川西地区侏罗系浅层气勘探配套技术研究

川西侏罗系浅层气丰富,属河流—湖泊三角洲沉积体系的构造—岩性圈闭次生气藏。储层以河口坝和分流河道砂体为主,砂体小而多呈透镜状、敏感性和非均质性强,单井自然产能低,属非常规致密型气藏。经反复试验、攻关,深化了气藏内在规律的认识,形成了一系列针对性强的勘探配套综合技术:即以岩性识别、油气水判识为核心的测井评价技术;以地震有井约束反演为主的砂体、含气砂体定性—定量的储层预测技术;减小伤害、保护油气层的欠平衡钻井技术;旨在提产增效的低温破胶压裂液体系的加砂压裂储层改造技术等。此套技术用于白马庙蓬莱镇气藏,使气井成功率从40 %提高到80 %;用于川西侏罗系浅层,3 年钻井61 口,获气井44 口,成功率77 % ,发现了白马庙等两个气田和5 个含气构造;提交探明储量268. 72 ×10⁸ m³ ,控制加预测储量1 463. 31 ×10⁸m³ 。在储层改造上也取得了显著成效,单井产能成倍或数十倍的增加。

STUDY ON THE INTEGRATED TECHNIQUES APPLIED IN THE EXPLORATION OF JURASSIC SHALLOW GASES IN WESTERN SICHUAN

Shallow gases are abundant within the J urassic in northwestern Sichuan. These gases are secondary in nature and pooled in structuralOlithologic traps within fluvialOlacustrine deltaic systems. The reservoir beds consist mainly of riverO mouth bars and distributary channel sandbodies which are smallin size , numerous in number , and typically lensiod in shape ,displaying strong sensitivity and nonhomogeneity. The single well productivity is low , and the pools can be put into the tight reservoir category. On the basis of detailed research of the reservoir geological characteristics , a series of techniques focusing on the exploration of these gas pools were established. Thetechniques include log evaluation centered on lithology recognition and oil/ gas/ water beds discrimination , qualitativeOquantitative reservoir prediction based on seismic inversion tagged to wells , underbalanced drilling , and hydrologic fracturing with lowOtemperature breaker systems. Application of these tech niques witnessed an increase of explorationOwell success ratefrom 40 % to 80 % in the Penglaizheng gas field and a total success rate of 77 % in the J urassic shallow formations in northwestern Sichuan for the past three years (of the 61 wells drilled , 44 hit gas) . As a result , two gas fields and five gasO bearing structures were found , a proved gas reserve of 286. 72×108m3 was established , and singleOwell productivity was increased by several to tens of times.