Apparatus and Method for Gravel Packing a Well

The present invention generally relates to an apparatus for gravel packing or sand packing an annular space in a well such as the space between a sand screen or liner and a well casing or well bore with accurately sized gravel or sand. The gravel or sand is pumped down through a production tubing or drill string and diverted into the annular space by a hydraulically actuated means which diverts the fluid flow externally into the annular space and releases the run-in tool from the liner. The diverting and releasing means can be closed without removing the assembly from the well after injection of the gravel or sand in order to facilitate resumption of fluid production from the well. But, if necessary to remove the run-in tool from the well, this is easily accomplished because of the unique design and operation of the diverting and releasing means.

When drilling and completing oil, gas or water wells, many operations and processes are performed in which a fluid or granular material is placed in the annular space between the exterior of a well casing and the wall of a well bore and in many situations, this material is also placed in the annular space between the well casing and a sand screen or liner positioned interiorly of the well casing. In all types of wells, an undesirable condition is sometimes encountered when fine sand is produced along with the production fluid. One well known process for overcoming this problem is known as "gravel packing" or "sand packing" which basically involves positioning a perforated or slotted sand screen or liner in the well bore or casing and packing the annular space between it and the well bore and casing with accurately sized sand or gravel to prevent the intrusion of well sands into this annular space. The sand screen or liner is positioned in the well bore to perform this packing process and the run-in tool must be released to enable the packer and tubing to be withdrawn from the well bore. Release of the run-in tool is necessitated by the fact that the diverting mechanism for directing the sand or gravel flow to the outside of the tubing or drill pipe during the packing operating in prior structures does not have the facility for closing the openings in the diverting mechanism after the packing operation to allow production without first removing the run-in tool.

Further, the operation of disconnecting the run-in tool from the liner or screen in prior art structures requires that the tubing be raised to engage a clutch joint in the assembly and the tubing is then rotated to release the tubing from the sand screen or liner. Frequently, this clutch joint and threaded releasing mechanism fails to release properly because small particles get lodged in the threads because of other complications in the releasing mechanism due to the sand environment. When this occurs, the entire assembly must be recovered to correct the problem which necessitates the re-running of the screen or liner and again performing the gravel or sand packing operation.

U.S. Pat. No. 3,072,204 issued Jan. 8, 1963 discloses one type of such apparatus for gravel packing a well.

The primary object of the invention resides in the method and apparatus by which the sand screen is released from the run-in tool before the sand or gravel packing operation begins, by which the fluid diverting crossover device is operated and by which the openings in the crossover device can be closed upon completion of the packing operation to allow production to proceed without removal of the run-in tool or equipment.

The primary object of the invention is attained by a structural arrangement in which a hydraulically actuated mechanism causes the release of the run-in tool from the sand screen hook-up nipple. As initially placed down-hole, the run-in tool is connected to the hook-up nipple through several radially movable balls which, in their anchoring position, are partially received in holes in the connected components with a mandrel retaining the balls in their anchoring position. The mandrel is sectional and retained in its initial position by one or more shear pins which are sheared by hydraulic pressure exerted on a plug or dart placed in the upper end of the mandrel. Shearing of the shear pins actuates the mandrel to enable the balls to move into a recess so that the connected components may be separated. In addition, hydraulic actuation of the mandrel will open slots in the fluid diverting crossover component which diverts fluid flow externally into the annular space.

A further object of the invention is provided by the ability of the operator to subsequently close the open slots in the fluid diverting crossover component from outside the well and thereby again reseal the inside of the tubing or drill pipe from the annulus to thereby permit production operations to proceed without withdrawing any equipment from the well.

Another object of the invention is to provide an apparatus which eliminates the previously encountered difficulty in releasing the tubing from the sand screen in present type constructions thus eliminating the additional trip with the tubing in order to place the well into production with the apparatus being dependable in operation and effective for diverting fluid and releasing the run-in tool from the hook-up nipple.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

FIG. 1 is a diagrammatic sectional view of a typical well in which the apparatus of the present invention is used for gravel or sand packing.

FIG. 2 is a longitudinal, sectional view of the present invention including the sand screen or liner together with a wash tube and wash-down shoe, if desired.

FIG. 3 is a longitudinal, sectional view of the invention including the device for running and releasing the sand screen along with the mechanism for actuating the fluid diverting crossover.

FIG. 4 is a longitudinal, vertical sectional view, on an enlarged scale, illustrating the releasing and fluid diverting crossover mechanism in which the crossover is closed and the releasing mechanism is in anchoring position.

FIG. 5 is a sectional view similar to FIG. 4 but illustrating the fluid diverting crossover in open position and the releasing mechanism in release position.

FIG. 6 is a vertical sectional view similar to FIG. 5 but with the fluid diverting crossover having been closed by lowering the tubing string and the dart or tripping plug recovered.

FIG. 7 is a sectional view similar to FIG. 6 but illustrating the run-in device having been recovered and a production stinger placed in the hook-up nipple in preparation for production.

FIG. 8 is a transverse, sectional view taken substantially upon a plane passing along section line 8-8 of FIG. 4 illustrating the relationship of the releasing mechanism when in anchored position.

FIG. 9 is a fragmental sectional view taken substantially upon a plane passing along section line 9-9 of FIG. 5 illustrating the releasing mechanism in released position.

FIG. 10 is a transverse, sectional view taken substantially upon a plane passing along section line 10--10 of FIG. 5 illustrating the crossover slots when in open condition and their association with the dart or tripping plug.

FIG. 11 is a diagrammatic view illustrating the assembly in a well bore in preparation to perform a gravel or sand packing operation.

FIG. 12 is a view similar to FIG. 11 illustrating reverse circulation for removal of sand fill in the annular space by the use of the wash tube and wash-down shoe.

FIG. 13 is a view similar to FIGS. 11 and 12 illustrating the packer in the set position to isolate the area below the packer from the annulus above and the tripping dart in position after activating the fluid diverting crossover and releasing mechanism so that the sand or gravel can be injected into the formation through the annulus between the sand screen and the well casing.

FIG. 14 is a similar diagrammatic view illustrating the gravel or sand pack in the annulus between the sand screen and well casing and into the well formation with the packer in the released or unset position permitting reverse circulation of excess material from the run-in tubing string.

FIG. 15 is a similar view illustrating the run-in assembly removed and the gravel or sand pack in position along with the sand screen.

Referring now specifically to the drawings, FIG. 1 illustrates the present invention installed in a typical well with the portion of the well extending to the surface being omitted but with a production zone 20 of a formation 22 being illustrated along with a well casing 24 having a perforated area 26 in the production zone. In some instances, the casing 24 may terminate above the production zone with it being pointed out that the present invention may be used with various types of wells either with or without a casing with the production tubing or drill pipe 28 being packed off by a conventional packer assembly 30 oriented above the production zone in a conventional and well known manner. Positioned below the packer 30 is a fluid diverting crossover, sand screen or liner releasing mechanism generally designated by reference numeral 32 including a hook-up nipple generally designated by numeral 34 connected to a blank pipe 36 at its lower end and connected with a stinger assembly 38 at its upper end. The blank pipe 36 is connected with a perforated or slotted sand screen or liner 40 which is provided, as shown, with a wash-down shoe 42 at its lower end. In some installations, the blank pipe 36 need not be used in which event the liner 40 would be connected directly to the hook-up nipple 34.

The wash-down shoe 42 is conventional and includes a bottom opening 44 and a coiled compression spring 46 retaining a vertically disposed wash tube 48 in an upper position so that a valve 50 separate from the lower end thereof is maintained in a closed condition except during periods of reverse flow. In some installations it is not necessary or desirable to use the wash tube 48 since its inclusion in the assembly requires withdrawal of the run-in tool in order to remove the wash tube from the well prior to production operations.

The hook-up nipple 34 includes a threaded adapter 52 having a depending elongated housing 54 threaded thereto at 56. The lower end of the housing 54 is threaded to the pipe 36 or connected directly to the screen or liner 40 if the blank pipe 36 is not used, with this latter arrangement being illustrated in FIG. 2, the threaded connection being designated at 58. The wash tube 48 extends through a wash tube retaining adapter 60 which has setscrews 62 in the lower end thereof for locking the wash tube 48 in the lowermost position thus holding the valve 50 in the open position to permit reverse circulation in order to wash any sand fill from the casing. Recovery of the wash tube is attained by the upset upper end 64 thereof being larger than the adapter 60.

Movably positioned within the hook-up nipple 34 and forming part of the stinger assembly is a tubular mandrel 66 which has its lower end threadedly connected to the wash tube adapter 60 by a threaded connection 68 which will recover the wash tube when the diverting crossover assembly is removed. The mandrel 66 extends up through the housing 54 with the upper end being threadably connected to a connector collar 67 on the lower end of packer assembly 30 or tubing string 28. The threaded adapter 52 has a wiper ring 70 disposed interiorly thereof and housing 54 includes seal rings 72 engaging the external surface 74 of the mandrel 66 which is of substantially constant diameter through its length. Mandrel 66 is also provided with an internal shoulder 76 and a plurality of radial holes 78 above the shoulder 76 (FIG. 4). The holes 78 are in registry with and in alignment with similar holes 80 in the hook-up nipple with the holes 80 being adjacent the upper end of the housing 54. As illustrated in FIG. 4, the holes 78 and 80, when in registry, receive balls 82 which are partially disposed in the holes 78 and partially in holes 80 thus locking the mandrel 66 to the housing 54 and adapter 52 thereby preventing relative movement therebetween and connecting the mandrel 66 to the hook-up nipple 34. As shown in FIG. 8, six balls are spaced equidistant around the circumference of mandrel 66. However, it is contemplated that additional balls may be employed on wider diameter tools, such as eight or ten or more, and that even as few as four balls may be employed on narrower tools.

Longitudinally movably disposed within the interior of the mandrel 66 is an inner lower mandrel 84 having external seal rings 86 adjacent the upper and lower ends thereof. Mandrel 84 has a longitudinally extending, external, reduced diameter portion 88 which has inclined end walls and which will register with the holes 78 when the inner mandrel 84 is moved downwardly to its unlocking position illustrated in FIG. 5. In the unlocking position, balls 82 can move away from and thus out of holes 80 in the upper part of housing 54 and be completely received in holes 78 thus releasing the mandrel 66 from the housing 54 and adapter 52. For releasably securing the inner lower mandrel 84 in its upper or anchoring position with the external surface 85 aligned with holes 78, a threaded shear pin 90 is threaded through the mandrel 66 into the mandrel 84 thus retaining the mandrel 84 in the position of FIG. 4 until a downward force is exerted on the mandrel 84 with respect to the mandrel 66 sufficient to shear pin 90 or multiple similar shear pins 90 if more than one is desired.

The structure for moving the inner lower mandrel 84 downwardly includes an upper inner mandrel or sleeve valve 92 having a valve seat 94 formed in the upper end thereof and the bottom end abutting against the lower mandrel 84. Seal rings 96 are provided on the exterior of the upper mandrel 92 for sealing engagement with the inner surface of the mandrel 66 illustrated in FIG. 4. When it is desired to move the lower mandrel 84 downwardly to release the mandrel 66, a tripping dart or plug 98 is positioned in engagement with the valve seat 94 (See FIG. 5). The plug 98 includes an outwardly flared upper end 100 engaging the seat, a tapered lower end 102 and a seal ring 104 for sealing the plug in the interior of the upper mandrel 92. The upper end of the plug 98 is provided with a projection 106 by which the plug 98 may be manipulated. When the plug is in the position illustrated in FIG. 5, hydraulic pressure through the tubing will force the plug and inner mandrels 92 and 84 downwardly to shear pin 90, release mandrel 66 from lower mandrel 84, and force the recessed portion 88 of the mandrel 84 into registry with the holes 78 thus partially receiving the balls therein as illustrated in FIG. 5. Thus, balls 82 will move out of the holes 80 in the mandrel 66 so that the mandrel 66 may move longitudinally in relation to the adapter 52 and housing 54 which supports and is connected to sand screen or liner 40. Accordingly, by this mechanism the sand screen or liner 40 which is supported by nipple 34 is released from the run-in tool or equipment which is connected to and supports mandrel 66 before the sand or gravel packing operation is begun. Hence, removal of the run-in tool is simply and conveniently accomplished without the possibility of malfunction which has plagued prior structures.

To provide discharge of fluid with sand or gravel entrained therein from the tubing, the upper end portion of the mandrel 66 is provided with longitudinally elongated, radial slots or ports 108 which are closed by the upper mandrel 92 when the upper mandrel 92 is in its original upper position, as illustrated in FIG. 4, but opened when the mandrel 92 has moved downwardly to its lower position, as illustrated in FIG. 5. Thus, upper mandrel 92 acts as a sleeve valve for slots 108. The downward movement of the upper mandrel 92 is guided and controlled by pins 110 which extend through the slots 108 and have their outer ends anchored in a sleeve 112 and their inner ends threaded into the exterior of the upper mandrel 92 as indicated by numeral 114. Also, the sleeve 112 covers the slots 108 when mandrel 92 and sleeve 112 are in their upper position, and sleeve 112 serves to limit downward movement of the mandrel 92 which is also limited by the lower end of the mandrel 84 engaging the shoulder 76 as illustrated in FIG. 5.

Having sheared pin 90 and moved lower mandrel 84 and upper mandrel 92 to their down positions, slots 108 are then open. Fluid with sand or gravel entrained therein is then fed down the tubing and out through the slots 108 into the annulus between the sand screen and well casing and well bore where it is then forced into the formation, as by passing through the perforated area 26 of casing 24. Once the sand or gravel packing is completed slots 108 are closed by lowering mandrel 66 which thus lowers slots 108 with respect to upper mandrel 92 and sleeve 112 to thereby again block the passages 108 from inside the tubing to the now filled annulus. This reclosed position is shown in FIG. 6. Sleeve 112 also serves to hold mandrel 92 stationary when the tubing string 28 and mandrel 66 are lowered to reclose ports 108.

Once mandrel 66 is positioned to reclose slots 108, upper mandrel 92 with seals 96 at its upper and lower ends seals the fluid passage at each end and thereby prevents fluid passing in either direction. The well can then be placed on production through the interior of the sand screen 40 and into the production tubing 28 without further delay if the original equipment of this invention is run into the well without the wash tube 48 as aforedescribed. In the event that the tubing or drill pipe has to be withdrawn from the well in order to remove the wash tube 48 or place gas lift valves or other equipment in the tubing string, FIG. 7 illustrates a stinger or mandrel 66' which would replace the mandrel 66 and which is smooth on the exterior surface thereof and which can be run back into the hook-up nipple for sealing in the hook-up nipple to permit production through the sand screen.

FIGS. 11 through 15 illustrate schematically the operation of my invention whereby a gravel or sand pack can be achieved and the gravel or sand screen separated from the run-in equipment. FIG. 11 illustrates the apparatus placed in the well bore in preparation for a gravel or sand packing operation and FIG. 12 illustrates the reverse circulation, that is, down around the periphery of the packer and apparatus and in through the wash-down shoe as indicated by the arrows so that any fill sand that may have accumulated in the well bore will be removed. It will be appreciated by those skilled in the art that this step and the associated wash tube can be omitted under appropriate circumstances. FIG. 13 illustrates the assembly in the position for injecting the gravel or sand 116 into the annulus with the packer in the set position to isolate the area below the packer from the annulus above. As illustrated, the tripping dart is in position and the fluid diverting crossover has been activated to open position and the releasing mechanism is in the release position. In this condition, the sand screen assembly is free from attachment with the mandrel and the dart or tripping plug is in the seat of the mandrel thereby diverting the fluid being pumped down the tubing to the exterior of the sand screen assembly so that the gravel or sand material will be injected into the formation through the annulus between the sand screen assembly and the well casing as indicated by the arrows in FIG. 13. FIG. 14 illustrates the sand or gravel pack 116 having been accomplished and the packer unseated or released thereby permitting reverse circulation of excess material from the run-in tubing string as indicated by the arrows so that reverse circulation may occur down past the packer and in through the slots thereby removing any excess material that may be in the tubing above the tripping dart or plug. FIG. 15 illustrates the sand or gravel pack in position along with the sand screen or liner with the run-in assembly removed. This assembly enables the well to be placed back on production by connection with appropriate tubing whereby fluid entering the liner from the production zone will be filtered by passing through the sand or gravel pack.

As used herein, the terms "sand or gravel pack", "gravel packing", and "sand packing" contemplate the use of accurately sized sand or gravel or any other type of graded material that is used to bridge or retain formation sand in an oil or gas well or the like.

The foregoing describes the preferred embodiment and is intended only to be illustrative of the principles of my invention. Since those skilled in the art will readily appreciate numerous variations and modifications of the illustrated embodiment without departing from the spirit and scope of my invention, it is not intended that the foregoing be a limitation of my rights except as provided in the appended claims.