Method for determining pore size distribution and fluid distribution in porous media

Claim 1

A method for determining the pore size distribution of a porous media comprising the steps of: (a) substantially saturating a sample of said porous media with a fluid which exhibits a response in a nuclear magnetic resonance spectrometer; (b) positioning the thus saturated sample in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (c) subjecting the thus positioned sample to a first radiofrequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said sample approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (d) subjecting the thus treated sample to a second radio frequency pulse at a time t 2 , which is later in time that said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (e) subjecting the thus treated sample to a third radiofrequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (f) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (g) changing the magnetic field gradient G to a different magnitude; (h) repeating steps c-g to obtain a plurality of spin echo amplitudes as a function of the magnitude of the magnetic field gradient G; and (i) determining the pore size distribution of said sample based on the plurality of spin echo amplitudes which are a function of the magnetic field gradient G.

Claim 2

A method for determining the pore size distribution of a porous media comprising the steps of: (a) substantially saturating a sample of said porous media with a fluid which exhibits a response in a nuclear magnetic resonance spectrometer; (b) positioning the thus saturated sample in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (c) subjecting the thus positioned sample to a first radiofrequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said sample approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (d) subjecting the thus treated sample to a second radio frequency pulse at a time t 2 , which is later in time that said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (e) subjecting the thus treated sample to a third radiofrequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (f) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (g) changing the magnetic field gradient G to a different magnitude; (h) repeating steps c-g to obtain a plurality of spin echo amplitudes as a function of the magnitude of the magnetic field gradient G; and (i) determining the pore size distribution of said sample based on the plurality of spin echo amplitudes which are a function of the magnetic field gradient G.

Claim 9

A method for determining the size distribution of pores in a sample of a porous medium which contains an aqueous solution and an organic fluid comprising the steps of: (a) substantially displacing said aqueous solution with a third fluid which exhibits substantially no response in a nuclear magnetic resonance spectrometer; (b) positioning the thus treated sample in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (c) subjecting the thus positioned sample to a first radio frequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said sample approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (d) subjecting the thus treated sample to a second radio frequency pulse at a time t 2 , which is later in time than said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (e) subjecting the thus treated sample to a third radio frequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (f) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (g) changing the magnetic field gradient G to a different magnitude; (h) repeating steps c-g to obtain a plurality of spin echo amplitudes as a function of the magnetic field gradient G; and (i) determining the pore size distribution of the pores of said sample which contain said organic fluid based on the plurality of spin echo amplitudes which are a function of the magnitude of the magnetic field gradient G.

Claim 10

A method for determining the size distribution of pores in a sample of a porous medium which contains an aqueous solution and an organic fluid comprising the steps of: (a) substantially displacing said aqueous solution with a third fluid which exhibits substantially no response in a nuclear magnetic resonance spectrometer; (b) positioning the thus treated sample in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (c) subjecting the thus positioned sample to a first radio frequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said sample approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (d) subjecting the thus treated sample to a second radio frequency pulse at a time t 2 , which is later in time than said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (e) subjecting the thus treated sample to a third radio frequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (f) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (g) changing the magnetic field gradient G to a different magnitude; (h) repeating steps c-g to obtain a plurality of spin echo amplitudes as a function of the magnetic field gradient G; and (i) determining the pore size distribution of the pores of said sample which contain said organic fluid based on the plurality of spin echo amplitudes which are a function of the magnitude of the magnetic field gradient G.

Claim 17

A method for determining the size distribution of pores of a porous medium which contain a viscous organic fluid comprising the steps of: (a) stripping said viscous organic fluid from a sample of said porous media; (b) substantially saturating the thus stripped sample of said porous media with a substitute fluid which exhibits substantially no response in a nuclear magnetic resonance spectrometer; (c) introducing a second organic fluid having a lower viscosity than said viscous organic fluid into the saturated sample to thereby displace at least a portion of said substitute fluid to thereby produce a restored porous media; (d) flushing said restored porous media with said substitute fluid; (e) positioning the thus flushed restored porous media in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (f) subjecting the thus positioned flushed restored porous media to a first radio frequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said flushed restored porous media approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (g) subjecting the thus treated flushed restored porous media to a second radio frequency pulse at a time t 2 , which is later in time than said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (h) subjecting the thus treated flushed restored porous media to a third radio frequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (i) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (j) changing the magnetic field gradient G to a different magnitude; (k) repeating steps f-j to obtain a plurality of spin echo amplitudes as a function of the magnitude of the magnetic field gradient G; and (l) determining the pore size distribution of the pores of said sample which contain said viscous organic fluid based on the plurality of spin echo amplitudes which are a function of the magnitude of the magnetic field gradient G.

Claim 18

A method for determining the size distribution of pores of a porous medium which contain a viscous organic fluid comprising the steps of: (a) stripping said viscous organic fluid from a sample of said porous media; (b) substantially saturating the thus stripped sample of said porous media with a substitute fluid which exhibits substantially no response in a nuclear magnetic resonance spectrometer; (c) introducing a second organic fluid having a lower viscosity than said viscous organic fluid into the saturated sample to thereby displace at least a portion of said substitute fluid to thereby produce a restored porous media; (d) flushing said restored porous media with said substitute fluid; (e) positioning the thus flushed restored porous media in a static magnetic field H o and a magnetic field gradient G which is superpositioned on said static magnetic field H o ; (f) subjecting the thus positioned flushed restored porous media to a first radio frequency pulse at a time t 1 to thereby rotate the precessing nuclear magnets associated with the fluid in said flushed restored porous media approximately 90° to generally the positive Y-axis of a reference frame which is rotating around the direction of the static magnetic field H o where the direction of the static magnetic field H o is the positive Z axis of said reference frame and the direction of the alternating magnetic field H 1 produced by said first radio frequency pulse is the positive X axis of said reference frame; (g) subjecting the thus treated flushed restored porous media to a second radio frequency pulse at a time t 2 , which is later in time than said time t 1 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Z plane of said reference frame; (h) subjecting the thus treated flushed restored porous media to a third radio frequency pulse at a time t 3 , which is later in time than said time t 2 , to thereby rotate said precessing nuclear magnets approximately another 90° to generally the X-Y plane of said reference frame; (i) measuring, by means of a nuclear magnetic spectrometer, the amplitude of the spin echo signal which occurs when the magnetization of said precessing nuclear magnets refocuses on generally the negative Y-axis of said reference frame after said time t 3 ; (j) changing the magnetic field gradient G to a different magnitude; (k) repeating steps f-j to obtain a plurality of spin echo amplitudes as a function of the magnitude of the magnetic field gradient G; and (l) determining the pore size distribution of the pores of said sample which contain said viscous organic fluid based on the plurality of spin echo amplitudes which are a function of the magnitude of the magnetic field gradient G.