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The hydrocarbon production in the Bawu area of Lishu Depression is high. However, the Bawu area has undergone three main tectonic movements, the strata were strongly uplifted and eroded, and the fractures were extremely developed. The conditions of hydrocarbon preservation have become intricate. In this study, by analyzing isotopes compositions and geochemical features of formation water, and the characteristics of formation pressure, the hydrocarbon preservation can be deduced. The subnormal and lower normal pressure zones (away from Xiaokuan Fault) of Yingcheng and Shahezi Formations are relatively closed and more conducive to hydrocarbon preservation. [ABSTRACT FROM AUTHOR]

Reservoir properties of the fourth member of the Xujiahe Formation in the Western Sichuan Depression are quite poor (average porosity =5.9%, average permeability =1.41 mD). These properties were influenced by several diagenetic processes, especially compaction and carbonate cementation. Due to a combination of compaction of ductile fragments and carbonate cementation, sand/mud interfaces of the thick sandstone layer were tightly cemented, pore space also reduced sharply in positions where rich in ductile grains. Thus, space leaving for hydrocarbon is limited, except where both the detrital ductile grain content and carbonate cement content are low. [ABSTRACT FROM AUTHOR]