Method for judging whether rock pore structure changes along with particle size

Abstract

The invention provides a method for judging whether a rock pore structure changes along with the particle size of particles, which comprises the following steps of: crushing the same rock sample step by step from coarse to fine, and obtaining particle samples in a mesh interval at each stage; the particle samples with the same mass are screened out at each stage, permeability tests under different pressures are carried out, and the apparent permeability values of the particle samples under different pressures and the permeability ratio of the particle samples at each stage are obtained; and comparing the change difference of the permeability ratios of the adjacent-level particle samples under the same pressure parameter, and identifying that the pore structure of the rock basically does not change along with the particle size or obviously changes along with the particle size. By using the judgment method provided by the invention, the change characteristic differences of the apparent permeability values of the particles with different particle sizes along with the pressure are compared to identify that the pore structure basically does not change along with the particle size and obviously changes along with the particle size, and the judgment method has the advantages of easy operation and convenience; the problem that whether pore structures of a large number of particle samples change along with particle sizes is difficult to effectively judge is solved.

Description

technical field [0001] The invention belongs to the technical field of petroleum scientific research, and relates to a testing technology for characterizing rock pore structure and fluid flow capacity, in particular to a method for judging whether the rock pore structure changes with particle size. Background technique [0002] Petroleum-bearing reservoir rock is a typical porous medium. The ability of rock to allow fluid flow, generally expressed by permeability, is an important quality evaluation index. In engineering practice, there are many cases in which it is impossible to use regular-shaped samples for permeability testing due to the limitations of many factors, and then particle samples are used for testing. [0003] However, some existing studies have shown that there are significant differences between the permeability obtained by using particle samples with different particle sizes. Generally, the permeability value increases gradually with the increase of partic...

AI Technical Summary

Problems solved by technology

[0004] Such methods mainly include: image method, which is the most direct method, but it is expensive and has limited applicability; porosity method, porosity is only the percentage of total pore volume in rock volume, and has nothing to do with pore structure. Correspondence relationship; pore size distribution method, the pore size distribution measured by low-temperature gas adsorption (such as nitrogen adsorption) or high-pressure mercury intrusion only includes the number of pore volumes corresponding to different pore sizes, and does not include features such as the connectivity relationship of the pore space, and low-temperature gas adsorption It takes a long time, and the high-pressure mercury intrusion has the problem that the sample is contaminated by mercury and cannot be reused; the permeability method, the change of the permeability of the particle sample with the particle size may not only be caused by the change of the pore structure, but also may be due to the determined particle size and the true value. There is a deviation leading to

[0005] In general, there is currently a lack of an easy-to-operate, convenient, and effective method for judging whether the pore structure of a large number of granular samples changes with particle size, and it is difficult to obtain a comprehensive understanding of the characteristics of rock pore structure with size and its representative scale , there is no sufficient basis for answering the question of which particle size permeability should be used to represent the flow capacity of the matrix

Images