Multi-scale joint characterization of coal seam pore structure and its influence on movable fluid
Li Tian,
Ren Dazhong,
Ning Bo,
Li Qihui,
Zhang Hanpeng,
Zhou Junli,
Zhang Zhifeng
Affiliations
Li Tian
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China, Ministry of Education, College of Petroleum Engineering, Xi'an Shiyou University, Xi'an Shaanxi 710065, China
Ren Dazhong
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China, Ministry of Education, College of Petroleum Engineering, Xi'an Shiyou University, Xi'an Shaanxi 710065, China
Ning Bo
PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China
Li Qihui
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China, Ministry of Education, College of Petroleum Engineering, Xi'an Shiyou University, Xi'an Shaanxi 710065, China
Zhang Hanpeng
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China, Ministry of Education, College of Petroleum Engineering, Xi'an Shiyou University, Xi'an Shaanxi 710065, China
Zhou Junli
Shenhua Shendong Quality Technical Inspection and Test Center, Ordos Inner Mongolia 017000, China
Zhang Zhifeng
Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an Shaanxi 710018, China
Micro-pore structure affects the fluid storage and seepage in coal seams.In this paper, six samples from the Jurassic Yan'an Formation coal seam in the Shenmu area of the Ordos Basin were taken as the object of study.The pore distribution characteristics of coal seams were jointly characterized by NMR, CO2 adsorption and N2 adsorption at multiple scales, and the connectivity and homogeneity of microscopic pores were investigated by combining multi-scale joint characiterization with CT scanning.Results show that the micro-pores of coal are the main contributors to the specific surface area and pore volume, followed by meso-pores.There is a good uniformity in the pore size distribution of the micro-pores and meso-pores by combing NMR and adsorption, while considerable differences are found in the macro-pores.Displacement NMR and CT excel in reflecting the degree of connectivity, both of which are consistent in the characterization of connectivity.Parameters such as coordination number and seepage pore ratio can effectively reflect the degree of connectivity of the sample, whose patterns of connectivity is M6>M2>M12>M15>M10>M4.The saturation of bound water shows a satisfactory positive correlation with pore-throat ratio of coal samples.It can be seen that the pore structure has a great influence on the degree of fluid migration, which is the basis for studying and evaluating gas occurrence and seepage.
