EP0580056B1 - Air percussion drilling assembly for directional drilling applications - Google Patents
Air percussion drilling assembly for directional drilling applications Download PDFInfo
- Publication number
- EP0580056B1 EP0580056B1 EP93111146A EP93111146A EP0580056B1 EP 0580056 B1 EP0580056 B1 EP 0580056B1 EP 93111146 A EP93111146 A EP 93111146A EP 93111146 A EP93111146 A EP 93111146A EP 0580056 B1 EP0580056 B1 EP 0580056B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- piston
- hammer
- housing
- bit
- hammer bit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/006—Mechanical motion converting means, e.g. reduction gearings
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/16—Plural down-hole drives, e.g. for combined percussion and rotary drilling; Drives for multi-bit drilling units
Definitions
- This invention relates to an air percussion hammer according to the preamble part of claim 1 and to a method according to the preamble part of claim 10. More particularly, this invention relates to a downhole air compression hammer tool for directional drilling operations. The hammer impacts while simultaneously rotating the bit, thereby assuring maximum penetration of the bit in an earthen formation independent of the rotation of the drill string.
- the drill bit rotational parameters e.g. torque and rpm
- the drill bit rotational parameters are not relevant from a rock formation breaking point of view, except for the necessity that the cutting elements of the bit need to be "indexed" to fresh rock formations.
- this need is achieved by rotating the drill string slowly. This is accomplished in conventional hammer bit operations by incorporating longitudinal splines which key the bit body to a cylindrical sleeve at the bottom of the hammer (commonly known as the driver sub). The drill string rotation is then transferred to the hammer bit itself.
- the bit optimum rotational speed is approximately 20 rpm for an impact frequency of 1600 bpm (beats per minute). This rotational speed translates to an angular displacement of approximately 4 to 5 degrees per impact of the bit against the rock formation.
- Another way to express this rotation is the cutters positioned on the outer row of the hammer bit move at the approximate rate of one half the cutter diameter per stroke of the hammer.
- a typical hammer bit connected to a rotatable drill string is described in US-A-4,932,483.
- the downhole hammer comprises a top sub and a drill bit separated by a tubular housing incorporating a piston chamber therebetween.
- a feed tube is mounted to the top sub and extends concentrically into the piston chamber.
- a piston is slidably received within the housing and over the feed tube. Fluid porting is provided in the feed tube and the piston to sequentially admit fluid in a first space between the piston and top sub to drive the piston towards the drill bit support and to a second space between the piston and the drill bit support to drive the piston towards the top sub.
- Rotary motion is provided to the hammer assembly and drill bit by the attached drill string powered by a rotary table typically mounted on the rig platform.
- the rotation of the drill string in the conventional hammer bit operation described above takes away the ability to turn, build, or drop angle which is fundamental in directional drilling operations.
- a method for rotating the hammer bit without rotating the drill string is instrumental in any directional drilling or steerable system. Such a rotation can be accomplished by a motor mechanism positioned above the hammer that induces rotational motion to the bit itself.
- the air percussion hammer tool taught in this specification has particular application for use with the technology taught in US-A- Re. 33,751, for directional drilling utilizing a system approach to design the hardware for drilling according to the well plan.
- the bend angle of a bent housing, connected between the bit and downhole motor, the diameter of a plurality of stabilizers and placement of the stabilizers with respect to the drill bit are selected and predetermined on the basis of the desired well plan.
- the direction of the progressing borehole is tracked from the surface. Direction changes as required are controlled from the surface simply by controlling rotation of the drillstring.
- US-A-4958691 discloses a down hole oil well tool for a pipe string.
- the tool is fluid-operated and moves upwardly and downwardly. It carries an impact receptive working member at its lower end that rotates when the working member is not subject to weight of the pipe string from above.
- a single rotation directional clutch is provided between the tool and the working member. As soon as the tool moves downwardly in relation to the working member, the working member is rotated until the tool subjects the working member to an impact. During subsequent upward movement of the tool relative to the working member the clutch is rotated without rotating the working member.
- the air percussion hammer for directional drilling operations has a cylindrical housing having an upstream end connectable to a drill string component and a downstream end with means for mounting a hammer bit.
- a piston is slidably retained within the housing has a downstream end for striking a hammer bit mounted on the end of the housing.
- Pneumatic porting in the housing provides fluid flow for alternately driving the piston upwardly in the housing and driving the piston downwardly in the housing for striking a hammer bit.
- Means are provided for rotating the piston during the downward stroke of the piston and preventing rotation of the piston during the upward stroke of the piston.
- the hammer bit is keyed to the piston for permitting relative longitudinal movement of the hammer bit while preventing relative rotation between the hammer bit and the piston.
- the air percussion hammer converts axial motion of a reciprocating piston to rotary motion of a hammer bit as the bit works in a borehole.
- the kinetic energy of the reciprocating piston is employed to rotate the bit.
- the linear motion of the piston is converted into rotational motion by using one or more helical grooves formed by the piston body.
- an indexing clutch mechanism is provided to induce rotation of the bit in one direction only.
- the upper portion of the hammer bit (normally splined) is replaced by a shaft that is slidably engaged with and keyed to a complementarily shaped female receptacle or bore formed by the lower portion of a piston.
- the shaft of the hammer is, therefore, slidably engaged at all times to the base of the piston and is so designed to be rotated by the piston with a minimum of drag.
- axial motion between the piston and bit body is allowed but relative rotational motion is not, i.e. the bit would rotate if the piston rotates and vice versa.
- One or more longitudinal helical grooves are machined on the piston upper section. These grooves are keyed to an inner race of a "sprag" clutch assembly via dowel pins or spherical balls. The outer race of this clutch assembly is locked to the inner bore of a cylindrical hammer housing. The clutch sprags are set to clockwise motion and to prevent counter-clockwise rotational movement of the inner race with respect to the outer race.
- the downward motion of the piston mandates either a counter-clockwise rotation of the inner race or a clockwise rotation of the piston. Since counter-clockwise rotation of the inner race is not possible, the piston must rotate clockwise when the piston moves downward. Similarly, the upward motion of the piston requires either the clockwise rotation of the inner race or the counter-clockwise rotation of the piston. Since the friction against the clockwise rotation of the inner race is significantly less than that against the piston/bit rotation, the inner race rotates clockwise and allows the piston to move straight upward. Therefore, on the downstroke of the piston the bit is forced to rotate clockwise; while on the upstroke the inner race rotates instead, thereby preventing the bit from "turning back".
- the bit rotating means comprises a cylindrical housing having an open upstream end connectable to a drill string component and a downstream end comprising means for mounting a hammer bit.
- a pneumatic feed tube has an open upstream end and a substantially closed downstream end, the upstream end of the feed tube being concentric with and fixed within the housing.
- the feed tube is positioned near the upstream end of the housing, the downstream end of the feed tube has one or more metered openings between the ends of the feed tube.
- a piston body is slidably retained within the housing.
- the piston body has upstream and downstream open ends with the upstream end being concentrically retained and slidably engaged with the downstream end of the feed tube.
- the downstream end of the piston forms a hammer striking surface.
- the piston further has at least one axially oriented helical groove in an outside wall of the upstream end of the piston and a pair of pneumatic communication ports between an outside wall of the piston and an interior chamber formed by the piston.
- one of the ports leads between an interior chamber formed by the piston and the downstream end of the feed tube to a chamber formed between the upstream end of the piston and the cylindrical housing.
- the other of the ports leads from an interior chamber formed between an exterior wall of the piston and the housing and the downstream open end of the piston.
- One or the other of the ports in the body sequentially registers with the metered openings in the feed tube when the reciprocating piston is moved into alignment therewith during an operating cycle of the apparatus.
- a hammer bit body is slidably contained within the downstream end of the cylindrical housing.
- the bit body has an upstream shaft end adapted to slidably engage the bore formed in the downstream portion of the piston. Means are provided between the shaft of the bit and the bore of the piston to slidably key the shaft to the piston so that the bit rotates with the piston.
- a clutch means is contained within the housing and is positioned adjacent to and interconnected with the helical groove formed in the piston.
- the clutch mean serves to rotate the piston and the bit keyed thereto, incrementally and in one direction only, each time the piston reciprocates within the cylindrical housing during operation of the air percussion hammer.
- An advantage of the present invention over the prior art hammer tools is the ability to rotate the bit independent of any rotation of the drill string.
- FIGURE 1 illustrates an air percussion drilling assembly generally designated as 10.
- the air percussion apparatus consists of a cylindrical housing 12 that forms an upstream threaded female end 14 adapted to be connected to, for example, a drill string 15.
- the drill string may comprise a conventional bent housing sub-assembly utilized in a directional drilling operation (not shown).
- a hammer bit generally designated as 18 is slidably retained within the opposite or downstream end 16 of cylindrical housing 12.
- a check valve 20 is retained within housing 12 adjacent threaded end 14. Valve body 21 is biased closed by valve spring 22 when the percussion apparatus is not functioning or the apparatus is "tripped" out of the borehole to prevent water or formation detritus from backing up the drill string.
- a pneumatic feed tube generally designated as 24, is mounted within a feed tube support member 25; the support member being secured within housing 12.
- An interior chamber 28 communicates with the drill string 15 at an upstream end of the housing 12 and with slotted, axially aligned openings 26 formed in the feed tube wall at an opposite end of the tube 24.
- a small diameter choke 27 substantially closes off the downstream end of the tube just below the slotted openings 26.
- a pneumatic piston generally designated as 30 slidably engages a cylinder wall 13 formed by the housing 12.
- the body 31 of the piston 30 has an upper, reduced diameter cylindrical segment 32.
- An inner cylindrical wall 33 in the piston overlaps and partially engages the outside wall 29 of the concentric feed tube 24.
- An annular chamber 35 within segment 32 provides a pneumatic conduit for pressurized air to the slots 26 formed in feed tube 24, depending upon the axial position of the piston 30 within housing 12.
- the piston body 31 also has diagonal ports or conduits 38 and 39 that communicate with slots 26 in the feed tube 24. The ports direct pressurized air either to slots 40 formed in the piston 30 and from there to a chamber 41 formed below the piston 30 in the housing 12 or to an annular chamber 37 above the piston, depending on the axial position of the piston as the mechanism cycles through its operating modes.
- FIGURE 1 illustrates the hammer bit 18 positioned above a borehole bottom 8; the bit being suspended from a retaining ring 49 attached to the inside wall 13 near the bottom of the housing 12.
- pressurized air 11 is directed down the drill string 15 into the chamber 28 formed in the feed tube 24.
- the air is then directed through slots 26 to the upper annular chamber 35 and from there to chamber 37.
- Ports 39 in the piston 30 then direct the pressurized air to an air passage 53 formed through the center of hammer bit 18 then out through one or more nozzles 54 formed in the bit cutting face.
- the air under pressure serves to clean the rock chip debris and other detritus such as accumulated water from the borehole bottom 8 prior to commencement of further drilling operations.
- the bit 18 contacts the bottom 8 (Fig. 3).
- the bit 18 and piston 30 is subsequently pushed back into housing 12 a distance wherein a shoulder 51 formed on the bit 18 contacts a rim 16 formed on the housing 12.
- air is shut off to chambers 35 and 37 when the piston moves over the fixed feed tube 24.
- the pressurized air is then redirected down through the diagonal ports 38 to slotted channels 40 and into chamber 41 below piston 30.
- the piston is then forcibly accelerated up cylinder walls 13 separating the impact surface 34 formed at the bottom of the piston from the top of the hammer bit 18 as illustrated in Fig. 1.
- the momentum of the piston mass carries the piston 30 to the upper end of chamber 37.
- Pressurized air is then redirected to the top of the piston (chamber 37) through slots 26 in feed tube 24 into piston ports 39.
- the piston then is accelerated down cylinder walls 13; end 34 of the piston subsequently impacting end 55 of the hammer bit 18 thereby completing the cycle (Fig. 8).
- FIGURE 3 depicts the piston 30 at the top of its travel within the cylindrical sleeve 13 formed by the housing wall prior to being accelerated toward the impact surface 55 of the hammer bit 18.
- a clutch mechanism generally designated as 56, engages a ball 58 with a helical groove 36 formed in the upper reduced diameter section 32 of piston 30 (FIG. 2).
- the piston moves in a clockwise direction as it moves down toward the hammer bit and, since the hammer bit is keyed to the piston by a flattened shaft 50, the bit moves rotationally in concert with the piston.
- the clutch slips hence preventing the piston (and hammer bit) from rotating in a counter-clockwise direction.
- the piston and hammer bit therefore is rotationally indexed in a clockwise direction only.
- the piston and hammer is preferably rotated on the downstroke of the piston for the following reasons; there is tremendous formation resistance imparted to the piston hammer mechanism on the upward cycle of the piston due to the fact that the lower chamber 41 is charged, forcing impact surfaces 34 and 55 apart and driving the cutting face 19 of the hammer bit into the formation, thereby resisting the turning or rotational force exerted on the piston by the ball 58 in the helical groove 36. Therefore, if the rotational forces were exerted on the piston and the bit on the downstroke, the bit is released from the formation and the rotational forces easily rotate or index the bit to its new position without unnecessary wear on the various sliding surfaces.
- FIGURE 4 illustrates a section taken through housing 12 (Fig. 1) showing the piston 30 with the flattened shaft 50 of the hammer 18 slidably retained within a sleeve 42 formed by the piston.
- the generally rectangular shaped shaft 50 with rounded ends, for example, is slidably retained within the complementarily shaped sleeve 42 formed in the piston 30.
- the central air passage 53 communicates with the nozzles 54 formed in the cutter face 19 of hammer 18.
- FIGURE 5 depicts a section through the hammer body 47 slidably retained in a cylindrical sleeve 17 fastened to the lower housing 12.
- Air passages 52 in the body 47 allow air under pressure to escape around the hammer body when the apparatus 10 is suspended above the borehole bottom 8 (Fig. 1).
- a free flow of air prevents debris (and water) from contaminating the air percussion apparatus while the mechanism is being tripped in and out of the borehole.
- FIGURE 6 details part of the clutch mechanism 56. This view locates the helical groove engaging balls 58 at the bottom of the helix 36 in the shank 32 of the piston 30 (Fig. 3). The balls 58 are each retained in a ball race 59; the race 59 being secured within ball and clutch housing 60.
- FIGURE 7 is a view taken through the clutch mechanism primarily comprising a multiplicity of "sprags" or clutch dogs 57 that allow rotation in one direction only. Since rotation preferably occurs only on the piston downstroke, the clutch dogs 57 engage the walls and prevent circumferential rotation of the ball races. The balls within the helical tracks 36 result in a clockwise rotation of the piston and hammer bit as heretofore described. On the upstroke of the piston the clutch releases the ball driver mechanism. The piston then travels up the housing 12 without rotation.
- FIGURE 8 illustrates the percussion tool 10 at the completion of an operating cycle.
- the hammer has been rotated or indexed the preferred 4 to 5 degrees prior to impact of the cutting face 19 of the hammer bit with the formation bottom 8. Since the hammer bit rotates independent of the drill string, it does not matter whether the drill string rotates, hence the air percussion tool is ideal for directional drilling operations wherein a bent housing sub-assembly is normally incorporated.
- FIGURES 9 and 10 illustrate an alternative piston shank sliding engagement mechanism.
- the piston 130 forms an internal sleeve 142 with, for example, three parallel, axially aligned semi-circular grooves 120 degrees apart formed in the sleeve wall of the body.
- the shank 150 of hammer bit 118 retains three ball bearings 160 that are aligned with each of the complementary grooves 143 formed in the piston body 131.
- the shank of the hammer bit then is slidably "splined" to the piston with a minimum of drag.
Description
- This invention relates to an air percussion hammer according to the preamble part of claim 1 and to a method according to the preamble part of
claim 10. More particularly, this invention relates to a downhole air compression hammer tool for directional drilling operations. The hammer impacts while simultaneously rotating the bit, thereby assuring maximum penetration of the bit in an earthen formation independent of the rotation of the drill string. - In percussion drilling the rock cutting mechanism is of an impacting nature rather than shearing. Therefore, the drill bit rotational parameters, e.g. torque and rpm, are not relevant from a rock formation breaking point of view, except for the necessity that the cutting elements of the bit need to be "indexed" to fresh rock formations. In straight hole air drilling, and especially in mining, this need is achieved by rotating the drill string slowly. This is accomplished in conventional hammer bit operations by incorporating longitudinal splines which key the bit body to a cylindrical sleeve at the bottom of the hammer (commonly known as the driver sub). The drill string rotation is then transferred to the hammer bit itself. Experience has proven that the bit optimum rotational speed is approximately 20 rpm for an impact frequency of 1600 bpm (beats per minute). This rotational speed translates to an angular displacement of approximately 4 to 5 degrees per impact of the bit against the rock formation. Another way to express this rotation is the cutters positioned on the outer row of the hammer bit move at the approximate rate of one half the cutter diameter per stroke of the hammer.
- A typical hammer bit connected to a rotatable drill string is described in US-A-4,932,483. The downhole hammer comprises a top sub and a drill bit separated by a tubular housing incorporating a piston chamber therebetween. A feed tube is mounted to the top sub and extends concentrically into the piston chamber. A piston is slidably received within the housing and over the feed tube. Fluid porting is provided in the feed tube and the piston to sequentially admit fluid in a first space between the piston and top sub to drive the piston towards the drill bit support and to a second space between the piston and the drill bit support to drive the piston towards the top sub.
- Rotary motion is provided to the hammer assembly and drill bit by the attached drill string powered by a rotary table typically mounted on the rig platform. The rotation of the drill string in the conventional hammer bit operation described above, takes away the ability to turn, build, or drop angle which is fundamental in directional drilling operations. A method for rotating the hammer bit without rotating the drill string is instrumental in any directional drilling or steerable system. Such a rotation can be accomplished by a motor mechanism positioned above the hammer that induces rotational motion to the bit itself.
- The air percussion hammer tool taught in this specification has particular application for use with the technology taught in US-A- Re. 33,751, for directional drilling utilizing a system approach to design the hardware for drilling according to the well plan. The bend angle of a bent housing, connected between the bit and downhole motor, the diameter of a plurality of stabilizers and placement of the stabilizers with respect to the drill bit are selected and predetermined on the basis of the desired well plan. With the use of a measurement while drilling sub, the direction of the progressing borehole is tracked from the surface. Direction changes as required are controlled from the surface simply by controlling rotation of the drillstring. For curved path drilling, only the downhole motor or the air percussion hammer of the present invention is rotated, causing the borehole to travel along the curve determined by the bend angle in the bent housing and the diameter and location of the concentric stabilizers. When straight hole drilling is required, both the downhole motor or air percussion hammer and the entire drill string are rotated, effectively nullifying the effect of the bend angle in the bent housing.
- US-A-4958691 discloses a down hole oil well tool for a pipe string. The tool is fluid-operated and moves upwardly and downwardly. It carries an impact receptive working member at its lower end that rotates when the working member is not subject to weight of the pipe string from above. A single rotation directional clutch is provided between the tool and the working member. As soon as the tool moves downwardly in relation to the working member, the working member is rotated until the tool subjects the working member to an impact. During subsequent upward movement of the tool relative to the working member the clutch is rotated without rotating the working member.
- According to the invention the air percussion hammer for directional drilling operations has a cylindrical housing having an upstream end connectable to a drill string component and a downstream end with means for mounting a hammer bit. A piston is slidably retained within the housing has a downstream end for striking a hammer bit mounted on the end of the housing. Pneumatic porting in the housing provides fluid flow for alternately driving the piston upwardly in the housing and driving the piston downwardly in the housing for striking a hammer bit. Means are provided for rotating the piston during the downward stroke of the piston and preventing rotation of the piston during the upward stroke of the piston. The hammer bit is keyed to the piston for permitting relative longitudinal movement of the hammer bit while preventing relative rotation between the hammer bit and the piston.
- The air percussion hammer converts axial motion of a reciprocating piston to rotary motion of a hammer bit as the bit works in a borehole.
- The kinetic energy of the reciprocating piston is employed to rotate the bit. The linear motion of the piston is converted into rotational motion by using one or more helical grooves formed by the piston body. To prevent the piston from oscillating in the rotary mode, an indexing clutch mechanism is provided to induce rotation of the bit in one direction only.
- The upper portion of the hammer bit (normally splined) is replaced by a shaft that is slidably engaged with and keyed to a complementarily shaped female receptacle or bore formed by the lower portion of a piston. The shaft of the hammer is, therefore, slidably engaged at all times to the base of the piston and is so designed to be rotated by the piston with a minimum of drag. Thus, axial motion between the piston and bit body is allowed but relative rotational motion is not, i.e. the bit would rotate if the piston rotates and vice versa.
- One or more longitudinal helical grooves are machined on the piston upper section. These grooves are keyed to an inner race of a "sprag" clutch assembly via dowel pins or spherical balls. The outer race of this clutch assembly is locked to the inner bore of a cylindrical hammer housing. The clutch sprags are set to clockwise motion and to prevent counter-clockwise rotational movement of the inner race with respect to the outer race.
- The downward motion of the piston, (the piston being coupled to the clutch through interaction between the helical groove, the engaged ball and the clutch) mandates either a counter-clockwise rotation of the inner race or a clockwise rotation of the piston. Since counter-clockwise rotation of the inner race is not possible, the piston must rotate clockwise when the piston moves downward. Similarly, the upward motion of the piston requires either the clockwise rotation of the inner race or the counter-clockwise rotation of the piston. Since the friction against the clockwise rotation of the inner race is significantly less than that against the piston/bit rotation, the inner race rotates clockwise and allows the piston to move straight upward. Therefore, on the downstroke of the piston the bit is forced to rotate clockwise; while on the upstroke the inner race rotates instead, thereby preventing the bit from "turning back".
- An air percussion hammer apparatus with means for rotating the hammer bit while its piston reciprocates in a housing independent of an attached drill string is disclosed. The bit rotating means comprises a cylindrical housing having an open upstream end connectable to a drill string component and a downstream end comprising means for mounting a hammer bit.
- A pneumatic feed tube has an open upstream end and a substantially closed downstream end, the upstream end of the feed tube being concentric with and fixed within the housing. The feed tube is positioned near the upstream end of the housing, the downstream end of the feed tube has one or more metered openings between the ends of the feed tube.
- A piston body is slidably retained within the housing. The piston body has upstream and downstream open ends with the upstream end being concentrically retained and slidably engaged with the downstream end of the feed tube. The downstream end of the piston forms a hammer striking surface. The piston further has at least one axially oriented helical groove in an outside wall of the upstream end of the piston and a pair of pneumatic communication ports between an outside wall of the piston and an interior chamber formed by the piston.
- More specifically, one of the ports leads between an interior chamber formed by the piston and the downstream end of the feed tube to a chamber formed between the upstream end of the piston and the cylindrical housing. The other of the ports leads from an interior chamber formed between an exterior wall of the piston and the housing and the downstream open end of the piston. One or the other of the ports in the body sequentially registers with the metered openings in the feed tube when the reciprocating piston is moved into alignment therewith during an operating cycle of the apparatus. A hammer bit body is slidably contained within the downstream end of the cylindrical housing. The bit body has an upstream shaft end adapted to slidably engage the bore formed in the downstream portion of the piston. Means are provided between the shaft of the bit and the bore of the piston to slidably key the shaft to the piston so that the bit rotates with the piston.
- A clutch means is contained within the housing and is positioned adjacent to and interconnected with the helical groove formed in the piston. The clutch mean serves to rotate the piston and the bit keyed thereto, incrementally and in one direction only, each time the piston reciprocates within the cylindrical housing during operation of the air percussion hammer.
- An advantage of the present invention over the prior art hammer tools is the ability to rotate the bit independent of any rotation of the drill string.
- The following description is made in conjunction with the drawings wherein:
- FIGURE 1 is a cross-sectional view of a hammer mechanism connected to a drill string, e.g. of a bent housing sub-assembly;
- FIGURE 2 is a perspective view of the hammer drive piston;
- FIGURE 3 is a cross-sectional view of the hammer mechanism, the piston being at the top of its stroke;
- FIGURE 4 is a cross section taken through 4-4 of FIGURE 1;
- FIGURE 5 is a cross section taken through 5-5 of FIGURE 3;
- FIGURE 6 is a cross section taken through 6-6 of FIGURE 3 illustrating a clutch mechanism;
- FIGURE 7 is a cross section taken through 7-7 of FIGURE 3;
- FIGURE 8 is a cross-sectional view of the percussion mechanism at the termination of one complete cycle;
- FIGURE 9 is a partially cutaway view of an alternative embodiment; and
- FIGURE 10 is a view taken through 10-10 of FIGURE 9.
- FIGURE 1 illustrates an air percussion drilling assembly generally designated as 10. The air percussion apparatus consists of a
cylindrical housing 12 that forms an upstream threadedfemale end 14 adapted to be connected to, for example, adrill string 15. The drill string may comprise a conventional bent housing sub-assembly utilized in a directional drilling operation (not shown). A hammer bit generally designated as 18 is slidably retained within the opposite ordownstream end 16 ofcylindrical housing 12. - A
check valve 20 is retained withinhousing 12 adjacent threadedend 14.Valve body 21 is biased closed byvalve spring 22 when the percussion apparatus is not functioning or the apparatus is "tripped" out of the borehole to prevent water or formation detritus from backing up the drill string. - A pneumatic feed tube generally designated as 24, is mounted within a feed
tube support member 25; the support member being secured withinhousing 12. Aninterior chamber 28 communicates with thedrill string 15 at an upstream end of thehousing 12 and with slotted, axially alignedopenings 26 formed in the feed tube wall at an opposite end of thetube 24. Asmall diameter choke 27 substantially closes off the downstream end of the tube just below the slottedopenings 26. - A pneumatic piston generally designated as 30 slidably engages a
cylinder wall 13 formed by thehousing 12. Thebody 31 of thepiston 30 has an upper, reduced diametercylindrical segment 32. An innercylindrical wall 33 in the piston overlaps and partially engages theoutside wall 29 of theconcentric feed tube 24. Anannular chamber 35 withinsegment 32 provides a pneumatic conduit for pressurized air to theslots 26 formed infeed tube 24, depending upon the axial position of thepiston 30 withinhousing 12. Thepiston body 31 also has diagonal ports orconduits slots 26 in thefeed tube 24. The ports direct pressurized air either toslots 40 formed in thepiston 30 and from there to achamber 41 formed below thepiston 30 in thehousing 12 or to anannular chamber 37 above the piston, depending on the axial position of the piston as the mechanism cycles through its operating modes. - FIGURE 1 illustrates the
hammer bit 18 positioned above aborehole bottom 8; the bit being suspended from a retainingring 49 attached to theinside wall 13 near the bottom of thehousing 12. As long as the bit remains off bottom 8,pressurized air 11 is directed down thedrill string 15 into thechamber 28 formed in thefeed tube 24. The air is then directed throughslots 26 to the upperannular chamber 35 and from there tochamber 37.Ports 39 in thepiston 30 then direct the pressurized air to anair passage 53 formed through the center ofhammer bit 18 then out through one ormore nozzles 54 formed in the bit cutting face. The air under pressure serves to clean the rock chip debris and other detritus such as accumulated water from theborehole bottom 8 prior to commencement of further drilling operations. - As the
air percussion assembly 10 is lowered down theborehole 6 formed inearthen formation 4, thebit 18 contacts the bottom 8 (Fig. 3). Thebit 18 andpiston 30 is subsequently pushed back into housing 12 a distance wherein ashoulder 51 formed on thebit 18 contacts arim 16 formed on thehousing 12. Upon contact, air is shut off tochambers feed tube 24. The pressurized air is then redirected down through thediagonal ports 38 to slottedchannels 40 and intochamber 41 belowpiston 30. The piston is then forcibly accelerated upcylinder walls 13 separating theimpact surface 34 formed at the bottom of the piston from the top of thehammer bit 18 as illustrated in Fig. 1. The momentum of the piston mass carries thepiston 30 to the upper end ofchamber 37. Pressurized air is then redirected to the top of the piston (chamber 37) throughslots 26 infeed tube 24 intopiston ports 39. The piston then is accelerated downcylinder walls 13; end 34 of the piston subsequently impactingend 55 of thehammer bit 18 thereby completing the cycle (Fig. 8). - FIGURE 3 depicts the
piston 30 at the top of its travel within thecylindrical sleeve 13 formed by the housing wall prior to being accelerated toward theimpact surface 55 of thehammer bit 18. As the piston moves downward toward the hammer bit, a clutch mechanism generally designated as 56, engages aball 58 with ahelical groove 36 formed in the upper reduceddiameter section 32 of piston 30 (FIG. 2). The piston moves in a clockwise direction as it moves down toward the hammer bit and, since the hammer bit is keyed to the piston by a flattenedshaft 50, the bit moves rotationally in concert with the piston. When the piston is cycled in the reverse or upward direction, the clutch slips hence preventing the piston (and hammer bit) from rotating in a counter-clockwise direction. The piston and hammer bit therefore is rotationally indexed in a clockwise direction only. - The piston and hammer is preferably rotated on the downstroke of the piston for the following reasons; there is tremendous formation resistance imparted to the piston hammer mechanism on the upward cycle of the piston due to the fact that the
lower chamber 41 is charged, forcing impact surfaces 34 and 55 apart and driving the cuttingface 19 of the hammer bit into the formation, thereby resisting the turning or rotational force exerted on the piston by theball 58 in thehelical groove 36. Therefore, if the rotational forces were exerted on the piston and the bit on the downstroke, the bit is released from the formation and the rotational forces easily rotate or index the bit to its new position without unnecessary wear on the various sliding surfaces. - FIGURE 4 illustrates a section taken through housing 12 (Fig. 1) showing the
piston 30 with the flattenedshaft 50 of thehammer 18 slidably retained within asleeve 42 formed by the piston. The generally rectangular shapedshaft 50 with rounded ends, for example, is slidably retained within the complementarily shapedsleeve 42 formed in thepiston 30. Thus, the hammer is keyed to the piston and rotates therewith. Thecentral air passage 53 communicates with thenozzles 54 formed in thecutter face 19 ofhammer 18. - One may also utilize conventional hammer bit splines as a means to key the shank of the hammer bit to the piston without departing from the scope of this invention.
- FIGURE 5 depicts a section through the
hammer body 47 slidably retained in acylindrical sleeve 17 fastened to thelower housing 12.Air passages 52 in thebody 47 allow air under pressure to escape around the hammer body when theapparatus 10 is suspended above the borehole bottom 8 (Fig. 1). As heretofore mentioned, a free flow of air prevents debris (and water) from contaminating the air percussion apparatus while the mechanism is being tripped in and out of the borehole. - FIGURE 6 details part of the
clutch mechanism 56. This view locates the helicalgroove engaging balls 58 at the bottom of thehelix 36 in theshank 32 of the piston 30 (Fig. 3). Theballs 58 are each retained in aball race 59; therace 59 being secured within ball andclutch housing 60. - FIGURE 7 is a view taken through the clutch mechanism primarily comprising a multiplicity of "sprags" or
clutch dogs 57 that allow rotation in one direction only. Since rotation preferably occurs only on the piston downstroke, theclutch dogs 57 engage the walls and prevent circumferential rotation of the ball races. The balls within thehelical tracks 36 result in a clockwise rotation of the piston and hammer bit as heretofore described. On the upstroke of the piston the clutch releases the ball driver mechanism. The piston then travels up thehousing 12 without rotation. - FIGURE 8 illustrates the
percussion tool 10 at the completion of an operating cycle. The hammer has been rotated or indexed the preferred 4 to 5 degrees prior to impact of the cuttingface 19 of the hammer bit with theformation bottom 8. Since the hammer bit rotates independent of the drill string, it does not matter whether the drill string rotates, hence the air percussion tool is ideal for directional drilling operations wherein a bent housing sub-assembly is normally incorporated. - FIGURES 9 and 10 illustrate an alternative piston shank sliding engagement mechanism. The
piston 130 forms aninternal sleeve 142 with, for example, three parallel, axially aligned semi-circular grooves 120 degrees apart formed in the sleeve wall of the body. Theshank 150 ofhammer bit 118 retains threeball bearings 160 that are aligned with each of thecomplementary grooves 143 formed in thepiston body 131. The shank of the hammer bit then is slidably "splined" to the piston with a minimum of drag.
Claims (10)
- An air percussion hammer comprising:a cylindrical housing (12) having an upstream end (14) connectable to a drill string component (15) and a downstream end (16) including means for mounting a hammer bit (18,118);a piston (30,130) slidably retained within the housing (12), a downstream end of the piston including a surface (34,134) for striking said hammer bit (18,118);fluid porting in the housing for alternately driving the piston (30,130) upwardly in the housing and driving the piston (30;130) downwardly in the housing for striking said hammer bit (18,118) characterized by:means (58,36) for rotating the piston (30,130) during the downward stroke of the piston;clutch means (56) for preventing rotation of the piston during the upward stroke of the piston; andkeying means (50,42;160,143) for permitting relative longitudinal movement while preventing relative rotation between the hammer bit (18,118) and the piston (30,130).
- An air percussion hammer as recited in claim 1, characterized in that the hammer bit (18,118) is mounted for reciprocal movement in the housing (12) and that means (38,39) for venting fluid from the hammer is provided when the hammer bit (18,118) is relatively down in the housing and for applying fluid pressure for driving the piston (30,130) when the hammer bit (18,118) is relatively up in the housing (12).
- An air percussion hammer as recited in any of the preceding claims, characterized in that the hammer bit (18,118) is slidably contained within the downstream end of the cylindrical housing (12), the hammer bit (18,118) comprising an upstream shaft end (50,150) axially slidable within the piston (30,130), the shaft end of the hammer being rotationally keyed to the piston (30,130) by an engagement means (42,160,143) such that the hammer bit (18,118) rotates in concert with the piston (30,130).
- An air percussion hammer as recited in any of the preceding claims, characterized in that the clutch means (56) comprises at least a pair of spherically shaped detents (58) for slidably engaging complementary shaped helical grooves (36) in the upstream end of the piston (30,130).
- An air percussion hammer as recited in any of the preceding claims, characterized in that the keying means for permitting relative longitudinal movement while preventing relative rotation between the hammer bit (118) and the piston (130) comprises three spherically shaped detents (160) between the upstream end of the shank (150) of the hammer bit (118) and the inside of the piston (130), the detents (160) being positioned about 120 degrees apart and slidably engaged with complementary shaped longitudinally extending grooves (143).
- An air percussion hammer as recited in any of the preceding claims characterized in that the means for rotating the piston (30) during the downward stroke of the piston comprises a helical groove (36) in the piston (30) with a helix angle and length sufficient for rotating the piston (30) approximately five degrees per cycle of the piston.
- An air percussion hammer as recited in any of the preceding claims characterized in that the means for rotating the piston (30) during the downward stroke of the piston comprises a helical groove (36) in the piston and a ball bearing (59) engaging the housing and the helical groove.
- An air percussion hammer as recited in claim 7 characterized in that there are three helical groove (36) formed in the upstream end of the piston (30) 120 degrees apart, each of the grooves (36) being engaged with a ball bearing (59) retained within the housing.
- An air percussion hammer as recited in any one of the preceding claims, characterized in that the means for rotating the piston (30) during the downward stroke of the piston and means for preventing rotation of the piston (30) during the upward stroke of the piston comprises:a pneumatic feed tube (24) having an open upstream end and a substantially closed downstream end, the feed tube being concentric with and fixed within the housing (12), the second end of the feed tube having one or more opening (26) between the first and second ends of the feed tube;the piston (30) having open ends, an upstream end (32) of the piston being reduced in diameter and slidably engaged around the second end of the feed tube (24), a downstream end of the piston being engaged with the interior of the housing and including a hammer bit striking surface (34);at least one axially oriented helical groove (36) in an outside wall of the reduced diameter upstream end (32) of the piston (30);at least a pair of pneumatic communication ports (38,39) through the piston (30), one of said ports leading between an interior chamber (35) in the piston and a chamber (37) formed between the open upstream end (32) of the piston and the cylindrical housing (12), the other of said ports leading between a chamber (41) formed between an exterior wall of the piston and the inside of the housing adjacent to the downstream end of the piston, one or the other of the ports in the body sequentially registering with the openings in the feed tube when the reciprocating piston is moved into alignment therewith during an operating cycle of the hammer bit (18); andclutch means (56) contained within the housing (12) adjacent to and interconnected with such a helical groove (36) in the reduced diameter end (32) of the piston (30), for rotating the piston (30) and the hammer bit (18) engaged therewith incrementally and in one direction only, each time the piston oscillates within the cylindrical housing during operation of the hammer.
- A method of rotating a hammer rock bit (18,118) of an air percussion hammer bit apparatus (10) while it reciprocates in a housing (12), the rotation of the bit being independent of an attached drill string characterized by the steps of;forming a cylindrical housing (12) with an open upstream end connectable to a drill string component (15) and a downstream end containing a hammer bit (18,118), the hammer bit being free to reciprocate longitudinally in the housing;mounting a longitudinally movable annular piston (30,130) in the housing defining a first chamber having an upstream end and a downstream end having a hammer striking surface (34,134), and including a helical groove (36) in an outside wall of the piston (30,130);
alternatelypassing air from a chamber (37) above the upstream end (32) of the piston (30,130) to the inside of the piston, andpassing air from the inside of the piston to a chamber (41) outside of the piston adjacent to the downstream end of the piston, for reciprocating the piston in the housing and striking the hammer bit (18,118);engaging the helical groove (36) with a detent (58) for rotating the piston during a downward stroke of the piston;rotating the hammer bit (18,118) in concert with the piston;
andpreventing rotation of the piston (30,130) during an upward stroke of the piston.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/916,285 US5322136A (en) | 1992-07-17 | 1992-07-17 | Air percussion drilling assembly |
US916285 | 1992-07-17 | ||
US07/916,046 US5305837A (en) | 1992-07-17 | 1992-07-17 | Air percussion drilling assembly for directional drilling applications |
US916046 | 1992-07-17 | ||
CA002099917A CA2099917C (en) | 1992-07-17 | 1993-07-06 | Air percussion drilling hammer for directional drilling applications |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0580056A1 EP0580056A1 (en) | 1994-01-26 |
EP0580056B1 true EP0580056B1 (en) | 1997-02-12 |
Family
ID=27169493
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93111146A Expired - Lifetime EP0580056B1 (en) | 1992-07-17 | 1993-07-12 | Air percussion drilling assembly for directional drilling applications |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0580056B1 (en) |
AU (1) | AU662063B2 (en) |
NO (1) | NO306570B1 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AUPO698197A0 (en) * | 1997-05-26 | 1997-06-19 | Sds Digger Tools Pty Ltd | A percussive hammer drill |
GB0108934D0 (en) * | 2001-04-10 | 2001-05-30 | Weatherford Lamb | Downhole Tool |
GB2389129B8 (en) * | 2002-05-29 | 2008-01-29 | Lattice Intellectual Property | Method and dual reamer apparatus for forming boredhole |
CN103939010B (en) * | 2013-01-17 | 2016-04-27 | 中国石油化工股份有限公司 | Percussion drill apparatus |
CN105525868B (en) * | 2014-09-28 | 2017-10-10 | 中国石油化工集团公司 | A kind of pulsating double direction impulse device |
CN106050159A (en) * | 2016-08-11 | 2016-10-26 | 中石化石油工程技术服务有限公司 | Drill string clutching tool |
CN107420031B (en) * | 2017-05-11 | 2023-07-07 | 能诚集团有限公司 | Impact drilling tool and impact drilling machine with same |
CN108331527B (en) * | 2018-01-17 | 2019-11-05 | 中国石油大学(华东) | A kind of down-hole motor driving generates the drilling speed device of impact vibration effect |
CN108360974B (en) * | 2018-04-12 | 2023-10-13 | 中国石油大学(北京) | Composite impact tool |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3912023A (en) * | 1974-03-28 | 1975-10-14 | Chicago Pneumatic Tool Co | Rock bit decoupler |
US3978931A (en) * | 1975-10-30 | 1976-09-07 | Boris Vasilievich Sudnishnikov | Air-operated drilling machine or rotary-percussive action |
DE2551303C3 (en) * | 1975-11-14 | 1981-04-02 | Institut gornogo dela Sibirskogo otdelenija Akademii Nauk SSSR, Novosibirsk | Compressed air operated deep hole hammer drill |
GB8406957D0 (en) * | 1984-03-16 | 1984-04-18 | Ennis M S J | Hammer |
US4819739A (en) * | 1984-08-31 | 1989-04-11 | Dresser Industries, Inc. | Fluid actuated rock drill hammer |
EP0303635B1 (en) * | 1987-02-25 | 1991-10-02 | Salzgitter Maschinenbau Gmbh | System with a hydraulic lifting generator for earth drilling |
US4924948A (en) * | 1988-11-15 | 1990-05-15 | Sandvik Rock Tools, Inc. | Shock absorbing bit retaining ring |
US4958691A (en) * | 1989-06-16 | 1990-09-25 | James Hipp | Fluid operated vibratory jar with rotating bit |
-
1993
- 1993-07-06 AU AU41789/93A patent/AU662063B2/en not_active Expired
- 1993-07-12 EP EP93111146A patent/EP0580056B1/en not_active Expired - Lifetime
- 1993-07-15 NO NO932568A patent/NO306570B1/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
NO932568L (en) | 1994-01-18 |
AU662063B2 (en) | 1995-08-17 |
NO306570B1 (en) | 1999-11-22 |
NO932568D0 (en) | 1993-07-15 |
AU4178993A (en) | 1994-01-20 |
EP0580056A1 (en) | 1994-01-26 |
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