Method for inverting rock pore distribution characteristics by utilizing pore and fracture medium elastic wave theory

A pore distribution, elastic wave technique, applied in the field of rock physics

Active Publication Date: 2021-03-16
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for inverting the distribution characteristics of rock pores using the elastic wave theory of pores and fractured media, so as to solve the problem of further expanding the traditional theory to include the interaction of pores and multi-form fracture systems. The change of the fracture system with pressure is described as the closure of fractures of different shapes (aspect ratio) under different pressures, in order to obtain the characteristics of the rock pore structure more accurately, and determine the mechanical, acoustic and fluid permeability properties of the rock and other technical issues

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  • Method for inverting rock pore distribution characteristics by utilizing pore and fracture medium elastic wave theory
  • Method for inverting rock pore distribution characteristics by utilizing pore and fracture medium elastic wave theory
  • Method for inverting rock pore distribution characteristics by utilizing pore and fracture medium elastic wave theory

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Embodiment 1

[0184] Implementation example 1: Kayenta sandstone (saturated compressional and shear wave velocities)

[0185] First, the core measurement data of Kayenta sandstone (Coyner, 1984) were processed by inversion method. Kayenta sandstone is a high-porosity rock with a porosity of 22.2% and a skeleton density of 2017kg / m 3 , the permeability is taken as 63mD, the sound velocity measurement frequency is 1MHz, and the effective pressure range of the experiment is 1MPa to 70Mpa, Figure 2-a The measured data (circle identifiers) of the variation of P- and S-wave velocities with pressure for the sandstone sample under benzene-saturated conditions are given. The bulk modulus and shear modulus of rock matrix obtained by inversion are 31.00GPa and 24.04GPa, respectively.

[0186] exist Figure 2-a In , the abscissa is the effective pressure (MPa), the ordinate is the velocity (m / s), the black circles are the measured P-wave and S-wave velocities under saturation conditions; the black sol...

Embodiment 2

[0190] Implementation Example 2: Navajo Sandstone (Combined Saturated, Dry P- and S-Wave Velocities)

[0191] Process the core measurement data (Coyner, 1984) of Navajo sandstone with the inversion method of the present invention below, and Navajo sandstone is comparatively compact, and porosity is 11.8%, and skeleton density is 2316kg / m 3 , the frequency of sound velocity measurement is 1MHz, and the effective pressure range of the experiment is from 1MPa to 100MPa. Figure 3-a The measured data (circle identifiers) of the longitudinal and shear wave velocities as a function of pressure under benzene-saturated, dry conditions are given. The difference from Example 1 is that we adopt saturated and dry joint inversion of compressional and shear wave velocities. In particular, for sandstone, in order to better fit the data, we set two rock matrix shear moduli for saturated and dry conditions in the inversion, and the rock matrix bulk modulus and The matrix shear modulus at sat...

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Abstract

The invention discloses a method for inverting rock pore distribution characteristics by utilizing a pore and fracture medium elastic wave theory. The method comprises the following processing steps of: 1, measuring saturation and drying speeds of a rock core under different pressures, and determining properties such as rock density; 2, simulating an elastic wave velocity of a rock by using a porefracture theory of polymorphic fractures; 3, calculating a pore aspect ratio spectrum under different pressure points according to the pore aspect ratio spectrum under the effective pressure of 0 forfractures with various forms in the rock; 4, establishing an inversion objective function; 5, setting fractures with various aspect ratios, wherein the fractures comprise pores; and 6, repeatedly adjusting the aspect ratio and the fracture density of each form of fracture of the rock under the effective stress of 0 to enable the objective function to reach the minimum value, so as to obtain the pore aspect ratio spectrum of the rock under each pressure point. The method can obtain rock pore structure characteristics more accurately, and analyze the mechanical, acoustic and fluid permeabilityproperties of the rock.

Description

technical field [0001] The invention belongs to the field of rock physics, and in particular relates to a method for inverting the distribution characteristics of rock pores by using the elastic wave theory of pores and cracked media. Background technique [0002] The distribution characteristics of pores in rocks have a very important impact on the mechanical, acoustic and fluid permeability properties of rocks, and are the focus of reservoir rock acoustics. Measured by the parameter of aspect ratio, the remarkable feature of rock pore distribution is that it contains pores with aspect ratio ~1 and fractures with aspect ratio <<1, and the distribution of fractures with different shapes can be well described by aspect ratio spectrum. Determining the aspect ratio spectrum of rock pores has been a research direction of rock physics for many years; elastic wave velocity measurement under experimental pressure loading conditions provides an effective way for this research....

Claims

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Application Information

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IPC IPC(8): G01V1/30
CPCG01V1/306G01V2210/6242
Inventor 唐晓明王鹤鸣苏远大陈雪莲
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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