Simulating method of forming process of unconventional oil and gas reservoir hydraulic fracturing complex fracture net

Abstract

The invention discloses a simulating method of the forming process of an unconventional oil and gas reservoir hydraulic fracturing complex fracture net. The method includes the steps of a, reestablishing natural fracture distribution, estimating the properties of natural fractures, obtaining rock mechanical information and stratum stress information of a stratum from log data or a geological model, and obtaining a data file related to the well factory construction process; b, inputting the obtained parameters in an established natural fractured reservoir fracturing model coupling a well cylinder, fractures and the stratum; c, conducting numerical value solving on the model to obtain after-fracturing information such as fracture forms, opening degree distribution and pressure intensity distribution; d, analyzing the fracturing effect through a model calculating result, and making a preparation for numerical value simulation of the later-period production process. The fractured reservoirfracturing numerical value simulating method coupling the well cylinder flowing, the fracture deformation expanding, the multi-state natural fractures and the flowing of fluid in the fractures can quantitatively analyze the form of the unconventional reservoir segmented volume fracture net and is an effectively means for evaluating and optimizing the fracturing scheme.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development, in particular to a method for simulating the formation process of complex fracture networks in hydraulic fracturing of unconventional oil and gas reservoirs. Background technique [0002] In unconventional reservoirs such as shale, the matrix permeability is only nano-darcy. If the horizontal well staged fracturing technology is not used, it will be far from meeting the requirements of economical production. However, the increase in the length of horizontal wells and the construction scale of hydraulic fracturing makes the construction cost of fracturing horizontal wells much higher than that of conventional wells. In the United States, the cost of drilling a new horizontal well is about 1.5 to 2.5 times that of a vertical well. Improving the fracturing effect is of great significance for increasing the productivity of fracturing wells and the economic benefits of shale gas...

AI Technical Summary

Problems solved by technology

UFM is a great improvement on the existing fracturing models, but there are still the following problems: 1) The displacement in the fracture shear direction is ignored; 2) The simulation of natural fractures is the same as that of fracturing fractures, and cannot reflect the natural fracture shear. 3) The re-initiation of fractures at the ends of natural fractures does not follow the mechanical principles

[0009] Although the above model is a great improvement on the model of a single straight double-wing fracture, since the simulation of complex fracture networks is much more difficult than that of single fractures, there is currently no perfect model for describing the expansion of fractures in natural fracture networks.

The numerical simulation method based on finite element and extended finite element needs to refine the grid around the fractures. When the natural fractures are densely distributed, the grid division is difficult and the calculation efficiency is low, so it is difficult to apply to reservoir-scale problems.

The simulation method based on the discrete element method is limited by the applicable scale of the simulation, and it is difficult to apply to the well factory problem of hundreds of meters

Although the existing numerical simulation algorithm based on the boundary element method can effectively improve the calculation efficiency, it ignores the processes of newly generated fractures and natural fracture shear slip to varying degrees, and cannot fully describe the fractures in the formation. Propagation of pre-existing natural fractures

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