Porosity and permeability measurement of underground formations containing crude oil, using EPR response data
First Claim
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1. An EPR/NMR apparatus for detecting petrophysical features of a fluid-filled underground formation having a region of static magnetic field sensitivity, comprising:
- at least one antenna for providing an RF magnetic field in said region at an EPR frequency, and for receiving an EPR response signal from the fluid;
a transmitter operable to provide power at said EPR frequency;
a detector for receiving said ESR response signal from said antenna;
a processor operable to analyze said EPR response signal by relating the amplitude of said EPR response signal to an estimated amount of crude oil in said underground formation;
at least one antenna for providing an RF magnetic field in said region at an NMR frequency and for receiving an NMR response signal, and wherein said processor is further programmed to analyze said NMR response signal by relating the amplitude of said NMR response signal to an estimated amount of hydrogen-bearing fluid in said underground formation; and
a transmitter operable to provide power at said NMR frequency to said antenna;
wherein said processor is further operable to calculate the oil and water fractions in said fluid, to determine a NMR relaxation rate, and to calculate a pore size distribution of pores of said underground formation, based on said relaxation rate.
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Abstract
A method and apparatus (10) for detecting and measuring the amount of crude oil in underground rock formations. EPR measurements are used to calculate the amount of crude oil, and may be calibrated to determine the particular type of crude oil. These measurements may be used in conjunction with NMR measurements, to provide accurate estimations of pore size and permeability.
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Citations
19 Claims
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1. An EPR/NMR apparatus for detecting petrophysical features of a fluid-filled underground formation having a region of static magnetic field sensitivity, comprising:
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at least one antenna for providing an RF magnetic field in said region at an EPR frequency, and for receiving an EPR response signal from the fluid;
a transmitter operable to provide power at said EPR frequency;
a detector for receiving said ESR response signal from said antenna;
a processor operable to analyze said EPR response signal by relating the amplitude of said EPR response signal to an estimated amount of crude oil in said underground formation;
at least one antenna for providing an RF magnetic field in said region at an NMR frequency and for receiving an NMR response signal, and wherein said processor is further programmed to analyze said NMR response signal by relating the amplitude of said NMR response signal to an estimated amount of hydrogen-bearing fluid in said underground formation; and
a transmitter operable to provide power at said NMR frequency to said antenna;
wherein said processor is further operable to calculate the oil and water fractions in said fluid, to determine a NMR relaxation rate, and to calculate a pore size distribution of pores of said underground formation, based on said relaxation rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A computer-implemented EPR/NMR method of detecting petrophysical features of a fluid-filled underground formation having a region of static magnetic field sensitivity, comprising the steps of:
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providing an RF magnetic field in said region at an EPR frequency;
receiving an EPR response signal;
analyzing said EPR response signal by relating the amplitude of said EPR response signal to an estimated amount of crude oil in said underground formation;
providing an RF magnetic field in said region at an NMR frequency;
receiving an NMR response signal;
analyzing said NMR response signal by relating the amplitude of said NMR response signal to an estimated amount of hydrogen-bearing fluid in said underground formation;
calculating the oil and water fractions in said fluid, using the results of said analyzing steps for both EPR and NMR responses; and
determining a NMR relaxation rate and calculating a pore size distribution of pores of said underground formation, based on said relaxation rate. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification