VALVE FOR USE IN FLOAT EQUIPMENT

Abstract: A valve (100) for use in a float collar or a float shoe is held open by frangible pins (129). As the valve is lowered down a well bore, the hydrostatic pressure acts on an end plate (119) of a piston (116). At a given depth, the frangible pins (129) fail and the piston (116) thrusts the head (112) of the valve (100) into sealing engagement with the body (101) of the valve (100).

Description: VALVE FOR USE IN FLOAT EQUIPMENT This invention relates to valves for use in float equipment and to float equipment including said valves. After a well bore has been drilled it is lined with casing and the annular space between the well bore and the casing filled with cement. The cement is pumped down the inside of the casing and passes radially out¬ ward around the bottom of the casing and travels upward¬ ly into the annular space between the well bore and the casing where it is allowed to set. In order to prevent the cement returning into the casing before it sets a float collar or a float shoe is situated near or at the bottom of the casing. Originally, float collars and float shoes were merely non-return valves. The difficulty with using such float equipment was that it limited the rate at which casing could be low¬ ered into the well since the casing tended to float and could only be lowered at an acceptable rate by pumping liquid into the casing as it was lowered. In order to meet this problem valves were designed for use in float equipment which could be held open as the casing was lowered and then converted to a simple non-return valve. Many ingenious mechanical devices have been pro¬ posed for this purpose. Some rely on remote control devices and timing devices whilst others rely on a force being applied through the casing, for example by drop¬ ping a ball down the casing or forcing a charge of cement through the valve. The present invention approaches the problem from a different perspective and provides a valve for use in float equipment which valve comprises means to hold said valve in an open position and means responsive to hydro- static pressure to move said valve towards a closed position . Other features are set out in Claims 2 et seq. For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a side cross-sectional view of a first embodiment of a valve according to the present invention in a partially open position; Fig. 2 is a side cross-sectional view of the valve shown in Fig. 1 in a closed position; Fig. 3 is a section taken on line III-III of Fig. 1; Fig. 4 is a side cross-sectional view of a second embodiment of a valve according to the present invention in a partially open position; Fig. 5 is a side cross-sectional view of a third embodiment of a valve according to the present invention in a closed position; Fig. 6 is a side cross-sectional view of a fourth embodiment of a valve according to the present invention in a partially open position; Fig. 7 is a side cross-sectional view of a fifth embodiment of a valve according to the present invention in a partially open position; Fig. 8 is a side cross-sectional view of a sixth embodiment of a valve according to the present invention in a partially open position; Fig. 9 is a side cross-sectional view of a seventh embodiment of a valve according to the present invention in a partially open position; and Fig. 10 is a side cross-sectional view of an eighth embodiment of a valve according to the present invention in a partially open position. Referring now to Fig. 1, there is shown a valve which is generally identified by the reference numeral 100. The valve 100 has a body 101 which comprises an upper section 102 secured to a lower section 103. A stem support 104 extends across a central fluid flow channel 105 of the body 101. The stem support 104 has a hub 106 and arms 107 between which fluid flows in use. A valve member 108 having a stem 109 with a lower end 110 is movably mounted in a central channel 111 of the stem support 104. The head 112 of the valve member 108 is movable to sealingly contact an interior surface 113 of the body 101 and prevent fluid flow therethrough. The valve member 108 also has an exterior area 114 which is movable to contact a concave surface 115 on the stem support 104 in response to fluid flowing downwardly through the valve 100. Movement of the valve member 108 can effect partial restriction of the central flow channel 105 to control fluid flow without entirely stopping it. A piston 116 has an upper end 117, a lower end 118 and an end plate 119. Four holes 120 extend through the piston 116 as shown. The upper end 117 of the piston 116 is screwed into a piston recess 121 in the stem 109. An upper shoulder 122 of the piston 116 is movable to abut the bottom of the stem 109 to limit movement of the piston 116. The piston 116 is slidably disposed in a central channel 123 of a piston housing 124. The lower end 118 of the piston 116 and the end plate 119 are disposed for slidable movement in a cham- ber 125 formed in the lower end 126 of the piston hous¬ ing 124. The chamber 125 is filled with a gas (e.g. air, nitrogen, helium, or other compressible material). The chamber 125 is defined between an 0-ring 127 in a recess in the piston housing 124 and an 0-ring 128 in a recess in the end plate 119. Frangible members 129 extend through holes 130 in the piston housing 124 and through the holes 120 in the piston 116. A spring 131 acts between the head 112 of the valve member 108 and the stem support 104. The end plate 119 is provided with a socket 132 for accommodating a tool (not shown) to rotate the piston 116. In use, a tool is first inserted in the socket 132 and rotated so that the piston 116 rotates relative to the stem 109 until the head 112 is spaced at a desired distance from the interior surface 113 of the body 101. The valve 100 (which usually forms part of a float collar or a float shoe) is attached to a casing string and lowered down a well bore. The partially open valve 100 allows liquid in the well bore to enter the inside of the casing at a controlled rate and allows the casing to be lowered more rapidly than if a convention float valve with a simple non-return valve had been used. As the casing is lowered deeper into the well bore the hydrostatic pressure on the end plate 119 increases. At a certain pressure the frangible members 129 fail. The head 112 rises into sealing engagement with the interior surface 113 of the body 101 and the piston housing 124 falls away from the stem support 104. Fig. 4 shows a second embodiment of a valve accord¬ ing to the present invention which is generally identi¬ fied by reference numeral 200. Features of the valve 200 which are similar to those shown in the valve 100 of Figures 1 to 3 have been identified by corresponding reference numerals but in the "200" series. The valve 200 has a body 201 which includes an upper section 202 and a lower section 203 with a stem support 204 thereacross. A valve member 208 having a stem 209 with a lower end 210 is movably mounted in a central channel 211 of the stem support 204. The valve member 208 has a head 212 for sealingly contacting the interior of the body 201. A piston 216 has an upper end 217 screwed into a piston recess 221 in the stem 209, a lower end 218, and an end plate 219. The piston 216 is movably disposed in a central channel 223 of a piston housing 224. A cham¬ ber 225 is defined between the piston housing 224, the lower end 218 of the piston 216 and the end plate 219 in a manner similar to chamber 125 of the embodiment shown in Figures 1 to 3. A frangible member 129 in the form of a diaphragm is threadedly mounted on the bottom of the piston hous- ing 224 as shown. The valve 200 is used in a similar manner to the valve 100. At the commencement of an operation the frangible member 229 is unscrewed and the valve 200 is opened by inserting a tool in socket 232 and rotating it so that the end plate 129 acts against the gas in the chamber 125 which may be compressed if desired. The frangible member 129 is then replaced. As the casing string is lowered down the well bore the hydrostatic pressure on the frangible member 229 is increased until it ruptures allowing liquid to enter the chamber 233 and urge the piston 216 upwardly so that the head 212 comes into sealing engagement with the body 201. Figure 5 shows a third embodiment of a valve ac- cording to the present invention. The valve, which is generally identified by reference numeral 300 comprises a body 301 having an upper section 302 and a lower section 303. The upper section 302 includes a tubular portion 334. A valve member 308 comprising a head 312 and a stem 309 is mounted in the body 301 with the stem 309 extend¬ ing upwardly from the head 312. The upper end of the stem 309 is provided with a recess 321 into which a connector 335 is screwed. The connector 335 is also connected to the end plate 319 of a piston 316, the upper end of which is slidably located in a hole 336 in a guide plate 337. The piston 316 is mounted in a piston housing 324 the upper end of which bears against the guide plate 337 and the lower of which is slidably located in a hole 338 in a guide plate 339. In operation the holes 320 in the stem 309 are first aligned with the holes 330 in the piston housing 324 and the required number of frangible members in the form of pins inserted therein. The valve member 308 is then rotated relative to the connector 335 to give the desired opening of the valve 300. As the casing is lowered down the well bore the hydrostatic pressure on the end plate 319 increases until the frangible members fail. At this point the piston 316 rises lifting the connector 335 and the head 312 into sealing engagement with the body 301. The chamber 325 is compressed to minimal volume. Fig. 6 illustrates a fourth embodiment of a valve in accordance with the invention. The valve, which is generally identified by the reference numeral 400 is generally similar to the valve 100 of Figs. 1 to 3. In particular, the valve 400 has a body 401 having an upper section 402 and a lower section 403. A stem support 404 extends across the valve body 401 and accommodates the stem 409 of a valve member 408. The valve member 408 is provided with a head 412 for sealingly contacting an interior surface 413 of the valve body 401. The stem 409 is provided with a piston recess 421 which accommo- dates the upper end 417 of a piston 416. The piston 416 is provided with a hole 420 and a slot 420'. Frangible members 429 and 429 ' extend through holes 430 in piston housing 424 and through the hole 420 and the slot 420' respectively. Frangible member 429 has a breaking force of 1 unit and 429 ' has a breaking force of 5 units. In operation, as the valve 400 is lowered down a well bore the hydrostatic pressure increases. When the pressure on the end plate 419 of the piston 416 reaches a certain level frangible member 429 fails. This allows the piston 416 to move upwardly but only to a position where the bottom of the slot 420' engages the frangible member 429' . This movement only partially closes the valve 400 since the head 412 does not contact the inter- ior surface of the valve body 401 at this stage. As the valve 400 is further lowered the hydrostatic pressure progressively increases until the frangible member 429' fails at which time the valve 400 closes. Fig. 7 shows a fifth embodiment of a valve accord- ing to the present invention. The valve, which is generally identified by reference numeral 500, comprises a body 501 with an upper section 502, a lower section 503, and a stem support 504 thereacross. The head 512 of a valve member 508 is movable to sealingly contact an interior surface 513 of the body 501. The stem 509 of the valve member is movably disposed in a central chan¬ nel 523 of the stem support 504. A piston recess 521 receives and holds the top of a piston 516 which is movably mounted in a piston housing 524. The piston housing 524 has a chamber 525 with fluid therein com¬ pressible by the action of a bottom plate 519 of the piston 516. A spring 531, acting between the head 512 and the stem support 504, is prevented from pushing the head 512 into engagement with 501 by two "memory metal" bands 529 which, upon exposure to heat at a known tern- perature (either heat encountered in the well bore or heat introduced therein via hot fluids or chemical reaction), contract so that fingers 529' of the bands initially projecting into recesses in an extension 540 of the piston 516 are retracted, freeing the piston 516 for movement effected by the force of the hydrostatic head of fluid in the well bore on the end plate 519. Fig. 8 discloses a sixth embodiment of a valve according to the present invention. The valve, which is generally identified by the reference numeral 600, is generally similar to that shown in Figure 6 except that the chamber 625 contains (or is formed by) one or more frangible capsules 641. In use, as the valve 400 is lowered down a well bore the end plate 619 ruptures the capsules 641. The head 612 partially closes to the extent permitted by the slot 620' . At the same time chemicals are released from the capsules which degrade the member 629. Fig. 9 illustrates a seventh embodiment of a valve in accordance with the present invention. The valve, which is generally identified by refer¬ ence numeral 700 is generally similar to that shown in Figs. 1 to 3. In this embodiment the valve is main¬ tained in an open position by raising the pressure in chamber 725 to the desired level. Fig. 10 illustrates an eighth embodiment of a valve in accordance with the invention. The valve, which is generally identified by reference numeral 800 is similar to that shown in Fig. 9 but with the addition of a timer trip mechanism 842 (shown schematically) interconnected between the piston 816 and the piston housing 824 which holds the piston 816 until a selected period of time has elapsed at which point the piston 816 is released.

Claims: Claims 1. A valve (100; 200; 300; 400; 500; 600; 700; 800) for use in float equipment, which valve comprises means to hold said valve in an open position, characterised in that said valve further comprises means (119; 219; 319; 419; 519; 619; 719; 819) responsive to hydrostatic pressure to move said valve towards a closed position. 2. A valve as claimed in Claim 1, comprising a body (101; 201; 301; 401; 501; 601; 701; 801), a valve member (108; 208; 308; 408; 508; 608; 708; 808) movably dis¬ posed in said body, said valve member having a stem and a head engageable with said body to inhibit fluid flow through said valve, a piston housing (124; 224; 324; 424; 524; 624; 724; 824), and a piston (116; 216; 316; 416; 516; 616; 716; 816) slidably mounted in said piston housing and connected to said stem. 3. A valve as claimed in Claim 2, wherein said piston and said piston housing define a chamber (125; 225; 325; 425; 525; 625; 725; 825) therebetween and said valve is held in an open position by compressible material in said chamber. 4. A valve as claimed in Claim 3, wherein said com¬ pressible material is a gas. 5. A valve as claimed in Claim 4, wherein said gas in said chamber (725) is at super-atmospheric pressure. 6. A valve as claimed in Claim 2, 3 or 4, wherein said means to hold said valve in an open position comprises a frangible member (129; 229; 329; 429, 429'; 529; 629) acting between said piston and said piston housing. 7. A valve as claimed in any of Claims 2 to 6, wherein said means to hold said valve in an open position com¬ prises a diaphragm (229) which isolates said piston from the ambient hydrostatic pressure until the ambient hydrostatic pressure is sufficient to rupture said diaphragm. 8. A valve as claimed in any of Claims 2 to 7, wherein said means to hold said valve in an open position com¬ prises a timer (842) . 9. A valve as claimed in any of Claims 2 to 8, wherein said means to hold said valve in an open position com¬ prises a thermally deformable member ( 529 ) . 10. A valve as claimed in any of Claims 2 to 9, where¬ in said valve comprises means to hold said valve in at least two separate and distinct open positions. 11. A valve as claimed in Claim 10, wherein said stem has a slot (420 1 ; 620' ) and said means to hold said valve in at least two separate and distinct open posi¬ tions comprises a frangible member supported by said piston housing and extending through said slot. 12. Float equipment including a valve as claimed in any preceding claim. * * *

Inventors: COLVARD RUBY LEE, COLVARD, RUBY, LEE
Applicants: LUCAS BRIAN RONALD, WEATHERFORD US INC, LUCAS, BRIAN, RONALD, WEATHERFORD U.S., INC.
Application year: 1995
Main classification: E21B21
IPC codes: E21B21, E21B34, F16K15