Hydraulically-Actuated Explosive Downhole Tool
A downhole tool comprising a first section having an internal sidewall defining at least a portion of a flowpath, and a ported outer sidewall and an explosive having at least a portion within said first section. An annular portion has at least one chamber having an end positioned adjacent to the explosive and an inlet providing a communication path to said flowpath. A detonator assembly is located within each chamber proximal to the explosive such that detonation of the assembly causes detonation of the explosive. A firing pin is propelled toward the detonation assembly by providing communication between the chamber and the flow path, causing a pressure differential between the pressure isolated ends of the firing pin.
This continuation-in-part application claims the benefit of the filing date of U.S. application Ser. No. 13/777,134, filed Feb. 26, 2013, which is a continuation application claiming the benefit of the priority date of U.S. application Ser. No. 12/637,255 (now U.S. Pat. No. 8,381,807), filed Dec. 14, 2009, each of which are incorporated by reference as a part of this application.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot applicable.
BACKGROUNDThe present disclosure relates to a well stimulation tool for oil and/or gas production. The embodiments described herein generally relate to an explosive stimulation downhole tool that may be hydraulically actuated and is for use in a hydrocarbon well.
DESCRIPTION OF THE RELATED ARTIn hydrocarbon wells, fracturing (or “fracing”) is a technique used to create and/or extend a fracture from the wellbore deeper into the surrounding formation, thus increasing the surface area for flow of formation fluids into the well. Fracing may be done by either injecting fluids at pressures sufficient to overcome the compressive and cohesive forces on the formation of interest (hydraulic fracturing), by using explosives to generate sufficient pressure and gas flow (e.g. TNT or PETN at up to 1,900,000 psi), and or by using propellant stimulation. Fluids used in hydraulic fracturing may carry proppants, which are typically granular material such as sand or ceramic particles. Further, fracturing may be performed using a combination of these techniques.
Gas generating propellants have been utilized in combination with, in addition to, or in lieu of other fracturing techniques as a more cost effective manner to create and propagate fractures in a subterranean formation. In accordance with conventional propellant stimulation techniques, a propellant is ignited to pressurize a perforated subterranean interval either simultaneous with or after the perforating step so as to propagate fractures therein.
For example, U.S. Pat. No. 5,775,426 (issued Jul. 7, 1998, the “'426 Patent”), which is incorporated by reference herein, describes a perforating apparatus wherein a shell of propellant material is positioned to substantially encircle a shaped charge. The propellant material is ignited due to shock, heat, and/or pressure generated from a detonated charge. Upon burning, the propellant material of the '426 Patent generates gases that clean perforations formed in the formation by detonation of the shaped charge and which extend fluid communication between the formation and the well bore.
BRIEF SUMMARYOne embodiment of the downhole tool has a flowpath therethrough and includes a first section having an internal sidewall, an outer sidewall, and at least a portion of an explosive volume, such as a propellant volume, within the first section. At least one chamber may be disposed, such as in an annular portion, between the outer surface of the tool and the flowpath, with a first end of each chamber positioned adjacent to the propellant, or other explosive, volume. A detonator assembly may be positioned in one or more chambers proximal to the propellant, or other explosive, volume to, when actuated, ignite or cause ignition of the propellant or other explosive. Actuation of the detonator assembly is caused by impact of a primer by a firing pin, which is caused to move by the pressure differential between the flowpath and a portion of the chamber. Ignition of the propellant causes pressure waves to be directed radially away from the tool and into the surrounding formation.
Also according to one embodiment, a plurality of flow ports may be disposed through the exterior surface to provide for fluid flow into and out of the flowpath. A moveable sleeve assembly operates to prevent and permit fluid flow through the flow ports, depending on its position. In a first position, a sleeve substantially prevents fluid flow through the flow ports, while in a second position fluid flow is substantially permitted. The moveable sleeve also prevents or allows pressure communication between the flowpath and each chamber to cause application of a hydraulic force to the firing pin. The moveable sleeve may, in some embodiments, be a sleeve assembly comprising two, or more, sleeves joined by a connector such that the sleeves may move together. In some embodiments, the sleeve assembly may comprise two or more sleeves that are disengageable, such that, at a defined point in the sleeve assembly's movements, the sleeve's separate, allowing at least a first sleeve of the sleeve assembly to continue its movement while a second sleeve of the sleeve assembly remains stationary or, possibly, moves in a different direction than the first sleeve.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
When used with reference to the figures, unless otherwise specified, the terms “upwell,” “above,” “top,” “downwell,” “below,” and “bottom,” and like terms are used relative to the direction of normal production through the tool and wellbore. Thus, normal production of hydrocarbons migrates through the wellbore and production string from the downwell to upwell direction without regard to whether the tubing string is disposed in a vertical wellbore, a horizontal wellbore, or some combination of both. In the figures, the arrow depicting flowpath 30 is pointing in the “downwell” direction (i.e., opposite the normal direction of fluid flow in the well during production).
The ported sleeve 26 has a plurality of circular ports 40 spaced equally radially around the outer sidewall 28, and is attached to the top connection 32 with a plurality of low head cap screws 42. The bottom end of the ported sleeve 26 is attached to the upper end of the middle sub 34 with a series of interlaced tabs 44 positioned in slots 45 disposed in the outer surface of the middle sub 34.
A second section 48 of the tool includes a plurality of oblong flow ports 50 that define a fluid communication path between the flowpath 30 and the exterior of the tool. The flow ports 50 may be spaced around, and disposed through, the cylindrical ported housing 36, which has an upper end connected to the lower end of the middle sub 34 with a plurality of circumferentially-aligned grub screws 52, and a lower end threadedly attached to the bottom connection 38. Sealing rings 60 are positioned throughout the embodiment to prevent undesired fluid communication between the various elements, except through the flowpath 30 and through the plurality of flow ports 50.
A pressure chamber 54, such as a cylindrical pressure chamber, is disposed longitudinally through a chamber, such as annular portion 56, of the middle sub 34. A detonator assembly 58 and firing pin 90 are located within the pressure chamber 54, with the detonator assembly 58 located proximal to the upper end of the pressure chamber 54.
The middle sub 34 and ported housing 36 enclose a moveable sleeve assembly 62 having an attached ball seat 64, or other plug seat, for selectively allowing communication through the flow ports 50 to the surrounding formation, as will be described infra. The sleeve assembly 62 is, in the embodiment of
A lower section of the piston sleeve 68 has a larger interior diameter than an upper section. In the first position, the upper end of the insert sleeve 70 initially abuts the shoulder 78 defining the top end of the second portion, and is coupled thereto with a circumferentially-positioned expandable piston locking key 80 or other bridging element. The insert sleeve 70 is initially secured to the ported housing 36 with shear screws 66. Upper and lower sealing rings 84, 86 are circumferentially disposed around the insert sleeve 70 to isolate the flow ports 50 from the flowpath 30, thus substantially preventing communication between the flowpath 30 and the exterior of the tool.
The detonator assembly includes a primer 92, primer case 94, shaped charge 96, and an isolation bulkhead 98. The primer 92 is spaced above the firing pin 90 within the primer case 94. The shaped charge 96 is positioned above and adjacent to the primer case 94. The isolation bulkhead 98 is positioned adjacent the shaped charge 94 and proximal to the propellant volume 46. In this position, detonation of the shaped charge 94 will cause corresponding ignition of the propellant volume 46.
After shearing the pins 66, increased fluid pressure within the flowpath 30 causes the insert sleeve 70 and piston sleeve 68 to move downwell until the lower section of the piston sleeve 68 contacts an inner shoulder 82 of the piston housing 36. In this position, the piston locking key 80 expands into an adjacent flanged section 81 and decouples the insert sleeve 70 from the piston sleeve 68. The insert sleeve 70 is thereafter allowed to continue downwell under the flowpath pressure until it contacts the bottom connection 38 (see
Movement of the sleeve assembly 62 to the second position causes hydraulic actuation of the firing pin 90 as follows. Engagement of the piston sleeve 68 with the interior shoulder 86 positions an outer groove 110 to allow the firing pin locking key 76 to radially contract thereinto. This contraction causes the firing pin locking key 76 to disengage from the firing pin 90.
As shown in
Referring specifically to
The middle sub 122 has an upper end surface 158 and an lower end surface 160. A cylindrical outer surface 161 extends between the upper end surfaces 158 and a shoulder surface 163. The middle sub 122 may have a varying inner diameter defined by a cylindrical upper inner surface 162, a cylindrical intermediate surface 164, and a cylindrical lower inner surface 166. An annular upper intermediate shoulder surface 168 is adjacent to and between the intermediate surface 164 and the upper inner surface 162. A lower intermediate shoulder surface 170 is adjacent to and between the intermediate surface 164 and the lower inner surface 166. In the embodiment of
Mandrel 172 occupies a portion of the interior of the tool, such as a portion of the top connection 118 and the middle sub 122 as shown in
The mandrel 172 is inhibited from translational and rotational movement relative to the top connection 118 and middle sub 122. For example, circumferentially-aligned screws 180 may fix the mandrel 172 to the top sub 118. Further, the upper end surface 174 may be in contact with the inner shoulder 156 of the top connection 118, 186 the lower end surface 176 may be in contact with the upper shoulder 168 of the middle sub 122, or both. A first section 177 of the embodiment 112 includes at least part of the internal sidewall of the mandrel 172 and at least part of the outer sidewall.
A detonator cord 259 is fastened to each of the shaped charges 187 and extends along one longitudinal groove 186a, into the circumferential groove 184, and into the next longitudinal groove 186b, around the shoulder surface 175 and into the next longitudinal groove (not shown), and so on. In this manner the detonator cord 259 may occupy one or more of the grooves 186. One end of the detonator cord 259 is fastened to the detonator assembly 258, as shown in
Referring back to
Referring jointly to
In certain embodiments, the downhole tool may contain a bridge assembly for connecting the pin sleeve and lower sleeve. In some embodiments, the bridge assembly releasably connects the pin sleeve and lower sleeve such that the pin sleeve and lower sleeve may be disconnected at a desired time or in response to a predetermined event. Referring to
Referring again to
A ball seat 236 may be threaded to the seat carrier 220. Plugs other than balls are within the scope of the present disclosure and the ball seat 236 may be substituted with any seat configured to seal with the desired plug, provided that the plug and plug seat fit within the geometry, both size and shape, of the downhole tool, and, in the case of plug, any structures in the well through which the plug must pass to reach the plug seat. The ball seat 236 has an upper end surface 238 adjacent to the lower end surface 206 of the lower sleeve 202, and a lower end surface 240 positioned adjacent to the upper intermediate shoulder surface 228 of the seat carrier 220. The ball seat 236 defines an orifice 242 intersecting the flowpath.
In some embodiments, a cement sleeve 244 is attached to the seat carrier 220 below the lower shoulder surface 230. The cement sleeve 244 may be a tubular body having an upper end surface 246 and a lower end surface 248. A cylindrical outer surface 252 is positioned adjacent to the lower end surface 248. A shoulder 254 is adjacent to and positioned above the outer surface 252.
An actuator, such as a detonator assembly 258, for actuating the charges 187 is placed adjacent to the grooves 186. For example, and referring back to
Referring to embodiment shown in
A retaining pin 264 may be connected to the firing pin 260, such as the retaining pin 264 shown in
A detonator assembly 258, such as illustrated in
In some embodiments, a bridge element between the pin sleeve and lower sleeve may disengage, break, or other otherwise disconnect such that the pin sleeve 190 and lower sleeve 202 no longer move together. For example, in the embodiment of
Movement of the pin sleeve 190 to the second position shown in
In some embodiments, the number of longitudinal channels may exceed the number of detonator assembly, as illustrated for the embodiment shown in
The present invention is described above in terms of specific illustrative embodiments. Those skilled in the art will recognize that alternative constructions of such an apparatus can be used in carrying out the present invention. Other aspects, features, and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.
Claims
1. A downhole tool for stimulating a hydrocarbon-producing formation, the downhole tool comprising:
- a first section having an internal sidewall defining at least a portion of a flowpath, and an outer sidewall;
- at least one explosive having at least partly within said first section;
- an annular portion with at least one chamber having an end positioned adjacent to said at least one explosive and an inlet;
- at least one detonator assembly within said at least one chamber proximal to said end;
- at least one firing pin within said at least one chamber, said at least one firing pin having a first end pressure isolated from a second end;
- at least one sleeve defining at least a portion of said flowpath and moveable between a first position and a second position, wherein in said first position said sleeve assembly is between the inlet of said at least one chamber and said flowpath.
2. The downhole tool of claim 1 wherein at least a portion of said at least one explosive is between said internal sidewall and said outer sidewall.
3. The downhole tool of claim 2 wherein said at least one detonator assembly comprises a isolation bulkhead proximal to said at least one explosive, a shaped charge adjacent said isolation bulkhead, a primer case adjacent said shaped charge, and a primer adjacent said primer case.
4. The downhole tool of claim 1 further comprising a retaining pin connected to said firing pin and occupying a portion of said inlet.
5. The downhole tool of claim 1 wherein said sleeve assembly comprises:
- a first sleeve having a first end surface, a second end surface, a cylindrical outer surface extending between said first end surface and said second end surface and defining a first groove circumscribing said first sleeve;
- a second sleeve having a first end surface, a second end surface, a cylindrical outer surface extending between said first end surface and said second end surface and defining a second groove circumscribing said second sleeve; and
- a collet ring occupying said first groove and said second groove.
6. The downhole tool of claim 5 wherein in said first position said second sleeve is attached to said second section with a plurality of shear pins.
7. The downhole tool of claim 1 further comprising a detonator cord connected to the detonator assembly and the at least one explosive.
8. A downhole tool for stimulating a hydrocarbon-producing formation, the downhole tool comprising:
- a mandrel defining at least a portion of a flowpath;
- at least one explosive adjacent said mandrel;
- a sleeve adjacent said at least one explosive;
- at least one detonator assembly adjacent to said at least one explosive;
- at least one firing pin operable to contact said at least one detonator assembly, said firing pin having a first end pressure isolated from a second end;
- a housing; and
- a sleeve assembly moveable between a first position and a second position and defining a portion of said flowpath.
9. The downhole tool of claim 8 wherein:
- said at least one explosive is circumferentially disposed around at least a portion of said mandrel; and
- said sleeve is circumferentially disposed around at least a portion of said at least one explosive.
10. The downhole tool of claim 8 further comprising:
- an annular portion;
- at least one chamber disposed within said annular portion, said at least one chamber having an end longitudinally adjacent to said at least one explosive and an inlet; and
- wherein said at least one detonator assembly is located at said end of said at least one chamber.
Type: Application
Filed: Jul 26, 2013
Publication Date: Apr 23, 2015
Inventors: Raymond Hofman (Midland, TX), William Sloane Muscroft (Midland, TX), Steve Jackson (Richmond, TX)
Application Number: 14/120,428
International Classification: E21B 43/263 (20060101);