Wells – Processes – With indicating – testing – measuring or locating
Reexamination Certificate
1998-11-25
2001-05-01
Pezzuto, Robert E. (Department: 3672)
Wells
Processes
With indicating, testing, measuring or locating
C166S122000
Reexamination Certificate
active
06223821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to method and apparatus for verifying positive inflation of inflatable tools such as packers. More particularly, the invention relates to installing sensors within the inflatable tool, connecting the sensors to a controller which when it receives information from the sensors communicates the information to the surface using a device or procedure capable of so communicating.
2. Prior Art
Past methods for verifying positive inflation of inflatables such as an external casing packer (ECP) have been to monitor the pressure gauge employed to measure the applied pressure to inflate the packer. The applied pressure is provided either through an internal tubing string using an inflation tool or by pressuring the casing string in which the ECP is installed. When the ECP opens and begins inflating, fluid in the pressurized column begins to rapidly disperse in an amount equal to the displacement of the inflating packer. Where the ECP is large or is being inflated in a hole that is significantly larger than the outside diameter of the ECP in the uninflated condition the displaced fluid is of a relatively large volume. A large volume of fluid moving out of the pressurized column creates a pressure drop. The pressure drop occurs suddenly and is recognized by the gauge measuring the applied pressure. As long as the displaced volume is large the pressure drop is easily measured and noted and the setting of the packer is confirmed with high confidence. The method has been used for many years successfully and reliably on all larger ECP applications. Unfortunately, however, where the ECP is being set in a hole not much larger than its own uninflated outside diameter, the amount of fluid displaced into the packer is too small to be recorded by the gauge monitoring the applied pressure. This is not to say that the displaced fluid does not actually produce a pressure drop because indeed it does, it simply is to say that the drop in pressure is small because the displacement of fluid is small and the gauge employed to monitor applied pressure at many locations does not have sufficient resolution to detect the drop. Inflation of ECP's set in this type of environment cannot be confidently verified.
One prior art method that has been attempted to confirm positive inflation of an ECP in a hole not much larger than its own uninflated outside diameter is to measure displaced fluid from surface tanks. In situations where there is a long fluid column however, and the amount of fluid for inflation is very small the percentage of fluid depletion in the tanks may not be within a measurable range with equipment common at drilling sites. Therefore, the art is in need of a system for confidently verifying inflation of an inflatable tool such as an ECP which is inflated with a relatively small amount of displaced fluid.
Another prior art method to provide information about ECPs is not direct, but as a confirmation system. More specifically, memory pressure gauges are placed in an inflation tool and measure pressure in the packer. The gauges remember the pressure and can be downloaded after removal of the packer. Drawbacks to the system are that there is no real time information and the gauges only measure pressure. They do not in fact measure whether or not inflation has taken place. Thus the information supplied is helpful but not conclusive and not timely.
SUMMARY OF THE INVENTION
The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the method and apparatus of the invention.
The inflatable tool inflation verification system of the invention comprises employing an information collector in the interior of the inflatable tool or proximate thereto such as a pressure sensor or a fluid flow device such as a turbine. The pressure sensor would be calibrated to send a signal to a downhole controller in proximity with the inflatable tool when a predetermined pressure within the inflatable tool is reached or the flow device would send a signal when a predetermined volume of fluid (sufficient to fill the tool) has entered the tool. The controller activates a communication device to send confirmation of inflation to the surface. The addition of these devices makes for high confidence verification of inflation of ECPs inflated in holes not much larger than the ECPs uninflated outside diameter.
Confirmation may be sent to the surface in a number of ways but in one preferred method, which is preferred because it enables employing the same surface equipment, is to program the controller to open an atmospheric chamber of about 150 to about 250 cubic inches in volume attached to the inflatable tool itself which displaces fluid into the chamber and thus creates a pressure drop. The drop is significant because the differential between atmospheric pressure and the ambient pressure can be 5000 psi or more. This can be largely different from the pressure drop while inflating an ECP because the ECP inside the element is at well pressure as opposed to atmospheric pressure. Thus the pressure drop in the ECP will only be perhaps 1000 psi. As is appreciated it is more difficult to measure a 1000 psi drop than a 5000 psi drop in pressure. The pressure drop caused by flooding of the atmospheric chamber is easily measurable by a commercially available specially sensitive differential pressure monitoring gauge employed in the invention. Due to the method and apparatus of the invention, the verification of inflation of inflation tools employing only a small amount of displaced fluid (as well as larger ECPs) can be confidently confirmed. This is a great benefit to the industry both because it provides for verification of inflation and additionally the invention enables the use of conventional surface techniques with the improved equipment. In addition, more atmospheric chambers could be provided to add to the information gained at the surface.
Other modes in which confirmation may be sent to the surface are by supplying an electromagnetic pulse generator in the vicinity of the inflation tool and operably connected to the controller and by using acoustic telemetry through the pipe.
Although the foregoing summary of the invention discusses external casing packers specifically, it should be understood that any type of inflatable tool can benefit from the invention. As such, the detailed description which follows is directed generically to inflatable tools/inflatable elements.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.
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patent: 5732776 (1998-03-01), Tubel et al.
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patent: 5803167 (1998-09-01), Bussear et al.
patent: 5868201 (1999-02-01), Bussear et al.
patent: 6050131 (2000-04-01), Wiilauer
patent: WO 98/09163 (1998-03-01), None
H. Gai and G. Elliot, Monitoring and Analysis of ECP Inflation Status Using Memory Gauge Data,—(No Date).
Baker Hughes Incorporated
Cantor & Colburn LLP
Mammen Nathan
Pezzuto Robert E.
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