Shale brittleness evaluation method based on mechanical heterogeneity

Abstract

The invention discloses a shale brittleness evaluation method based on mechanical heterogeneity. The shale brittleness evaluation method comprises the steps: the mineral constituent deviation factor is determined according to shale mineral compositions; the dynamic Young modulus and the dynamic Poisson ratio of various minerals are determined; according to the dynamic Young modulus and the dynamicPoisson ratio of the various minerals, the estimation Young modulus and the estimation Poisson ratio of a reservoir are determined through a constituent model, and through linear fitting, a linear fitting formula for calculating the corresponding fitting Young modulus and fitting Poisson ratio through the dynamic Young modulus and the dynamic Poisson ratio is obtained; through linear fitting dataand actually-measured data, the corresponding multiple lower limit and multiple upper limit are calculated, the estimation Young modulus multiple, the estimation Poisson ratio multiple, the estimation Young modulus and the estimation Poisson ratio are determined; and the brittleness factor is calculated. The shale brittleness evaluation method considers the influence of the shale mechanical heterogeneity on brittleness evaluation, the magnitude of brittleness of all intervals of a located stratum can be determined through the method, and the theoretical guidance is provided for fracturing.

Description

technical field [0001] The invention relates to the field of exploration and development of shale reservoirs, in particular to a shale brittleness evaluation method based on mechanical heterogeneity. Background technique [0002] With the large-scale exploration and development of shale in my country, it is found that the porosity and permeability of shale in my country are extremely low, and it is necessary to rely on fracturing to form a complex fracture network in shale to make the mining effect better. However, when evaluating shale brittleness in the prior art, the mechanical heterogeneity of shale is ignored, and the fracturing brittleness index is related to mechanical heterogeneity, and previous studies did not take into account the factors caused by different mineral contents. Due to the mechanical heterogeneity of shale in different formation conditions, most of the current on-site brittleness evaluation methods are based on semi-empirical or empirical methods, whi...

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Problems solved by technology

However, when evaluating shale brittleness in the prior art, the mechanical heterogeneity of shale is ignored, and the fracturing brittleness index is related to mechanical heterogeneity, and previous studies did not take into account the factors caused by different mineral contents. The mechanical heterogeneity of shale, and the current field evaluation methods of brittleness are mostly based on semi-empirical or empirical methods, which have great uncertainty in the evaluation of shale brittleness in different formation conditions.

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