Method and apparatus for in situ determination of permeability and porosity
First Claim
1. In a method for in situ determination of permeability in a borehole extending through an underground formation of interest, the steps comprisingdefining an isolated test interval along the borehole between spaced-apart primary packers,defining additional isolated guard regions respectively at opposite ends of the test interval by means of guard packers respectively spaced-apart from the primary packers,developing a pressure differential between the test interval and the surrounding formation for inducing fluid flow therebetween, andsimultaneously and separately monitoring selected flow conditions in the test interval and in the separate guard regions in order to permit determination of multidimensional formation characteristics and possible leakage of fluid past the primary packers in an axial direction relative to the borehole.
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Accused Products
Abstract
A method and apparatus for in situ measurement of flow characteristics in boreholes or the like is disclosed for determining various formation characteristics such as permeability, particularly in the range of approximately 100-1,000 microdarcies and lower. One embodiment of the method and apparatus contemplates formation of a test interval in the borehole by a pair of expandable packers, additional guard zones being formed in the borehole at either end of the test interval by two additional guard packers, suitable flow conditions being simultaneously and separately measured within the test interval and each of the guard zones in order to permit determination of multidirectional components of permeability, porosity and other characteristics of the particular formation. Another embodiment contemplates whole hole testing where similar data is developed for a test interval formed between a single packer and the end of the borehole and one guard zone formed by a single additional guard packer. The method and apparatus of this invention are particularly contemplated for obtaining unambiguous measurements of multidirectional flow in low permeability formations.
68 Citations
41 Claims
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1. In a method for in situ determination of permeability in a borehole extending through an underground formation of interest, the steps comprising
defining an isolated test interval along the borehole between spaced-apart primary packers, defining additional isolated guard regions respectively at opposite ends of the test interval by means of guard packers respectively spaced-apart from the primary packers, developing a pressure differential between the test interval and the surrounding formation for inducing fluid flow therebetween, and simultaneously and separately monitoring selected flow conditions in the test interval and in the separate guard regions in order to permit determination of multidimensional formation characteristics and possible leakage of fluid past the primary packers in an axial direction relative to the borehole.
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16. A guarded straddle packer assembly for in situ determination of permeability in a borehole extending through an underground formation of interest, comprising
a pair of spaced-apart primary packers defining an isolated test interval along the borehole, an additional pair of guard packers being respectively spaced apart from the primary packers in order to define additional isolated guard regions separately formed at opposite ends of the test interval, means for developing a pressure differential between the test interval and the surrounding formation for causing fluid flow therebetween, and means for simultaneously and separately monitoring selected flow conditions in the test interval and in the separate guard regions in order to permit determination of multi-directional formation characteristics and possible leakage past the primary packers in an axial direction relative to the borehole.
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31. In a method for in situ determination of formation characteristics in a borehole extending through an underground formation of interest by means of whole hole testing, the steps comprising
defining an isolated test interval between the end of the borehole and a primary packer arranged in spaced-apart relation from the end of the borehole, defining an additional isolated guard region adjacent the test interval by means of a guard packer spaced-apart from the primary packer, developing a pressure differential between the test interval and the surrounding formation for inducing fluid flow therebetween, and simultaneously and separately monitoring selected flow conditions in the test interval and in the separate guard region in order to permit determination of multi-dimensional formation characteristics and possible leakage of fluid past the primary packers in an axial direction relative to the borehole.
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38. A guarded straddle packer assembly adapted for in situ whole hole testing and determination of permeability in a borehole extending through an underground formation of interest, comprising
a primary packer being spaced apart from the end of the borehole for defining an isolated test interval therebetween, an additional guard packer being spaced apart from the primary packer in order to define an isolated guard region separately formed adjacent the test interval, means for developing a pressure differential between the test interval and the surrounding formation for causing fluid flow therebetween, and means for simultaneously and separately monitoring selected flow conditions in the test interval and in the separate guard region in order to permit determination of multi-dimensional formation characteristics and possible leakage past the primary packer in an axial direction relative to the borehole.
Specification