AUTHOR=Yang Fu , Ma Dongmin , Duan Zhonghui , Ren Dazhong , Tian Tao , Fu Deliang 

TITLE=Micropore Structural Characteristics and Influence Factors of Triassic Shale Gas Adsorption in the Ordos Basin

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.851131

DOI=10.3389/fphy.2022.851131

ISSN=2296-424X

ABSTRACT=Continental shale is investigated for potential terrestrial shale gas reservoirs in the Tongchuan area, southern Ordos Basin. The kerogen macerals of Upper Triassic Chang 7 shale are vitrinite 28~43%, exinite 4~7%, and inertinite 52~69% and Ro is 0.85~0.88% and the kerogen type is II. The total organic carbon (TOC) content is 9.75~29.92%, free hydrocarbon (S1) is 3.21~12.14%, pyrolysis hydrocarbon(S2) is 41.86~165.39%, and maximum pyrolysis temperature (Tmax) is 439~445℃. The mineral composition is mainly quartz 3.94~43.27%, followed by feldspar 9.65~30.07% and clay minerals 13.46~59%. illonite/smectites (I/S) is the main clay mineral, accounting for 47~69%. The liquid nitrogen adsorption curve showed that the pore types were tubular and plate-like. The pores are mainly micropores (<2nm) and mesoporous (2~50nm). Isothermal adsorption results show that langmuir volume (VL) is 2.06~5.57 cm3·g-1, langmuir pressure (PL) is 2.16~3.28 MPa, and shale adsorption capacity is small and easy to desorption. A quartz content less than 25% is negatively correlated with specific surface area (SSA); otherwise it is positively correlated. A clay mineral content less than 45% is negatively correlated with SSA; otherwise it is positively correlated. The relationship of carbonate content and pore structure are not obvious. Pyrite content less than 2% is positively correlated with SSA, otherwise it is negatively correlated. The SSA is positively correlated with TOC, inertinite and exinite, and negatively correlated with vitrinite. The adsorbed gas content is positively correlated with TOC content, SSA, inertinite content and exinite content, and negatively correlated with vitrinite.