Patent Publication Number: US-6702020-B2

Title: Crossover Tool

Description:
FIELD OF THE INVENTION 
     The field of this invention is crossover tools frequently used in gravel packing operations and features of such tools post gravel packing, which allow chemical treating or packer inflation. 
     BACKGROUND OF THE INVENTION 
     Crossover tools are frequently used in performing gravel-packing operations. They allow the gravel to pass through a packer and exit to an annular space outside one or more screens. The returns pass through the screen up a wash pipe and back through the crossover and out into the annulus above the packer for the trip to the surface. After deposition of the gravel, the crossover tool is picked up so that remaining gravel in the tubing can be reversed out with fluid pumped down the annulus above the packer. 
     Following gravel pack operation, the need may arise to acid treat the gravel pack area around the screens. In the past the gravel packing service tool assembly, including the crossover had to be pulled out and the treating string run in. The present invention presents a crossover tool with modifications to allow pumping down the string through the crossover tool, after the gravel packing operation is concluded so as to eliminate a trip out of the hole for acid treating. It also allows the excess chemical to be reversed out using a unique assembly that captures a plug that was used to shift a sleeve, on that sleeve during reverse flow. 
     In prior gravel packing techniques that used isolators in conjunction with the screens, it was also the practice to pull the gravel packing assembly, including the cross-over, and run in with another string to selectively inflate the external casing packers in the gravel pack zone. The present invention with the access provided through the crossover tool after the gravel packing allows such packers to be inflated in the same trip. This prior two-trip procedure is illustrated in U.S. Pat. No. 6,311,772. With the present invention the technique described in that patent can be streamlined. 
     Relevant patents that show gravel packing or sliding sleeve devices in downhole tools are U.S. Pat. Nos. 2,994,280; 4,424,864; 4,427,070; 4,520,870; 5,411,095; 5,597,040 and 5,823,254. 
     Those skilled in the art will be better able to appreciate the value of the invention from a description of the preferred embodiment and the claims below. 
     SUMMARY OF THE INVENTION 
     A crossover tool is disclosed that permits access through to the wash pipe below after the conclusion of a known gravel packing operation. A ball is trapped to a sleeve after shifting it so as to allow flow through the crossover for acid treatment in the screen area and a reversing out procedure to remove excess acid. Alternatively, pressure delivered through the wash pipe can operate packers, as part of a gravel packing procedure as outlined in two steps in U.S. Pat. No. 6,311,772 is a single trip. The acid treating or other downhole operation through the wash pipe can also be accomplished in a single trip with the gravel packing assembly. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevation view of the crossover in the gravel packing operation; 
     FIG. 2 is the view of FIG. 1 with the upper ball dropped after the conclusion of the gravel packing operation; 
     FIG. 3 is the view of FIG. 2 showing the flow for treating or other downhole operation through the crossover after gravel packing; 
     FIG. 4 is a close-up of the ball approaching the upper seat; 
     FIG. 5 is the view of FIG. 4 with the ball passing the upper seat and moving into contact with the sliding sleeve; 
     FIG. 6 is the view of FIG. 5 with pressure applied on the ball to shift the sleeve; 
     FIG. 7 is the view of FIG. 6 with pressure coming from below and showing the ball trapped by the upper seat; 
     FIG. 8 is a close-up view of the crossover during the gravel packing operation; 
     FIG. 9 is the view of FIG. 8 with the ball past the initial seat and trapped against the sliding sleeve; 
     FIG. 10 is the view of FIG. 9 showing the sleeve assembly shifted to permit the downhole operation through the crossover after gravel packing; 
     FIG. 11 is a view of the crossover during a subsequent operation below it in a single trip and showing the position of the wash pipe with respect to the packer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the crossover of the present invention in the gravel packing position. A ball  10  is dropped onto a seat  12 . The gravel is pumped through a packer (not shown) through which the crossover tool  14  extends. The gravel goes down passage  16  and out lateral port  18 . Returns come through the screen (not shown) and into ports  20  just below ball  10 . The flow is through an annular passage  22  in the crossover tool  14  and out above the packer (not shown) through ports  24  as indicated by arrows  26 . In this manner, the crossover tool  14  accomplishes gravel deposition in the manner previously known. 
     FIG. 2 shows the ball  28  having been dropped down. That sequence is more clearly shown in FIGS. 4-7. In FIG. 4, the ball  28  lands on a thin sleeve  30  which acts as the initial ball seat. Upon pressure buildup, the ball  28  is forced past sleeve  30  and into sealing contact with seat  32  on sleeve  34 . Sleeve  34  is an extension of sleeve  30 . A shear pin  36  holds sleeve  34  in its initial position. A snap ring  38  is mounted to sleeve  34  and it is able to snap out into recess  40  when sleeve  34  shifts as a result of applied pressure to ball  28  when on seat  32 . This movement is shown in FIG.  6 . As a result of this movement, the internal diameter of sleeve  30 , through which ball  28  has already been forced, is further reduced as it is pulled through a reduced diameter of a surrounding body  42 . The ball  28  is locked onto seat  32 . FIG. 7 shows pressure from below to a predetermined level, cannot dislodge the ball  28 . This can occur during a reversing out procedure after an acid treatment or some other downhole procedure, as will be explained below. 
     FIGS. 8-10 illustrate the normal gravel packing position and subsequent positions. These Figures show in detail portions for the crossover tool  14  illustrated in FIGS. 1-3. In the gravel-packing step, the ball  10  (see FIG. 1) is in position and gravel is pumped down passage  16 . Eventually the gravel exits port  18  (see FIG. 1) and the returns go through the screen (not shown) into a wash pipe  44  and into annular passage  22  to exit at ports  24 . Ports  24  are located above a packer (not shown) and the returns from gravel packing go to the surface in the annulus above this packer. FIG. 8 also indicates the position of thin sleeve  30 , seat  32 , sleeve  34 , shear pin  36 , snap ring  38 , and recess  40 . FIG. 9 shows that when the sleeve  34  is displaced due to pressure on ball  28 , it bottoms on shoulder  46  on sleeve assembly  48 . After buildup of sufficient pressure on ball  28 , sleeve  34  takes sleeve assembly  48  with it, as shear pin  49  shears, to open passages  50  into annular passage  22 , through passages  51 , and to close ports  24 . The shifted position is secured by keeper ring  53  expanding past the stop ring  55 . Referring to FIGS. 3 and 10, flow can come from the surface through the tubing (not shown) that supports the crossover  14  and into passages  50  as shown by arrows  52 . Referring to FIG. 3, the flow continues down annular passage  22  to ports  20 , as indicated by arrows  52 . Flow then goes through the wash pipe  44  to the area of the screens (not shown). Those skilled in the gravel packing art will readily see that in a single trip, the gravel packing can be accomplished in the previously done manner and that access to the screen area is obtainable for acid treating or for inflation of external packers into the gravel pack or for other downhole operations which require flow through the crossover tool  14 . The single trip capability comes from not having to pull the crossover tool  14  after the gravel pack to gain access to the screen area through the wash pipe. 
     If doing an acid treatment, it may be desirable to reverse out any excess acid. To do this, the crossover tool  14  is picked up out of the packer, just like when the ball  28  is first dropped onto sleeve  30 , so that only the wash pipe  44  is still in the packer P, shown schematically in FIG.  3 . Reverse flow, indicated by arrows  54  comes down outside the crossover tool  14  and goes down into and back up through the wash pipe  44 . It should be noted that the reversing flow, indicated by arrows  54  has to go right past openings  18 . It would normally enter there and go up hole through passage  16 , except for the fact that ball  28  is sealingly retained against seat  32  to prevent uphole flow (see FIG.  7 ). What happens is that the reverse flow shown by arrow  54  forces ball  10  down against its seat  12  and the reverse flow path is now in the opposite direction as arrows  52  after entering the wash pipe  44 . In essence, the reverse flow bypasses trapped ball  28  as it re-enters passage  16  above it for the trip to the surface. Ball  10  is held against its seat  12  by a higher pressure above it than the returning flow represented by arrow  54 , which comes in below it. 
     Different pressure levels on ball  28  can trigger the described movements. For example at 200-500 pounds per square inch (PSI), ball  28  will go through sleeve  30 . At 750-800 PSI the snap ring  38  will go into recess  40  trapping ball  28 . At 1400-1600 the sleeve assembly  48  will move down after breaking shear pins  49  opening passages  50 , to get access to annular passage  22  through passages  51 . Other non-overlapping pressure ranges can be used. 
     FIG. 11 is an illustration of access through the crossover tool  14  after dropping trapping and shifting ball  28 . It shows the wash pipe  44  lifted up with respect to packer P to open return passage  45  when performing a downhole treatment or other task through the crossover tool  14  after gravel packing and without an addition trip into the hole. Those skilled in the art will appreciate that a variety of tasks can be done below the crossover tool  14  after gravel packing without another trip into the hole. 
     While the preferred embodiment has been described above, those skilled in the art will appreciate that other mechanisms are contemplated to accomplish the task of this invention, whose scope is delimited by the claims appended below, properly interpreted for their literal and equivalent scope.