川西坳陷中段须家河组致密砂岩气藏成藏模式探讨

通过分析流体包裹体均一温度和砂岩碳酸盐胶结物氧同位素数据，并结合沉积-埋藏史，研究须家河组流体活动特征，进行储层致密化分析. 在此基础上，结合烃源岩演化、储层致密化、流体活动等研究，探讨川西坳陷须家河组致密砂岩气藏成藏模式. 认为：须家河组具有形成“连续型”气藏的地质条件，砂岩持续致密化，自烃源岩沉积后持续生烃，流体包裹体的显微观测也表明油气充注在持续进行. 据此认为，须家河组气藏成藏模式是“前期边致密边成藏，后期裂缝发育成藏”.

Study on gas accumulation modes of Xujiahe Formation tight sand gas reservoirs,in the middle of Western Sichuan Depression,China

Combined with the burial and thermal history of Western Sichuan Depression, homogenization temperature of geofluid inclusion and oxygen isotope of carbonate cement are used to study the geofluid activity of Xujiahe Formation. And then sandstone densification is analyzed. A study on gas accumulation modes of tight sand gas reservoirs of Xujiahe Formation in the Western Sichuan Depression is conducted based on evolution of hydrocarbon source rocks, sandstone densification and geofluid activities, and so on. It concludes that (i) the Xujiahe Formation of Western Sichuan Depression meets all the factors of continuous tight sand gas reservoir, (ii) the sandstone of Xujiahe Formation continues to be identified, (iii)source rocks of the Xujiahe Formation can continuously produce hydrocarbon since their deposition, and (iv)the microscopic observation of geofluid inclusion shows that hydrocarbon continuously charges. Based on the above results, a model of the Xujiahe Formation gas accumulation is presented, namely gas accumulation is synchronization with sandstone densification in the earlier stage and gas accumulation restarts after cracks formed in the later stage.