陇东煤田侏罗系煤层气成藏主控因素与模式  

Main controlling factors and models of Jurassic coalbed methane accumulation in Longdong coalfield

作　　者：朱志良 高小明 ZHU Zhiliang;GAO Xiaoming(Coalfield Geology Research Institute of Gansu,Lanzhou 730000,China)

机构地区：[1]甘肃煤田地质研究所,兰州730000

出　　处：《岩性油气藏》2022年第1期86-94,共9页Lithologic Reservoirs

基　　金：甘肃省2012年度省级基础地质调查类科研项目“甘肃省陇东煤层气赋存状况评价”(编号:国土资勘发[2012]33号)资助。

摘　　要：鄂尔多斯盆地西南缘陇东煤田低阶煤层气资源丰富,勘查开发处于起步阶段,成藏主控因素及模式认识尚不足。为弄清气体的富集规律,优选勘探靶区,运用钻探(现场解吸、试井、岩芯)、测井、水文、地球化学测试等资料,从构造演化、埋深条件、沉积环境和水文地质条件等方面讨论了气藏的煤储层特征、主控因素和富气成藏机制,划分出4种煤层气富集成藏模式及对应的气藏类型;评价优选出3个有利勘探区。结果表明:陇东地区煤层厚度大,煤系地层非均质性强,煤岩煤化程度低,含气量横向变化大;煤岩生烃能力强,储集性能好,富气成藏的主控因素为盖层的发育程度和后期次生生物气的调整;埋深控藏呈现出"最佳深度"的特征。该结果为后期煤层气勘探的井位部署提供了参考和指导。Longdong coalfield in the southwestern margin of Ordos Basin is rich in low-grade coalbed methane resources.The exploration,exploitation and research in this area are still in the initial stage,and the understanding of main controlling factors and models of reservoir accumulation is still insufficient.To clarify coalbed methane enrichment law and optimize the exploration target areas,the drilling(field desorption,well test and core),logging,hydrological and geochemical test data were used to discuss the coal reservoir characteristics,main controlling factors and gas rich accumulation mechanism of the gas reservoir from the aspects of tectonic evolution,buried depth,sedimentary environment and hydrogeology conditions,and four coalbed methane accumulation models and corresponding gas reservoir types were classified and three favorable exploration areas were optimized.The results show that the thickness of coal seam in Longdong area is large,the heterogeneity of coal measure strata is strong,the coalification degree of coal rock is low,and the lateral variation of gas content is fast.Coal rocks have strong hydrocarbon generation capacity and good reservoir performance,the main controlling factors of rich gas accumulation are the development degree of caprocks and the adjustment of secondary biogas in the later stage.Buried depth controlling reservoir presents the characteristics of“optimal depth”.The results provide reference and guidance for the well deployment of coalbed methane exploration in the later stage.

关 键 词：成藏模式 煤层气 低阶煤储层 侏罗系 陇东煤田 

分 类 号：TE122.2[石油与天然气工程—油气勘探]