Wells – Processes – Placing or shifting well part
Patent
1998-03-26
2000-05-23
Lillis, Eileen Dunn
Wells
Processes
Placing or shifting well part
166127, 166142, 166147, 166186, 166187, 166191, E21B 3312
Patent
active
060655445
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method and a system for use in activating an inflatable packer about a casing for sealing engagement with the wall of a bore hole, and more particularly, to a method and system for effectively inflating a packer in a zone defined between a pair of previously expanded packers by simultaneously relieving entrapped fluid pressure from the zone.
A packer is utilized in conjunction with a casing installed in a bore hole so that on expansion of the packer, it engages the wall of the bore to prevent the flow of fluid and material carried by the fluid along the annular space between the casing and wall of the bore hole. The packer also resists any axial shifting of the casing within the bore as the well is being operated. It is common to use at least two axially spaced packers to isolate a length of the axial space between the casing and the wall of the bore hole so that, for example, water being produced from a particular zone or earth formation is not allowed to flow either upwardly or downwardly so as to thereby mix with other fluid being pumped from the borehole and up the casing.
A common type of packer now used includes a sleeve of resilient material which surrounds the casing and is closed at opposite ends so that as a pressurized fluid is pumped into the casing and through a valve into the space between the resilient sleeve and the casing, the resilient sleeve inflates to the extent it tightly engages the wall of the bore and thereby deploys as a seal of the annulus between the casing and the bore wall. When sufficient pressure is achieved to ensure an effective seal, the valve closes to hold the pressurized fluid in the inflated packer so as to maintain it in its initially inflated condition.
The casing in the well may be provided with a pair of like separate inflatable packers which are axially spaced along the casing and when both of the pair of packers are inflated, the fluid in the annular space between the pair is entrapped. This entrapped fluid, for example, may be water which is being produced at a particular level or zone of the well and spaced from another zone of interest. It is not uncommon, however, to provide additional packers in the string which are not inflated initially with the first pair. Eventually, it may become desirable to inflate an additional packer located between the already inflated pair. It has been found that due to the pressure of the fluid between the already inflated pair, and which pressure may in fact increase as the inflation of the additional packer commences, the pressure of this entrapped fluid can become sufficient to prevent the proper inflation of the additional packer. Moreover, as this high fluid pressure, called the squeeze pressure, bleeds off either into the formation forming the wall of the bore, or even past the previously inflated pair of packers, the sealing effort of the newly inflated packer may become ineffective.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a squeeze relief valve, which is relatively inexpensive and which functions on inflation of an associated inflatable packer to provide a relief of the pressure of the fluid in the annular space about the casing in the vicinity of the packer.
It is also an object of the present invention to provide a method of achieving automatic bleeding of the annular space in the vicinity of a packer means during the inflation of such packer means.
According to one aspect of the present invention there is provided a relief valve system for use in a casing positioned in a well bore wherein the valve system provides a relief of entrapped pressurized fluid in an annular space between an exterior surface of the casing member during expansion of an associated inflatable packer means provided on the exterior surface of the casing member. The system allows effective sealing of the packer means against the wall of the well bore. The packer means is of the type having packer valve means for permitting the flow into the packer means of inflating
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Kerins John C.
Kreck John
Lillis Eileen Dunn
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