Research Of New Core Analyze Method For Particular Lithology Rock

Core analysis is one of the most necessary means to recognize the geological characteristics of reservoirs. Recently, the oil and gas exploration of particular lithology such as volcanic, conglomerate, mud and carbonate rocks continued to make new breakthroughs. As a result, core analysis of particular lithology reservoir rock is increasingly significant. However, conventional methods of core analyzing have great limitations on particular lithology due to the complex chemical components and variable physical status. In order to obtain accurate experimental data and understand the seepage law of particular lithology, advanced core analysis methods are developed through the application of two modern core analysis tool, computed tomography (CT) and nuclear magnetic resonance (NMR), and two data analysis methods, artificial intelligent (AI) and computer visualization (CV). Corresponding software are developed and applied to core analysis works bases on these methods, the application has archived good results.Through the application of nondestructive CT testing for inner construction of core, the establishing of CT evaluation criterion for the heterogeneity of particular lithology, the research of CT visualization technology for core, and the development of CT analyzing software, the goals of analyzing the features and growth of holes and fractures in core and heterogeneity of core are archived. The evaluation criterion is composed by qualitative evaluation and quantitative evaluation, and gives the corresponding evaluation method and formula. The evaluation criterion provides the basis for CT analysis of particular lithology. The research of CT visualization technology for core used 3D cube model, Freeman chain, improved Marching Cubes algorithms, visual enhancements and many other graphics algorithms. Software developed based on these algorithms provides necessary means for CT analysis of particular lithology.The application of CT analysis for 211 particular lithology cores shows:1) Most conglomerates develops gravel-edge fractures, growth of the fracture is proportional to the level of gravel and inverse proportional to the degree of compaction. Holes in conglomerate are mainly corroding holes between gravel and corrode gravel holes. The growth of holes is related to the composition of cement and compaction. With the lower gravel level, the number of holes and fractures decline.2) Most volcanic rocks develop holes, some of them develop big holes or lots of holes. Several volcanic samples contain micro-fractures. Very few contain big fractures or many micro-fractures. The growth of holes and fractures in different volcanic rock categories are equivalent, but the type of holes and fractures are different.For the strong heterogeneity and complex pore structure of particular Iithology, methods using NMR for physical parameter testing are proposed, and a corresponding expert system is developed. These methods contain irreducible water saturation measurement for whole core, the NMR porosity measurement refined by AI algorithms, and the NMR permeability estimation model using artificial neural network based on genetic algorithm. These new methods achieved the goal of physical parameters detection for full-diameter and special Iithology core, and solved the defacts of conventional methods, such as size and shape restricts, long test cycles and viscous fingering. The use of AI algorithms reduced the influence of complex chemical components and variable physical status to NMR testing. With higher degree of automation, the new methods successfully reduced the average relative error of NMR porosity by 50%, and increased the accuracy of NMR permeability by 3 times. The expert system uses B/S structure, and achieved on experimental results calibration and reservoir parameters prediction and evaluation. This system filled a blank of NMR data analysis expert system of core samples in China, and has becomes the most efficient tool for physical parameter measurement of particular Iithology.This research has opened new experimental means and new data analysis methods for particular Iithology cores. By increasing the skills of core analysis, this research has increased people's knowledge of particular Iithology reservoir, and means a lot to oil and gas exploration and development.