A Permeability Evaluation Method for Unconventional Reservoir Based on Core Image

Abstract

The present invention provides a method for evaluating the permeability of unconventional reservoirs based on rock core images, which includes the following steps: using rock imaging technology to scan and identify real rock samples to obtain corresponding images, and divide the rock samples in the images into corresponding features; Extract the frequency spectrum of each feature separately, and then use the mixed fractal method to fit the analysis results to obtain the fractal parameters of each corresponding feature; combine the fitted fractal parameters to obtain a rock pore model based on the mixed fractal theory; through The pore connectivity algorithm calculates the connectivity probabilities between different types of pores in the rock pore model according to the connectivity probability matrix, and then the evaluation results of the apparent permeability of the current unconventional reservoir can be obtained. The invention starts from the real rock sample data and combines the pore connectivity algorithm to obtain the connectivity probability matrix between different types of pores, and finally realizes fast and accurate evaluation of the apparent permeability of unconventional reservoirs.

Description

technical field [0001] The invention belongs to the field of petroleum exploitation, in particular to an evaluation method based on rock core images that can quickly and accurately evaluate the apparent permeability of unconventional reservoirs. Background technique [0002] Shale gas is natural gas extracted from shale reservoirs. It is mainly composed of methane and is an important emerging energy source. However, the successful development of shale gas needs to solve many problems, and one of the basic problems is to quickly and effectively evaluate the apparent permeability of shale. [0003] There are many factors that affect the apparent permeability of shale gas, mainly as follows: first, shale is very tight, with low porosity and permeability, small seepage space, and the diameter of the main pores is on the order of nanometers; second, seepage There are various types of space, poor connectivity, and different scales, including nano-scale organic pores and micron-sc...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that after simplifying the complex pore space into a standard square network structure model, it will be randomly dispersed into the network after being broken up, and the independence of the spatial distribution of pores and throats will be canceled.

In addition, the tortuosity of the throat, and the pore size distribution of the throat itself were not considered

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