Prediction method of complex network fractures in tight sandstone reservoirs

Abstract

The invention belongs to the field of petroleum exploration, and in particular relates to a method for predicting complex network fractures in tight sandstone reservoirs. The steps of the prediction method are as follows: establish a structural geological model and a fracture development model, test the magnitude and direction of the ancient and present in-situ stress, complete the rock mechanics parameter experiment, test the rock mechanics parameter and the stress sensitivity of the fracture, establish the fractured rock multi-level composite fracture criterion, Conduct rock deformation physical tests to obtain peak strength, establish a relationship model between uniaxial state stress-strain and fracture body density, establish a relationship model between triaxial state stress-strain and fracture body density, and occurrence, and establish a uniaxial state stress-strain and fracture body The density relationship model calculates and simulates the fracture parameters under the current conditions, and verifies the reliability of the fracture quantitative prediction results. The invention can accurately obtain and quantitatively characterize complex fracture parameters of tight sandstone reservoirs, is suitable for quantitative prediction of fractures mainly in any brittle reservoirs, and reduces the risk and cost of exploration and development.

Description

technical field [0001] The invention belongs to the field of petroleum exploration, and in particular relates to a method for predicting complex network fractures in tight sandstone reservoirs. Background technique [0002] As the exploration and development of oil and gas resources gradually shifts from the east to the west, and from conventional reservoirs to unconventional reservoirs, finding fractured oil and gas reservoirs has become a hot spot. How to predict the spatial distribution of fractures and quantitatively characterize fracture parameters is a key issue in petroleum geology research. frontier issues. Compared with other reservoirs, tight sandstone reservoirs have a large burial depth, high formation pressure coefficient, strong diagenesis, multiple structural movement periods, and well-developed network fractures. Structural fractures are important storage spaces and seepage channels. and development are directly controlled by the tectonic stress field and th...

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Problems solved by technology

Practice has proved that fracture space prediction based on geomechanics theory is an inevitable trend, but there are still defects and deficiencies. Strong heterogeneity of reservoir geological structure, complex and changeable stress conditions, and many periods of tectonic activity all affect the development of fractures. At the same time, the local structure and sedimentary characteristics will also change the redistribution of local stress, so that different groups of fractures overlap and reform each other, and finally form a complex network system; in addition, the fracture origin based on the homogeneous geomechanics model Mechanism analysis only considers the mutual conversion of various elastic energies, ignoring the friction energy consumption and plastic deformation energy of the fracture surface, so it is impossible to establish a more suitable rock composite fracture criterion and a more accurate fracture parameter mechanical model, wasting a lot of time. Computational resources, making fracture modeling and prediction encounter a bottleneck effect

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