Fracturing simulation method for broken and soft low-permeability oil and gas reservoir

Abstract

The invention provides a fracturing simulation method for a broken and soft low-permeability oil and gas reservoir. The method comprises the following steps: S1, compiling a broken and soft low-permeability reservoir structural plane three-dimensional network model program, and establishing a broken and soft low-permeability oil and gas reservoir fracturing numerical calculation model; s2, establishing a reservoir ductile failure-seepage constitutive model, and respectively developing a solution algorithm based on display and implicit time integration for a fracture unit and an entity unit; s3, embedding crack units in a structural plane and a reservoir matrix in the numerical model, and combining pore pressure nodes; s4, acquiring and inputting material parameters, and setting boundary conditions and initial conditions; s5, solving the model and outputting a result, and S6, analyzing a simulation effect, optimizing fracturing process parameters, and further improving the oil and gas yield in the fractured and soft low-permeability reservoir. The method can be used for analyzing the form of the fracturing fracture net under the influence of different fracturing engineering parameters and different engineering geological parameters, optimizing the fracturing parameters and realizing efficient exploitation of oil and gas resources, and has a relatively great application prospect.

Description

technical field [0001] The invention relates to the technical field of natural gas and petroleum development, in particular to a fracturing simulation method for soft and low-permeability oil and gas reservoirs. Background technique [0002] my country's foreign dependence on natural gas and oil has reached 43.1% and 67.4%, making energy security face huge risks. However, my country's reserves of coalbed methane resources shallower than 2000m are as high as 30 trillion cubic meters, and the efficient development of this unconventional clean energy will effectively promote the realization of the goal of "realizing carbon neutrality by 2060". However, the coal seams in most parts of China are characterized by fragmentation, weakness, and extremely low permeability, which will pose great challenges to the efficient extraction of coalbed methane. [0003] In the practice of coalbed methane extraction in Zhaozhuang Mine of Qinshui Coalfield, it is shown that in the process of su...

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Problems solved by technology

[0005] However, there are abundant and complexly distributed structural planes and strong ductile failure characteristics in fractured, soft and low-permeability reservoirs.

The former will cause hydraulic main fractures to propagate along structural planes, while secondary fractures will press through the reservoir matrix to form a complex fracture network structure. The fluid energy is used to consume the non-elastic energy that has nothing to do with the fracture propagation. At the same time, once the reservoir matrix is ​​plastically damaged, a large amount of fracturing fluid will be lost. The area of ​​the fracture network is very small, and the existing numerical calculation models for fracturing engineering generally simplify soft and low-permeability reservoirs into continuous media and brittle materials, which seriously affect the accuracy of numerical simulation results

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