Wells – Processes – Graveling or filter forming
Reexamination Certificate
1999-03-17
2001-04-17
Neuder, William (Department: 3672)
Wells
Processes
Graveling or filter forming
C166S051000
Reexamination Certificate
active
06216785
ABSTRACT:
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 '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 appare
Achee, Jr. Timothy T.
Bissonette Harold S.
Dancause Charles M.
Bani-Jamali Maryan
Griffin Jeffrey E.
Neuder William
Schlumberger Technology Corporation
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