Novel shale gas fracture network comprehensive compressibility evaluation method

Abstract

The invention discloses a novel shale gas fracture network comprehensive compressibility evaluation method which comprises the following steps: S1, according to a conventional well logging interpretation result, carrying out statistics on reservoir stratums and mechanical parameters corresponding to each fracturing section of a horizontal well; s2, obtaining indexes such as comprehensive brittleness of the horizontal well; s3, obtaining indexes such as natural weak surface development of the horizontal well; s4, obtaining indexes such as crack propagation capacity of each fracturing section ofthe horizontal well; s5, establishing a gas content index; s6, establishing a fracture network comprehensive compressibility evaluation index by combining the comprehensive brittleness index, the natural weak surface development index, the fracture expansion capability index and the total gas content. Based on an existing evaluation method considering matrix compressibility, engineering dessert and geological dessert are comprehensively considered, three aspects of natural weak surface development strength, crack propagation capacity and resource abundance are added, fracturing dessert distribution is reflected, the crack net development scale is quantified, the fracturing implementation process is optimized, the fracturing transformation effect is guaranteed, and full well section cracknet fracturing is achieved.

Description

technical field [0001] The invention relates to the technical field of shale gas development, in particular to a new method for comprehensive compressibility evaluation of shale gas fracture networks. Background technique [0002] Shale gas resources buried at a depth of more than 3,500 meters in southern Sichuan account for about 86.5% of the total resources, and its efficient development has become an important goal in the industry's long-term planning. Compared with shallow layers, the development of deep shale gas also faces many difficulties, such as: more complex geological conditions, unclear resource occurrence forms and production dynamics, long drilling cycle, and difficulty in forming fracture networks by fracturing. Effective fracability evaluation makes an accurate understanding of the reservoir and achieves a better fracturing effect. In the prior art, factors affecting the shale gas fracturing effect have been analyzed from various perspectives such as minera...

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Problems solved by technology

In the prior art, factors affecting the shale gas fracturing effect have been analyzed from various perspectives such as mineral and rock mechanical properties, natural fractures and in-situ stress, bedding, and intrinsic sedimentary diagenesis. The evaluation index of compressibility is relatively simple, and the mainstream technology still uses brittle minerals, Young's modulus and Poisson's ratio as evaluation indexes, which only reflect the compressibility of reservoir matrix, and the development of natural weak planes (natural weak plane development strength , occurrence), fracture penetration and diversion ability during hydraulic fracturing (whether hydraulic fractures penetrate or divert when encountering natural weak surfaces), and resource abundance (free gas and adsorbed gas content) in the stimulated area are not involved. , failed to fully reflect the characteristics of "effective fracturing" and "stimulation" defined by fracability, and could not be effectively applied to shale gas reservoirs with deep or complex structures

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