Wells – Processes – With indicating – testing – measuring or locating
Reexamination Certificate
2001-04-16
2003-06-10
Bagnell, David (Department: 3672)
Wells
Processes
With indicating, testing, measuring or locating
C166S278000, C166S051000
Reexamination Certificate
active
06575243
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to tools used to complete subterranean wells. More particularly the present invention describes a means of pressure testing the effectiveness of a zonal isolation system after installation.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
Sand or silt flowing into the wellbore from unconsolidated formations can lead to an accumulation of fill within the wellbore, reduced production rates and damage to subsurface production equipment. Migrating sand has the possibility of packing off around the subsurface production equipment, or may enter the production tubing and become carried into the production equipment. Due to its highly abrasive nature, sand contained within production streams can result in the erosion of tubing, flowlines, valves and processing equipment. The problems caused by sand production can significantly increase operational and maintenance expenses and can lead to a total loss of the well. One means of controlling sand production is the placement of relatively large sand (i.e., “gravel”) around the exterior of a slotted, perforated, or other type liner or screen. The gravel serves as a filter to help assure that formation fines and sand do not migrate with the produced fluids into the wellbore. In a typical gravel pack completion, a screen is placed in the wellbore and positioned within the unconsolidated formation that is to be completed for production. The screen is typically connected to a tool that includes a production packer and a cross-over, and the tool is in turn connected to a work or production tubing string. The gravel is pumped in a slurry down the tubing and through the cross-over, thereby flowing into the annulus between the screen and the wellbore. The liquid forming the slurry leaks off into the formation and/or through the screen, which is sized to prevent the gravel in the slurry from flowing through. The liquid that passes through the screen flows up the tubing and then the cross-over directs it into the annulus area above the packer where it can be circulated out of the well. As a result of this operation, the gravel is deposited in the annulus area around the screen where it forms a gravel pack. The screen prevents the gravel pack from entering into the production tubing. It is important to size the gravel for proper containment of the formation sand, and the screen must be designed in a manner to prevent the flow of the gravel through the screen.
At times it is desirable to complete a zone and then isolate the zone until production is initiated at a later date. One example of when delayed production might be beneficial is when multiple productive zones having significantly different formation pressures are to be completed in a single well. If a first zone having greater formation pressures is completed with a second zone that has lower pressures, hydrocarbons from the first zone will migrate to the second zone and may decrease the ultimate recovery that is obtained from the first zone. To maximize the ultimate recovery from the well, it may be beneficial to initially produce only the first zone with the higher pressure. Once the formation pressure of the first zone has decreased to where it is close to the formation pressure of the second zone, the second zone can be produced along with the first zone, and the commingled zones can be depleted together without any loss of reserves from interzonal migration. Economically it would be beneficial to complete both zones while the drilling/completion equipment is on the well, but isolate the second zone until production is desired at a later date.
Zonal isolation systems are used to isolate and selectively produce oil or gas from separate zones in a single well. U.S. Pat. Nos. 5,579,844; 5,609,204 and 5,988,285 describe systems for the zonal isolation of wells. The high variability in downhole conditions and well tool configurations create a need for testing the integrity of zonal isolation systems after their installation. If a zone is not adequately isolated, substantial quantities of hydrocarbon reserves can be lost, resulting in significant economic losses. One method of testing the integrity of zonal isolation system is by running in the well with one or more packer assemblies on a workstring. The packers are set to isolate individual segments of the isolation system, which can then be tested for any leakage. This method requires additional trips in and out of the wellbore that results in increased expense. Any reduction in the number of trips required to complete a well will result in significant cost savings.
There is a need for improved tools and methods to test the integrity of zonal isolation systems after their installation.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a zone isolation apparatus for use in completing a wellbore comprising a sand screen assembly and a tubular string disposed within the wellbore. Also included is an isolation assembly that is movable within the sand screen assembly and capable of being selectively positioned in an open configuration and a closed configuration, and a test assembly attached to the tubular string and capable of being selectively positioned in an open configuration and a closed configuration. When the isolation assembly is in its closed configuration fluid communication through the sand screen assembly is restricted, and when the test assembly is in its open configuration, hydraulic communication of the isolation assembly with the surface is achieved. The test assembly can be retained in the closed configuration by a releasable retaining element and can further comprise a sliding sleeve having at least one aperture and a stationary sleeve having at least one aperture. When the test assembly is in its open configuration the apertures of the sliding sleeve are aligned with the apertures of the stationary sleeve and fluid communication is provided through the aligned apertures. The sand screen assembly may also comprise a packer element.
The tubular member placed within the wellbore defines an annulus area. When the isolation assembly is in its closed configuration and the test assembly is in its open configuration, hydraulic communication between the annulus area above the packer and the interior of the isolation assembly can be achieved while also providing hydraulic isolation from the annulus area below the packer. The isolation assembly can comprise an isolation pipe and at least one seal element. When the isolation assembly is in its closed configuration, the isolation pipe forms a seal within the sand screen assembly and fluid communication through the sand screen assembly is restricted. The isolation assembly may comprise a shifting collet assembly attached to the tubular member that is capable of engaging with the isolation pipe. The shifting collet may include flex beam portions that are capable of engaging with the isolation pipe. The isolation assembly can also have a latching collet assembly that engages with the sand screen assembly when the isolation assembly is in its closed configuration.
The test assembly can comprise a test port and at least one seal assembly, where the test port and the seal assemblies are capable of aligning with the packer and the sand screen assembly to provide hydraulic communication of the interior of the isolation assembly with the annulus above the packer and hydraulic isolation from the annulus below the packer.
Another embodiment of the inventio
Bagnell David
Dougherty Jennifer R.
Griffin Jeffrey
Jeffery Brigitte
Schlumberger Technology Corporation
LandOfFree
Zonal isolation tool with same trip pressure test does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Zonal isolation tool with same trip pressure test, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Zonal isolation tool with same trip pressure test will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3112714