川西北部地区侏罗系气藏成藏特征——与川西南部侏罗系气藏比较

通过对比分析川西南部和川西北部地区侏罗系气藏在烃源、储集、圈闭、保存条件及异常高压等方面的成藏特征的差异，总结出川西北部地区侏罗系气藏可能的成藏模式。结果认为：作为气源的上三叠统的生烃强度在川西南部明显优于川西北部，南部拥有丰富的气源断裂，有利于油气的垂向运移，北部有可能形成侏罗系自生自储的油气藏；川西的南部地区和北部地区储集层厚度相差不大，沙溪庙组和千佛崖组在北部地区储集条件更为优越；构造圈闭条件南部更优；保存条件南部有白垩系的膏盐层作为区域盖层、北部有异常高压封存箱。地层异常高压在川西北部对侏罗系成藏起着关键作用，有助于压力封存箱内部形成油气藏。钻探情况证实，川西北部地区所有侏罗系产层和显示层段都集中在中侏罗统沙溪庙组及其以下层位。因此在今后的勘探实践中，应该重点注意该层段。

RESERVOIRING CHARACTERISTICS OF JURASSIC GAS POOLS IN NORTHERN PART OF WEST SICHUAN BASIN: CORRELATION WITH JURASSIC GAS POOLS IN SOUTHERN PART

Possible reservoiring patterns are summarized for the Jurassic gas pools in the northern part of West Sichuan Basin based on a correlation of the source rocks, reservoirs, traps, reservation conditions and abnormally high pressure between the southern and northern parts of West Sichuan Basin. The hydrocarbon generation intensity of the Upper Triassic source rocks is stronger in the southern part than that in the northern part. In the southern part, the faults are abundant  which are favorable for vertical migration of hydrocarbons, while in the northern part, the Jurassic gas pools with hydrocarbons generated by and accumulated in the same layer may occur. The reservoir rocks in both parts are similar in thickness, but the source rocks in the Shaximiao and Qianfuya formations are better developed in the northern parts. The structural trapping conditions are better in the southern part, but lithologic traps also occur in the Jurassic gas pools. In the southern part, the Jurassic evaporates act as seals, while in the northern part, abnormal high pressure compartments occur. The abnormally high pressure plays a key role in the formation of the Jurassic gas pools in the northern part of West Sichuan Basin, leading to the formation of gas pools in the pressure compartment. Current drilling results also verify that all the Jurassic pay zones and intervals with oil and gas shows occur in the Middle Jurassic Shaximiao Formation and the underlying strata, to which much attentions should be paid in future exploration in the study area.