Apparatus and methods for canceling the effects of fluid storage in downhole tools
First Claim
1. An apparatus for the investigation of an earth formation traversed by a borehole, comprising:
- a) a first probe including means for injecting fluid into the formation or withdrawing fluid from the formation;
b) a second probe vertically displaced relative to the first probe and in fluid contact with the formation, said second probe including a first fluid flow line and a first pressure measurement means for measuring pressure in said first fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe; and
c) a third probe azimuthally displaced relative to the first probe and in fluid contact with the formation, said third probe including a second fluid flow line and a second pressure measurement means for measuring pressure in said second fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe, wherein said first fluid flow line has a first storage volume, said second fluid flow line has a second storage volume, and at least one of said second probe and said third probe includes means for adjusting at least one of said first volume and said second volume.
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Accused Products
Abstract
The effects of storage on the interpretation of data obtained at observation probes of a borehole tool are eliminated by controlling the storage volumes relative to the observation probes. For a homogeneous medium, the effect of storage on the interpretation of data is eliminated by causing the flow line volumes connected to each observation probe to be equal to each other. For a heterogeneous medium, the effect of storage on the interpretation of data is eliminated by causing the flow line volumes to vary in proportion to the relative permeabilities of the strata of the heterogeneous medium adjacent the probes. The borehole tool is provided with mechanisms for conducting flow line volume adjustment.
12 Citations
22 Claims
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1. An apparatus for the investigation of an earth formation traversed by a borehole, comprising:
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a) a first probe including means for injecting fluid into the formation or withdrawing fluid from the formation;
b) a second probe vertically displaced relative to the first probe and in fluid contact with the formation, said second probe including a first fluid flow line and a first pressure measurement means for measuring pressure in said first fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe; and
c) a third probe azimuthally displaced relative to the first probe and in fluid contact with the formation, said third probe including a second fluid flow line and a second pressure measurement means for measuring pressure in said second fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe, wherein said first fluid flow line has a first storage volume, said second fluid flow line has a second storage volume, and at least one of said second probe and said third probe includes means for adjusting at least one of said first volume and said second volume. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for the investigation of an earth formation traversed by a borehole, comprising:
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a) a first probe including means for injecting fluid into the formation or withdrawing fluid from the formation;
b) a second probe vertically displaced relative to the first probe and in fluid contact with the formation, said second probe including a first fluid flow line and a first pressure measurement means for measuring pressure in said first fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe; and
c) a third probe azimuthally displaced relative to the first probe and in fluid contact with the formation, said third probe including a second fluid flow line and a second pressure measurement means for measuring pressure in said second fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe, wherein said first fluid flow line has a first storage volume, and said second fluid flow line has a second storage volume equal to said first storage volume.
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16. A method for investigating an earth formation traversed by a borehole utilizing an apparatus having a first probe having means for injecting fluid into the formation or withdrawing fluid from the formation, a second probe vertically displaced relative to the first probe and in fluid contact with the formation and having a first fluid flow line having a first storage volume and a first pressure measurement means, and a third probe azimuthally displaced relative to the first probe and in fluid contact with the formation and having a second fluid flow line having a second storage volume and a second pressure measurement means, the method comprising:
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a) adjusting one of said first storage volume and second storage volume;
b) injecting fluid into or withdrawing fluid from the formation through the first probe; and
c) measuring pressures at the second and third probes resulting from said injecting or withdrawing. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification