Dynamic prediction method of shale reservoir permeability under the synergistic influence of complex mechanisms

Abstract

The invention discloses a method for dynamic prediction of shale reservoir permeability under the synergistic influence of complex mechanisms, correcting the shale reservoir pore cross section from non-circular pores to circular pores; using the pore equivalent diameter to quantitatively characterize the pore size evolution; based on The fractal coarsening theory determines the fractal factor of the pore size; according to the fractal factor of the pore size, the capillary length and the number of pores in the preset range are calculated, and the cross-sectional area of ​​the porous medium and the volume of the capillary bundle are calculated by using the real-time equivalent pore radius and the number of pores in the preset range Flow rate, using the capillary length, capillary bundle volume flow rate and porous medium cross-sectional area to calculate the apparent permeability of shale in different cross-section pores, and calculate the apparent permeability of shale according to the proportion of pores in different cross-sections and the apparent permeability of pores in different cross-sections. The invention can quantitatively characterize the influence of shale reservoirs on seepage due to complex multi-scale pores, storage methods, stress sensitivity and other characteristics, and realize effective dynamic prediction of shale reservoir permeability.

Description

technical field [0001] The technical field of the invention is the field of theoretical calculation of shale reservoir permeability in unconventional oil and gas development, and specifically relates to a dynamic prediction method of shale reservoir permeability under the synergetic influence of complex mechanisms. Background technique [0002] With the increasing demand for oil and gas resources and the increasing difficulty in the exploration and development of conventional oil and gas resources, the exploration and development of unconventional oil and gas resources has become an inevitable trend, the only way and the inevitable choice for the development of the world's oil and gas industry. Among them, shale gas, as a new type of unconventional natural gas resource, is attracting increasing attention and attention due to its wide distribution and large amount of resources. Compared with conventional gas reservoirs, shale gas reservoirs have completely different character...

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Problems solved by technology

[0003] The current theoretical calculation methods for shale reservoir permeability mainly have the following problems: 1. The pore geometry is oversimplified, and the pore cross-section is generally assumed to be a circular cross-section; 2. The mass transfer of a single capillary is constructed considering the slip boundary and the Knudsen diffusion mechanism The model oversimplifies the complexity and discontinuity of the pore structure in the process of coarsening to the core scale. It is generally assumed that the geometric size and shape of each capillary are the same, and the conventional capillary bundle model is used for coarsening; 3. In the pressure relief dynamic During the development process, real-time changes in seepage channels caused by pore size evolution caused by shale reservoir properties were not considered effectively

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