Rock fracture parameter inversion method

A rock fracture and inversion technology, applied in the field of rock fracture parameters, can solve problems such as the inability to fully describe the characteristics of elastic fluctuations

Inactive Publication Date: 2013-08-07
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the existing poroelastic wave mechanics represented by Biot's theory is based on O'Connell and Budiansky's theory (O'Connell R J, Budiansky B. Seismic velocities in dry and saturated cracked solids. J Geophys. Res, 1974, 79: 4626-4627), none of the fracture elastic mechanics can completely describe the elastic fluctuation characteristics in the medium with pores and fractures

Method used

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Examples

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Embodiment Be

[0127] Example Berea sandstone:

[0128] The physical properties of the Berea sandstone are high porosity and high permeability, with a porosity of 17.8% and a permeability of 200mD. figure 2 It is the data and theoretical fitting results of the longitudinal wave velocity and shear wave velocity of Berea sandstone under dry and water-saturated conditions inversion and simulation according to the method of the present invention. It can be seen from the figure that whether it is dry or water-saturated, the elastic wave velocity Both rise with the increase of pressure, and the rise is faster at low pressure. According to the above inversion steps 2 to 5, the fracture density and fracture aspect ratio of Berea sandstone are obtained by inversion, respectively as follows image 3 and Figure 4 shown. image 3 According to the method described in the present invention, the fracture density value obtained by inversion of the longitudinal wave velocity and shear wave velocity data...

Embodiment T

[0130] Example Troy Granite:

[0131] Figure 5 It is the data and theoretical fitting results of compressional wave velocity and shear wave velocity of Troy granite under dry and water-saturated conditions inverted and simulated according to the method of the present invention. Unlike the Berea sandstone, the Troy granite is very dense, with a porosity of only 0.2%. Image 6 and Figure 7 According to the above inversion steps 2 to 5, the fracture density and fracture aspect ratio of Troy granite are obtained by inversion. Image 6 According to the method described in the present invention, the fracture density value obtained from the inversion of the longitudinal wave velocity and shear wave velocity data of Troy granite under laboratory pressurized conditions, the results show that the fracture density is higher at low pressure, reaching 0.22, which means that the When the rock is not under pressure, the micro-cracks are relatively developed, and as the pressure increase...

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Abstract

The invention belongs to the field of application of geophysical wave technology and relates to a method of inversing rock fracture parameters under different pressures by rock ultrasonic measurement data. The method includes the steps of firstly, respectively measuring longitudinal wave velocity and transverse wave velocity of a rock sample in dry and fluid-saturated states under different pressures; secondly, forward-modeling and calculating the longitudinal wave velocity and transverse wave velocity by a model of 'general theory of porous and fissured medium elastic wave motion; thirdly, joint-establishing an inversion target function; fourthly, solving a global minimum of the target function by optimal GA (genetic algorithm); and fifthly, outputting corresponding model target parameters when the global minimum of the target function is obtained. By the method, the change of different-scale fractures or fissures in rock can be reflected, and the fracture density and facture aspect ratio of the rock under different pressures can be acquired conveniently.

Description

technical field [0001] The invention belongs to the technical field of applied geophysical sound waves, and in particular relates to a method for inverting rock fracture parameters under different pressures by using rock ultrasonic measurement data. Background technique [0002] At present, many oil and gas fields at home and abroad are low-porosity and low-permeability reservoirs, such as carbonate reservoirs and tight sandstone reservoirs. In recent years, shale gas development has also been put on the agenda, and has attracted more and more attention and attention Note that a very important feature of these unconventional reservoir rocks is very low porosity. Considerable oil and gas shows can often be seen from these tight oil and gas reservoirs, mainly because the fractures in the rock medium are relatively developed. Therefore, it is very important to detect and evaluate fractures in such tight reservoirs. In view of this, the fracture parameters in rocks should be m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/28
Inventor 魏周拓唐晓明钱玉萍陈雪莲
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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