US4716973A
Expired / Lapsed
US
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Method for evaluation of formation invasion and formation permeability
Assignee: Baker Hughes Oilfield Operations LLC
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Filing: 1986-12-15
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Granted: 1988-01-05
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Expires: 2006-12-15
Abstract
Abstract A method is presented for evaluation of formation invasion and formation permeability by conducting a series of formation resistivity loggings in the operation of a measurement while drilling (MWD) logging system.
Inventors
- 👤 Martin E. Cobern
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:58
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
176 words
A method for determining a permeability parameter for a formation, including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred; taking a plurality of resistivity measurements of said zone subsequent to said first measurement to obtain incremental data of the degree of invasion of said zone by drilling fluid at the subsequent times, at least some of said subsequent measurements being taken prior to the zone being flushed; determining an invasion factor F(t), said invasion factor F(t) being proportional to said degree of invasion of said zone by said drilling fluid, where: ##EQU3## where R(t) is formation resistivity at time (t), T(t o ) is the initial or unperturbed formation resistivity, and R(∞) is the final or flushe formation resistivity determining a permeability parameter of said zone from said resistivity measurements wherein the step of determining a permeability parameter includes; plotting F(t) versus time to determine the permeability parameter from the slope of the plot.
Claim 2
Independent Claim
176 words
A method for determining a permeability parameter for a formation, including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred; taking a plurality of resistivity measurements of said zone subsequent to said first measurement to obtain incremental data of the degree of invasion of said zone by drilling fluid at the subsequent times, at least some of said subsequent measurements being taken prior to the zone being flushed; determining an invasion factor F(t), said invasion factor F(t) being proportional to said degree of invasion of said zone by said drilling fluid, where: ##EQU3## where R(t) is formation resistivity at time (t), T(t o ) is the initial or unperturbed formation resistivity, and R(∞) is the final or flushe formation resistivity determining a permeability parameter of said zone from said resistivity measurements wherein the step of determining a permeability parameter includes; plotting F(t) versus time to determine the permeability parameter from the slope of the plot.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein: said first resistivity measurement is taken prior to any significant invasion of said zone by said drilling fluid.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein: at least one of said resistivity measurments is taken after the resistivity in said zone ceases to change due to effects of invasion of the drilling fluid.
Claim 5
Dependent Claim
33 words
The method of claim 2 wherein: at least one of said resistivity measurments is taken after the resistivity in said zone ceases to change due to effects of invasion of the drilling fluid.
Claim 6
Dependent Claim
14 words
The method of claim 1 including: plotting F(t) versus time on a semilogarithmic scale.
Claim 7
Dependent Claim
26 words
The method of claim 1 including: determining formation pressure from changes in the slope of said plot which are commensurate with changes in the borehole pressure.
Claim 8
Dependent Claim
30 words
The method of claim 1 including: determining an absolute value of permeability from said permeability parameters and from the viscosities and pressures of the drilling fluid and the formation fluid.
Claim 9
Dependent Claim
30 words
The method of claim 1 wherein: said first resistivity measurement is taken while drilling the borehole, and said subsequent resistivity measurements are taken at know times after said first measurement.
Claim 10
Independent Claim
159 words
A method for determining an invasion parameter of a formation including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred and prior to any significant invasion of that zone by the drilling fluid or the liquid portion thereof; taking a plurality of resistivity measurements of the zone at known times subsequent to said first measurement, at least some of said subsequent measurements being taken prior to the zone being flushed, and at least one of said subsequent measurements, R(∞), being taken after the zone is completely flushed by the drilling fluid; and determining an invasion parameter, F(t), which is proportional to the difference between the resistivity measured at a time t after drilling, R(t), and the resistivity measured after the zone is completely flushed, R(∞),said invasion parameter, F(t), being determined from the said measurements of R(t) and R(x).
Claim 11
Independent Claim
159 words
A method for determining an invasion parameter of a formation including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred and prior to any significant invasion of that zone by the drilling fluid or the liquid portion thereof; taking a plurality of resistivity measurements of the zone at known times subsequent to said first measurement, at least some of said subsequent measurements being taken prior to the zone being flushed, and at least one of said subsequent measurements, R(∞), being taken after the zone is completely flushed by the drilling fluid; and determining an invasion parameter, F(t), which is proportional to the difference between the resistivity measured at a time t after drilling, R(t), and the resistivity measured after the zone is completely flushed, R(∞),said invasion parameter, F(t), being determined from the said measurements of R(t) and R(x).
Claim 12
Dependent Claim
31 words
The method of claim 9 wherein the invasion parameter F(t) is determined by the equation: ##EQU4## where R(t o ) is the first resistivity measurement, taken before significant invasion has occurred.
Claim 13
Dependent Claim
42 words
The method of claim 9 wherein the resistivity of the zone after flushing, R(∞), is determined by the equation: R(∞)=R(to)×Rmf/Rw where Rmf is the resistivity of the drilling fluid filtrate, and Rw is the resistivity of the connate water in the formation.
Claim 14
Dependent Claim
26 words
The method of claim 9 including the step of: determining a permeability parameter of a zone a formation by plotting F(t) as a function of time.
Claim 15
Dependent Claim
25 words
The method of claim 12 including: plotting F(t) versus time on a semi-logarithmic scale to determine the permeability parameter from the slope of the plot.
Claim 16
Dependent Claim
27 words
The method of claim 13 including; determining the formation pressure from changes in the slope of said plot which are commensurate with changes in the borehole pressure.
Claim 17
Dependent Claim
29 words
The method of claim 13 including: determining an absolute value of permeability from said permeability parameter and from the viscosities and pressures of the drilling fluid and the formation.
Claim 18
Dependent Claim
16 words
The method of claim 9 wherein: said first resistivity measurement is taken while drilling the borehole.
Claim 19
Dependent Claim
27 words
The method of claim 16 including the step of: determining a permeability parameter of a zone of a formation by plotting F(t) as a function of time.
Claim 20
Dependent Claim
25 words
The method of claim 17 including: plotting F(t) versus time on a semi-logarithmic scale to determine the permeability parameter from the slope of the plot.
Claim 21
Dependent Claim
27 words
The method of claim 18 including; determining the formation pressure from changes in the slope of said plot which are commensurate with changes in the borehole pressure.
Claim 22
Dependent Claim
29 words
The method of claim 18 including: determining an absolute value of permeability from said permeability parameter and from the viscosities and pressures of the drilling fluid and the formation.
Claim 23
Independent Claim
173 words
A method for determining a permeability parameter of a formation, including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred and prior to any significant invasion of that zone by the drilling fluid or the liquid portion thereof; taking a plurality of resistivity measurements of the zone at known times subsequent to said first measurment, at last some of said subsequent measurements being taken prior to the zone being flushed, and at least one of said subsequent measurements, R(∞), being taken after the zone is completely flushed by the drilling fluid; determining an invasion factor, F(t), which is proportional to the difference between the resistivity measured at a time t after drilling, R(t), and the resistivity measured after the zone is completely flushed, R(∞); and determining a permeability parameter of the zone from said resistivity measurements by plotting F(t) versus time to determine the permeability parameter from the slope of the plot.
Claim 24
Independent Claim
173 words
A method for determining a permeability parameter of a formation, including the steps of: taking a first resistivity measurement of a zone of a formation within a short and known time after drilling of a borehole in the zone has occurred and prior to any significant invasion of that zone by the drilling fluid or the liquid portion thereof; taking a plurality of resistivity measurements of the zone at known times subsequent to said first measurment, at last some of said subsequent measurements being taken prior to the zone being flushed, and at least one of said subsequent measurements, R(∞), being taken after the zone is completely flushed by the drilling fluid; determining an invasion factor, F(t), which is proportional to the difference between the resistivity measured at a time t after drilling, R(t), and the resistivity measured after the zone is completely flushed, R(∞); and determining a permeability parameter of the zone from said resistivity measurements by plotting F(t) versus time to determine the permeability parameter from the slope of the plot.
Claim 25
Dependent Claim
31 words
The method of claim 21 wherein the invasion parameter F(t) is determined by the equation: ##EQU5## where R(t o ) is the first resistivity measurement, taken before significant invasion has occurred.
Claim 26
Dependent Claim
42 words
The method of claim 21 wherein the resistivity of the zone after flushing, R(∞), is determined by the equation: R(∞)=R(to)×Rmf/Rw where Rmf is the resistivity of the drilling fluid filtrate, and Rw is the resistivity of the connate water in the formation.
Claim 27
Dependent Claim
25 words
The method of claim 21 including: plotting F(t) versus time on a semi-logarithmic scale to determine the permeability parameter from the slope of the plot.
Claim 28
Dependent Claim
27 words
The method of claim 24 including; determining the formation pressure from changes in the slope of said plot which are commensurate with changes in the borehole pressure.
Claim 29
Dependent Claim
29 words
The method of claim 24 including: determining an absolute value of permeability from said permeability parameter and from the viscosities and pressures of the drilling fluid and the formation.
Claim 30
Dependent Claim
16 words
The method of claim 21 wherein: said first resistivity measurement is taken while drilling the borehole.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-04 | 1991-07-06 | 1992-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-04 | 1995-07-06 | 1996-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-04 | 1999-07-06 | 2000-01-05 | $7700.00 | Window Closed / Lapsed |