BACKGROUND

[0001 ] In the oil and gas industry, wellbores are drilled into the surface of the earth to access reservoirs for the extraction of hydrocarbons. Wellbores are often lined with casing or a string of casing sections or lengths, and the casing is then secured into place using cement. In one cementing technique, a cement composition is pumped through the interior of the casing and allowed to flow back toward the surface via the annulus defined between the wellbore wall and the casing. Once the cement composition cures within the annulus to form a hardened mass, the casing serves to stabilize the walls of the surrounding subterranean formation to prevent any potential caving into the wellbore.

[0002] When casing is being run into a wellbore it is sometimes desirable to "float" the casing down to its intended location within the wellbore fluid prior to the time the casing is cemented in the well. Float valves are one-way valves (i.e., check valves) that can be installed at or near the interior bottom end of a casing string. Once operational, float valves permit fluid (such as mud or cement) to flow down through the inside of the casing, but prevent fluids from flowing in the reverse direction back up the inside of the casing. By doing so float valves prevent cement that is pumped down through the casing and into the annular space from flowing back up through the valves once the cement is in place.

[0003] Float shoes and float collars permit automatic filling of the casing and incorporate a backpressure valve to prevent cement back flow into the casing after the cementing operation. Certain backpressure valves also permit the option of terminating the filling of the casing at any point in time. During the insertion of casing into the wellbore, a traditional auto-fill, flapper-type float valve is held open by a pin set across a sleeve in the valve assembly bore. When it is desired to actuate the backpressure valve to prevent further filling of the casing a weighted tripping ball is dropped, or carried in with the float valve, which breaks the pin holding the sleeve and thereby freeing the flapper valve to close. After cementing has been completed, the released flapper valve prevents cement flow back into the casing from the wellbore annulus. Due to the close operating pressures of the float valve, premature release of the flapper valve can occur. Additionally, the same operating conditions can cause the flapper vaive to not release entirely.

DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 illustrates a cross-sectional side view of a casing with the fill valve assembly disclosed herein.

[0005] FIG. 2 is a cross-sectional view of a fill valve assembly of the current disclosure employed in a casing float collar.

[0006] FIG. 3 is a cross-sectional view of a fill valve assembly in an open position with a tripping ball engaged with a retaining ring.

[0007] FIG. 4 is a cross-sectional view of a fill valve assembly in an open position with the tripping ball in a first sleeve.

[0008] FIG. 5 is a cross-sectional view of a fill valve assembly with a first flapper valve in a closed position.

[0009] FIG. 6 is a cross-sectional view of a fill valve assembly with first and second flapper valves in a closed position after a tripping ball has passed therethrough.

DESCRIPTION OF AN EMBODIMENT

[00010] Referring now to the figures a wellbore 15 is shown with a casing string 20 lowered therein. Casing string 20 and wellbore 15 define an annulus 25 therebetween. Casing string 20 will be lowered from a wellhead installation at the surface of the earth in a manner known in the art. A casing shoe 36 may be attached at or near the end of casing string 20. To secure the casing string 20 within wellbore 15, cement 30 is pumped therethrough until it passes out the bottom end 34 of casing string 20. A casing shoe 36 may be attached to bottom end 34. Cement will flow out of bottom end 34 through casing shoe 36 and will travel upwardly in annulus 25. [00011] A fill valve assembly 50 may be provided within a float collar 40 of casing string 20. Float collar 40 may be connected at its upper end 46 to upper casing 42 and at its lower end 48 to lower casing 44. Fill valve assembly 50 is fixed in float collar 40 with a cementitious body 41. The fill valve assembly 50 is held firmly in place by the cementitious body 41. As is apparent from the drawings, fluid, for example cement 30 will be directed through fill valve assembly 50 as there is no path around fill valve assembly 50 through float collar 40.

[00012] Fill valve 50 has outer housing 52, and has upper end 54 and lower end 56 and a central flow passage 57 therethrough. Fill valve 50 comprises a first flapper valve 58 and a second flapper valve 60 connected thereto. A ball cage 64 is connected to the upper end 54 of the housing 52, which is the upper end of the fill valve assembly 50. Cage 64 comprises a retaining ring 66 and a crows nest 68. A tripping ball 70 is initially trapped between retaining ring 66 and crows nest 68. Retaining ring 66 defines a diameter 74 that is smaller than diameter 72 of tripping ball 70. Tripping ball 70 may comprise a phenolic tripping ball or other material such that upon the application of pressure tripping ball 70 will deform slightly and pass through the diameter 74 of retainer 66. Crows nest 68 has a space 78 between the feet 76 thereof that will not allow tripping ball 70 to pass upwardly therethrough.

[00013] First flapper valve 58 comprises first flapper valve housing 62 which forms a part of outer housing 52. First flapper valve housing 62 comprises an upper housing portion 82 and a lower housing portion 86. A flapper 80 is pivotally connected to upper housing portion 82 with a pivot pin 84 or other mechanism. Flapper 80 is biased with a spring or otherwise to move from the open position 102 to the closed position 106 which is shown in FIG. 6.

[00014] Lower housing portion 86 of first flapper valve 58 is connected to upper housing portion 82. Flapper 80 in the open position extends downwardly into lower housing portion 86 and is restrained in the open position by a first sleeve 88. First sleeve 88 is detachably connected in housing 52 and more specifically in lower housing portion 86 of first flapper valve housing 62. First sleeve 88 has upper end 90 and lower end 92.

[00015] First sleeve 88 defines an interior 89 and has a plurality of tapered openings 91 with tapered surface 93. Openings 91 are generally frustoconically shaped. A plurality of disconnected solid bodies 94 are received in tapered openings 91. In one embodiment the disconnected solid bodies comprise spherical balls. The figures show solid bodies 94 received in only a portion of openings 91 to allow other features to be seen clearly. It is understood that solid bodies 94 may, and in some embodiments will be received in all of openings 91. Solid bodies 94 extend radially inwardly from an inner surface 96 into interior 89 of first sleeve 88. Solid bodies 94 define a seat 98 for receiving tripping ball 70. Seat 98 defines a diameter 100 w hich is smaller than diameter 72 of tripping ball 70.

[00016] FIGS. 3 and 4 show the first position 104 of first sleeve 88 in which sleeve 88 restrains flapper 80 in its open position 102. In the open position 102 two-way flow is permitted through the first flapper valve housing 62. Thus, to the extent fluid can flow upwardly to first flapper valve 58 fluid will flow therethrough as casing 20 is lowered into the wellbore 15 to the desired location. The closed position 106 of flapper 80 is shown in FIG. 6. In the closed position 106 one-way flow only is allowed through first flapper valve 58. Thus, cement can flow downwardly therethrough but upward flow is prevented by flapper valve 58 and specifically by flapper 80 which is biased towards upper housing 82 in which the closed position 106 will engage a seat 83 defined on upper housing portion 82 to prevent upward flow therethrough. Flapper 80 moves to the closed position 106 when first sleeve 88 is detached from first flapper valve housing 62 and moves downwardly to its second position 108.

[00017] Upper housing portion 82 has a bore 1 10 with a diameter 111 that is large enough to allow tripping ball 70 to pass therethrough. Housing 52 has a bore 112 and specifically lower housing portion 86 of first flapper valve housing 62 has a bore 112 that extends radially outwardly from bore 110. Bore 112 has a first portion 114 and a second portion 1 15 below first portion 1 15. Second portion 115 is a generally cylindrical portion. Second portion 115 has at least one groove 1 16 therein. The at least one groove 116 comprises a first pair of grooves 118. The pair of first grooves 1 18 comprises a first upper groove 120 and a first lower groove 122.

|00018] At least one lock ring 124 engages first sleeve 88 and extends into the at least one groove 1 16 in lower housing portion 86 of first flapper valve housing 62. The at least one lock ring in the embodiment disclosed comprises a first pair of lock rings which comprises a first upper lock ring 126 and a first lower lock ring 128. In the first position 104 of first sleeve 88 first upper lock ring 126 engages sleeve 88 and extends radially outwardly into first upper groove 120. First lower lock ring 128 engages first sleeve 88 and extends radially outwardly into first lower groove 122. The first and second upper lock rings 126 and 128 detachably connect first sleeve 88 in housing 52 in the first position 104 thereof.

[00019] Bore 1 12 has a third portion 132 below second portion 1 15. Third portion 132 has a greater diameter than second portion 1 15, and defines an annular channel 134. In the first position of first sleeve 88 an inner surface 130 of second portion 1 15 engages solid bodies 94 and holds them in openings 91 against the surface 93 thereof.

[00020] Bore 1 12 of lower housing 86 extends radially inwardly from annular channel 134 and defines a shoulder 138. When first sleeve 88 is moved to its second position 108 solid bodies 94 will move outwardly and be received in annular channel 134. Tripping ball 70 will urge solid bodies 94 outwardly into annular channel 134, and will pass through first sleeve 88.

[00021] In operation once casing 20 has been lowered to a desired location in the well cementing can begin. Fluid may be displaced ahead of the cement 30 and pressure increased so that tripping ball 70 will engage and pass through retaining ring 66. Tripping ball 70 will be displaced downwardly until it engages ball seat 98. Pressure is applied thereabove until a sufficient force is reached to disengage first sleeve 88 from first upper and lower lock rings 126 and 128. First lower lock ring 128 will be received in a groove in first sleeve 88 in the second posit ion 108 thereof to prevent further downward movement of first sleeve 88. Solid bodies 94 will move radially outwardly into annular channel 134 to allow tripping ball 70 to pass through sleeve 88. One-way flow in the downward direction through housing 52 and thus through float collar 40 is allowed, but upward flow is prevented. Cementing of casing string 20 can therefore be performed through flapper valve 58. In one embodiment more than one flapper valve may be utilized. The current disclosure includes a second flapper valve 60.

[00022] Flapper valve 60 is generally like flapper valve 58. Second flapper valve 60 comprises second flapper valve housing 162 which forms a part of outer housing 52. Second tlapper valve housing 162 comprises an upper housing portion 182 and a lower housing portion 1 86. A flapper 180 is pivotally connected to upper housing portion 182 with a pivot pin 184 or other mechanism. Flapper 180 is biased with a spring or otherwise to move from the open position 202 to the closed position 206 which is shown in FIG. 6. [00023] Lower housing portion 186 of second flapper valve 60 is connected to upper housing portion 182. Flapper 180 in the open position extends downwardly into lower housing portion 186 and is restrained in the open position by a second sleeve 188 that is detachably connected in housing 52 and more specifically in lower housing portion 1 86 of second flapper valve housing 162. Second sleeve 188 has upper end 190 and lower end 192.

[00024] Second sleeve 188 has an interior 189 and a plurality of tapered openings 191 with tapered surfaces 193. Openings 191 are generally frustoconically shaped. A plurality of disconnected solid bodies 194 are received in tapered openings 191. In one embodiment the disconnected solid bodies comprise spherical balls. The figures show solid bodies 194 received in only a portion of openings 191. It is understood that solid bodies 194 may be received in all of openings 191 , and in some embodiments will be received in all of openings 191. Solid bodies 194 extend radially inwardly from an inner surface 196 into interior 189 of second sleeve 188. Solid bodies 194 define a seat 198 for receiving tripping ball 70. Seat 198 defines a diameter 200 which is smaller than diameter 72 of tripping ball 70.

[00025] FIGS. 3-5 show the first position 204 of second sleeve 188 in which second sleeve 188 restrains flapper 180 in its open position 202. In the open position 202 two-way flow is permitted through the second flapper valve housing 162. The closed position 206 of flapper 180 is shown in FIG. 7. In the closed position 206 one-way flow only is allowed through second flapper valve 60. Thus, cement can flow downwardly therethrough but upward flow is prevented by flapper valve 60 and specifically by flapper 180 which is biased towards upper housing 182 in which the closed position 206 will engage a seat 183 defined on upper housing portion 82 to prevent upward flow therethrough. Flapper 180 moves to the closed position 206 when second sleeve 1 88 is detached from second flapper valve housing 162 and moves downwardly to its second position 206.

[00026] Upper housing portion 182 of second sleeve 188 has a bore 210 with a diameter

21 1 that is large enough to allow tripping ball 70 to pass therethrough. Housing 52 has a bore

212 and specifically lower housing portion 186 of second flapper valve housing 162 has a bore 2 12 that extends radially outwardly from bore 210. Bore 212 has a first portion 214 and a second portion 215 below first portion 214. Second portion 215 is a generally cylindrical portion. Second portion 215 has at least one groove 216 therein. The at least one groove 216 comprises a second pair of grooves 218. The second pair of grooves 218 comprise a second upper groove 220 and a second lower groove 222.

[00027] At least one lock ring 224 engages second sleeve 188 and extends into the at least one groove 216 in lower housing portion 186 of second flapper valve housing 162. The at least one lock ring 224 in the embodiment disclosed comprises a second pair of lock rings which comprises a second upper lock ring 226 and a second lower lock ring 228. In the first position 204 of sleeve 188 second upper lock ring 226 engages second sleeve 188 and extends radially outwardly into second upper groove 220. Second lower lock ring 228 engages sleeve 188 and extends radially outwardly into second lower groove 222. The second upper and lower lock rings 226 and 228 detachably connect sleeve 188 in housing 52 in the first position 204 thereof. Bore 212 has a third portion 232 below second portion 215. Third portion 232 has a greater diameter than second portion 1 15, and defines an annular channel 234. In the first position 204 of second sleeve 188, an inner surface 230 of second portion 215 engages solid bodies 194 and holds them in openings 191 against the surface 193 thereof.

[00028] Bore 212 of lower housing 186 extends radially inwardly from annular channel 234 and defines a shoulder 238. When second sleeve 188 is moved to its second position 208 solid bodies 194 will move outwardly and be received in annular channel 234. Tripping ball 70 will urge solid bodies 194 outwardly into annular channel 234, and will pass through second sleeve 188.

[00029] In operation once casing 20 has been lowered to a desired location in the well cementing can begin. Fluid may be displaced ahead of the cement 30 and pressure increased so that tripping ball 70 will engage and pass through retaining ring 66. Tripping ball 70 will be displaced downwardly until it engages the first plurality of disconnected solid bodies 94 that define first ball seat 98. Pressure is applied thereabove until a sufficient force is reached to disengage sleeve 88 from first upper and lower lock rings 126 and 128 respectively. First sleeve 88 will move downwardly to its second position 108 and flapper 80 will move to the closed position 106. First sleeve 88 will engage shoulder 138 in the second position thereof to prevent further downward movement of first sleeve 88. Solid bodies 94 will move radially outwardly into annular channel 134 to allow tripping ball 70 to pass through to second sleeve 188.

|()0030] Tripping ball 70 will be displaced downwardly until it engages the second plurality of disconnected solid bodies 194 that define second ball seat 198. Second sleeve 188 will move downwardly to its second position 208 and flapper 180 will move to the closed position 206. Second sleeve 188 will engage shoulder 238 in the second position thereof to prevent further downward movement of first sleeve 88. Solid bodies 194 will move radially outwardly into annular channel 234 to allow tripping ball 70 to pass through second sleeve 188. One-way flow in the downward direction through housing 52 and thus through float collar 40 is allowed, but upward flow is prevented. Cementing of casing string 20 can therefore be performed through flapper valve 60.

[00031] Embodiments disclosed herein include:

[00032] A. A valve assembly comprising: a housing defining a flow passage therethrough; a first flapper movable from an open position in the housing in which two-way flow is allowed to a closed position in which only one-way flow through the housing is permitted; a first sleeve detachably connected to the housing and movable from a first position to a second position in the housing, the first sleeve in the first position retaining the flapper in the open position; a plurality of disconnected solid bodies extending radially inwardly into an interior of the first sleeve through a plurality of openings defined in the first sleeve and configured to engage a tripping ball delivered into the first sleeve; at least one lock ring engaging the first sleeve and extending into a groove in the housing, the at least one lock ring configured to hold the first sleeve in the first position until a tripping ball is engaged with the plurality of disconnected bodies and a force is applied to move the first sleeve from the first to the second position.

[00033] B. A valve assembly comprising: a first flapper in a valve housing; a first sleeve in the valve housing, the first sleeve having a first position in the housing retaining the first flapper in an open position; a plurality of first spherical balls extending radially inwardly into the first sleeve and defining an inner diameter smaller than an outer diameter of a tripping ball; a second flapper in the valve housing; a second sleeve in the valve housing, the second sleeve having a first position in the housing retaining the second flapper in an open position; and a plurality of second spherical balls extending radially inwardly into the second sleeve and defining an inner diameter smaller than an outer diameter of the tripping ball.

[00034] C. A valve assembly comprising: a casing; a valve housing connected in the casing; a first flapper positioned in the housing and restrained in an open position by a first sleeve movably connected in the valve housing; a first ball seat defined in the first sleeve by a plurality of disconnected solid bodies extending radially inwardly from an inner surface of the sleeve; a second flapper positioned in the valve housing below the first sleeve and restrained in an open position by a second sleeve movably connected in the valve housing; a second ball seat defined in the second sleeve by a plurality of disconnected solid bodies extending radially inwardly from an inner surface of the sleeve, the first and second ball seats configured to receive a tripping ball displaced through the casing.

[00035] Each of the embodiments A, B and C may have one or more of the following additional elements in combination:

[00036] At least one lock ring comprising a first upper lock ring and a first lower lock ring, the first upper and lower lock rings engaging the first sleeve and extending into first upper and lower grooves in the housing in the first position of the sleeve.

[00037] A ball seat in a second sleeve for receiving the tripping ball after the first sleeve has moved to its second position.

[00038] A second upper lock ring engaging the second sleeve and extending into a second upper groove in the valve housing; and a second lower lock ring engaging the second sleeve and extending into a second lower groove in the valve housing.

[00039] Annular channels defined in the valve housing to receive the disconnected solid bodies in the second position of the first and second sleeves.

[00040] Thus it is seen that the apparatus and methods of the present invention readily achieve the ends and advantages mentioned as well as those inherent therein. While certain preferred embodiments of the invention have been illustrated and described for purposes of the present disclosure, numerous changes in the arrangement and construction of parts and steps may be made by those skilled in the art, which changes are encompassed within the scope and spirit of the present invention.