A method for establishing an orthotropic shale petrophysical model

Abstract

The invention discloses a method for establishing an orthotropic shale rock physical model. The method comprises the following steps: through logging, mud logging, indoor testing, anisotropic SCA andDEM models, isotropic SCA and DEM models, a Schoenberg linear sliding model and a Brown-Korringa model, establishing a rock physical model capable of predicting the shale stiffness tensor. According to the method, the influence of inorganic matter pores and organic matter pores on a modeling result is considered respectively; the contents of organic matter pores and inorganic matter pores are respectively calculated by utilizing the contents of the adsorbed gas and the free gas and combining the total porosity, the cause of shale anisotropy and the condition that vertical cracks are developedare comprehensively considered, and the problem that the orthotropic shale rigidity coefficient is difficult to obtain is solved.

Description

technical field [0001] The invention relates to a method for establishing an orthotropic shale rock physics model, and belongs to the technical field of rock physics. Background technique [0002] The microscopic properties of shale will have an important impact on the macroscopic properties. For example, the directional arrangement and layering of organic minerals and the existence of flat pores (micro-cracks developed in the lateral direction) in the rock are the main factors that cause the shale to exhibit transverse isotropy. reason. There are large differences in the elastic properties of shale rocks in the direction parallel to the bedding and perpendicular to the bedding, the most obvious being the difference in Young's modulus and Poisson's ratio in the two directions. Conventional oil and gas reservoirs (such as sandstone oil and gas reservoirs and carbonate rock oil and gas reservoirs) often exhibit isotropic properties, and their elastic parameters can be charact...

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Problems solved by technology

Considering the fluid connection problem, Hu used the clay and fluid mixture simulated by anisotropic SCA and DEM as the background medium, and used the V-R-H limit to simulate the equivalent elastic modulus of the mixture of kerogen, quartz, calcite and other minerals, and finally used Anisotropic DEM adds the mixture to the background medium. Due to the large difference in the elastic modulus of minerals such as kerogen and quartz, the model also has a large error; Liu Zichun regards kerogen as the In the background medium, the pores are added to the kerogen with the SCA+DEM model to ensure the interconnection of the pores and the kerogen, and the equivalent elastic modulus of the minerals other than the kerogen is calculated using the H-S limit and used as inclusions, and then added to the In the background medium, the saturated shale petrophysical model is finally obtained by fluid replacement. This model takes into account the interconnection of kerogen and pores, but does not consider the influence of different pores on the modeling results

[0004] Most of the above-mentioned shale petrophysical modeling regards the shale formation as transversely isotropic, but cannot describe the elastic characteristics of orthotropic shale with fractures.

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