Shale gas formation ground stress calculating method

A technology of formation stress and calculation method, applied in calculation, special data processing application, instrument, etc., can solve problems such as not considering horizontal bedding

CN106295119AActive Publication Date: 2017-01-04CHINA UNIV OF PETROLEUM (EAST CHINA)
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2017-01-04

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Abstract

The invention relates to the field of non-conventional oil-gas seismic exploration, in particular to a shale gas formation ground stress calculating method. The method includes the following steps of firstly, derivation of an orthogonal anisotropic medium ground stress equation based on a rock physical theory; secondly, approximate representation of orthogonal anisotropic medium ground stress; thirdly, estimation of an orthorhombic differential horizontal stress ratio (ODHSR) of an orthogonal anisotropic medium through rock mechanical parameters and anisotropic parameters obtained through azimuth prestack 3D seismic data inversion. The horizontal bedding characteristics of a VTI medium and the fracture perturbation properties of an HTI medium are comprehensively considered, a calculation formula of the ODHSR based on the orthogonal anisotropic medium is put forward, the solution of the ODHSR is achieved, the method is a new shale gas formation ground stress evaluating method, and whether a shale oil-gas reservoir is prone to fracturing and net formation or not can be effectively evaluated.
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Description

technical field

[0001] The present invention relates to the field of unconventional oil and gas seismic exploration, in particular to a method for calculating the ground stress of shale gas formations, and specifically discloses an important indicator factor for evaluating whether unconventional shale gas formations can be fractured into a network, that is, orthogonal and isotropic Orthorhombic Differential Horizontal Stress Ratio (ODHSR, Orthorhombic Differential Horizontal StressRatio). Background technique

[0002] In-situ stress is the mechanical parameter of the earth’s solid medium that is affected by gravity, various earth tectonic dynamics, astronomical dynamics, and additional dynamics of excavation engineering, causing response deformation in the internal units of the medium, and has an important impact on the exploration and development of unconventional shale oil and gas. significance.

[0003] At first, due to the complex causes of in-situ stress and the change...

Examples

Embodiment Construction

[0075] A method for calculating the ground stress of a shale gas formation proposed by the present invention is as follows: figure 1 Shown:

[0076] Step 1: Derivation of In-situ Stress Equation in Orthotropic Media Based on Rock Physics Theory

[0077] The orthotropic medium is an anisotropic medium composed of thin layers of horizontal layered interbedded minerals and cracks arranged along the horizontal symmetry axis. It consists of three mutually perpendicular symmetry planes, and its stiffness matrix is :

[0078] c 11 c 12 c 13 0 0 0 c 12 c ...