Shale reservoir permeability dynamic prediction method under synergistic effect of complex mechanism

Abstract

The invention discloses a dynamic prediction method for shale reservoir permeability under the synergistic effect of a complex mechanism. The method comprises the following steps: correcting a non-circular pore with a pore section of a shale reservoir into a circular pore; carrying out quantitative characterization on pore size evolution by utilizing a pore equivalent diameter; determining a poresize fractal factor based on a fractal coarsening theory; calculating the length of a hollow billet and the number of pores in a preset range according to the pore size fractal factor, calculating thesectional area of the porous medium and the volume flow of a hollow billet bundle by utilizing a real-time pore equivalent radius and the pore number in the preset range; calculating the shale apparent permeability of the pores with different sections by utilizing hollow billet length, hollow billet bundle volume flow and the porous medium sectional area, and calculating the shale apparent permeability according to the proportions of the pores with different sections and the apparent permeability of the pores with different sections. The method can quantitatively characterize the influence ofcomplex multi-scale pores, reservoir modes, stress sensitivity and other characteristics of the shale reservoir on seepage, and realize the effective dynamic prediction of the permeability of the shale reservoir.

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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