临兴区块深部煤层气富集规律与勘探开发前景

临兴地区位于鄂尔多斯盆地东缘,横跨晋西挠褶带和伊陕斜坡,东部断层发育,西部地层平缓,中部紫金山岩体侵入。煤层气富集受到构造、成熟度和水文地质条件的三重控制,较高的成熟度反映煤岩已经大量生烃;后期构造破坏煤层气藏,但地层水滞留,水文条件有利于煤层气保存。含气量呈现东低西高的整体趋势。中部紫金山热液作用和断层破坏作用形成了环形含气量低值区和高值区。区内含气饱和度总体受到成熟度的控制,与含气量总体规律不一致,研究区中部出现含气饱和度高值窗口(1 600~2 000 m)。本区煤岩微孔发育,煤岩孔隙的差异小,结构相对均匀,整体扩散性和渗透性较强。总体评价该区煤层气资源量大、丰度高、含气饱和度高和物性较好。在评价有利区具备进一步开展先导试验的条件。

Deep coalbed methane enrichment rules and its exploration and development prospect in Linxing

Linxing block is located in the eastern margin of the Ordos basin,crossing Jinxi flexural fold belts and Yishan slope area.In the block,some faults were developed in eastern part,the formation is gentle in western part,and the intrusive rock of Zijin Mountain exists in middle part.The enrichment of coalbed methane is controlled by construction,maturity and hydrogeological condition.High grade of maturity indicates that a large amount of hydrocarbon was generated in coal.In the late period,the coalbed methane reservoir was destroyed by construction,however the formation water retention is beneficial to keep coalbed methane.Gas content distributes high in west and low in east.In Zijin Mountain,which is located in the middle,the annular gas content high value zone and low value zone were formed by hydrothermal process and fault destructive effect.Within the zone,gas content is controlled by mature grade generally,but it disagrees with the gas content total regularity,because there is a gas content high value window (1 600-2 000 m) in the middle part of study zone.In the block,the micropore was developed in coal,pore difference is small,structure is relatively uniform,total diffusivity and permeability are great.Overall,the evaluation shows that the coalbed methane in the block is a large quantity of resource with high abundance,high gas saturation and great physical properties.Therefore,this block have the potential for a further pilot test.