准噶尔盆地白家海凸起深部含煤层气系统储层组合特征

准噶尔盆地东部白家海凸起发育较稳定的侏罗系煤层,埋深大于1 500 m。以往该区西山窑组和八道湾组煤层气试采取得了较好的效果,显示了白家海凸起深层煤层气具有较好的勘探前景。由于区内以常规油气开发为主,丰富的煤层气资源有待勘探开发。基于此,分析了区内侏罗系深部煤层赋存特征、热演化程度、煤层含气量及煤层顶底围岩等成藏地质条件,认为西山窑组煤层气为独立含煤层气系统,八道湾组煤层及其顶底砂岩组合为统一含煤层气系统。八道湾组源内型、源外型含煤层气系统成藏条件优越,煤层气及煤系砂岩气资源丰富,具有较大的共采潜力。

Characteristics of reservoir assemblage of deep CBM-bearing system in Baijiahai dome of Junggar Basin

Coal seams in Jurassic Xishanyao and Badaowan Formation were developed well in the Baijiahai dome of Junggar Basin.The burial depth of main coalbed is more than 1 500 m.Over the past ten years,the pre-production of several conventional oil and gas wells in coal seams had obtained good results,the volume of coalbed methane were more than 7 000 m3,which shows a good deep coalbed methane exploration prospect in Baijiahai dome.The amount of coalbed methane resources remains to be developed in Cainan oilfield.Based on the in-depth analysis of deep coalbed distribution characteristics,coal thermal evolution degree,the distribution of gas content and adjacent formation,it is considered that the Xishanyao coalbed is an independent CBM-bearing system,and the combination of Badaowan coalbed and its adjacent sandstone is another CBM-bearing system.The superior accumulation conditions of the inner-source type and outside source type of Badaowan CBM-bearing system are enriched in CBM and sandstone gas resources,both two have a potential in commingled production.