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An experimental method for testing rock fracture toughness under pore pressure conditions

A technology of pore pressure and fracture toughness, applied in the direction of using stable tension/pressure to test material strength, measuring device, strength characteristics, etc., can solve the problem that the fracture toughness test result cannot be obtained accurately, does not consider pore pressure, cannot reflect problems such as the real situation of the formation, to achieve the effect of accurate fracture toughness, strong practicability and convenient operation

Active Publication Date: 2019-06-14
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the fracture toughness research and testing of rock materials do not consider the influence of pore pressure, and the fracture toughness test results of rock materials cannot reflect the real situation of the formation
In addition, regardless of the effect of pore pressure inside the rock, the obtained fracture toughness test results will not be able to obtain accurate results when used in model calculations

Method used

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  • An experimental method for testing rock fracture toughness under pore pressure conditions
  • An experimental method for testing rock fracture toughness under pore pressure conditions
  • An experimental method for testing rock fracture toughness under pore pressure conditions

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] An experimental method for testing rock fracture toughness under pore pressure conditions, comprising the following steps:

[0056] 1. Preparation of test pieces

[0057] Use a rock slicer to cut the rock material into cuboid specimens 17 with a length, width, and height of 76mm, 30mm, and 38mm, and then use a wire cutting saw to cut a prefabricated crack with a thickness of 1mm and a length of 15mm in the middle of the specimen 17.

[0058] 2. Sealing and fixing of test piece

[0059] First, cover the processed test piece 17 and the two hole-pressing heads 15 with a thermoplastic tube. The thermoplastic tube should cover the seal on the hole-pressing head 15, but not cover the liquid injection port II, and then The thermoplastic tube is blown soft with a hot blower, and the thermoplastic tube seals the test piece 17 and the hole-pressing head 15. After the thermoplastic pipe is cooled, the sealing member and the thermoplastic pipe on the hole pressing head 15 are cru...

Embodiment 2

[0070] Figure 1-Figure 6 Shown is a preferred embodiment of an experimental device for testing rock fracture toughness under pore pressure conditions used in the experimental method described in Example 1, which includes a testing machine, a confining pressure chamber and a clamping fixture. The testing machine includes testing machine rigid frame 1, rigid frame pressure head 2, trolley 7, slide rail 8, hydraulic shaft 9, hydraulic cylinder 10, rigid frame pressure head 2 is installed on the upper end of testing machine rigid frame 1, and rigid frame pressure head 2 is installed on the lower end of testing machine rigid frame 1. Hydraulic cylinder 10, there is a hydraulic shaft 9 inside the hydraulic cylinder 10, the trolley 7 is located on the platform of the rigid frame 1 of the testing machine, the trolley 7 is installed on the hydraulic cylinder 10, when the hydraulic cylinder 10 drops to the lowest position, the trolley 7 can move along the slide rail 8 sliding; the conf...

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Abstract

An experimental method for testing fracture toughness of rock under a pore pressure condition is characterized by (1) processing a rock material into a test piece with a preset size, and preprocessing a crack on the test piece; (2) sealing the test piece between pore pressure sealing heads, then placing the test piece into a clamping jig, and then fixing the clamping jig into a confining pressure cavity; (3) lifting a trolley until a pressure head of a confining pressure cylinder is tightly attached to a rigid frame pressure head, fully filling the confining pressure cavity with hydraulic oil, applying confining pressure and pore pressure to the test piece in sequence, heating liquid in the confining pressure cavity to a preset temperature, loading the test piece according to a set loading rate, and recording experimental data until the test piece is damaged; (4) sequentially removing axial pressure, the pore pressure and the confining pressure which are applied to the test piece, and taking out the test piece after the liquid in the confining pressure is cooled to room temperature. The experimental method provided by the invention can be used for studying the effects of factors including the pore pressure, the confining pressure, temperature and the like on the fracture toughness of a rock material, and an obtained study result can provide accurate parameter support for hydrofracture model calculation.

Description

technical field [0001] The invention belongs to the field of petroleum engineering rock mechanics, in particular to an experimental method for testing rock fracture toughness under pore pressure conditions. Background technique [0002] my country's low-permeability oil and gas fields are very rich in resources. Among my country's proven oil geological reserves in recent years, low-permeability reserves account for 60% to 70%. It can be seen that low-permeability oil fields or extra (ultra) low-permeability oil fields will be a considerable period in the future. The main resource base for increasing domestic reserves and production. Low-permeability reservoirs have low porosity, low permeability, strong heterogeneity, low reserve abundance, and are vulnerable to damage. Most oil and gas wells must implement fracturing stimulation measures before they can see production. Hydraulic fracturing technology has become an important measure for the reconstruction of low-permeability...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/12
CPCG01N3/12G01N2203/0067
Inventor 张广清刘志斌王元元董昊然
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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