Multiple depths and frequencies for simultaneous inversion of electromagnetic borehole measurements
First Claim
1. A wave propagation method for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for the adverse effects of drilling fluid invasion and bed boundary conditions, comprising:
- (a) providing a borehole instrument comprising at least two transmitter-receiver pairs;
(b) operating each said transmitter at a first operating frequency and at a second operating frequency thereby inducing electromagnetic radiation within the borehole and formation environs at each operating frequency;
(c) measuring the amplitude and phase of electromagnetic radiation detected by the receiver component of each said transmitter-receiver pair and computing values of apparent resistivity, at each said operating frequency, from the ratios of said amplitude measurements from each receiver pair, and from the differences of said phase measurements from each said receiver pair;
(d) providing a model of the response of said borehole instrument which relates said apparent resistivity measurements to a plurality of formation and borehole parameters representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from apparent resistivity determinations made with said borehole instrument operating in environs of known formation and borehole parameters;
(e) selecting, from said plurality of formation and borehole parameters, parameters of interest to be determined;
(f) mathematically combining said apparent resistivity measurements with said instrument response model to compute said parameters of interest and simultaneously correct said parameters of interest for the adverse effects of formation bed boundary and borehole perturbation effects; and
(g) repeating (b) through (f) as said borehole instrument is conveyed along the borehole.
1 Assignment
0 Petitions
Accused Products
Abstract
A wave propagation measurement-while-drilling system is used to determine selected formation and borehole properties. One or more transmitter-receiver pairs are utilized with the transmitter components operating at one or more frequencies to provide a measured data set. A model relating the borehole instrument response to a wide range of formation and borehole conditions is also utilized. Inversion techniques are employed to determine selected formation and borehole parameters of interest and to simultaneously correct the selected formation parametric measurements for the adverse effects of the borehole and formation bed boundaries thereby avoiding serial type corrections which can yield erroneous results in certain frequency ranges.
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Citations
33 Claims
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1. A wave propagation method for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for the adverse effects of drilling fluid invasion and bed boundary conditions, comprising:
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(a) providing a borehole instrument comprising at least two transmitter-receiver pairs; (b) operating each said transmitter at a first operating frequency and at a second operating frequency thereby inducing electromagnetic radiation within the borehole and formation environs at each operating frequency; (c) measuring the amplitude and phase of electromagnetic radiation detected by the receiver component of each said transmitter-receiver pair and computing values of apparent resistivity, at each said operating frequency, from the ratios of said amplitude measurements from each receiver pair, and from the differences of said phase measurements from each said receiver pair; (d) providing a model of the response of said borehole instrument which relates said apparent resistivity measurements to a plurality of formation and borehole parameters representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from apparent resistivity determinations made with said borehole instrument operating in environs of known formation and borehole parameters; (e) selecting, from said plurality of formation and borehole parameters, parameters of interest to be determined; (f) mathematically combining said apparent resistivity measurements with said instrument response model to compute said parameters of interest and simultaneously correct said parameters of interest for the adverse effects of formation bed boundary and borehole perturbation effects; and (g) repeating (b) through (f) as said borehole instrument is conveyed along the borehole. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A wave propagation apparatus for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for the adverse effects of drilling fluid invasion and bed boundary conditions, comprising:
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(a) a borehole instrument comprising at least two transmitter-receiver pairs with the transmitter components of said transmitter-receiver pairs operating at at least two frequencies thereby inducing a response within the receiver components of said transmitter-receiver pairs; (b) a borehole instrument response model which relates said responses of said receiver components of said transmitter-receiver pairs to a plurality of formation and borehole parameters representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from determinations of the responses of said receiver components of said transmitter-receiver pairs in environs in which formation and borehole parameters are known; (c) power and control circuits for said transmitter-receiver pairs; (d) a conveyance apparatus for conveying said borehole instrument along the borehole; (e) a CPU for mathematically processing by combining said responses by said receiver components of said transmitter-receiver pairs with said borehole instrument response model stored in said CPU thereby obtaining processed data, said processed data comprising parameters of interest selected from said plurality of formation and borehole parameters; (f) a data transfer system for transferring said receiver responses to said CPU; (g) a depth indicator for tracking the depth of said borehole instrument along said borehole; and (h) a recorder for recording said processed data as a function of depth along said borehole at which data used to generate said processed data is measured. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A wave propagation method for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for drilling fluid invasion and bed boundary conditions, comprising:
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(a) providing a borehole instrument comprising four transmitter-receiver pairs; (b) operating each said transmitter at a first operating frequency and a second operating frequency thereby inducing electromagnetic radiation within the formation and borehole environs; (c) measuring the amplitude and phase of electromagnetic radiation detected by the receiver component of each said transmitter-receiver pair and computing values of intermediate resistivity, at each said operating frequency, from the ratios of said amplitude measurements from each receiver pair, and from the differences of said phase measurements from each said receiver pair thereby obtaining a total of sixteen said intermediate resistivity measurements; (d) combining said intermediate resistivity measurements from transmitter-receiver pairs of equal longitudinal spacing thereby obtaining eight measures of apparent resistivity in which the adverse effects of rapidly changing borehole conditions and variations in the circuitry of said borehole instrument are minimized; (e) providing a model of the response of said borehole instrument which relates said eight measures of apparent resistivity to a plurality of formation and borehole parameters representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from determinations of said eight measures of apparent resistivity in environs in which formation and borehole parameters are known; (f) selecting, from said plurality of formation and borehole parameters, parameters of interest which are to be determined; (g) computing said parameters of interest and simultaneously correcting said parameters of interest by mathematically combining said eight measures of apparent resistivity with said instrument response model; (h) tracking the depth of said borehole instrument along the borehole; (i) recording said parameters of interest as a function of depth within the borehole at which they were determined; (j) conveying said borehole instrument along the borehole by means of a drill string; and (k) repeating (b) through (i) as said borehole instrument is conveyed along the borehole. - View Dependent Claims (14, 15, 16, 17)
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18. A wave propagation apparatus for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for drilling fluid invasion and bed boundary effects, comprising:
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(a) an elongated borehole instrument comprising two receivers and four transmitters; (b) means for operating said transmitters at a first operating frequency and a second operating frequency thereby producing responses of said receivers to electromagnetic radiation produced by the operation of said transmitters; (c) power and control circuits for said transmitters and said receivers contained within the borehole instrument; (d) a model of the response of said borehole instrument which relates the responses of said receivers to electromagnetic radiation, resulting from said transmitter operations, to a plurality of formation and borehole parameters representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from determinations of the responses of said receivers with said transmitters operating in environs in which formation and borehole parameters are known; (e) a CPU for mathematically processing responses of said receivers with said borehole instrument response model thereby obtaining processed data, said processed data comprising parameters of interest selected from said plurality of formation and borehole parameters; (f) a data transfer system for transmitting said responses of said receivers to said CPU; (g) a conveyance apparatus for conveying said borehole instrument within the borehole; (h) a depth indicator for tracking the depth of said borehole instrument within the borehole; and (i) a recorder for recording said responses of said receivers and said processed data as a function of said depth. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A wave propagation method for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for the adverse effects of drilling fluid invasion and bed boundary conditions, comprising:
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(a) providing a borehole instrument comprising one or more transmitter-receiver pairs; (b) operating each said transmitter at one or more operating frequencies thereby inducing electromagnetic radiation within the borehole and formation environs at each operating frequency; (c) measuring the amplitude and phase of electromagnetic radiation detected by the receiver component of each said transmitter-receiver pair and at each said operating frequency thereby obtaining a set of data parameters; (d) providing a model of the response of said borehole instrument which relates mathematically said data parameters to a plurality of formation and borehole parameters representative of the borehole and formation environs in which said borehole instrument is expected to operate, and wherein said model is obtained from determinations of said data parameters in environs in which formation and borehole parameters are known; (e) selecting, from said plurality of formation and borehole parameters, parameters of interest to be determined; (f) combining mathematically said set of data parameters with said instrument response model to compute said parameters of interest and simultaneously to correct said parameters of interest for the adverse effects of formation bed boundary and borehole perturbation effects; and (g) repeating (b) through (g) as said borehole instrument is conveyed along the borehole. - View Dependent Claims (26, 27, 28, 29)
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30. A wave propagation apparatus for measuring electromagnetic properties of earth formation penetrated by a borehole and simultaneously correcting said measurements for the adverse effects of drilling fluid invasion and bed boundary conditions, comprising:
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(a) a borehole instrument comprising one or more transmitter-receiver pairs with the transmitter components of said transmitter-receiver pairs operating at at least one frequency; (b) power and control circuits for said transmitters and receivers contained within said borehole instrument; (c) a conveyance apparatus for conveying said borehole instrument along the borehole; (d) a model of the response of said borehole instrument which relates the responses of the receiver components of said transmitter-receiver pairs to electromagnetic radiation produced by the operation of said transmitter components in a plurality of formation and borehole conditions representative of the environs in which said borehole instrument is expected to operate, and wherein said model is obtained from determinations of the responses of said receiver components of said transmitter-receiver pairs in environs in which formation and borehole parameters are known; (e) a downhole processor contained within said borehole instrument for mathematically processing the responses of the receiver components of said transmitter-receiver pairs with said borehole instrument response model thereby obtaining processed data, said processed data comprising parameters of interest selected from said plurality of formation and borehole parameters; (f) a depth indicator for tracking the depth of said borehole instrument along said borehole; (g) a data transfer system for transferring said processed data or said responses of said receivers or both to the surface of the earth; and (h) a recorder for recording said processed data as a function of depth along said borehole at which said responses of said receivers used to generate said processed data are measured. - View Dependent Claims (31, 32, 33)
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Specification