四川盆地西南边缘地区天然气保存条件研究

四川盆地西南边缘地区具有深层震旦系、二叠系产淡水,浅层下三叠统产天然气的特殊性.在充分利用地层流体性质、地层压力等资料综合分析边缘地区各构造保存条件的基础上,认为研究区保存条件主要影响因素为盖层、断层、储集层岩性、露头地表水渗入.震旦系和下二叠统为厚层块状灰岩,在构造作用下容易产生裂隙带,为露头区地表水渗入提供通道.嘉陵江组透镜状储集层的分布特点决定了嘉陵江组受地表水的影响较小.建议盆地西南边缘地区勘探以三叠系嘉陵江组气藏为主. 

STUDY ON THE PRESERVATION CONDITION OF GAS RESERVOIR IN SUOTHWESTERN EDGE OF SICHUAN BASIN

In the southwestern edge area of Sichuan Basin there is an abnormal phenomenon, i.e. the lower strata (Upper Sinian and Lower Permian) produce the formation water with low salinity, but the upper stratum (the Jialingjiang formation of Lower Triassic) produces gas. On the basis of comprehensive stu-dies for the properties of formation liquid and formation pressure of all wells in the area, the author has drawn out the influencing factors of the gas preservation. They are, faults, the reservoir character, and the subaerial meteoric water penetration from the outcrop of reservoir. Under the influence of structure movement, the thick and tight carbonate in the Upper Sinian and the Lower Permian is easy to create fi-ssure zone, through which the subaerial meteoric water could penetrate into the deeper formations from the outcrop. The thin and low-porosity carbonate of the Jialingjiang formation was little influenced by the subaerial meteoric water. It has been advised that Jialingjiang Formation is the main prospecting formation in the southwestern edge area of Sichuan Basin.