川西新场大型气田地质特征与预测关键技术

Geological Characteristics of large Xinchang gas field in western Sichuan depression and key predication technologies

川西新场大气田由浅层构造-岩性气藏、中层构造-成岩气藏、深层构造-裂缝气藏叠置而成,纵向跨度4 000多米,具多层、多类气藏叠合型大气田特征。该气田纵向上以浅层上侏罗统蓬莱镇组、中层中侏罗统上沙溪庙组、深层上三叠统须家河组二段为主力气藏。蓬莱镇组气藏的主控因素为鼻状背斜上的河道砂岩亚相,上沙溪庙组气藏的主控因素为古隆起上的河口坝与分支河道叠加微相砂岩中的有利成岩相,须家河组气藏的主控因素为大型古隆构造带上的裂缝发育系统。针对浅层气藏天然气富集带预测的关键技术是“低频强振幅”地震响应亮点识别技术;针对中层气藏天然气富集带预测的关键技术是多学科结合的储层综合建模预测评价技术;针对深层气藏天然气富集带预测的关键技术是地质-地震-测井多学科相结合的裂缝综合预测技术和含气性检测技术。

Xinchang gas field in western Sichuan depression is a large superi gas field characterized by multiple layers and various reservoir types, with a vertical span of over 4 000 m, and is composed of the shallow structural-lithologic gas reservoirs, the middle structural-diagenetic gas reservoirs and the deep structural-fracture gas reservoirs. Vertically, its major gas reservoirs include the shallow layer Upper Jurassic Penglaizhen Formation, the middle layer Middle Jurassic Upper Shaximiao Formation and the deep layer Upper Triassic 2nd member of Xujiahe Formation. The main control factors of Penglaizhen Formation gas reservoirs are the channel sandstone subfacies in the nose-like anticline, the main control factors of the Upper Shaximiao Formation gas reservoirs are the favorable diagenetic facies in the sandstones of superi mouth bar and distributary channel mierofacies on the palaeohigh, while that of Xujiahe Formation gas reservoirs are the fracture systems developed in the large palaeohigh strucutral zone. The key technology for prediction of prolific zone in the shallow gas reservoirs is bright spot identification of seismic response with ＂low frequency but strong amplitude＂ ; the key technology for prediction of prolific zone in the middle gas reservoirs is multi-disciplinary comprehensive reservoir model building; while the key technology for prediction of the prolific zone in the deep gas reservoirs is the comprehensive prediction technology through geology-seismic-logging integration and gas-bearing property detection technology.