川中地区须家河组天然气成藏机制研究

以天然气形成时期研究、天然气地球化学特征分析及运移地质条件分析为基础，对川中地区上三叠统须家河组天然气成藏机制进行了系统研究。研究认为川中地区须家河组气藏为2期气相充注，在燕山末期-喜山期构造抬升过程中，储层水溶气脱溶可能性小、残余气相的卸压膨胀具有一定贡献；虽然须家河组砂岩厚度大、分布广，但储层强烈的非均质性以及较平缓的区域地层，限制了油气进行长距离运移；天然气及凝析油等地球化学特征表现为近距离运聚成藏特点。从而为川中地区须家河组构造-岩性气藏的勘探提供了新的依据。

MECHANISM OF GAS RESERVOIRING IN XUJIAHE FORMATION IN CENTRAL SICHUAN BASIN

Based on the timing of natural gas generation, and the analysis of geochemical behaviors and geologic conditions of gas migration, the mechanism of gas reservoiring is systematically studied in the Upper Tertiary Xujiahe Formation in Central Sichuan Basin. It is believed that the gas reservoirs in the Xujiahe Formation in Central Sichuan Basin have experienced two stages of gas charging. During tectonic uplifting in the late Yanshan-Himalayan period, the possibility of degasification was low for formation water with solution gas, but expansion of residual gas from pressure relief have contributed to gas charging to a certain extent. Long distance migration of hydrocarbons was prevented by the strong heterogeneity of the reservoirs and the relatively low relief of the stratigraphy, though the Xujiahe Formation sandstone is thick and widely distributed. Based on the geochemical behaviors of natural gas and gas condensate, gas reservoiring is characterized by short distance migration and accumulation of hydrocarbons. This paper provides a new basis for exploration of the structural-lithologic gas reservoirs in the Xujiahe Formation in Central Sichuan Basin.