沁水盆地郑庄区块构造演化与煤层气成藏

基于沁水盆地郑庄区块的构造发育特征,研究了自二叠纪煤系形成以来该区域构造应力场演化,分析了其对煤层气藏的控制作用,包括构造-埋藏史、后期成藏演化及成藏控制因素.研究表明:郑庄地区主要经历了印支期、燕山期、喜马拉雅早期和喜马拉雅晚期—现代4个期次的构造应力场演化.在构造控制下,二叠纪煤层经历了印支期和燕山中—晚期两次成烃作用,特别是燕山中、晚期煤层生气量巨大,是煤层气的主要成藏期.此后,随着地壳持续抬升剥蚀,煤层埋藏不断变浅,并发育了多组封闭性较好的节理.受南东侧的寺头断层控制,煤层埋深处于600～1 200m,为煤层气成藏以来的最浅埋藏,虽然本区二叠系煤层气的成藏时间较早,但保留的煤层气含量大,煤储层厚度大,且煤层埋藏适中.

Tectonic evolution and reservoir formation of coalbed methane in Zhengzhuang block of Qinshui basin

Based on the structural characteristics of Zhengzhuang area in Qinshui basin,this article studies the tectonic stress field evolution of Zhengzhuang area and analyzes its role in controlling coal bed methane(CBM) reservoir including tectonic-burial history,late accumulation evolution and formation control factors.The research shows that Zhengzhuang area went through four periods of tectonic stress field including Indo-Chinese,Yanshan,Early Himalayan and Late Himalayan period.Under structure control,Permian coals twice went through hydrocarbon generation in the Indo-Chinese and Middle-late Yanshan periods,Middle-late Yanshan period was the main CBM reservoir evolution period with a huge amount of CBM.Since then,with continued crust uplifting and erosion,the burial depth of coal seams gradually shoaled and several groups joined to form good sealing properties.The CBM reservoir in Permian coals is the most shallow with coal seams depth of 600-1 200 m since it was controlled by Sitou fault.Although the Permian CBM reservoir is the earlier,the CBM content is abundant,and the coal reservoir is thick with appropriate burial depth.