吐哈盆地致密砂岩气成藏条件与分布预测

在分析大量实验及统计资料的基础上,根据源岩、储层及构造条件,利用地质信息叠合法,预测吐哈盆地致密砂岩气的有利分布区。研究表明,吐哈盆地中、下侏罗统煤系烃源岩的母质类型主要为Ⅲ型,有利于大量生气,其中煤岩分布更为广泛,热演化程度中等—较高,供气能力更强。由于快速堆积和微弱的溶蚀作用,吐哈盆地水西沟群储层自侏罗纪末以来普遍致密化,裂缝和孔隙是影响储层含气的主要因素,三角洲相和冲积扇相为有利的"低熟"储层发育区。根据致密砂岩气的成藏特征,采用配置系数P,将有利区的定性预测进行定量化。结合源储配制地质评价,认为在吐哈盆地山前带地区水西沟群西山窑组地层中,煤系地层和炭质泥岩与储层叠置发育,有利于致密砂岩气的成藏。

Accumulation conditions and distribution prediction of tight sandstone gas in Turpan-Hami Basin

Based on experimental analysis and statistical data, beneficial distribution areas of tight sandstone gas are predicted in Turpan-hami Basin through tile analysis of source ruck, reservoir and structure conditions and using tile superposition method of geological information. Study resuh shows that the organic matter type of coal measure source rock in Middle-Lower Jurassic of Turpan-hami Basin is mainly type III. which is rawer of gas generation in quantity. Coal hed is widely distributed. Thermal evolution degree is medium to higher, with gas supply capahility being strong. Because of the rapid accumulation and weak denudation, the reservoir has been universally tight since the end of Jurassic Period in Shuixignu Group of Turpan-hami Basin. Fractures and pores are the main factors of affecting gas reservoir. Delta facies and alluvial fan facies are the favorable reservoir development area with low maturity. Allocation factor P is adopted to make the qualitative prediction quantification according to the accumulation characteristics of tight sandstone gas. Combined with the geological evaluation of source rock and reservoir preparation, coal measure formation, battie and reservoir are developed wilh superpousiliun in Xishanyao Furmaion of Shuixigou Group of fuothill belt in Turpan-Hami Basin. which is favor of the accumulation of tight sandstone gas.