Patent Publication Number: US-6216785-B1

Title: System for installation of well stimulating apparatus downhole utilizing a service tool string

Description:
REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of provisional application 60/079,445 filed Mar. 26, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a system including an apparatus and method for the installation of well stimulation apparatus downhole utilizing a service tool string for gravel packing a downhole formation, and more particularly to such a system in which the tool string forms the production string for production of the downhole formation to provide a one trip gravel pack and production system. 
     2. Background of the Invention 
     Heretofore, it has been common to provide well stimulating apparatus for fracturing a formation in which the apparatus is lowered within a well bore on the lower end of a service tool on a work string. The stimulating apparatus for hydraulic fracturing with a proppant, such as a sand slurry, may include a lower perforating gun which is utilized for perforating the well casing at the production zone, and a production screen or filter is then positioned. After perforation of the well casing, a gravel packing packer assembly is lowered by a service tool to a position where the production screen is adjacent the production zone. The packers are then set and the proppant is injected into the fissures of the formation upon actuation of a crossover tool member to open a crossover port for flow of the proppant downwardly in the annulus between the tool and casing to the perforated casing for fracturing the formation to increase the size of the fissures receiving the slurry. After injection of the proppant or hydraulic slurry into the producing zone and the actuation of the crossover tool member to block further downward flow, the service tool may be disconnected from the gravel packing packer assembly and the service tool string removed from the well by a suitable rig. Then, a production tubing string is lowered into the well and connected to the gravel packing packer assembly adjacent the upper packer for the production of a hydrocarbon fluid from the producing zone. The production tubing string is supported from a wellhead. 
     Such a process is time consuming and requires a rig for running in the production string and for removing the work string after the fracturing process has been completed. A single trip for a work string to provide perforation and sand control has commonly been used heretofore but the installation of production tubing has normally required a separate trip after the work string has been removed. 
     However, U.S. Pat. No. 5,174,379 dated Dec. 29, 1992 shows a sand packing system in which the well is perforated, gravel packed, and placed on production with a single trip of the tool string into the well. The system includes a crossover assembly having a closure mechanism operated to preclude downward fluid flow through the tool, to establish a downward slurry flow path, and to establish a carrier fluid return flow path. At the end of the gravel pack operation, the tool string is placed on production without tripping the tool string. 
     The &#39;379 patent includes a crossover assembly that is effective to provide a first flow path from the interior of the tubing string at a location above the packer to the wellbore annulus below the packer, and is selectively operable to provide a second flow path from the interior of the tool string below the packer to the annulus in the wellbore above the packer. The operating mechanism associated with the crossover assembly includes a probe or dart assembly which is lowered into the well after the crossover assembly is in the well. A wireline is normally utilized for removal of the probe. 
     SUMMARY OF THE INVENTION 
     The present invention discloses, a sand control completion system utilizing only one trip for the tool string which is placed on production after the perforation and gravel pack operations. Production tubing is used for the work string in the sand control completion system and is then used as the production string. 
     The tool utilizes only one flow path and provides for hydraulic fracturing as well as perforating in a single trip. The use of a single flow path permits relatively large internal diameters to be utilized which is desirable for high volume hydraulic fracturing. A fluid diversion ball or probe is pumped down the tool with the slurry for the gravel pack operation and is effective to divert the fracturing fluid through aligned crossover ports from the interior of the tool string to the annulus for flow out the perforated casing section at the production zone for fracturing the formation. 
     A gravel packing packer assembly includes a slidable sleeve mounted below the gravel pack packer. This slidable sleeve is alignable with a crossover port in the service tool housing when the crossover port is in a retracted crossover position. The crossover port is movable between an extended position in which the weight of the crossover port and force of the spring maintains the crossover port in an extended relation at the end of the service tool with the crossover ports out of alignment, and a retracted position in which the crossover port assembly contacts the gravel pack packer assembly and is moved to the retracted position in which the crossover ports are in alignment. The crossover port contacts the top of the gravel pack packer assembly for movement to the retracted position in the circulating position, and the secondary reverse position of the service tool. 
     In a reverse position for cleaning the interior of the tool string after the fracturing operation, the tool string is lifted above the upper packer and fluid flow down the annulus outside the tool is directed upwardly within the tool string to unseat the ball or probe for upward movement with the fluid for removal of the ball or probe without any separate step being required for removal. An equalizing valve adjacent the sand screen is effective to equalize the fluid pressure within the bottom hole assembly and the fluid pressure outside the sand screen is the reverse position of the tool. 
     After the fracturing and reversing steps have been completed, the tool string is raised to the position at which a surface controlled subsurface safety valve is required and the subsurface safety valve is installed. Then the tool string is run back to the gravel packing packer assembly with the service tool assembly acting as production seals and placed in a sealing relation within the gravel pack packer. Then, a tubing hanger may be landed for production. Thus, the tool string of the present invention forms the production string and the seal assembly on the tool string which is effective for the crossover assembly also functions as the production seal assembly. 
     Suitable monitoring apparatus may be provided to monitor the gauge pressure downhole during the hydraulic fracturing. After the hydraulic fracturing, suitable monitoring apparatus such as electromagnetic and telemetric devices may be utilized for permanent monitoring of selected parameters. 
     An object of the present invention is to provide a system to perforate, pack, and place a well on production with only a single trip of the work string which also functions as the production string. 
     Another object is to provide a work string for gravel packing of a well with the work string being a production string after packing of the well. 
     Another object is to provide such a system in which the lower end of the service tool is positioned above the bottom hole assembly in the reverse position to allow unrestricted fluid flow from the annulus up the lower end of the service tool. 
     Another object is to provide such a system in which an equalizing valve in the bottom hole assembly permits equalizing of fluid pressure within the bottom hole assembly with fluid pressure outside the sand screen in the reverse position. 
     An additional object is to provide such a system which allows a surface controlled subsurface safety valve to be easily inserted within the work string after gravel packing of the well by raising the work string above the bottom hole assembly to the desired position of the subsurface safety valve. 
     Other objects, features, and advantages of the invention will be apparent from the specification and drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a bottom hole assembly for isolating a production zone and including a service tool releasably connected to the upper end of the bottom hole assembly; 
     FIGS. 2A-2D are sectional view in sequence of the service tool mounted within the upper portion of the bottom hole assembly shown in FIG. 1; 
     FIGS. 2E and 2F are sequential sectional views of the lower portion of the bottom hole assembly shown in FIG. 1 mounted within a perforated casing section and including a sump packer and production string with an equalizing valve; 
     FIGS. 3A and 3B are sequential sectional views of the service tool hydraulically connected to the bottom hole assembly with the upper packer and slips in engagement with the casing for sealing the annulus; 
     FIGS. 4A and 4B are sequential sectional views showing the service tool engaging the slidable sleeve mounted below the gravel pack packer, and moving a releasable slide valve ring into a closed position over the ports in the outer housing of the slidable sleeve; 
     FIGS. 5A and 5B are sequential sectional views showing a circulating position of the service tool after a ball has been dropped down the tool string with a crossover port shown in open position for transverse alignment of the crossover ports in the tool string for directing the circulating fluid upwardly along the annulus; 
     FIGS. 6A and 6B are sequential sectional views of the service tool in a squeeze position for fracturing formation by gravel packing of the production zone with the sliding sleeve of the service tool in alignment with the crossover port in the housing of the bottom hole assembly for directing the fracturing fluid down the annulus to the perforated casing section; 
     FIGS. 7A and 7B are sequential sectional views of the service tool in a reverse position with the service tool raised out of engagement with the bottom hole assembly to allow the upward flow of fluid within the interior of the tool string for unseating the ball; 
     FIGS. 8A and 8B are sequential sectional views of the service tool raised above the bottom hole assembly to the depth location of the surface controlled subsurface safety valve for installation of the safety valve; 
     FIGS. 9A and 9B are sequential sectional views of the service tool mounted within the bottom hole assembly in a final position for production with a production seal assembly on the service tool shown in sealing relation with the bottom hole assembly; 
     FIG. 10 is an enlarged sectional view of the equalizing valve adjacent the sand screen showing the relief valve in an intermediate operable position; 
     FIG. 11 is a sectional view similar to FIG. 10 showing the relief valve in an open position; and 
     FIG. 12 is a sectional view similar to FIGS. 10 and 11 but showing the relief valve in a closed position. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring now to the drawings for a better understanding of the invention, and more particularly to FIG. 1, a casing  10  is shown mounted within a bore hole  12  in the earth formation having a production or zone of interest at  14 . Casing  10  is normally secured by cement within borehole  12  as well known. 
     A bottom hole assembly shown generally at  18  is received within casing  10 . Casing  10  has a perforated casing section  23  including perforations  22 . Perforated casing section  23  is normally perforated by a separate perforating string having a perforating gun on its lower end prior to the insertion of bottom hole assembly  18 . 
     Bottom hole assembly  18  include a lower, packer assembly generally indicated at  24  and an upper packer assembly generally indicated at  26  for isolation of the production zone  14 . An annulus  27  is defined between bottom hole assembly  18  and casing  10 . A gravel pack screen indicated at  28  is positioned between packers  24 ,  26  adjacent perforations  22 . An equalizing valve is shown at  29  above screen  28  effective to equalize fluid pressure between the inner bore of bottom hole assembly  18  and annulus  27  outside screen  28 . After the perforating of casing section  23 , bottom hole assembly  18  is lowered to the position of FIG. 1 with lower packer assembly  24  and upper packer assembly  26  set as will be described further below. Lower packer assembly  24  designated a Model 18L or “Quantum” type packer may be purchased from Dowell Schlumberger of Houston, Tex. Upper packer assembly  26  designated as a “Quantum” HS packer may also be purchased from Dowell Schlumberger of Houston, Tex. 
     A service tool string or work string shown generally at  34  suspends bottom hole assembly  18  for installation and acts also as the production string after the gravel pack operation. Service tool string  34  includes a service tool  35  connected to the lower end of a tubing string  36 . An upper annulus  37  is formed between tubing string  36  and casing  10 . At the completion of the perforating and gravel packing operation, production commences directly through the service tool string  34  without removal or substitution of the service tool string  34 . Thus, tool string  34  is arranged for completion of the entire gravel pack operation and for sealing against bottom hole assembly  18  for production. By utilizing the tool string  34  as both a work string and a production string for a sand control completion system, a one trip sand control run can be made with production tubing for the work string. Such an arrangement eliminates a trip commonly utilized heretofore where a service tool string has been utilized for well completion and then removed from the well with a separate production string with production seals run in the well in a separate trip for production. 
     Referring now to FIGS. 2E and 2F, the lower portion of bottom hole assembly  18  is shown adjacent the perforated casing section  23 . Bottom hole assembly  18  has an outer housing  38  forming outer annulus  27  with outer casing  10 . Housing  38  has perforations  40  adjacent a sand screen  43 . An inner slidable isolation sleeve  42  is received within housing  38  and has a slide valve  44  over openings  46  in sleeve  42 . Slide valve  44  remains in a closed position over openings  46  until tool string  34  is utilized as a production string for product flowing through screen  42  as shown in FIGS. 9A and 9B. Slide valve  44  is moved mechanically to open position when the tool string is utilized as a production string by a shifting tool via slick line or coiled tubing. The sliding sleeve may be opened and closed repeatedly. Equalizing valve  29  is also mounted on the upper end portion of slidable sleeve  42  and will be explained further in FIGS. 10-12 for the reverse position of tool  35 . 
     Lower packer assembly  24  forms a sump packer including an elastomeric packer member  54  and slips  56  set against casing  10  for the lower end of annulus  27 . As indicated previously, lower packer assembly  24  is sold as a Model 18L or “Quantum” type packer by Dowell Schlumberger of Houston, Tex. 
     Referring now particularly to FIGS. 2A-2D, the upper portion of bottom hole assembly  18  is shown releasably connected to service tool  35  which is inserted within bottom hole assembly  18 . Bottom hole assembly  18  which includes outer housing  38  has an upper packer sub  58  with internal threads  60  and an upper annular shoulder or abutment  62  adjacent threads  60  acts as a stop engaging tool string  34  when tool string  34  is releasably connected to bottom hole assembly  18 . upper packer assembly  26  of bottom hole assembly  18  includes an elastomeric packer member  64  and slips  66 . A slidable actuating sleeve assembly  68  is secured to housing  38  by shear pins  70 . An upper ring  72  is provided adjacent elastomeric packer member  64 . An outer sleeve  74  is secured to slidable sleeve assembly  68  by shear pins  76  adjacent slips  66 . A fluid piston  78  shown in FIG. 2B is selectively energized through port  80  from internal fluid pressure. Wedge members  82  on slidable sleeve assembly  68  are positioned adjacent slips  66 . For setting packer assembly  26 , the fluid pressure down service tool string  34  is increased to a predetermined amount and exerted against piston  78  for shearing of shear pins  70 , and thus applies a load through sleeve  74  into ring  72  for engaging and squeezing elastomeric packer member  64  into sealing relation with casing  10 . Then upon a further increase in fluid pressure in service tool string  34  to a higher predetermined amount, shear pins  76  are sheared with wedge members  82  camming slips  66  radially outward for biting into casing  10  thereby to set packer assembly  26  as shown in FIGS. 3A and 3B for isolation of production zone  14  as well known. U.S. Pat. No. 4,862,957 dated Sep. 5, 1989, the entire disclosure of which is incorporated herein for all purposes, shows a suitable upper packer assembly and hydraulic release for the service tool. As indicated above, a suitable upper packer assembly is sold as a “Quantum” HS packer by Dowell Schlumberger of Houston, Tex. 
     Housing  38  of bottom hole assembly  18  has a lower annular abutment  86  as shown in FIG. 2D which acts to actuate a crossover valve sleeve for tool  35  as will be explained further. Housing  38  as shown in FIG. 2C has a laterally opening or port  88  therein and a slidable valve member  90  is positioned over openings  88  in a closed position. Slidable fingers  92  have upper ends  94  fitting in an annular groove  96  in housing  38  in the closed position of port  88 . For opening of port  88  in a crossover position, abutment  97  is engaged by tool  35  as will be explained further hereinafter for movement of slidable valve member downwardly with fingers  92  to open or uncover crossover port  88 . 
     Service tool  35  is shown in FIGS. 2A-2D releasably connected to bottom hole assembly  18 . As shown particularly in FIG. 2A, tool  35  is received within upper packer sub  58  and has external threads  104  on collet fingers engaging internal threads  60  of upper packer sub  58 . A release piston  106  is actuated by external pressure and internal port  108  vents the pressurized fluid allowing piston  106  to move upwardly for a hydraulic release of tool  35  from bottom hole assembly  18  if desired. A suitable hydraulic release and locator assembly is sold as a “Quantum” hydraulic release assembly by Dowell Schlumberger of Houston, Tex. 
     As shown particularly on FIGS. 2C and 2D, a mandrel  110  of service tool  35  has a lower end  112  and a crossover port  114  adjacent lower end  112 . Production seals  115  are mounted about the outer periphery of mandrel  110 . Crossover port  114  is formed through mandrel  110 . Mounted about the outer periphery of mandrel  110  and extending downwardly from the lower end  112  of mandrel  110  is a crossover slide valve assembly generally indicated at  116  and forming an important feature of this invention. Slide valve assembly  116  includes an outer sleeve  118  having internal shoulder  119  for engaging mandrel end  112  in a retracted position of sleeve  118  shown in FIG.  2 C. Sleeve  118  has an upper end  120  engaging an abutment  122  on mandrel  110 . A crossover port  124  in sleeve  118  is aligned with crossover port  114  in mandrel  110  in the position of FIG.  2 C. Slidable valve  90  in a closed position prevents communication of crossover ports  114 ,  124  with crossover port  88  in bottom hole assembly  18 . Sleeve  118  has a lower shoulder  127  at its lower end and an adjacent shoulder  129  spaced upwardly from shoulder  127 . 
     FIGS. 4A and 4B show slidable valve assembly  116  in an extended position. A spring  126  is biased between stops or abutments  131  on mandrel  110  and sleeve  118  of slidable valve assembly  116  to continuously urge valve assembly  116  to an extended position. The extended position of slide valve assembly  116  is shown also in FIGS. 8A,  8 B and  9 A,  9 B as will be explained further. Slide valve assembly  116  is urged by resistance of collet fingers  130  on the lower shoulder  123  of bottom hole assembly  18  to the extended position and spring  126  merely assists slide valve assembly  116  in movement to an extended position when lower end  127  or shoulder  129  of slide valve assembly  116  are not engaged with an internal stop or abutment on bottom hole assembly  18  for movement to a retracted position. The travel distance between extended and retracted positions of slide valve assembly  116  relative to mandrel  110  is shown in FIG. 4B (and also FIGS. 7B,  8 B) by distance D. Service seals  128  are provided about the outer periphery of sleeve  118 . Also as shown in FIG. 4B, collet fingers  92  hold slide valve  90  in a closed position. Downward movement of service tool  35  from the position of FIG. 4B effects downward movement of collet fingers  92  into abutting relation with abutment  97  for downward movement of slide valve  90  and opening of crossover port  88  as shown in FIG.  6 B. Downward movement of the service tool positions the recess of collet fingers  130  over lower shoulder of sleeve  90 , engaging sleeve  90  until collet  130  is forced inward by the seal bore internal diameter of bottom hole assembly  18 . 
     Referring now to FIGS. 5A and 5B, service tool  34  is shown in a circulating position prior to hydraulic fracturing. In the circulating position, the lower end of the slidable valve assembly  116  is seated on and engages inner shoulder  62  of bottom hole assembly  18  to move slide valve assembly  126  to a retracted position in which upper end  120  is in engagement with shoulder  122  on mandrel  110 . Shoulder  119  on slide valve assembly  116  also is in engagement with end  112  of mandrel  110  in the retracted position. In the circulating position, ports  114  and  124  are in alignment at a location above the bottom hole assembly  18 . A ball  132  is dropped down the bore of the service tool string  36  and seats on ball catcher  134  to block and divert fluid flow outwardly in annulus  37  between tool  35  and casing  10  for upward flow of fluid from annulus  37  for circulation. 
     Next, referring to FIGS. 6A and 6B a squeeze position for hydraulic fracturing of formation  14  is shown. In the squeeze position, collet fingers  92  are cammed out of engagement with groove  96  by tool  35  and move downwardly against stop  97  to permit downward movement of slide valve  90  thereby to place crossover port  88  in communication with crossover ports  114  and  124 . Annular shoulder  126  on slide valve assembly  116  engages abutment  86  on bottom hole assembly  18  to move slide valve assembly  116  to a retracted position in which ports  114  and  124  are in alignment. Annular seals  128  about sleeve  118  are in sealing engagement with bottom hole assembly  18 . Collet fingers  92  have been moved downwardly against shoulder  97  by tool  35  for movement of slide valve  90  to an open position with crossover ports  114 ,  124  and  88  in aligned position. 
     Fracturing fluid flows down the annulus  27  between the bottom hole assembly  18  and casing  10  to the production zone for flow through perforations  22  in perforated casing section  23  into the formation. Ball  132  on ball catcher  134  diverts the fracturing fluid through aligned ports  114 ,  124  and  88  into annulus  27 . After the fracturing fluid has flowed into the formation under a predetermined pressure at a predetermined flow rate for a time sufficient to open the fissures, tool string  34  is lifted to a reverse position as shown in FIGS. 7A and 7B. In the reverse position, tool  35  is lifted above the bottom hole assembly  18  as shown in FIGS. 7A and 7B and a suitable slurry is pumped down annulus  37  for removal of the fracturing fluid from the service tool string  36 . Diverter ball  132  is lifted from ball catcher  134  by the upward fluid flow and moves upwardly with the fluid within the bore of the tool string  102  for removal from the tool string  34 . 
     To equalize the fluid pressure within bottom hole assembly  18  with the fluid pressure outside bottom hole assembly  18  in the annulus  27  adjacent sand screen  28  for effective operation of the reverse position shown in FIGS. 7A and 7B, equalizing valve  29  is provided above slidable sleeve  42  as shown schematically in FIGS. 1 and 2E, and specifically in FIGS. 10-12. By equalizing the internal pressure within bottom hole assembly  18  with the external fluid pressure in the adjacent formation, the reversing fluid is easily directed from annulus  37  above bottom hole assembly  18  into the lower end of tool  35  as shown in FIGS. 7A and 7B. The equalizing valve  29  shown in FIGS. 10-12 is mounted above slidable sleeve  42  as shown schematically in FIG.  2 E. Equalizing valve  29  includes an upper sub  142  and a lower sub  144  with an outer housing  146  extending between subs  142  and  144 . Lower sub  144  is connected to slidable sleeve  42 . In some instances, an isolation tube may be utilized connecting sleeve  42 . An upper operating piston is shown at  148  responsive to external fluid pressure from port  150 . Spring  152  is mounted between piston  148  and an annular poppet valve generally indicated at  154 . A collet  156  having collet fingers is provided adjacent operating piston  148  and is effective to transfer force from upper piston  148  to the concentric poppet valve  154 . A plurality of fluid ports  158  are provided about the circumference of outer housing  146  and extend through housing  146  and sub  144  to the interior or bore of valve  29 . Annular poppet valve  154  blocks fluid flow through ports  158  in the closed position shown in FIG. 11 in which the internal pressure is greater than or equal to the external pressure or external pressure is below the pressure required to force piston  148  over collet  156 . When the external pressure exceeds the internal pressure, piston  148  responsive to a differential pressure actuates collet fingers  156  to counteract the load on valve  154  and hold poppet valve  154  closed. When piston  148  snaps over collet  156 , valve  154  is allowed to move up a distance D 1  to the position of FIG. 12 for opening of ports  158  to provide equalization of the internal and external pressures. Upon equalizing of external and internal fluid pressures, the internal fluid pressure and spring force acting against piston  148  recocks collet fingers  156  to return poppet valve  154  to the closed position of FIG.  11 . FIG. 10 shows poppet valve  154  in a run in position for installation of equalizing valve  29  within bottom hole assembly  18  with collet fingers  156  transferring force between piston  148  and poppet valve  154 . External pressure tends to push piston  148  down and valve poppet  154  up. The preload in spring  152  holds valve poppet  154  closed while piston  148  applies a greater load through collet  156 . When collet  156  snaps, the piston  148  applied load is lost and poppet valve  154  opens. 
     After the reverse operation for a subsea well, tool string  34  is lifted around 400 feet from the sea floor for installation of the surface controlled subsurface safety valve shown generally at  164  by connection between pipe sections of tool string  34 . The subsurface safety valve  164  includes suitable fluid connections for operation thereof from a surface location. 
     After insertion of subsurface safety valve  164 , tool string  34  is then lowered as a production string into bottom hole assembly  18  as shown in FIGS. 9A and 9B. Tool string  34  is installed for production with production seals  115  engaging bottom hole assembly  18  as shown. In the producing position shown in FIGS. 9A and 9B slide valve assembly  116  is in an extended position and is positioned above slide valve member  90  and openings  88  in bottom hole assembly  18 . Slide valve  44  shown particularly in FIG. 2F is moved mechanically to an open position of production openings  46  by a suitable shifting tool. 
     OPERATION 
     In operation, as shown particularly in FIG. 1 with casing section  23  previously perforated, bottom hole assembly  18  connected to service tool string  34  is lowered within the borehole adjacent pay zone  14 . Lower packer assembly  24  is set above production zone  14  and upper packer assembly  26  is set above production zone  14 . 
     A circulating position is shown in FIGS. 5A and 5B in which shoulder  129  of slidable valve assembly  116  on the end of tool  35  contacts shoulder  62  on upper packer sub  58  of bottom hole assembly  18 . Contact of slidable valve assembly  116  with shoulder  62  moves sleeve assembly  116  upwardly relative to mandrel  114  for alignment of ports  114  and  124 . In this position, ball  132  is dropped down the bore of tool string  34  and seats on ball catcher  134  for diverting the downward flow of circulating fluid through aligned ports  114  and  124  into annulus  37  between tool string  34  and casing  10  for suitable circulation of the fluid. 
     Next, the tool string  34  is lowered within bottom hole assembly  18  to the squeeze or gravel pack position shown in FIGS. 6A and 6B with slidable sleeve assembly  116  contacting annular shoulder  86  as shown in FIG. 6B to move slidable sleeve assembly  68  upwardly to a retracted position for alignment of ports  114  and  134  in a crossover position. In this position, fingers  92  are moved out of engagement with annular groove  96  and against abutment  97  by slidable sleeve assembly  68  for movement of slide valve  90  downwardly as shown in FIG. 6B for opening of ports  88  to communicate annulus  27  with the bore of tool string  34  through ports  114 , 124  and  88  in the crossover position. Fracturing fluid is diverted by ball  132  and the downward flow of pressurized fracturing fluid in annulus  27  is forced outwardly through the perforations  22  into the formation for hydraulic fracturing of pay zone  14  with a suitable proppant. 
     After the squeeze or gravel pack operation has been completed, tool string  34  is hydraulically released from bottom hole assembly  18  and raised to the reverse position shown in FIGS. 7A and 7B in which tool string  34  is positioned above the upper packer assembly  26 . To allow fluid transfer, the equalizing valve shown at  29  in FIG.  1  and particularly in FIGS. 10-12 is actuated so that the fluid pressure within bottom hole assembly  18  is equalized with the fluid pressure outside bottom hole assembly  18 . The flow of fluid in the reverse operation is down annulus  37  between the tool string  34  and casing  10  and up the bore of the tool string  34 . Ball  132  moves upwardly with the fluid in the reverse position as shown in FIG.  7 B and is removed from the service tool string  34 . 
     After the reverse operation, tool string  34  is lifted to a position for installation of a surface control subsurface safety valve such as shown at  164  in FIG.  8 A. Tool string  34  may be lifted around 400 feet, for example, from the sea floor for a subsea well for installation of subsurface safety valve  164  at the desired height in service tool string  34  which becomes the production tool string. After installation of subsurface safety valve  164 , the tool string  34  which also forms the production string is lowered into bottom hole assembly  18  as shown in FIGS. 9A and 9B for production with production seals  115  engaging the upper sub  62  of bottom hole assembly  18  and slidable valve assembly  116  in an extended position. Slide valve  44  is moved upwardly or downwardly by a suitable shifting tool to open openings  40  for production. 
     It is apparent from the above that the utilization of a service tool string as a production string is effective in eliminating a trip in the well which is normally provided from a rig. The tool or work string is not removed from the wellbore but forms the production string. The tool string  34  includes a slidable valve assembly  116  about the tool mandrel which moves by engagement of collet  130  to an extended position closing crossover ports  114 ,  124  in the tool mandrel  112  and slidable valve assembly  116 . The crossover ports  114 ,  124  in the sliding valve assembly and the tool mandrel are aligned only when the lower end of slide valve assembly  116  is engaged and moved upwardly to a retracted position relative to the tool mandrel  112 . Such an arrangement provides a highly effective valve assembly for the circulating position, the gravel pack position, and the reverse position. In the reverse position the service tool  35  is moved out of the upper packer assembly  26  of bottom hole assembly  18  to permit the reverse flow of fluid for removal of any proppant or the like from tool string  34 . A diverter  102  is easily moved upwardly with the reverse flow of fluid for removal from the service tool string  34 . An equalizer valve  29  as shown in FIGS. 10-12 is effective to equalize the fluid pressure within bottom hole assembly  18  as service tool  35  is moved between operational positions. The production seals  115  and  128  are easily carried by the service tool  35 . 
     While a preferred embodiment of the present invention has been illustrated in detail, it is apparent that modifications and adaptations of the preferred embodiment will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims.