关键词: Sichuan basin, Gaoshiti-Moxi area, Sinian, Dengying formation, lithological-stratigraphic gas reservoir, productivity difference

Abstract: Sinian Dengying Formation in Gaoshiti-Moxi area of central Sichuan basin is characterized by complicated lithologies and strong heterogeneity. The productivity in the western platform margin area is higher than that in eastern platform area and efficient exploration is facing great challenges. Using the data of core, logging and seismic and starting from sedimentary environment, reservoir diagenesis and hydrocarbon charging distance, the paper discusses the main factors controlling the productivity differences of the gas reservoirs in the fourth member of Dengying formation in the study area and proposes technical countermeasures on geological engineering. The results show that the tested productions in the western platform margin and the eastern platform are significantly different, the tested production of the western platform margin area is high due to large thickness of the gas zone, while that of the eastern platform is low due to small thickness of the gas zone; the main influencing factors for the productivity difference include the distribution of favorable dome-beach facies, intensity of karstification at the end of Tongwan movement, reservoir vertical distribution and position, and lateral distance to hydrocarbon-generating center etc. According to the characteristics of the reservoir and its seismic responses, vertical well, highlydeviated well and horizontal well are selected to improve high quality reservoir penetration ratio and single well production, which can effectively guide the natural gas exploration and development and good effects have been gained in the study area.

Key words: Sichuan basin, Gaoshiti-Moxi area, Sinian, Dengying formation, lithological-stratigraphic gas reservoir, productivity difference