Abstract: A drill pipe protector assembly for providing hydraulic lift and improved sliding lubrication to a drill string. The protector defines a tubular sleeve that is attached to a section of drill pipe and resides over the outer diameter of the drill pipe while moving within an associated well casing or well hole. The sleeve is adapted to provide hydraulic lift and sliding lubrication relative to the well casing and thus, increase the proclivity of the drill pipe to slide down the hole while also reducing the development of cutting dams. The sleeve includes a plurality of radially oriented openings which direct drilling mud from the annular space between the sleeve and drill pipe to the annular space between the sleeve and the casing or outer well wall. The sleeve also includes a plurality of wedge shaped longitudinal channels in communication with the radial openings.

Abstract: A downhole drilling method comprises producing pressure pulses in drilling fluid using measurement-while-drilling (MWD) apparatus (18) and allowing the pressure pulses to act upon a pressure responsive device (16) to create an impulse force on a portion of the drill string.

Abstract: The system and method of the present invention permits control of down hole fluid pressures during under balanced drilling, tripping of the drill string, and well completion to substantially avoid “killing” of the well and thereby damaging the producing formations in the well bore. The system and method utilizes separate and interconnected fluid pathways for introducing a downwardly flowing hydrodynamic control fluid through one fluid pathway and for removing through the other fluid pathway a commingled fluid formed by mixing of the hydrodynamic control fluid and the well bore fluids flowing upwardly in the well bore.

Abstract: A preferred novel circulating sub includes an electric motor, hydraulic intensifier, connecting rod, valve sleeve, valve plug, and angled nozzles. Upon activation of the circulating sub the electric motor drives the valve sleeve over the valve plug, causing a flow of drilling fluid to exit the angled nozzles. Upon deactivation of the circulating sub, the electric motor removes the valve sleeve from the valve plug, allowing the flow of drilling fluid to once again flow to the drill bit. Because the electric motor is reversible, the circulating sub can be repeatedly activated and deactivated.

Abstract: A flexible hose assembly for horizontal well drilling is provided. The flexible hose assembly has a number of spaced thruster couplings along its length to impart drilling force to a nozzle blaster at an end of the flexible hose. The thruster couplings have rearwardly oriented holes which impart a forward drilling force upon the exit of high pressure water through the holes. A method of horizontal well drilling using the above-described flexible hose is also provided. The method is particularly useful for shallow wells, such as 50-2000 feet.

Abstract: A bottomhole assembly (BHA) for use in well operations, with particular application to use in drilling with a downhole drilling motor and with coiled tubing and directional drilling, including a novel power pack, orienting tool, arrangement of bottomhole assembly tools, and method of use of the BHA for orienting while drilling.

Abstract: The present invention is directed to a method of cleaning a well riser. In particular, the method comprises the steps of suspending in a drill pipe from the surface a circulating tool in the well riser, and causing the circulating tool to axially collapse so as to open one or more radial outlets in the tool and allow cleaning fluid to be expelled out of the tool and impact on the inside of the well riser.

Abstract: Method and apparatus for drilling into earth strata surrounding a well casing utilizing a rotating fluid discharge nozzle and reduction of static head pressure in the well casing in conjunction with the drilling operation.

Abstract: A method is disclosed for controlling the mud circulation system for deepwater marine drilling operations in which a drill string is run from surface facilities, through a blowout preventor and into a borehole. Mud is injected into the drill string, up a borehole and through the blowout preventor adjacent the sea floor. There the mud is withdrawn from a mud exit return line near the blowout preventor and the hydrostatic head from the mud in the drill string is isolated from the relatively lesser ambient pressure at the sea floor seen at the mud exit return line with a pressure activated drill string shut-off valve when mud circulation is interrupted. A drill string shut-off valve system for controlling the mud circulation system for deepwater marine drilling operations is also disclosed. Further, a method of well control to overcome formation pressure in a well control event is disclosed.

Abstract: A cutting bed impeller comprises a body portion and a plurality of paddles projecting outwardly from the body portion, at least one of the paddles comprising a radially outer face extending between a leading edge and a trailing edge in a normal direction of rotation of the impeller about an axis of rotation of the cutting bed impeller, a leading face, and a trailing face. The radially outer face extends between the leading face and the trailing face. The leading face is inclined at a first angle &agr; to a first tangent T1 to the radially outer face at the leading edge. The trailing face is inclined at a second angle &bgr; to a second tangent T2 to the radially outer face at the trailing edge, the second angle &bgr; being less than the first angle. The radially outer face of one or more of the paddles may be provided with one or more replaceable wear elements.

Abstract: Apparatus and associated methods are provided which facilitate underbalanced drilling and completion of wells. In a described embodiment of a well control valve, the valve is opened and closed when a drill string is displaced therethrough. A shifting device is carried on a drill bit and deposited in the valve when the drill string enters and opens the valve. The valve is closed and the shifting device is retrieved from the valve when the drill string is tripped out of the well. A packer hydraulic setting tool usable in conjunction with the well control valve in underbalanced completions is also provided.

Abstract: A drive steel member for driving engagement with a rotary drilling machine, including a chuck adapter having main body and chuck seating elements and being constructed and arranged in fixed, sealing relation on on one end of the drive steel member.

Abstract: A subterranean drilling assembly for linear and nonlinear drilling. A downhole motor-based bottomhole assembly with a bit deflection device includes a torque compensation device and is secured to the drill string via a swivel assembly to permit independent rotation of the string and the bottomhole assembly. In the case of a drill pipe string, the string may be rotated continuously during both linear and nonlinear drilling to reduce drag. In the case of a tubing string, the bottomhole assembly is rotated by the torque compensation device during straight drilling. In both cases, the torque compensation device is employed to adjust TFO for nonlinear drilling when the bottomhole assembly is not rotated. In an alternative embodiment, a torque-sensitive clutch is employed in lieu of the torque compensation device to provide rotational orientation to, and rotation of, the bottomhole assembly.

Abstract: An improved stabilizing tool includes a body with a pocket, and a roller rotatably disposed in the pocket. The body includes a fluid passageway formed axially therethrough. The passageway has a first zone wherein the pressure of the fluid is relatively high and a second zone wherein the pressure is relatively low. A first conduit provides fluid communication between the first zone and an interior of the roller for the ingress of fluid to the interior, and a second conduit provides fluid communication between the interior of the roller and the second zone for the egress of the fluid back to the fluid passageway.

Abstract: A pressure converter for mounting above the drill bit on a drill pipe for generating a higher fluid pressure in a portion of a drilling fluid flow, comprises a piston moveable in a cylinder. The piston has a large piston area and an opposite small piston area, which provides an increased pressure in a smaller portion of the drilling fluid flow. A valve arrangement controls the drilling fluid flow to and from the cylinder. A high pressure conduit with a check valve connects the space in front of the small piston area to a header conduit for drilling fluid at the increased pressure. The piston also has another large piston area facing oppositely of the first large piston area and being adapted to be influenced by the drilling fluid pressure in the drill pipe so as to move the piston in an opposite direction. Another small piston area facing oppositely of the first small piston area, is adapted to provide an increased drilling fluid pressure upon piston movement in the opposite direction.

Abstract: A cutting bed impeller (10) comprises a body portion and a plurality of paddles (24) projecting from the body portion, one or more of the paddles (24) having a recess (18) on its leading face in the direction of rotation of the impeller (10). The radially outer face (26) of one or more of the paddles (24) may be provided with one or more replaceable wear elements (30, 38). For example the elements may comprise nylon inserts (30) fitted into openings (28) in the radially outer faces (26) of the paddles (24).

Abstract: An erosion resistant downhole diverter tool (210) comprises a generally cylindrical body (212) which may be configured as a slick sub or may include stabilizing blades (260). Located within the body 212 are a plurality of erosion-resistant, removable, cylindrical inserts (220). Each insert has an aperture (222) formed therein, aligned with a corresponding aperture (218) formed in the cylindrical body (212). Located within the apertures (218) in the cylindrical body (212) are pressure responsive, normally-closed valve assemblies (300), incorporating jet nozzles, which open in response to increased fluid pressure within the tool to provide fluid jets directed into the annulus surrounding the tool in a borehole or the like. The upper ends of the stabilizer blades (260) may include cutting structures to provide a back-reaming function.

Abstract: There is provided a circulating sub apparatus (50) having a tubular outer body member (51, 53, 54, 55, 56, 57) and a tubular inner body member (52, 65). The outer body member (51, 53, 54, 55, 56, 57) and the inner body member (52, 65) each have one or more holes (66, 68) substantially transverse to the longitudinal axis of the outer (51, 53, 54, 55, 56, 57) and inner (52, 65) body members. A displacement mechanism produces relative movement between the outer (51, 53, 54, 55, 56, 57) and inner (52, 65) body members such that the outer (51, 53, 54, 55, 56, 57) and inner (52, 65) body members may be repeatably moved between an aligned position, in which the one or more holes (66, 68) on the inner body member (52, 65) are aligned with the one or more holes (66, 68) on the outer body member (51, 53, 54, 55, 56, 57), and an obturated position, in which the one or more holes (66, 68) on the inner body member (52, 65) are obturated by the outer body member (51, 53, 54, 55, 56, 57).

Abstract: The present invention is an improved apparatus for controlling the weight on the drill bit during operation. In this invention, an inner mandrel has a telescoping movement in response to added drill string length at the surface. As the inner mandrel telescopes closed, it approaches a restrictor which is fixedly disposed in the lower housing of the drill string assembly. When the inner mandrel mates with the restrictor, a stand-pipe pressure increase noticeable to the operator occurs. The operator then stops the drill string and allows the motor to drill ahead. As the motor drills ahead, the inner mandrel telescopes open and the operation is then repeated.

Abstract: A travel joint provides economical manufacture, installation, service, and operation thereof. The travel joint substantially reduces the number of parts potentially exposed to corrosive fluid, eliminates cavities wherein such corrosive fluid may become trapped, and substantially reduces the number of dynamic and static seals required for its operation. Additionally, a torque transmitting member is utilized to prevent torquing through threaded service breaks in the travel joint. In a preferred embodiment, a travel joint has a tubular upper case, a torque collar rotationally and axially coupled to the upper case, a tubular mandrel axially slidably received in the upper case and torque collar, and rotationally coupled to the torque collar, and an adapter which axially and radially inwardly retains the torque collar.

Abstract: A jet assisted drill system which uses a high pressure intensifier, positioned in a down hole drill assembly. Drill fluid from a drill stem is directed into the drill assembly, and in one mode this drill fluid is passed through the pressure intensifier to cause a piston assembly of the intensifier to reciprocate, with high pressure pistons of the piston assembly delivering high pressure drill fluid to a discharge jet in the drill bit assembly. The lower pressure fluid which drives the low pressure pistons is discharged into a downstream annular passageway and to the drill bit assembly. In a by-pass mode, a selector valve directs drill fluid from an upstream main passageway portion directly to a downstream main passageway portion to pass out the drill bit assembly. This flushes out debris which is carried upwardly out of the drill hole. There is a control valve to operate the piston assembly and a trigger valve operated by the piston assembly to direct fluids selectively to the control valve.

Abstract: A downhole activated circulating sub is adapted to be interconnected between various tools installed on coiled tubing and placed into a wellbore; for example, between a coiled tubing/measurement while drilling tool and a downhole motor/drill bit for drilling a wellbore. The circulating sub can be repeatedly set and reset while the circulating sub is disposed in the wellbore. As a result, it is not necessary to retrieve the circulating sub to the wellbore surface for the purpose of resetting the sub. The circulating sub includes a latch mechanism which locks and latches the sub in either a set condition or a reset condition when a fluid is pumped through the circulating sub. When fluid flow through the circulating sub stops, the latch mechanism is unlocked and the circulating sub can change between the set condition and the reset condition.

Abstract: A pneumatic drilling chip removal system for removing drilling chips from a well bore, comprising sub-surface drilling equipment having a plurality of components and a drilling bit, a central passageway extending through the components and to the air jets in the drilling bit, wherein at least one component above the drilling bit in the sub-surface drilling equipment is a pneumatic component having an opening forming a pneumatic conduit from the central passageway to the annulus, a bypass valve disposed therein selectively permitting air flow from the central passageway to the annulus, forming a supplementary air source for removal of drilling chips from the well bore. Methods for using a pneumatic drilling chip removal system.

Abstract: A modulated bias unit is provided for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations. The unit comprises a plurality of hydraulic actuators spaced apart around the periphery of the unit and having movable thrust members hydraulically displaceable outwardly for engagement with the formation of the borehole being drilled. Each actuator has an inlet passage for connection to a source of drilling fluid under pressure and an outlet passage for communication with the annulus. A selector control valve connects the inlet passages in succession to the source of fluid under pressure, as the unit rotates, and a choke is provided to create a pressure drop between the source of fluid under pressure and the selector valve. A further choke is provided in the outlet passage from each actuator unit. The actuators and control valve arrangements may take a number of different forms.

Abstract: A device for drilling holes (1) in the crust of the earth, especially for drilling oil wells, wherein a rotary bit (2) is fitted in a drill string (4), within which drilling fluid is pumped downwardly and, upon return, conveys cuttings to the surface. A piston (5) is mounted on the drill string (4) above the bit (2) and adapted to form a sliding seal against the wall of the hole (1). A seal (8) is mounted above the piston (5) within the hole (1) and adapted to seal against the wall of the hole (1), against the drill string (4), against a return line (6) adapted to conduct drilling fluid with cuttings from the under side of the piston (5) to the top of the seal (8), as well as against a pipe (9) communicating with a pump (10) adapted to pump liquid in between the seal (8) and the piston (5), whereby liquid pressure acting against the upper face of the piston (5) urges the bit (2) against the bottom of the hole (1).

Abstract: The present invention relates to a device for remote actuating an equipment through a variation of the flow of a fluid in a pipe. The device includes an adjusting throttle (2, 3; 52, 51) adapted for varying the opening of the passageway of said fluid through a hydrodynamic action. The device further includes delay timing for adjusting the throttle. The present invention further relates to a method for actuating at least one equipment. Application of the device and of the method is to the actuation of equipment adapted for controlling the trajectory of a wellbore.

Abstract: A pneumatic drilling chip removal system for removing drilling chips from a well bore, comprising sub-surface drilling equipment having a plurality of components and a drilling bit, a central passageway extending through the components and to the air jets in the drilling bit, wherein at least one component above the drilling bit in the sub-surface drilling equipment is a pneumatic component having an opening forming a pneumatic conduit from the central passageway to the annulus, a bypass valve disposed therein selectively permitting air flow from the central passageway to the annulus, forming a supplementary air source for removal of drilling chips from the well bore. Methods for using a pneumatic drilling chip removal system.

Abstract: A method and apparatus for removing drilling mud within entrained cuttings is provided using a pump for forcing fluid into a borehole, such that the fluid mixes with cuttings formed during the formation of the hole. The pipe receives the fluid and entrained cuttings at a first end of the pipe and returns the fluid and entrained cuttings to the surface at the second end of the pipe. At the first end of the pipe, air is injected into the drilling fluid with entrained cuttings to form bubbles therein, thereby increasing the velocity of the fluid and entrained cuttings through the pipe. In one alternative embodiment, a suction is provided at one end of the pipe to increase the speed of fluid and entrained cuttings therethrough. In a third embodiment of the present invention, an Archimedes screw is used to remove the fluid and entrained cuttings from the borehole.

Abstract: An hydraulic device for forming a cavity in a borehole. The device includes generally the following modular sections: a hub section for connection to a drill pipe; hydromonitor (cutting nozzle); hydroelevator (eductor); and drill bit box. Through each section, except the drill bit box, extends first and second concentric pipelines for delivering fluid into the device and directing slurry out of the device. Only the drill pipe extends to the surface to receive standard well blowout prevention equipment. The second pipeline releases slurry into a casing which channels, in cooperation with an upper portion of the first pipeline and the drill pipe, the slurry to the surface. The hydromonitor includes a nozzle which is hydraulically associated with the first pipeline, and extends through the second pipeline, for delivering fluid into the borehole to form the cavity. The eductor pulls spent cutting fluid, coal fines, etc., out of the cavity as the slurry.

Abstract: A process and apparatus for high pressure drilling are disclosed. The apparatus comprises an essentially solid drill head with horizontally extendable nozzle arms hingedly connected by shear pins thereto. Flow of high pressure fluid both extends the nozzle arms and flows through the nozzle arms, thereby fracturing and shearing material surrounding the drill head. Cessation of fluid flow returns the arms to the vertical position.

Abstract: A pressure converter for deep drilling keeps contaminated drill mud outside of the working mechanisms of the drill fluid. Thus, the inner drill mechanisms are kept clean by drill fluid. The device contains a rotatable valve positioned above the controlling piston. A tap cover, containing the valve, has two diametrically opposed inlets and two diametrically opposed outlets. The valve has a through passage which is connected to the inlets when the valve is in a second position. Thus, when the piston is operating in a return fashion, the drilling fluid is provided to the area beneath the piston head, keeping this area clean of drill mud.

Abstract: Apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.

Abstract: A hole cleaning device 100 includes a housing having a porous region to communicate cuttings from a bore hole to the interior of the housing. A Venturi-effect pump creates a suction to draw cuttings from the hole into the housing. An outlet pipe coupled to the Venturi pump transports the cuttings out of the housing.

Abstract: A pressure converter for a drill pipe includes a housing with a header channel therein which is in communication with a drill bit, a drive unit which is driven by a driving drilling fluid flow of the drill pipe, a valve which is operatively connected to and moved by the drive unit, a piston which moves in a reciprocating manner thereby creating a pressure stroke and a return stroke, and a check valve through which a portion of the drilling fluid flow is discharged to the drill bit via the header channel.

Abstract: A device for use within a backhead of a down-the-hole percussive drill, for removing debris from a drillhole, includes a separator for separating water and other matter from the percussive fluid prior to the percussive fluid actuating the piston of the drill. The water and other matter are exhausted out the drill bit, to remove the debris. The device includes a one-way flow valve to prevent backflow of debris and water into the drillhead during periods when the percussive fluid flow ceases. The device can be added to existing drill backheads, or included as part of newly manufactured units.

Abstract: An apparatus for removing debris from a bore hole comprises a housing having apertures formed therein such that rotation of the housing causing entrapment of the cuttings from the bore hole. The positive displacement pump comprises a rotor surrounded by a stator coupled to the housing such that rotation of the stator rotates the housing. The positive displacement pump is operable to pump material from the housing responsive to relative movement between the rotor and stator. A motor rotates the stator, thereby cleaning the bore hole.

Abstract: A dry, vertical shaft drilling system including an inverted raiseboring cutterhead fitted with air nozzles and vacuum pickups. Weights are detachably stacked above the cutterhead. Cuttings are extracted through the weights into a swivel circumscribing the drill string. The swivel is a transition from the rotating cutterhead to the stationary extraction riser pipes disposed above the swivel. Non-rotating stabilizers stabilize the drill string.

Abstract: A floating seal adapted particularly for sealing the bearings in a drill string for deep wells. The seal has an outer slide ring slidable longitudinally in the drill casing and an internal support ring mounted in the slide ring against relative axial displacement but adapted for eccentric radial displacement of the mounting ring relative to the slide ring. Rotary discs are provided in the outer slide ring to allow axial displacement of the slide ring but to resist rotary displacement of the slide ring in the casing. The mounting ring is mounted in the slide ring to afford radial displacement of the mounting ring but to resist relative rotational displacement between the mounting ring and the slide ring. Seals are provided between the outer surface of the slide ring and the interior surface of the casing; between the interior surface of the mounting ring and the exterior surface of the shaft; and also between the slide ring and the mounting ring.

Abstract: A mud saver valve in which a cylindrical resilient sleeve is pressed against an inner tubular member by a pressurized gas to prevent flow from above the valve to below the valve at low pressures, and which is fully opened for free flow at higher pressures.

Abstract: A device for use adjacent to a down-the-hole percussive drillhead, for removing debris from a drillhole, includes a separator for removing water and other matter from the percussive fluid prior to the percussive fluid entering the drillhead. The water and other matter are ejected into the drillhole to remove the debris, and the separator includes a one-way flow valve to prevent backflow of debris and water into the drillhead during periods when the percussive fluid flow ceases.

Abstract: A method for removing debris from a drillhole, includes positioning a separator adjacent to a down-the-hole percussive drillhead, for removing water and other matter from the percussive fluid prior to the percussive fluid entering the drillhead. The water and other matter are ejected into the drillhole to remove the debris, and backflow of debris and water into the separator and drillhead is prevented, during periods when the percussive fluid flow ceases.

Abstract: The invention relates to the drilling of a hole for the study of the underground. The roto-percussion head acts on the drilling tube of which the base carries a cutter. The cutter is integral with the sleeve inside which drilling water is injected. The water and the rock debris go up and out through the evacuation opening. Application to the reverse flow drilling allowing to extract at the evacuation opening cores or rock debris which go up inside the axial tube as soon as they are taken without any risk of being contaminated by the previously traversed layers of ground.

Abstract: A method and apparatus for creating an underground bore hole employing a steerable boring head at the end of a remotely driven drill string. The boring head, preformed at an angle to the longitudinal axis of the trailing pipe string to bore along a curvilinear path is straightened by increasing the pressure of the fluid within the drill string above a predetermined range to enable drilling along a linear path. Subsequent reduction of the fluid pressure to normal drilling pressure returns the boring head to its former state along a resumption of a curvilinear drill path.

Abstract: An actuator for an appliance associated with a ducted body, through the duct of which flows an incompressible fluid, includes a differential piston axially moveable within the duct and operatively connected to the appliance. The piston has a tubular shape and a central bore which includes a first profiled throttling portion the minimum internal diameter of which is smaller than the internal diameter of the duct. A protruding profiled element secured in the duct body is disposed coaxially with the piston and cooperates therewith for selectively increasing the loss of head of the incompressible fluid as it flows in the direction of circulation. A spring is arranged between the piston and part of the drill-string for biasing the piston in a direction of movement opposite the direction of circulation of the incompressible fluid. A measurement device is provided for measuring the pressure of the incompressible fluid at the first end of the drill-string.

Abstract: A well drilling assembly including a drill bit projecting beyond the bottom of a hollow casing at the bottom of the hole. A fluid motor mounted in the casing has a rotary shaft to rotate the drill bit. The lower end of the rotary shaft is hollow to provide a central flow passage therein, and has an outer pressure diameter less than the inner diameter of said casing to provide an outer pressure passage therealong. Bearings are mounted in the outer passage to support the shaft against radial and axial displacement, and are engulfed in a body of lubricant confined between upper and lower floating seals which limit flow of drilling mud into the lubricant and flow of lubricant from the body into the drilling mud. A labyrinth provides a rotating orifice in the outer passage below the lower seals to maintain a pressure differential between the exterior of said drill bit and the lower seals.

Abstract: A drilling system comprises a drill string (1) incorporating inbuilt tubular conductors (25), a mud supply passage, and passages for protective or other fluids. The drill string can be advanced by selectively actuable pistons (51,60) exposed to drilling mud flow, by electrically driven traction units (71,74) engaging the drill hole wall or by a linear electric motor element (82) co-operating with a drill hole casing (24), which can be moved thereby relative to the drill string. The drill bit (106) of the drill unit is driven rotatably by an electric motor (111,112) or reciprocably by a linear electric motor (125). The drill unit can be of two relatively slidable parts, with fluid pressure, which may be generated within the unit (189) axially loading the drill bit. Drilling forms can be resisted by clamps (129) clamping the unit and/or the drill string to the drill hole wall. The drilling direction can be adjusted by use of these clamps.

Abstract: A flushing device for drilling tools comprises a guide member (10) carrying a drill bit (20) and being rotatably centered by the mouth of a casing tube (11) which is adapted to follow the drilling tool downhole during drilling. The drill bit (20) has a bit portion (22) that projects laterally beyond and is spaced axially in front of the casing tube (11) so as to drill a hole larger than the casing tube (11). There are external flushing grooves (70,71) on the guide member (10) adapted to lead the outflow of flushing medium and debris from the hole during drilling into the casing tube (11). At least one of these grooves (70) extends from front to rear of the guide member (10). One or more further grooves (71) are open towards said rear while ending blindly into the periphery of the guide member (10) spaced from its front. By retraction of the guide member (10) its front enters the casing tube (11).

Abstract: A filter apparatus for a percussion device powered by fluid pressure includes a percussion device housing having a fluid inlet and a fluid outlet. A valve is displaced between an open and a closed position. A filter recess is formed within the housing. A filter is inserted within the filter recess for moving the valve from the closed to the open position, thereby permitting fluid pressure to be supplied from the inlet to the outlet.

Abstract: A check valve sub assembly for series connection in a dual pipe string that extends downhole in a borehole for permitting flow of fluid in one direction through the annular passageway of the dual pipe string and preventing flow of fluid in the other direction. The check valve sub assembly includes an inner tube and an outer annular member for connection into series relationship respective to the inner and outer dual pipe so that fluid flow through the inner pipe is conducted through said inner tube and is maintained separate from the annulus.

Abstract: For a self-controlling drill rod for rotary boring rods of machine rock drills, comprising an inner drilling shaft adapted to be connected with the boring rods and the boring tool and having a flush channel and a housing mounted on the drilling shaft so as to be rotatable thereabout, control bars capable of swinging out being disposed on the outside of the housing, and the parts of the hydrostatic drives acting on the control bars as well as the control electronics and control electrical system being provided within the housing, whereby the required energy is generated by the rotary motion during the boring operation, the inventive improvement is that an annular space exists between the drilling shaft and the housing having a radial connection with the flush channel of the drilling shaft and being closed off at each end by a rotary check valve keeping out the borehole fluid, and that the annular space serves as a tank for the working fluid of the hydraulic system, said fluid being formed by the drilling shaft