Anisotropic reservoir fracture pressure prediction method and device

Abstract

The invention discloses an anisotropic reservoir fracture pressure prediction method and device. The method comprises the steps that basic parameters needed by calculation are collected; solving by adopting a high-order mixed partial differential characteristic equation method and a stress decomposition and superposition method, establishing a horizontal shaft stress model, and calculating a stress component at any position; a three-dimensional displacement discontinuous method is adopted to solve extra induced stress generated by strain dislocation of surrounding rocks caused by the perforation holes, then the total stress distribution parameters of the horizontal shaft are superposed, and the induced stress of the perforation holes is obtained through the stress decomposition and superposition principle; calculating stress distribution around the perforation holes according to reservoir parameters corresponding to the perforation holes; and calculating the anisotropic tensile strength by using the tensile strength of the vertical bedding and the tensile strength of the parallel bedding, and further calculating the fracture pressure of the anisotropic reservoir based on an anisotropic failure criterion. Compared with the prior art, the anisotropic reservoir fracture pressure prediction model provided by the invention is more perfect in consideration factors and more accurate in calculation result.

Description

technical field [0001] The invention relates to the field of petroleum and natural gas engineering, in particular to a method and device for predicting fracture pressure of anisotropic reservoirs. Background technique [0002] Accurate prediction of fracturing pressure is the basis for optimization of construction parameters such as fracturing construction displacement, sand-liquid ratio, etc. It is also the premise of completion string, fracturing crew power, fracturing wellhead and surface manifold preparation; if the fracturing pressure prediction is inaccurate , it will bring about a series of problems such as the construction displacement failing to meet the design requirements, the small safety pressure window for fracturing construction, and even the inability to complete the fracturing construction, resulting in property losses. Accurately predicting the fracturing pressure is very important for fracturing projects. [0003] Due to the development of bedding fracture...

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Problems solved by technology

[0004] However, the existing fracture initiation pressure prediction models are mainly aimed at isotropic and linear elastic media, and are studied through experimental physical simulation, finite element, and mathematical methods. For the dynamic damage constitutive model of strongly anisotropic rocks with bedding development, At present, there are few studies, not comprehensive, and the understanding is still unclear

Moreover, factors such as formation anisotropy characteristics, pore pressure distribution, in-situ stress, cement sheath induced stress, perforation perforation induced stress, and horizontal wellbore trajectory have not been fully considered. , the percolation characteristics of fracturing fluid in the injection process, the prediction model of the wellbore stress of the horizontal well under the influence of fluid disturbance, etc., and then based on the anisotropic formation rock failure criterion, the anisotropic reservoir fracture pressure prediction model is established

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