WO1996007009A2

WO1996007009A2 - Casing and filling circulating head

Info

Publication number: WO1996007009A2
Application number: PCT/GB1995/001981
Authority: WO
Inventors: Arie Bezemer; Sigbjorn Ove Bjelland; Stephen Lee Albright; Jim Lawrence Hollingsworth; Michael Warren Hayes; Guy L. Mcclung
Original assignee: Weatherford/Lamb, Inc.; Lucas, Brian, Ronald
Priority date: 1994-08-20
Filing date: 1995-08-21
Publication date: 1996-03-07
Also published as: AU3262795A; WO1996007009A3

Abstract

A conventional mud saver valve (9) used to inhibit leakage from fill tubes (7) onto the working platform while new stands of casing are being fitted is replaced by a valve having a metal valve member (109') and a vulcanized rubber seat (120). In addition, a pressure gauge (128) is fitted to the cover (2) of the filling and circulating head (1) to detect excess pressure after circulation. A part (210) is also provided to release the filling and circulating head (1) from 'lock-up'. Further described is an extension sub which is installed above the filling and circulating head (1) to prevent 'lock-ups' of the top drive (6) fixed to elevator (13). The sub is locked in an extended position by hydraulic fluid in a lower chamber. In the case of a 'lock-up' the fluid is released into an upper chamber so that the length of the sub is shortened. The top drive can be lowered with respect to the casing (12) to release the elevator (13).

Description

FILLING AND CIRCULATING HEAD FOR USE IN THE CONSTRUCTION OF OIL AND GAS WELLS

This invention relates to a filling and circulating head for use in the construction of oil and gas wells. During the construction of oil and gas wells a bore is drilled into the ground. The bore is then lined with casing. A float valve is normally fitted at or near the bottom of the casing and the rate at which the casing can be lowered into the bore is limited by the resis- tance of the fluid in the bore.

Various proposals have been made to increase the rate at which the casing can be lowered down the bore. One common solution is to pump mud into the casing as it is lowered (run) into the well. This solution is very effective and various devices have been designed to facilitate the introduction of mud into the top of the casing.

One of the problems which can arise when lowering casing is that the casing may stick. This problem is particularly apparent when lowering casing down deviated bores. If the casing sticks the usual procedure is to "circulate" the mud. This involves pumping mud down the casing under pressure and allowing it to flow back to the surface in the annular space between the outside of the casing and the bore. Generally, circulating will free any minor obstruction and allow the running of the casing into the bore to be continued.

It will be appreciated that for the purposes of running casing the mud is simply allowed to flow into the casing whilst for circulation the top of the casing must be sealed so that the interior of the casing can be pressurized, typically from 100 to 300 bar.

One very effective device for use in running and circulating is the LaFleur Autoseal Circulating Head which is described in greater detail hereinafter. In use, mud is introduced into the casing via a flexible mud supply hose generally referred to as a "fill tube" while casing is being run. It will be appreciated that it is necessary to remove the fill tube each time a stand of casing has to be added to the casing string. Conventionally the fill tube is pivoted to one side of the drill string while the new stand is moved into place.

In order to inhibit mud dropping onto the working platform and making it very slippery and dangerous it is usual to provide the lower end of the fill tube with a valve which us usually referred to as a "mud saver valve" .

Known mud saver valves have several disadvantages. In particular, they employ metal to metal seals which are rapidly eroded by the abrasive flow of mud rending the valves non-sealing. In addition, they are mounted in a length of rigid tubing the inner wall of which rapidly erodes, particularly during circulation. When the LaFleur Autoseal Circulating Head is used for circulating there is considerable pressure below the head. Normally, this pressure drops immediately the supply of mud is stopped. However, it is possible for the mud in the casing to be under considerable pressure. This could, of course, be dangerous if the head were to be removed under such conditions. In order to check whether the casing is under pressure the mud saver valve used in the LaFleur Autoseal Circulating Head incorpor¬ ates a small passageway with a check valve arranged so that if the casing is under pressure the pressure will be transmitted through the small passageway to the pressure gauges downstream of the mud pumps. Unfortuna¬ tely, this arrangement is not totally reliable.

According to one aspect of the present invention there is provided a filling and circulating head, for use in the construction of oil and gas wells, having a fill tube provided with a valve which comprises a valve seat, a valve member engageable with said valve seat, and means biasing said valve member towards said valve seat, characterised in that at least one of said valve seat and said valve member comprises an elastomeric material.

Preferably, said elastomeric material comprises vulcanized rubber or natural or synthetic rubber. Advantageously, said fill tube comprises a length of rigid tube and said valve is mounted in said rigid tube.

Preferably, said rigid tube is provided with at least one removable liner mounted downstream of said valve seat.

Advantageously, said circulating head is provided with a pressure gauge to measure any pressure in said head after a circulating operation.

Preferably, said circulating head is provided with a vent for allowing the controlled reduction of pressure from said head after a circulating operation.

As more fully explained hereinafter the filling and circulating head is lowered onto the casing before circulation is commenced. The elevator is then applied to support the casing. In order to release the elevator it is necessary to lower the top drive relative to the elevator. However, if the filling and circulating head is initially lowered into contact with the casing this is not possible resulting in "lock-up". Although various technigues can be used for releasing the elevator in this situation they are all comparatively time consum¬ ing.

As a simple solution the present invention provides a filling and circulating head characterised in that it is provided with a part of adjustable length with a bore to allow the flow of fluid therethrough.

Preferably, said part defines a first fluid cham¬ ber and a second fluid chamber.

In one embodiment, said first fluid chamber and said second fluid chamber are interconnected.

Preferably, said first fluid chamber and said second fluid chamber are interconnected internally of said part.

Another embodiment includes a first control circuit associated with said first fluid chamber and a second control circuit associated with said second chamber and wherein said first control circuit is separate and distinct from said second control circuit.

A further embodiment includes a single pump, a cross-over valve and a reservoir so arranged that when said single pump is in use fluid can be directed to one of said first fluid chamber and said second fluid cham¬ ber and simultaneously returned to said reservoir from the other of said first fluid chamber and said second fluid chamber.

Preferably, said part comprises an expansion sub having a body with a nose protruding therefrom, a piston mounted on said nose, a body member slidably accommoda¬ ting said expansion sub and defining a first chamber with the body of said expansion sub and a second chamber with said piston.

For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which: -

Figure 1 is a schematic sectional side view of a prior art LaFleur filling and circulating head in use during the running of casing;

Figure 2 is a schematic sectional side view of the prior art circulating head in use during circulating;

Figure 3 shows, to an enlarged scale, a detail of the prior art filling and circulating head shown in Figure 1;

Figure 4 is a schematic sectional side view of part of a fill tube provided with a valve in accordance with the invention; Figure 5 is a schematic sectional side view of a filling and circulating head in accordance with the present invention during circulating;

Figure 6 is a vertical section through one embodi¬ ment of part of a filling and circulating head in accor- dance with the invention in an expanded position;

Figure 7 is a vertical section through the part shown in Figure 6 but in a contracted position;

Figure 8 is an exploded view of the part shown in Figures 6 and 7; Figure 9 is a vertical section through another embodiment of part of a filling and circulating head in accordance with the invention in a contracted position; and

Figure 10 is a schematic diagram of a further embodiment of part of a filling and circulating head in accordance with the invention.

Referring to Figure 1 there is shown a filling and circulating head which is generally identified by refer¬ ence numeral 1. The filling and circulating head 1 comprises a cover 2 which has a flared skirt 3.

A steel tube 4 extends through the cover 2 and is connected at its upper end to a pup joint 5 which is suspended from a top drive 6. A fill tube 7, often referred to as a "stinger", extends downwardly from the bottom of the steel tube 4 and includes a length of flexible tube connected to a short length of rigid tube 8 which accommodates a valve 9 which is sometimes referred to as a "mud-saver valve" . When casing is run into a bore additional stands of casing are successively added to the casing already in the bore and then lowered into the bore. Thus, after a length of casing has been run into a bore 10 slips 11 are applied to hold the casing already in the bore 10. A new stand of casing 12 is then moved into position above the slips 11 and connected to the casing.

The top drive 6 is then lowered until the elevator 13 can engage the casing 12 below the collar 14. As the top drive 6 is lowered the fill tube 7 is guided into the casing 12.

After the elevator 13 is connected a valve 27 is opened and a predetermined volume of mud is pumped from mud pump 28 through steel tube 4, and fill tube 7 into the casing 12. The volume of mud is such that the casing 12 is filled to just below the lowermost extrem¬ ity of the fill tube 7.

The top drive 6 is raised slightly on the draw works, the slips 11 released and the top drive 6 lowered until the socket 14 reaches the slips 11 whereupon the slips 11 are applied, the elevator 13 disconnected and the fill tube 7 and elevator 13 removed from the casing 12 in preparation for the addition of the next stand of casing.

It will be appreciated that if the valve 9 does not seat properly then mud will be spilt on the working platform each time the fill tube 7 is removed from the casing 12.

If the casing sticks, slips 11 are applied and elevator 13 relaxed. Top drive 6 is then lowered until the cover 2 of the filling and circulating head 1 sits over the top of the casing 12 as shown in Figure 2. In this position the seals 15 engage the wall of the casing beneath the socket 14. The elevator 13 is then reap- plied to the casing 12. Top drive 6 is then raised slightly to raise the casing 12 to enable the slips 11 to be released.

Mud is then pumped down the casing 12. The mud flows radially outwardly at the bottom of the casing 12 and upwardly to the surface through the narrow annular passageway between the outside of the casing 12 and the bore 10. Typically, the mud is pumped down the casing 12 at a pressure of from 100 to 300 bar. The filling and circulating head 1 is held down by the weight of the top drive 6 and also by the seals 15 which are applied against the wall of the casing 12 by the pressure of the mud.

During this time casing 12 is "worked", i.e. raised and lowered until the obstruction is cleared or until the uppermost collar has been lowered to or just above the slips 11. The valve 27 is then closed and a pres¬ sure gauge 24 immediately downstream of the valve checked to make sure the mud in the casing 12 is not under pressure. If excess pressure is detected valve 25 is opened to allow mud and gas to flow to tank 26. When the pressure reaches the desired level valve 25 is closed. The slips 11 are then applied and the top drive 6 lowered slightly to enable the elevator 13 to be disconnected. The top drive 6 is then raised to lift the filling and circulating head 1 clear of the casing 12 after which the next stand of casing is added and circulation continued if the obstruction is still pre¬ sent or simply run if the obstruction has been cleared.

The valve 9 comprises a metal valve member 9 ' and a metal valve seat 16. The metal valve member 9' is biased upwardly by a spring 17 which acts against a spider mounted on the rigid tube 8. In use, the mud flowing past the valve seat 16 is deflected radially outwardly by the valve member 9'. Small guantities of solids in the mud make it extremely abrasive and rapidly damage the valve seat 16 and the wall of the rigid tube 8 in the area 18.

As shown in the enlarged section of Figure 3, the valve member 9' comprises a hollow stem 19 which con¬ tains a seat 20, a ball 21 and two channels 22 and 23. When the filling and circulating head 1 is in the circulating mode and the supply of mud has been cut off any pressure in the mud in the casing 12 is transmitted through the hollow stem 19, past the ball 21, through the channels 22 and 23 to the pressure gauge 24. If any pressure is present valve 25 is opened to vent the mud to tank 26.

Unfortunately, problems arise with this arrange¬ ment. At one extreme the channels 22 and 23 can become blocked. At the other extreme the ball 21 can fail to seat properly thus allowing mud to ooze onto the working platform while new strands of casing are being filled during a running operation.

Figure 4 shows a valve in accordance with the invention. Parts having similar functions to parts shown in Figures 1, 2 and 3 have been given the same reference number increased by 100. In particular, the rigid tube 108 is provided with a valve 109 which com¬ prises a valve member 109' and a valve seat 120. The valve member 109 ' includes a stem 119 which is slidably mounted in a spider 128 and biased upwardly by a spring. Unlike the prior art the stem 119 is not hollow. In addition the valve seat 120 is made of vulcanized rubber supported by a metal flange 126. The spider 128 is welded to a stainless steel liner 130 which is held in position by a stainless steel liner 127.

In trials, the valve 109 has successfully closed repeatedly whilst running casing and even after repeated circulation. The stainless steel liners 127 and 130 can readily be removed and replaced as required whereas the entire rigid tube 8 had to be replaced in the prior art. In this connection the rigid tube 108 may be removed from the fill tube and the metal flange 126, valve seat 120, valve member 109' , stainless steel liner 130 and stainless steel liner 127 removed upwardly. Alternat- ively, the tip 131 of the fill tube may be threadedly mounted on the rigid tube 108 so that the valve 109 may be serviced without removing the rigid tube 108.

In order to check the pressure in the casing 12 during or after circulation a pressure gauge 128 is mounted on the cover 2 and provides a reliable indica¬ tion as to the pressure in the casing 12. If pressure remains in the casing 12 after the valve is closed valve 129 may be opened to allow mud to flow back to the reservoir 26 via a hose (not shown). It will be noted from Figure 2 that during circula¬ tion the filling and circulating head 1 is NOT lowered into contact with the collar 14 but is spaced therefrom. This is extremely important. In particular, after the elevator 13 has been applied and used to support the casing string it can only be released easily by lowering the top drive 6 by a few centimetres relative to the casing 12. If the elevator 13 is initially applied when the top of the filling and circulating head 1 is in contact with the top of the collar 14 the top drive 6 cannot be released by lowering the top drive 6 relative to the casing 12 as no such movement is possible. This condition is referred to as "lock-up" and, should it occur, is time consuming and expensive to deal with.

In order to help reduce this problem it has been proposed to provide a thick resilient rubber bumper on the underside of the top of the filling and circulating head 1. In normal use the bumper provides a minimum distance between the underside of the top of the filling and circulating head 1 and the collar 14 and can be compressed by the top drive 6 sufficient to enable the elevator 13 to be released. However, it does not func¬ tion properly if the top drive 6 is lowered too much in the first place. This is particularly likely to happen when the top drive 6 is particularly heavy. Referring now to Figures 6 to 8 there is shown a part which can be used to overcome this problem. The part, which is generally identified by reference numeral 210 can be visualised as a replacement for the sub 5 shown in Figures 1, 2 and 5. As can be best seen in Figure 8, the part 210 comprises an expansion sub 220, an outer sleeve 230, a separator sub 240, a piston 250, and an upper sub 260 with a flow director 262.

The expansion sub 220 has a body 221; a lower exteriorly-threaded end 222 for mating directly or indirectly with the filling and circulating head, a central fluid flow bore 223 through the body 221; an upper surface 225; and a nose 226.

A wear ring 227 is mounted in a recess 228 in the body 221. A seal 229 is mounted in a recess 281 in the body 221 to seal the interface between the expansion sub 220 and the outer sleeve 230. Snap ring recesses 282 and 283 receive and hold snap rings 284 and 285 as described below. The outer sleeve 230 has a body 231 with an upper interiorly threaded end 232. An inner shoulder 233 abuts a lower end 242 of the separator sub 240. A portion of the body 221 and nose 226 of the expansion sub 220 move in an inner bore 234 of the outer sleeve 230. A wiper 35 in a recess 236 wipes the outer surface of the expansion sub 220.

The separator sub 240 has a body 241; the lower threaded end 242 of which mates with the upper interior¬ ly threaded end 232 of the outer sleeve 230; a central flow bore 311; and an upper interiorly threaded end 243 which mates with a lower end 266 (exteriorly threaded) of the upper sub 260.

A flow port 244 through the body 241 communicates with a flow line 245 which communicates with the inter- ior of the outer sleeve 230. A flow port 246 communi¬ cates with a flow line 247 that communicates with an interior chamber of the upper sub 260. A wear ring 248 in a recess 249 abuts the nose 226 of the expansion sub 220. A seal 286 in a recess 287 seals the interface between the nose 226 and the bore 227 of the separator sub 240. A seal 288 in a recess 289 seals the interface between the separator sub 240 and the outer sleeve 230.

The upper sub 260 has a body 261; an upper inter¬ iorly-threaded end 263; a central flow bore 264; and a chamber 265. The flow director 262 has an upper shoul¬ der 267 which rests on a shoulder 268 of the upper sub 260. A cylindrical pipe portion 269 of the flow direc¬ tor 262 has an inner fluid bore 291. A lower end 292 of the cylindrical pipe portion 269 projects into an upper end 294 of the central flow bore 223 of the expansion sub 220. The upper end 294 of the expansion sub 220 moves upwardly on and around the lower end 292 of the flow director 262. Thus internal parts of the upper sub 260 and the piston 250 are not exposed to fluids (e.g. corrosive or erosive fluids) flowing through the upper sub 260 and down through the expansion sub 220. A seal 295 in a recess 296 seals the interface between the upper sub 260 and the separator sub 240.

The piston 250 has a body 251 with a central bore 252. The piston 250 is secured to the nose 226 of the expansion sub 220 with the snap ring 284, part of which resides in a recess 301 in the body 251 and by the snap ring 285 which abuts a lower end 253 of the piston 250. A wear ring 254 in a recess 255 abuts an interior sur- face of the chamber 265 of the upper sub 260. A seal 256 in a recess 257 seals the interface between the body 251 of the piston 250 and the nose 226 of the expansion sub 220. Seals 258 in recesses 259 seal the interface between body 251 of the piston 250 and the interior of the chamber 265 of the upper sub 260. In one aspect the flow director is not secured in a fluid tight manner in the upper sub 260 so that fluid (e.g. air or drilling fluid) above the piston 250 may escape from the upper chamber 265 as the piston 250 moves upwardly therein. In another aspect the flow director is sealed fluid- tight in the upper sub 260 and a fluid purge device or vent is provided through the wall of the upper sub 260. In another aspect there is no fluid in the upper cham¬ ber. In operation, the part 210, with its components in the position shown in Figure 6, is positioned above the filling and circulating head. The head is then applied to an end of a piece of casing. The piston 250 is at the bottom of the chamber 265 in the upper sub 260 and, therefore, the expansion sub 220 is at the lower limit of its travel with respect to the outer sleeve 230 and the separator sub 240. The piston 250 and the expansion sub 220 are maintained in this position by the presence of hydraulic fluid maintained in a lower chamber 305 (defined by the upper surface 225 of the expansion sub 220, a portion of the outer surface of the nose 226, a portion of the inner surface of the outer sleeve 230, and a portion of the surface of the lower end 242 of the separator sub 240) by a closed valve 310. In the event that the filling and circulating head becomes locked-up as described hereinbefore, the valve 310 is opened. The flow line 312 provides for fluid communication between the lower chamber 305 and the upper chamber 365. The top drive can then be lowered to replace the elevator. In particular, downward force on the part 210 above the expansion sub 220 displaces the hydraulic fluid in the lower chamber 305 out from the chamber, through the flow line 312, and into flow port 246. This hydraulic fluid pushes up on the piston 250 and the piston 250 and expansion sub 220 move with respect to the other components of the part 210. This effectively shortens the overall length of the part 210 and provides a range of movement for the top drive, allowing the travelling block to be lowered and eleva- tors supporting the tubulars to be released. Due to the series of flow bores through each component of the part 210, mud or other fluid is permitted to circulate through the part 210 at all times. If desired a pump may be used in the flow line 112. The part 210 is returned to its initial lengthened position by opening the valve 210, disengaging the elevators, and lifting the travelling block to freely suspend the filling and circulating head below the block. The combined weight of the filling and circula- ting head, the expansion sub 220 and other components acts to displace fluid from the upper chamber 265 through the port 246 and line 312 into the lower chamber 305. When fluid transfer is complete, the valve 310 is closed and the part is again ready for the next opera- tion. It will be noted that, if desired, the part 210 may be used to set the initial distance between the filling and circulating head and the elevators in accordance with the manufacturers specifications. Fig. 9 illustrates a part 411 which is like the part 210 with similar parts bearing the same identifying numerals but in the 400 series. There is no flow line 312 and no valve 310 in the part 411. Instead, the lower chamber 505 has its own fluid supply system 520 with a flow line 521, pump 522, flow line 523, and fluid reservoir 524; and the upper chamber 465 has its own fluid supply system 530 with a flow line 531, pump 532, flow line 533 and fluid reservoir 534. A fluid flow line 552 bypasses the pump 530 and a three-way valve 550 controls flow in the line 531 and the line 552, permit¬ ting no flow, flow to the pump 532 or flow through the line 552. Similarly a flow line 556 bypasses the pump 522 and a three-way valve 554 controls flow in the line 521 and the line 556. In another aspect, the lower chamber 505 is eliminated and the flow lines 521, 523, 556, pump 522 and reservoir 524 are eliminated; i.e., this embodiment uses only one external reservoir and one internal chamber to move the piston.

Fig. 10 illustrates a system 600 according to the present invention which includes a part 610 which is generally similar to the part 210. A fluid flow line 601 connects an upper chamber ( similar to the chamber 265 of the part 210) to a cross-over valve 603. A fluid flow line 602 connects a lower chamber ( similar to the lower chamber 305) to the cross-over valve 203. A pump 606 in a line 605 pumps hydraulic fluid from a reservoir 607. When the valve 603 is in a first position the hydraulic fluid passes through the line 601 into the upper chamber whilst hydraulic fluid returns from the lower chamber to the reservoir 607 via lines 602 and 604. With the valve 603 in a second position, the pump 606 pumps fluid from the reservoir 607, through line 604, cross-over valve 203, and line 602 to the lower chamber whilst the hydraulic fluid returns from the upper chamber to the reservoir 607 via line 601, valve 603 and line 604. In another position the cross-over valve 203 closes both lines 601 and 602 to flow.

Claims

1. A filling and circulating head (1), for use in the construction of oil and gas wells, having a fill tube (7) provided with a valve (109) which comprises a valve seat (120), a valve member (109' ) engageable with said valve seat (120), and means biasing said valve member (109' ) towards said valve seat (120), characterised in that at least one of said valve seat (120) and said valve member (109' ) comprises an elastomeric material.

2. A valve as claimed in Claim 1, wherein said elasto¬ meric material comprises vulcanized rubber.

3. A filling and circulating head as claimed in Claim 1 or 2, wherein said fill tube (7) comprises a length of rigid tube ( 108 ) and said valve ( 109 ) is mounted in said rigid tube ( 108) .

4. A filling and circulating head as claimed in Claim 3, wherein said rigid tube (108) is provided with at least one removable liner (127, 130) mounted downstream of said valve seat (120).

5. A filling and circulating head as claimed in any preceding Claim, wherein said filling and circulating head (1) is provided with a pressure gauge (128) to measure pressure in said filling and circulating head (1) after a circulating operation.

6. A filling and circulating head as claimed in any preceding Claim, wherein said filling and circulating head (1) is provided with a vent (129) for allowing the controlled reduction of pressure from said filling and circulating head (1) after a circulating operation.

7. A filling and circulating head characterised in that it is provided with a part (210; 410; 610) of adju¬ stable length with a bore to allow the flow of fluid therethrough.

8. A filling and circulating head as claimed in Claim 7, characterised in that said part (210; 410; 610) de- fines a first fluid chamber (305; 505) and a second fluid chamber (265; 465).

9. A filling and circulating head as claimed in Claim

8, characterised in that said first fluid chamber (305) and said second fluid chamber (265) are interconnected

(112; 312).

10. A filling and circulating head as claimed in Claim

9, wherein said first fluid chamber and said second fluid chamber are interconnected internally of said part.

11. A filling and circulating head as claimed in Claim 8, characterised in that it includes a first control circuit (522) associated with said first fluid chamber (505) and a second control circuit (532) associated with said second chamber (465) and wherein said first control circuit is separate and distinct from said second con¬ trol circuit.

12. A filling and circulating head as claimed in Claim 8, characterised in that it includes a single pump (606), a cross-over valve (603) and a reservoir (607) so arranged that when said single pump ( 606 ) is in use fluid can be directed to one of said first fluid chamber and said second fluid chamber and simultaneously re¬ turned to said reservoir from the other of said first fluid chamber and said second fluid chamber.

13. A filling and circulating head as claimed in any of Claims 8 to 12, characterised in that said part (210; 410) comprises an expansion sub (220; 420) having a body (221; 421) with a nose (226; 426) protruding therefrom, a piston (250; 450) mounted on said nose (226; 426), a body member (230, 240, 250; 430, 440, 450) slidably accommodating said expansion sub (220; 420) and defining a first chamber (305; 505) with the body (221; 421) of said expansion sub (220; 420) and a second chamber (265; 465) with said piston (250; 450).