Evaluating the pore structure of low permeability glutenite reservoir by 3D digital core technology

Abstract

In order to analyze the micro pore structure characteristics of low-permeability glutenite reservoirs more intuitively and accurately, µ-CT scanning imaging technology is used to evaluate the development characteristics of pores, fractures and high-density interstitial materials in the three-dimensional core space of samples, and the rock pore structure is analyzed from the perspective of image gray, homogeneity and pore throat connectivity. According to the maximum sphere algorithm, a digital core pore network model is extracted and established, and the probability distribution characteristics of pore radius, throat radius, pore throat ratio and core pore throat coordination number of different rock samples are studied. The results show that the reservoir space of the samples in the study area is dominated by dissolution pores and micro fractures, with pore radius ranging from 0.1 to 10 μm, throat radius from 0.1 to 7 μm, pore throat ratio from 0 to 4, and coordination number from 0 to 7. The overall pore throat ratio, throat radius and poor throat connectivity are the main reasons for the low core permeability in the study area. It is found that the 3D digital core technology can more accurately evaluate the internal heterogeneity of rocks, and the calculated pore structure parameters include both connected pore information and isolated pore information. Compared with conventional mercury injection and nuclear magnetic resonance, the 3D digital core technology has obvious advantages in the evaluation of rock micro pore structure.