Multi-Scale Pore Structure Heterogeneity in Tuff Reservoirs Investigated with Multi-Experimental Method and Fractal Dimensions in Chang 7 Formation,Southern Ordos Basin  

作　　者：Hao Lu Qing Li Dali Yue Dongdong Xia Shenghe Wu Lang Wen Yu He 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing,102249,China [2]College of Geosciences,China University of Petroleum,Beijing,102249,China [3]Petroleum Exploration and Development Institute of SINOPEC,Beijing,100083,China

出　　处：《Journal of Earth Science》2024年第2期666-686,共21页地球科学学刊（英文版）

基　　金：supported by the Strategic Cooperation Technology Projects of CNPC and CUPB(No.ZLZX2020-02);the National Science and Technology Special(No.2017ZX05049-006-001);the National Natural Science Foundation of China(No.41602137);Science Foundation of China University of Petroleum,Beijing(No.2462020YXZZ022).

摘　　要：The tight tuff reservoir is an unusual type of unconventional reservoir with strong heterogeneity.However,there is a lack of research on the microscopic pore structure that causes the heterogeneity of tuff reservoirs.Using the Chang 7 Formation in Ordos Basin,China as a case study,carbon-dioxide gas adsorption,nitrogen gas adsorption and high-pressure mercury injection are integrated to investigate the multi-scale pore structure characteristics of tuff reservoirs.Meanwhile,the fractal dimension is introduced to characterize the complexity of pore structure in tuff reservoirs.By this multi-experimental method,the quantitative characterizations of the full-range pore size distribution of four tuff types were obtained and compared in the size ranges of micropores,mesopores and macropores.Fractal dimension curves derived from full-range pores are divided into six segments as D1,D2,D3,D4,D5 and D6 corresponding to fractal characteristics of micropores,smaller mesopores,larger mesopores,smaller macropores,medium macropores and larger macropores,respectively.The macropore volume,average macropore radius and fractal dimension D5 significantly control petrophysical properties.The larger macropore volume,average macropore radius and D5 correspond to favorable pore structure and good reservoir quality,which provides new indexes for the tuff reservoir evaluation.This study enriches the understanding of the heterogeneity of pore structures and contributes to unconventional oil and gas exploration and development.

关 键 词：tuff reservoir pore structure carbon-dioxide gas adsorption nitrogen gas adsorption high-pressure mercury injection fractal dimension petroleum geology 

分 类 号：P618.13[天文地球—矿床学]