Method and device for obtaining transverse relaxation time spectrum by depth-dimension nuclear magnetic resonance inversion

A nuclear magnetic resonance and transverse relaxation technology, which is applied in the direction of electronic magnetic resonance/nuclear magnetic resonance detection, electrical/magnetic detection for logging records, etc., to achieve the effect of high longitudinal resolution

Active Publication Date: 2012-07-25
CHINA UNIV OF PETROLEUM (BEIJING)
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Problems solved by technology

This method can make the longitudinal resolution of the well log curve reach twice the sampling interval, but this method is only for the conventional well log curve and cannot be applied to the NMR T 2 spectrum inversion

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  • Method and device for obtaining transverse relaxation time spectrum by depth-dimension nuclear magnetic resonance inversion
  • Method and device for obtaining transverse relaxation time spectrum by depth-dimension nuclear magnetic resonance inversion
  • Method and device for obtaining transverse relaxation time spectrum by depth-dimension nuclear magnetic resonance inversion

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Embodiment Construction

[0043] figure 1 Obtain T for the depth-dimensional NMR inversion of the present invention 2 The flowchart of the method embodiment of spectrum; figure 1 As shown, the depth-dimensional NMR inversion of the present invention obtains T 2 An embodiment of a spectral method, comprising the steps of:

[0044] Step 100: Use CPMG pulse sequence to collect spin echo trains at multiple depth points in the formation, and replace the relaxation time T in the echo amplitude with multiple B-spline basis functions 2 The pore volume percentage that the pore occupies, the data that will cover the formation information of the multiple depth points is expanded with the Walsh function on the depth dimension;

[0045] NMR logging is a logging technique suitable for open-hole wells, and it is also the only logging method that can directly measure the seepage volume characteristics of free fluid (oil, gas, water) in any lithologic reservoir.

[0046] Using CPMG (Carr-Purcell-Meiboom-Gill) pulse s...

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Abstract

The invention provides a method and device for obtaining a transverse relaxation time spectrum by depth-dimension nuclear magnetic resonance inversion. The method comprises the following steps of: for the spin echo string data of the stratum on multiple depth points, replacing the pore volume percentage of the pore with relaxation time T2 by multiple B spline primary functions on the T2 dimension, and expanding the data covering the stratum information on multiple depth points with a Walsh function on the depth dimension; constructing a kernel function for joint inversion according to the measurement parameter of an actual logging instrument and a longitudinal response function, and performing joint inversion to obtain the response parameter; and substituting the response parameter into the B spline primary function and the Walsh series of the Walsh function to obtain a nuclear magnetic resonance T2 spectrum on multiple depth points. Through the scheme, the obtained nuclear magnetic resonance T2 spectrum has relatively high longitudinal resolution, and a double sampling interval can be obtained for the horizontal layered stratum.

Description

technical field [0001] The invention relates to the nuclear magnetic resonance logging technology, in particular to a method and a device for acquiring a transverse relaxation time spectrum through depth-dimensional nuclear magnetic resonance inversion. Background technique [0002] The original spin echo series collected by NMR logging needs to be inverted by multi-exponential to obtain formation parameters and information such as porosity, irreducible water, permeability, pore size distribution and fluid type for formation evaluation. In the NMR logging process, given a long enough waiting time to ensure the complete polarization of the hydrogen nuclei in the rock pore fluid, the CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence is used to collect formation information. The spin echo amplitude can be expressed as: [0003] b i = φ ( T 2 ) ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V3/32
Inventor 肖立志黄科
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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