, to regulate the movement, or to reduce the rebound of a falling object received within receiver 110.
Referring FIG. 5 and FIG. 2, in a simple form, base 130, the other end member of media assembly 105, is a flat plate and may also be called a base plate or a retainer plate. Base 130 includes an upper surface 132, a lower surface 133 having a chamfered perimeter, a through-hole 134, a plurality of alignment apertures or holes 136 evenly-spaced around the through-hole 134. As shown, holes 136 may be through-holes. As such, each hole 136 is sized to slidingly receive or engage one of the guide rods 150 but small enough to block the fastener 159 on lower end 153 of that rod 150 from passing-through. In this embodiment, base 130 includes three holes 136, one for each rod 150 of media assembly 105; through-hole 134 is centrally-located on surfaces 133, 134 with a counter-bore at lower surface 133; and when installed in impact attenuator 100, through-hole 134 is aligned with attenuation axis 145. The perimeter of base 130 is filleted at lower surface 133. Through-hole 134 and alignment holes 136 extend through surface 132 and surface 133. Through-hole 134 may provide passage for the transfer of fluid to reduce, relieve, or inhibit the build-up of pressure within impact attenuator 100 during an impact by an object.
Referring again to FIG. 2, FIG. 3, and FIG. 4, guide rod 150 includes an upper end 152, a lower end 153 spaced-apart from upper end 152, and a central axis 155 extending longitudinally through ends 152, 153. In media assembly 105, upper end 152 threadingly receives a fastener 158, and lower end 153 threadingly receives another fastener 159. Fasteners 158, 159 may be internally threaded nuts and may be identical or different.
As stated earlier in reference to FIG. 2, each media stack 160 includes a plurality of resilient members 162 alternating among a plurality of spacers 180. FIGS. 6A and 6B shows a resilient member 162 in greater detail. Due to their generally toroidal shape, resilient members 162 of impact attenuating media assembly 105 may also be called impact absorbing donuts or, supply, donuts 162, and stack 160 may also be called a donut stack. In at least some embodiments, the resilient members 162 may be described as being discs, shaped like a hockey puck. Other embodiments may include resilient members 162 having other shapes, for example a cup-shape having a concave inner surface possibly with a convex outer surface. Each spacer 180 includes three alignment apertures or through-holes 188; each hole 188 slidingly receives or engages one of the three guide rods 150 of media assembly 105. Each spacer 180 extends among the three rods 150 and the three stacks 160. Thus, the three stacks 160 share the spacers 180, which may be called multi-stack spacers. The three stacks 160, including the shared the spacers 180 and the three groups of resilient members 162, may be also be described as a single or aggregate stack of impact attenuating media.
A shown in FIGS. 6A and 6B, each donut 162, i.e. the resilient member of this embodiment, is characterized by a relaxed-state diameter θ1 (“theta 1”) and a relaxed-state height or thickness H1. Donut 162 includes a first end 163 having a recessed surface, a second end 164 recess surface and spaced-apart from surface 163, along a central axis 165 that extends through surfaces 163, 164. Donut 162 further includes an alignment aperture 166 extending through surfaces 163, 164 and generally aligned on the central axis 165, and includes a disc-shaped interior recess 168 also generally axially aligned. Aperture 166 need not be formed at the exact center of the donut 162, but it is generally centrally located and thus aperture 166 is also referred to herein as a central aperture 166. Interior recess 168 intersects central aperture 166 and may also be called an annular groove. Donut 162 may be, for example, a suspension pad having the part number SK1129010, made from TECSPAK PER EPCTEED material by Miner Elastomer Products Corporation of Geneva, Illinois. This material has good resistance to sea water. In an example, the relaxed-state diameter θ1 is 7.28 inches (184.9 mm), the relaxed-state height H1 is 2.52 inches (64.0 mm), and the central aperture 166 includes a diameter of ranging from 2.09 inches (53.1 mm) to 2.44 inches (62.0 mm).
To prepare for operation, a donut 162 may be partially compressed to a pre-loaded state, having a pre-loaded diameter θ2 (“theta 2”) (FIG. 7), as will be discussed subsequently. The dashed lines 170 in FIG. 6B show the general shape and dimension of donut 162 when it is compressed to its fully-loaded design condition, achieving what may be called a “solid state.” In this condition, donut 162 has a solid state or fully-loaded diameter θ3 (“theta 3”) and a solid state or fully-loaded height H3. In an example, the fully-loaded diameter θ3 is 8.88 inches (225.4 mm) and fully-loaded height H3 is 1.45 inches (36.8 mm). In an example, the fully-loaded diameter θ3 is 122% of the relaxed-state diameter θ1, and the fully-loaded height H3 is 58% of the relaxed-state height H1. Other values for these several parameters of donut 162 are possible.
Referring now to FIG. 7, spacer 180 comprises a spacer plate having a first surface 182, a second surface 183 opposite the first, a central axis, 185 extending perpendicularly through surfaces 182, 183, an aperture or through-hole 186, the plurality of alignment apertures or through-holes 188—one for each guide rod 150, and a plurality of gripping features or, simply, grip elements 190 adjacent each hole 188. Three holes 188 are evenly spaced (both circumferentially and radially) about central axis, 185. In FIG. 7, aperture 186 is aligned along axis 185 and may be called a central aperture. The plan view on the left side of FIG. 7 includes three circles 191, 192, 193 to indicate the locations for three donuts 162 to be disposed on the first surface 182 concentric with each of the three holes 188. The first circle 191 shows the position of a first donut in a relaxed state, having a diameter θ1. The second circle 192 shows the position of a second donut in a pre-loaded state, having a pre-loaded diameter θ2 (“theta 2”). The pre-loaded state is discussed below. The third circle 193 shows the position of a third donut in its fully-loaded state, having a diameter θ3. The donut diameters shown in FIG. 7 are for reference only. Typically, all three adjacent donuts would be in a similar operational state (i.e. relaxed, fully-loaded, pre-loaded, or an intermediate state) and are anticipated to have a similar diameter during any particular operating condition of media assembly 105. In the example shown, holes 188 are positioned about axis 185 such that donuts 162 will not contact each other when fully-loaded, i.e. when all have a diameter similar to diameter θ3 of circle 193. One or both surfaces 182, 183 of spacer 180 may be sandblasted or otherwise disturbed to give them roughness or to increase their roughness, the surface roughness acting as an additional gripping feature or grip element adjacent alignment holes 188 for donuts 162.
Best seen in the side view of FIG. 7, each grip element 190 is a punched hole formed with a jagged, torn edge, which may be described as an axially-extending, annular projection. A plurality of grip elements 190 is disposed circumferentially around each alignment hole 188 of the spacer plate 180. Around each hole 188, three grip elements 190 projecting axially from the first surface 182, and three grip elements 190 project axially from the second surface 183. In some other embodiments, spacer plate 180 may use fewer or more grip elements, and some grip elements may be spaced at differing radial distances from hole 188. In a media assembly 105, each grip element 190 engages the adjacent donut 162 to control its rate of expansion or amount of expansion when compressed in pre-loaded state or when compressed by an impact load during operation. Due to the inclusion of grip elements 190, spacer 180 may also be called an expansion control device. Spacer 180 may act as a centralizer to keep donuts 162 centrally located about the rod 150 on which they are located or may act to keep the stacks 160 centrally located around attenuation axis 145. The capability of spacer 180 to act as a centralizer may be advantageous during assembly, storage, shipping, compression, or decompression. Thus, spacer 180 may also be called a centralizer comprising a centralizing plate. Furthermore, the outer perimeter of spacer 180 is located adjacent the circumferential inner surface of housing body 210, being in close proximity to or having sliding contact with body 210. Thus, spacer 180 extends from guide members 150, which are received in alignment holes 188, to the inner surface of housing body 210, extending in a direction perpendicular to attenuation axis 145. Being located in a stack of donuts 162 with this arrangement, spacer 180 is configured to provide a radial reaction force to inhibit or prevent buckling of rod 150 and stack 160 during an impact event, and therefore may also be called a stabilizer. The centralizing and stabilizing features or properties of spacer 180 overlap and are not intended to be exclusive of each other.
In various embodiments, a gripping feature 190 includes any of a variety of suitable bumps, extensions, projections that are configured and located so as to engage a portion of the impact attenuating media and thereby to control the rate or amount of expansion of a resilient member or donut 162 when compressed. In some embodiments, gripping feature 190 penetrates into the surface of donut 162, possibly breaking the surface. In one example, a grip element extends circumferentially around hole 188, projecting axially from the first surface 182, and another grip element extends circumferentially the same hole 188, projecting axially from the second surface 183. Multiple, concentric grip elements that extend in the same direction may also be used. In another example, gripping feature 190 may comprise pointed pins coupled to plate 180 around each hole 188, each pin extending uni-directionally or bi-directionally, i.e. from one or both surface 182 and surface 183.
Referring again to FIG. 2 and also to FIG. 4, impact attenuator housing 200 is elongate and includes a longitudinal axis 205 aligned with attenuation axis 145, a housing body 210 extending along axis 205 from a upper end 212 to a lower end 214, an internal chamber 215 extending between ends 212, 214, a gusseted flange 216 coupled at upper end 212, and a housing base 218 coupled at lower end 214. In the example of FIG. 2, housing body 210 is a cylindrical shell, and housing base 218 is contained within the lower end 214 of housing body 210. Flange 216 may be replaced by threads or another means of attaching housing 200 to other fixtures. For at least some embodiments, housing base 218 may also be called a closure member.
Shown in FIG. 2 and FIG. 8, housing base 218 comprises a circular base plate 220 centered on axis 205 and having a plurality of alignment apertures or holes 222 evenly-spaced around axis 205. As shown, holes 222 may be through-holes. Base plate 220 includes three holes 222, one for each rod 150 of media assembly 105. Each hole 222 is large enough to receive both a rod 150 and a fastener 159 attached to the lower end 153 of the rod, allowing these features 150, 159 to move into and through the hole 222. In this embodiment, each alignment hole 222 has a diameter larger than the diameter of a rod 150 and larger than the diameter of alignment holes 136, 188 of base 130 and spacer 180, respectively. Housing base 218 further includes a tubular central support 224 surrounded by a plurality of gussets 226 extending radially and axially from base plate 220 to central support 224 and to the inner surface of housing body 210. A though-hole 228 having a lower, threaded end 229 extends through base plate 220 and tubular central support 224, providing a passage way for fluid transfer as will be explained later when discussing fluid zones 250, 252, 254, 256 within impact attenuator 100. Threaded end 229 provides a location to couple a hose, a pump, or other fluid transfer equipment to facilitate the movement of fluid through the hole 228.
The sectional view of FIG. 9 shows media assembly 105 during the final stages of assembly prior to installation in the housing 200 (not shown). FIG. 9 shows only two guide rods 150 each with a donut stack 160, but this conversation applies to the three pair of rods 150 and donut stacks 160 of this embodiment (per FIG. 2 and FIG. 3). The upper ends 152 of the three guide rods 150 are attached to receiver 110, each by a fastener 158 installed in a counter-sunk portion of each hole 124 in receiver plate 115 and threadingly engaging the guide rod. A sealing washer may be slidingly received on rod 150 between fastener 158 and receiver plate 115 to aid in isolating fluid zone 250 from zone 252 within impact attenuator 100. Rods 150 are parallel to each other parallel to attenuation axis 145. To facilitate the assembly process, a rod extension 240 is attached or coupled to the lower end 153 of each rod 150 to form a lengthened guide member. Thus, three rod extensions 240 are attached. In this example, a rod extension 240 is axially-aligned and threadingly coupled to each rod 150. At a selected location along attenuation axis 145, a donut 162 is disposed on each of the three rods 150. Axially adjacent these three donuts 162, a single spacer 180 is slidingly received on all three rods 150. This alternating arrangement of three donuts 162 located adjacent a spacer 180 is repeated along the length of the each pair of rods 150 and rod extension 240 such that donut 162 engages a spacer 180 on each end 163, 164, and spacer 180 engages three resilient donuts 162 on each spacer surface 182, 183 to form the multiple media stacks 160. In this manner, each spacer 180 is shared as a member of all three media stacks 160. Each lengthened guide member (i.e. a pair that includes a guide rod 150 and a rod extension 240) extends through and is slidingly received or engaged by the central aperture 166 in each donut 162 of the corresponding media stack 160 and one of the alignment holes 188 in each spacer 180. In this manner, spacers 180 are shared by all adjacent media stacks 160. The two ends of the stacks 160 terminate with a spacer 180 adjacent the receiver 110 and another spacer 180 adjacent the base 130. Terminating the ends of stacks 160 with a spacer 180 rather than a donut 162 may improve the expansion or contraction behavior of the end-most donuts 162, providing grip elements 190 on both sides of even these donuts. Various other embodiments may terminate one or both ends of the stacks 160 with a donut 162 instead. Some of these other embodiments may include grip elements 190 on surfaces of receiver 110 and base 130.
In FIG. 9, each stack 160 extends from receiver 110 to base 130 along the corresponding guide rod 150 and the rod extension 240. Thus, each pair of a rod 150 and a rod extension 240 extends between the receiver and the base and slidingly extends through one of the stacks 160. Base 130 is disposed on rod extensions 240 adjacent the right end of stack 160, which eventually becomes the lower end in some installations. Fasteners 159 are threaded on the ends of rod extensions 240 to hold base 130 and stack 160 together on the rods and rod extensions. The plurality of donuts 162 are in their relaxed state, each having a relaxed-state thickness or height H1 (FIG. 6B). As a result each stack 160 of donuts 162 has a relaxed length of L1 in FIG. 9. To prepare the impact attenuating media assembly 105 for installation in housing 200 and for operation, assembly 105 is partially compressed to a pre-loaded state, reducing the parallel stacks 160 to a pre-loaded length L2 between the receiver 160 and the base 130 (shown in FIG. 2 and FIG. 10). To achieve this pre-load, a press (machine not shown) forces the base 130 toward receiver 110, partially compressing each donut stack 160 to a length that may be temporarily less than the pre-loaded length L2. Rod extensions 240 are removed and fasteners 159 are installed on the lower ends 153 of guide rods 150. Finally, the press relaxes, and the tension that it held, i.e. the pre-load compression force of the many donuts 162, is transferred to the frame of media assembly 105, which includes rods 150, base 130, fasteners 159, as well as receiver 110.
In this manner, the arrangement of media assembly 105 shown in FIG. 10 (minus the housing 200) may be achieved, and media assembly 105 is configured into its pre-loaded or “resting” state. The plurality of donuts 162 are in their pre-loaded state, each exhibiting, on average, a pre-loaded height and each exerting a pre-load force. The pre-loaded height of a donut 162 is less than the relaxed-state height H1 and greater than the fully-loaded height H3 (For H1 and H3, see FIG. 6B). The pre-loaded length L2 of donut stacks 160 is equivalent to and measures the same span as the distance D (FIG. 2) between receiver 110 and a base 130. In an example, the pre-loaded length L2 of the donut stacks 160 is 257.38 inches (6.5375 m).
Configuring media assembly 105 in a pre-loaded state prepares it to exert more effectively a reaction force to resist, arrest, or absorb, the movement of an object, for example the falling a of string of tubular members. In at least one embodiment, media assembly 105 may be pre-loaded by applying static or quasi-static compression force of 50 tons (English units: 2,000 pounds per ton, typical throughout), putting, on average, all donuts 162 in their pre-loaded state and compressing the stacks 160 from length L1 to length L2. The compression force may be applied to media assembly 105 by using a hydraulic press, for example. The pre-loaded state may be described by a pre-load ratio R_PL between the pre-loaded length L2 and the relaxed length L1 of donut stacks 160, i.e. R_PL=L2/L1. In an example R_PL equals 0.891, which means the length of stack 160 is compressed to 89.1% of its original, relaxed length L1.
In media assembly 105, each guide rod 150 extends through and is slidingly received by the central aperture 166 of each donut 162 of the corresponding media stack 160 and one of the holes 188 in each spacer 180. In some embodiments, including FIG. 10, each of the three media stacks 160 includes a quantity of one hundred and nine (109) of the donuts 162. In some embodiments, including FIG. 10, the media assembly 105 includes the three stacks 160 with a total of three hundred and twenty-seven (327) of the donuts 162. Various other embodiments include fewer or more of the donuts 162, within a practical limit appropriate for use as described herein.
As shown in FIG. 10 and also FIG. 2, assembly 105 is subsequently installed into housing 200 through upper end 212, with guide rods 150, receiver 110, base 130, and the multiple stacks 160 of donuts 162 coupled together and disposed within chamber 215, forming the impact attenuator 100. Receiver 110 is disposed adjacent the housing upper end 212 with guide tube 120 proximal the upper end 212. Lower surface 133 of base 130 engages and receives support from housing base 218, at least when impact attenuator 100 is vertical or an impact load is received. Each rod upper end 152 is attached to receiver 110, and each rod lower end 153 is slidingly received by one of the holes 136 in the base 130, configuring the receiver 110 and the rods 150 to be movable relative to the base 130 and the housing 200.
Within impact attenuator 100, at least four fluid zones 250, 252, 254, 256 may be defined. An upper fluid zone 250 is located in the upper end 212 of housing chamber 215 and includes volume within receiver 110. A central fluid zone 252 is located in housing chamber 215 between receiver plate 115 and base 130 and includes the many voids 196 between pairs of adjacent spacers 180. The voids 196 fluidically communicate with each other through the apertures 186 of spacers 180 or through space located between the perimeters of spacers 180 and housing body 210. A lower fluid zone 254 is located at the lower end 214 of housing chamber 215, below housing base plate 220. The fourth zone, which will be called fluid transfer zone 256, includes the though-hole 228 that extends through base plate 220 and tubular central support 224 of housing base 218. Fluid communication may occur between various pairs or groups of the zones 250, 252, 254, 256 depending on the seals, hoses, relief passages, or fluid transfer equipment that may be installed adjacent one or more of the four zones in various embodiments. In embodiments having no such seals, hoses, etc., fluid communication may occur between all four zones, directly or indirectly. The volume occupied by at least zones 250, 252 is variable, based on the axial location of receiver 110.
Within impact attenuator 100, each hole 136 of base 130 is aligned with a hole 222 of housing base 218. Each rod 150 is slidingly received by one of the holes 136 and is aligned with the corresponding hole 222 and is configured to extend the hole 222. In FIG. 2 and FIG. 10, each pair of rod 150 and fastener 159 is disposed in a hole 222. In FIG. 2, FIG. 10, and FIG. 11, the rod 150 extends through the corresponding hole 136 and hole 222.
In its pre-loaded state, impact attenuating media assembly 105 is installable in and removable from the housing 200 as a single unit. When media assembly 105 and impact attenuator 100 are assembled together in a pre-loaded state as shown in FIG. 10 and FIG. 2, impact attenuator 100 is ready to be installed in drilling system 10 of FIG. 1 or in another system.
Continuing to reference FIG. 10 and FIG. 2, media assembly 105 includes a plurality of voids 196 extending axially between each pair of adjacent spacers 180 and extending radially between and beyond the three donuts 162 that share a common axial position along the axis 145. The plurality of voids 196 are in fluid communication with each other due to the inclusion of an aperture 186 in each spacer 180. The plurality voids 196 and the plurality apertures 186 together may be considered to be a single void or volume and may contain, for example, air, water, or another fluid. In FIG. 2, the voids 196 and apertures 186 are in fluid communication with though-hole 228 in housing base 218 and with through-hole 117 in receiver 110. Therefore, the open, central volume of the receiver guide tube 120 is in fluid communication with the though-hole 228 in housing base 218.
The stacks 160 of donuts 162 are configured to exert a reaction force when an axial force acts to reduce the distance between the receiver 110 and the base 130. For example, when a tubular member or another object falls into or otherwise impacts receiver 110, media assembly 105 compresses further than shown in FIG. 10. The donuts 162 provide a reaction force to resist, arrest, or absorb the movement of the object. In the process, receiver 105 moves downward (or rightward, as-shown) from upper end 212 of housing 200 toward the lower end 214, and the media stack 160 compresses, reducing its length to less than length L2. The lower ends 153 of guide rods 150 and fasteners 159 extend further beyond housing base plate 220 and possibly beyond the housing body lower end 214. As the falling object comes to a rest, media assembly 105 may relax, but maintain some amount of compression to hold the weight of the object. In at least some instances after capturing a falling object, stack 160 and the receiver 110 rebound some distance before coming to rest.
As an example of loading, FIG. 11 shows impact attenuating device 100 with the media assembly 105 fully-compressed as it would be when experiencing a maximum compression or impact load. In at least one embodiment, media assembly 105 may be fully-compressed or fully-loaded by applying a static or quasi-static compression of force of 450 tons, putting, on average, all donuts 162 in their fully-loaded state “solid state,” as introduced earlier with respect to FIG. 6B and FIG. 7. In FIG. 11, the plurality of donuts 162 are in their fully-loaded state, each exhibiting, on average, the fully-loaded height H3. As a result donut stack 160 has a fully-loaded length L3, which includes the donuts 162 and spacers 180. The lower surface 118 of receiver 105 (i.e. the top of stack 160) is displaced by a distance or length L4 from upper end 212 of housing 200, the distance L4 in FIG. 11 being greater than the “relaxed” at-rest distance or length L5 between the same two locations in FIG. 10, i.e. the distance between lower surface 118 of receiver 105 and upper end 212 of housing 200. Continuing to reference FIG. 11, rods 150 extend beyond housing base plate 220 and beyond housing body lower end 214. The configuration of FIG. 11 demonstrates the maximum movement, i.e. the maximum compression, of media assembly 105. The fully-loaded state may be described by a fully-loaded length ratio R_FL between the fully-loaded length L3 and the relaxed length L1 of donut stacks 160, i.e. R_FL=L3/L1. In an example R_FL equals 0.600, which means the length of stack 160 is compressed to 60.0% of its relaxed length L1.
A comparison between the pre-loaded state and the fully-loaded state may be helpful for understanding the configuration of the exemplary media assembly 105 and device 100 further. A length ratio R_FP may be defined as the ratio between the fully-loaded length L3 and the pre-loaded length L2 of donut stacks 160, i.e. R_FP=L3/L2. Ratio_FP represents the maximum additional compression that media assembly 105 may achieve during assembly or operation. In an example R_FP equals 0.674, which means the length of stack 160 would be compressed to 67.4% of its pre-loaded length L2 to achieve the fully-loaded length L3. The parameter R_C will be defined as the ratio of the compression force needed to achieve a fully-loaded state versus the compression force needed to achieve a pre-loaded state. In an example, R_C is 9.00 (450 tons/50 tons), at least when the forces are applied statically or quasi-statically.
Typically, impact attenuating device 100 would be configured so that assembly 105, stacks 160, and donuts 162 would not reach the fully-loaded state shown in FIG. 11 when impacted by a maximum anticipated, dynamic load, which may be called the maximum design load or the selected load capacity. A maximum design load specifies, for example, a gravitationally-driven fall by the heaviest anticipated object through the greatest anticipated height that is intended to be dissipated or transferred by device 100. It is anticipated that an impact equal to the maximum design load will leave device 100 in a re-usable condition. The maximum design load is selected based on operational needs and is implemented in device 100 by standard engineering principles. Device 100 might achieve the fully-loaded state if dynamically impacted by an object weighing more than or impacted by an object falling farther than is specified by the maximum design load. Device 100 may or may not remain in a re-usable condition after an impact that achieves the fully-loaded state.
Referring to FIG. 12, in another embodiment, a spacer 280 is designed to be slidingly received on a single guide rod 150 and to engage a single stack of donuts 162. Thus, spacer 280 may be called a single-stack spacer. Spacer 280 comprises a spacer plate having a first surface 282, a second surface 283 opposite the first, an axis, 285 extending perpendicular to surfaces 282, 283, a single alignment aperture or through-hole 188 that is centered on axis 285, and at least one grip element 190 adjacent the hole 188. As before, each grip element 190 is a punched hole formed with a jagged, torn edge, which may be described as an axially-extending, annular projection. More specifically, in the FIG. 12, a plurality of grip elements 190 circumferentially surround the hole 188, with some grip elements 190 extending in a first direction away from first surface 282 and others extending in a second direction, away from second surface 283. As explained with regard to spacer 180, so also for spacer 280, other types of grip elements may be used. Although the outer edge of spacer 280 is shown a circular, other shapes may be used, and axis 285 may be in the center of the plate or may be off-set; similar variations may be applied to spacer 180. Due to the inclusion of grip elements 190, spacer 280 may also be called an expansion control device. During compression and decompression activity, spacer 280 may also act as a centralizer to keep donuts 162 centrally located about the rod 150 on which they are located. Thus, spacer 280 may also be called a centralizer comprising a centralizing plate.
Spacer 280 differs from spacer 180 because each spacer 280 includes a single alignment hole 188 and therefore slidingly receives or engages only one guide rod 150. When a plurality of spacers 280 are used in an impact attenuating media assembly having multiple rods 150, the stacks of impact attenuating media that are formed around each rod 150 may be separate, not interconnected to other stacks by a spacer. When spacers 280 are used to form a media assembly like media assembly 105 for use within the impact attenuator 100, three spacers 280 are used in place of each spacer 180, and a guide rod 150 extends through the central aperture 166 of each donut 162 (i.e. the resilient member) and the alignment hole 188 of each spacer 280. Consequently, three, independent stacks of impact attenuating media are formed, one stack coupled to and disposed around each rod 150, each stack having its own group of spacers 280. In contrast, in FIG. 2 and FIG. 9 the shared spacers 180 interconnect in the three stacks 160 of donut 162 that accompany the three rods 150. A stack of impact attenuating media formed with plurality of dedicated spacers 280 comprises a plurality of donut 162 alternately stacked among the spacers 280. Except perhaps at the ends of the stack, each spacer 280 is disposed between two adjacent donuts 162. On spacer 280, grip element 190 engages a surface of at least one adjacent donut 162.
FIG. 13 and FIG. 14 present another embodiment of an impact attenuating device. Impact attenuator 300 of FIG. 13 and FIG. 14 is similar to impact attenuator 100; however, impact attenuator 300 includes an impact attenuating media assembly 305 having four parallel guide members or guide rods 150 instead of three, and various other features are modified to accommodate the extra rod 150. Impact attenuating media assembly 305 also includes four impact attenuating media stacks 360; one stack is held on or is coupled to each of the four rods 150. Assembly 305 further includes a receiver 310 attached to the ends of the four guide rods 150 and an attenuator base 330 slidingly coupled to the opposite ends of the four guide rods 150. For this purpose, base 330 includes an additional alignment aperture or hole, giving it four holes 136, which are through-holes, and each hole 136 slidingly receives or engages one of the guide rods 150. Most other aspects of media assembly 305 are similar to corresponding features of impact attenuating media assembly 105. For example, most other aspects of base 330 are similar to base 130. Most other aspects of receiver 310 are similar to receiver 110, for example, receiver 310 includes a receiver plate 115 and a guide tube 120.
Continuing to reference FIG. 14 briefly, each stack 360 includes a plurality of impact attenuating media elements or resilient members, which in the embodiment are donuts 162, alternating among a plurality of multi-stack spacers 380. Each spacer 380 includes four alignment apertures or through-holes 188, each hole 188 slidingly receiving one of the four guide rods 150. Each spacer 380 extends among the four rods 150 and the four stacks 360. Thus, in impact attenuating media assembly 305, the four media stacks 160 share each of the spacers 380. The four stacks 160, including the shared the spacers 180 and the four groups of donuts 162, may be also be described as a single or aggregate stack of impact attenuating media.
Referring now to FIG. 15, spacer 380 comprises a round spacer plate having a first surface 382, a second surface opposite the first, a central axis 385 extending perpendicular to the first and second surfaces, a central aperture or through-hole 186 aligned along axis 385, the four holes 188, and a plurality of gripping features or, simply, grip elements 190 adjacent each hole 188. The alignment holes 188 are evenly spaced (both circumferentially and radially) about central axis 385. In the embodiment shown, holes 188 are designed to be positioned about axis 385 such that donuts 162 will not contact each other when fully-loaded, i.e. when and if all donuts 162 adjacent a spacer 280 have expanded to a diameter θ3 (“theta 3”) like circle 193 of FIG. 7.
Similar to spacer 180, around each alignment hole 188 of spacer 380, three grip elements 190 projecting axially from the first surface 382, and three grip elements 190 project axially from the second surface. In some other embodiments, a spacer plate may use fewer or more grip elements, and some grip elements may be located or spaced at differently. The grip elements 190 are similar to those described previously and similarly engage adjacent donuts 162 to control their rate of expansion or amount of expansion when compressed in pre-loaded state or when compressed by an impact load during operation. Due to the inclusion of grip elements 190, spacer 380 may also be called an expansion control device. During compression and decompression activity, spacer 380 may also act as a centralizer to keep donuts 162 centrally located about the rod 150 on which they are located or may act to keep the stacks 360 centrally located around attenuation axis 345. Thus, spacer 380 may also be called a centralizer comprising a centralizing plate.
Continuing to reference FIG. 14, impact attenuator 300 further includes an impact attenuator housing 400 having a longitudinal axis 405, a cylindrical shell or housing body 210, and a housing base 418. Housing base 418 includes a circular base plate 420 with an extra alignment hole and an extra gusset 226, but is otherwise similar to housing base 218 of FIG. 2 and FIG. 3.
In the assembled impact attenuator 300 of FIG. 14, impact attenuating media assembly 305 is slidingly received within housing 400. Thus, guide rods 150, the receiver 310, the base 330, and the four stacks 360 of donuts 162 are disposed within housing 400 with the lower surface of base 330 engaging and receiving support from housing base 418. FIG. 14 shows pre-loaded, “resting” condition of impact attenuator 300, wherein it is ready to be installed in drilling system 10 (FIG. 1) or in another system. The plurality of donuts 162 are in their pre-loaded state, each exhibiting, on average, a pre-loaded height.
The single-stack spacer 280 of FIG. 12 is compatible with impact attenuator 300 with four of the spacers 280 being used in place of each multi-rod spacer 380. In such embodiments, each of the four stacks 360 includes its own group of single-rod spacers 280 alternating between donuts 162.
Referring now to FIG. 16, a rectangular, multi-stack spacer 480 is similar to the round spacer 380. For example, like spacer 380, spacer 480 includes spacer plate having central axis 485, central aperture or through-hole 186, four alignment apertures or through-holes 188, and a plurality of grip elements 190 adjacent each hole 188. Spacer 480 differs from spacer 380 in having a rectangular perimeter, and, for at least some embodiments, holes 188 of spacer 480 are located further from central axis 385. In this example, spacer 480 is, more precisely, a square. An impact attenuating device or, equivalently, an impact attenuator that utilizes rectangular spacer 480, may include other rectangular features as well, such as a rectangular housing body in place of cylindrical housing body 210, or a rectangular receiver in place of circular receiver 310, or a rectangular base receiver in place of circular base 130, for example. Various embodiments designed to utilize spacer 480 may instead include four of the single-stack spacers 280 in place of each multi-stack spacer 480. Spacer 480 may also be called a centralizer comprising a centralizing plate.
FIG. 17 presents a receiver 510 coupled to an attenuator base 530 by a billow hose 520 for fluid communication. A resilient insert member 540 is installed within receiver 510. Receiver 510 includes a central axis 111, a round receiver plate 115 centered on axis 111, and a guide tube 120 coupled to receiver plate 115. Receiver plate 115 includes an upper surface 116 opposite a lower surface 118, a counter-sunk through-hole 117 extending from upper surface 116 through lower surface 118 for fluid communication, and a plurality of countersunk alignment apertures or holes 124 evenly-spaced around the axially aligned through-hole 117. Guide tube 120 extends away from upper surface 116, distal base 530 and includes two grooves 514A, 514B in perimeter surface 516, each groove receiving an annular seal 518. The two seals 518 may be, for example, a polypack-type seal having a lip that protrudes diagonally outward from the main body of the seal. The upper groove 514A receives a first seal 518A oriented with an upward-facing lip, the lip extending away from receiver plate 115, and the lower groove 514B receives a second seal 518B oriented with an downward-facing lip, the lip extending toward receiver plate 115. In some embodiments, both seals 518 are received in a single groove 514. Thus, receiver 510 is similar to receivers 110, 310 with the inclusion of various additional features described here or shown in FIG. 17.
Resilient insert member 540 includes a cylindrical outer surface 542 and conical inner surface 543, and a central through-hole 544. Resilient insert member 540 is positioned within receiver guide tube 120, abutting upper surface 116 of receiver plate 115 to aid in absorbing the impact, to regulate the movement, or to reduce the rebound of a falling object received within receiver 110. Resilient insert member 540 may protect the object that is dropped, such as possibly reducing damage to a threaded end. The through-hole 544 provides fluid communication with baffle hose 520 through upper end 522.
Base 530, which may also be called a base plate or a retainer plate, includes a through-hole 134 and a plurality of alignment apertures or holes 136 evenly-spaced around the through-hole 134. Thus, base 530 is similar to base 130 and base 330, and the number of holes 136 may be chosen to allow base 530 to replace either base 130, 330 or to form a distinct embodiment. Through-hole 134 is countersunk from the bottom.
Billow hose 520 includes a first or upper end 522, a second or lower end 523, an undulated or billowed hose body 524 extending between the ends 522, 523, and two flanges 526, one flange coupled at each end 522, 523. The flexible hose body 524 is extendable and contractible to accommodate the changeable distance D between receiver plate 115 and base 530. The upper end 522 of hose 520 and the corresponding flange 526 are sealingly received in the countersunk through-hole 117 in receiver plate 115. Likewise, the lower end 523 and its flange 526 are sealingly received in the countersunk through-hole 134 of base 530.
The arrangement of FIG. 17 may be used in an impact attenuating media assembly 105 or an impact attenuating media assembly 305 in place of the corresponding receiver 110, 310 and base 130, 330 and installed in a housing 200 to form alternate embodiments of impact attenuators 100, 300. A plurality of donut stacks 160 and guide rods 150 would be held between receiver 510 and base 530. Referring to the fluid zones of FIG. 2 and FIG. 14, the billow hose 520 and the seals 514A, B of FIG. 17 are configured to provide fluid communication between upper fluid zone 250 and the fluid transfer zone 256 of hole 228 while at the same time isolating these two zones from direct communication with central fluid zone 252. When a hose or a pump, for example, is coupled to threaded end 229 of hole 228, fluid zones 250, 256 may be fully isolated from both the central fluid zone 252 and the lower fluid zone 254. An additional seal or connecting member may be used to achieve fluid zone isolation. For example, a sealing member, such as a resilient O-ring or gasket, may be positioned between lower surface 133 of base 130 and the upper surface of housing base plate 220, and base plate 220 may be welded to tubular central support 224 to achieve the isolation of fluid zones 250, 256 from fluid zones 252, 254.
With fluid zones 250, 256 fully isolated as described, a well drilling fluid from may enter the mouse hole 90 through drilling deck 14 (FIG. 1) be contained, preventing, i.e. stopping or reducing the potential for, a release to the environment. The well drilling fluid may include hydraulic oil or drilling mud, as examples. Some embodiments include relief passages or other flow area in housing base 218 to provided fluid communication between central fluid zone 252 and the lower fluid zone 254, allowing, air or sea water to readily flow into and out of central fluid zone 252 when the impact attenuator receives a falling object or when an received object is later removed, helping the donut stacks and voids 196 to be compressed or to re-expand without sustaining pressure or vacuum in zone 252.
At least one embodiment having features shown in FIG. 1 as well as FIG. 2 or FIG. 14 includes a drilling apparatus having a drilling floor, a mouse hole in the drilling floor, an elongate housing supported in a position below the drilling floor and comprising an internal chamber positioned beneath the mouse hole, and at least a first impact attenuating stack disposed in the chamber. The first impact attenuating stack includes a plurality of resilient members disposed along a rod, each resilient member having an alignment aperture and receiving the rod therethrough; and includes a plurality of spacers disposed between adjacent resilient members, each spacer having an alignment hole and receiving the rod therethrough.
In at least some of these embodiments, the drilling apparatus further includes a plurality of impact attenuating stacks disposed generally parallel to one another in the chamber, each impact attenuating stack includes a plurality of the resilient members disposed along a rod having an alignment aperture and receiving the rod therethrough, and a plurality of the spacers disposed between adjacent resilient members, each spacer having an alignment holes and receiving the rod therethrough.
In at least some of these embodiments, each impact attenuating stack further includes: a first end member, a second end member spaced a distance D from the first end member and having an alignment hole therethrough; and the rod is attached to the first end member and is slidingly received through the alignment hole in the second end member.
FIG. 18 and FIG. 19 present another embodiment of an impact attenuating device compatible with mouse hole 90 of drilling system 10 and with other well systems. Impact attenuator 600 includes an impact attenuating media assembly 605 designed to absorb impacts along an attenuation axis 606, an impact attenuator housing 670, and a containment vessel or tube 680. Media assembly 605 includes a receiver 610, an attenuator base 620 spaced-apart from receiver 610, a single, tubular guide member 630 instead of a plurality of members 150. The elongate guide member 630 extends from receiver 610 and into base 620 along axis 606. Impact attenuating media assembly 605 also includes a single impact attenuating media stack 650, located along member 630, centered on axis 606.
Receiver 610 is similar to receivers 110, 310. Receiver 610 includes a receiver plate 612 and a guide tube 120, and plate 612 includes a central aperture 615. Base 620 is a flat plate and may also be called a base plate or a retainer plate. Base 620 includes a central alignment aperture or through-hole 622 also aligned on axis 606.
Referring to FIG. 18 and FIG. 20, tubular guide member 630, which includes an upper end 631 and a lower end 632, is a member of a guide member assembly 625. In addition to member 630, guide assembly 625 includes an upper end plate 634 coupled at upper end 631 and a fastener assembly 635 coupled at lower end 632. As best seen in FIG. 20, fastener assembly 635 includes an interior sleeve 636 held within the hollow, lower end 632, and a stop-washer 637 coupled to the lower ends of sleeve 636 and member 630 by a fastener 638.
Referring again to FIG. 18, end plate 634 is held adjacent the upper surface of receiver plate 612, and, in this embodiment, plate 634 is held against a shoulder within aperture 615. Plate 634 allows member 630 to be inserted through receiver plate 612 prior to the addition of stop-washer 637 and fastener 638. Plate 634 limits any further downward movement (to the right as depicted) of member 630 with respect to receiver 610. End plate 634 and fastener assembly 635 are configured to hold the entire media assembly 605 together, allowing it to be inserted or removed from housing 670 as a single unit.
Referring again to both FIG. 18 and FIG. 20, aperture 622 in base 620 is sized to slidingly receive guide member 630 but small enough to block the fastener 638 and stop-washer 637 on the lower end 632 from passing-through the aperture 622. For example, washer 637 may be round, having an outside diameter D637 that is greater than the diameter of aperture 622. Member end 632 may alternately extend further below the base 620 and then return upward as media stack 650 compresses and possibly re-expands due to the impact of a falling tubular member captured within receiver 610. Fastener assembly 635 keeps member 630 coupled to base 620 and limits the upward movement (to the left as depicted) of member 630 with respect to base 620.
Continuing to reference FIG. 18, media stack 650 includes a plurality of impact attenuating media elements or resilient members, which in the embodiment are generally flat toroids or donuts 652, placed side-by-side, each contacting one or two neighboring donuts. Positioned along member 630, multiple groups of donuts 652 are separated by stabilizers 660. Donuts 652 are flat and solid, in at least the embodiment shown, unlike donuts 162 (FIG. 6B), which includes recessed surfaces on ends 163, 164 and an interior recess 168. In the example of FIG. 18, a stabilizer 660 is positioned between groups of nineteen donuts 652, and the centralizers are spaced-apart from plates 612, 620 along axis 606 and member 630. A donut 652 rests against each of the plates 612, 620. Plates 612, 620 and guide member assembly 625 hold the donuts 652 and stabilizers 660 together in the unified assembly 605. In FIG. 21, stabilizer 660 comprises a round, flat plate having a central alignment hole 662, and a plurality of holes 664 located near the perimeter. Holes 664 are useful as handling locations during maintenance and installation. Alignment hole 662 slidingly receives guide member 630, and the outer perimeter of stabilizer 660 is located adjacent the circumferential inner surface of housing body 210, being in close proximity to or having sliding contact with body 210. Thus, stabilizer 660 extends from guide member 630 to inner surface of housing body 210, perpendicular to axis 672. In various embodiments, a clearance gap exists between all or a portion of the perimeter of stabilizer 660 and housing body 210, so as to reduce friction and/or allow communication therebetween for air or another fluid. Stabilizer 660 is configured to provide a radial reaction force to inhibit or prevent buckling of guide member 630 and stack 650 during an impact event. The use of multiple stabilizers 660 is intended to improve the effectiveness of these members. In the example shown, holes 664 lie radially beyond the donuts 652, at least when the donuts are in their relaxed, uncompressed state or prior to the donuts achieving a fully-loaded state. Holes 664 provide paths for fluid communication within housing 670, allowing air or another fluid to pass through stabilizers 660 as stack 650 compresses and the voids between stabilizers 660 and plates 612, 610 become smaller during an impact event.
In the embodiment shown in FIG. 18, the media assembly 605 of attenuator 600 is not pre-loaded with a compression force when assembled and prepared for operation. Instead, the donuts 652 remain in their relaxed, uncompressed stated, except for any loading that results from the weight of receiver 610 or other coupled members when media assembly 605 is positioned vertically. The lack of a pre-load force in the assembly may provide manufacturing and handling benefits and results in the use of fewer donuts to achieve a maximum design load.
As described above, stack 650 does not include spacers between each pair of adjacent donuts 652. Instead, as shown in FIG. 22, each donut 652 includes a central aperture 654 having a plurality of radially-inward protrusions 655 that touch or nearly touch guide member 630, which is slidingly received within aperture 654. Protrusions 655 are configured as centralizers, integral with the body of donut 652 to keep it centered or substantially centered about member 630 (i.e. is centered or is centered within a distance of +/−10% of the outer diameter of donut 652). In the example shown, there are eight protrusions 655 evenly spaced in the circumferential direction, and aperture 654 is generally star-shaped due to the triangular shape of protrusions 655. Donut 652 has an outside diameter that is less than the diameter of stabilizers 660 and less than the inner diameter of housing 670. In the example of FIG. 22, protrusions 655 extend radially inward for a distance of 20% of the outermost diameter of aperture 654, and the volume of each space is substantially equal (i.e. equal or within +/−10%) to the volume of each protrusion 655. Other proportions for the spaces and the protrusions are contemplated. For example, in various embodiments, the protrusions 655 extend radially for a distance of 5 to 40% of the outermost diameter of aperture 654.
The spaces or voids between adjacent protrusions 655 provide locations for the material of donut 652 to expand radially inward when it is compressed axially. Donut 652 also expands radially outward toward housing 670 when compressed axially due to an impact. Preferably, the annular gap 658 between the relaxed donut and inside surface of housing 670 is sufficiently large so that donut 652 does not touch housing 670 when expanded radially. FIG. 23 is a top view of donut 652, shown filleting 656 around the perimeter and along aperture 654, as may be formed for embodiments that are injection molded for example. Some embodiments of donut 652 may be formed as flat discs cut from a sheet of resilient material and lacking filleting 656.
Referring again to FIG. 18 and FIG. 19, housing 670 includes a longitudinal axis 671, a top end 672, a lower end 673 space-apart from end 672 along axis 671, a cylindrical shell or housing body 210 extending between ends 672, 673 and centered about axis 671, and a housing base 674. Housing base 674 includes a housing base, which, in this example, is a circular base plate with a central, alignment hole 675. Hole 675 is large enough to allow the stop-washer 637, fastener 638, and member lower end 632 to pass easily therethrough. At top end 672, an annular flange 676 supported by gussets is coupled to body 210 and configured to attach below a mouse hole or similar structure at a well. Referring now to FIG. 18, a circular barrier plate 678 spans radially across the entirety of flange 676 to act as a seal to prevent the entry of fluids and debris into housing 670 and impact attenuator 600 as a whole when the unit is waiting for a tubular member to fall. During operation, a falling tubular member would typically rupture and pass through the barrier plate 678 prior to impacting the receiver plate 612. Later, barrier plate 678 would be replaced.
Below housing 670, coupled and sealed at base 674, containment tube 680 extends downward and terminates at a closed lower end 683. Containment tube 680 may also be called a receiver can or a barrel. The inner diameter and length of tube 680 are sized larger than the portion of guide member assembly 625 that passes through housing base 674 during an impact event. Like plate 678 at the upper end of housing 670, tube 680 at the lower end of housing 670 prevents the entry of fluids and debris into impact attenuator 600. This function of tube 680 is particularly useful when attenuator 600 is submerged beneath water. Tube 680 also helps to surround and contain the moving members of attenuator 600 to prevent injury to personnel and property. Unlike plate 678, tube 680 is not physically impacted or damaged during normal operation. In some embodiments, a fluid sensor, such as a float device for liquids for example is coupled to tube 680 to detect an intrusion of fluid from outside tube 680.
Impact attenuating media assembly 605 is configured to be assembled separately from housing 670. In the assembled impact attenuator 600 of FIG. 18, impact attenuating media assembly 605 is received within housing 670. Receiver 610, base 620, guide member assembly 625, and the stack 650 of donuts 652 are disposed within housing 670 with the lower surface of base 620 resting on housing base 674. Barrier plate 678 covers the receiving end of attenuator 600, corresponding to housing upper end 672. FIG. 18 shows non-loaded, “resting” condition of impact attenuator 600, ready to be installed in drilling system 10 (FIG. 1) or in another system.
Referring now to FIG. 24, an impact attenuating media element 702 is a resilient member shaped like a donut. This impact absorbing donut 702 includes a flat end surface 703, a second, flat end surface (not shown) spaced-apart from surface 703 along a central axis 705 and includes an alignment aperture or hole 706 extending through the end surfaces and generally aligned on the central axis 705. End surface 703 and the opposite end surface each include a plurality of recesses 708. Recesses 708 are positioned and sized to receive one of the grip elements 190 of a spacer, such as a spacer 180, 280, 380, 480, for example. In the example, donut 702 includes three, equally spaced recesses 708, positioned circumferentially around axis 705 and hole 706. Thus, donut 702 is flat and solid, except for central hole 706 and recesses 708, but other embodiments may include an interior recess 168 (FIG. 6B).
A plurality of donuts 702 may be assembled in to a donut stack for an impact attenuating media assembly, like any of those disclosed above, including media assemblies having one, two, three, or more donut stacks. As an example, when assembled in a stack 160 for a media assembly 105 (FIG. 2), donuts 702 are pre-loaded, as described of donuts 162. However, in some embodiments, donuts 702 are not pre-loaded when assembled and prepared for operation. In other respects, these relaxed assemblies may be similar to media assembly 105 or another assembly disclosed herein.
In an assembly, adjacent donuts 702 are separated by a spacer, such as a spacer 180, 280 (FIG. 7, 12), as examples. Recesses 708 receive grip elements 190, allowing the surface 182, 183, 282, 283 of the spacer to rest immediately against an end surface of the donut without a gap, before any pre-load force or any impact load is received. In this manner, for a selected quantity of donuts assembled without a preloading force, a stack of donuts 702 and spacers is shorter than a similar stack that uses spacers along with donuts lacking end surface recess 708, such as a donut 162, for example. In addition, alignment hole 706 is larger than a guide member received therein, allowing free movement relative to the rod or tubular member. Hole 706 is sized so that it will not circumferentially touch or grip a guide member, even when the media assembly reaches a full-loaded state, leaving some space between the wall of hole 706 and the guide member. In some embodiments, that space will extend circumferentially even at the fully-loaded state. Typically, the fully-loaded state results from absorbing an impact that is greater than the maximum design load
During operation, air inside an impact attenuator 100, 600 may be compressed as the impact attenuating media assembly compresses under the weight of a falling object. For various embodiments that include containment vessel, such as tube 680 in FIG. 18, air inside the vessel may be compressed as a rod or tubular guide member extends into the vessel. As described for impact attenuator 100, so also various other embodiments include fluid communication passages or clearance gaps between various members to allow air or another fluid to escape from or return to the several air pockets inside the impact attenuator, optionally including the containment vessel if it is attached. Some embodiments retain the compressed air during an impact.
Additional Information
Examples of various embodiments have been presented. Some possible variations or additional embodiments are described next. Additional embodiments may share compatible characteristics of one or more of the previously-described embodiments or those described below. In various embodiments, where feasible based on design and operation needs, the guide members that were described as rods may be replaced by tubular members, and the guide members that were described as tubular members may be replaced by rods.
In assembly 105 of FIG. 2, guide rods 150 are attached to receiver 110 by threaded fasteners 158, but in various other embodiments, guide rods 150 are attached to receiver 110 by welding, by threads formed in receiver plate 115, or by any other suitable means known in the art. Although apertures 186 of spacers 180, 380 were axially-aligned, central apertures, other spacer embodiments having multiple alignment holes 188 may include apertures not aligned on a central axis of the spacer. Although shown as a flat plate in FIG. 2 and FIG. 5, in various other embodiments, the end member or base 130 of assembly 105, may include additional structural features such as support ribs, walls, reinforcements around holes, grooves and other such features as may be useful or may have a shape that is not similar to a flat plate.
In comparison to housing base 218 of FIG. 2 and FIG. 3, some embodiments have a housing base that comprises a tubular central support 224 surrounded by a plurality of gussets 226 without a circular base plate 220. The space between gussets 226 provides passageways through which the guide rods 150 of assembly 105 may extend during operation.
Various embodiments of an impact attenuating media assembly may include more than one type of spacer. For example, a modification of between impact attenuating media assembly 105 of FIG. 2 and FIG. 10 may include a plurality of groups of three spacers 280 in place of some of the spacers 180 in the three donut stacks 160. As a more specific example, a group of three spacers 280 may take the place of every-other spacer 180 between alternating pairs of adjacent donuts 162 with several donuts 160 contacting a spacer 180 on the first ends 163 and contacting a spacer 280 on the second ends 164. Spacers 280 may likewise installed in parallel stacks of resilient members along with spacer 380 or spacer 480. It would also be possible to form an impact attenuating media assembly with four parallel stacks of resilient members and having both a plurality of spacers 380 and a plurality of spacer 480 to separate or centralize the resilient members.
As explained in regard to spacers 180, any of the spacers 280, 380, 480 may likewise be configured as stabilizers to provide a radial reaction force to prevent the buckling of a guide member or members and a stack of impact attenuating media. In such embodiments, the spacer 280, 380, 480 extends from guide members 150 to the inner surface of a housing body, extending in a direction perpendicular to attenuation axis 145, the perimeter of the spacer being located in close proximity to or having sliding contact with the housing body.
Referring again to FIG. 18, some media stacks embodiments for use in attenuator 600 include spacers, such as spacers 280 of FIG. 12 for example, located between adjacent donuts, such as any of the donuts 162, 652, 702. Donuts 652 with inward protrusions 655 may be used, with or without spacers, in embodiments of the other media stacks 105, 305 disclosed herein.
While exemplary embodiments have been shown and described, modifications thereof can be made by one of ordinary skill in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations, combinations, and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.
