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, said means for adjusting being controlled to reduce storage effects on interpretation of data obtained from said second probe and said third probe.
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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.
26 Citations
21 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, said means for adjusting being controlled to reduce storage effects on interpretation of data obtained from said second probe and said third probe. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. 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; 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, and d) means for estimating permeability of the formation adjacent said second probe and adjacent said third 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, and said means for estimating permeability causing said means for adjusting at least one of said first volume and said second volume to adjust at least one of said first volume and said second volume. - View Dependent Claims (12)
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13. 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; 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, and d) means for estimating a ratio of a permeability of the formation adjacent said second probe and a permeability of the formation adjacent said third 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, and said means for estimating a ratio causing said means for adjusting at least one of said first volume and said second volume to adjust at least one of said first volume and said second volume such that a ratio of said first volume to said second volume is substantially equal to a ratio of said permeability. - View Dependent Claims (14)
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15. 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 to obtain a desired ratio of said first volume and second; 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, wherein said adjusting adjusts one of said first storage volume and second storage volume in order to reduce storage effects on interpretation of pressure data obtained from said second probe and said third probe. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification