鄂尔多斯盆地东南缘延川南深层煤层气富集高产模式探讨

Discussion on the model of enrichment and high yield of deep coalbed methane in Yanchuannan area at Southeastern Ordos Basin

鄂东南延川南区块以上二叠统山西组2号煤层作为主力煤层建成并投入商业开发的深层煤层气田,产气效果好于预期,显示了该区深层煤层气具有较好的勘探开发潜力。通过系统分析区内主力煤层构造特征、煤储层特征及煤层气富集高产控制作用,结合气田动态生产数据,认为延川南深层煤层气为含气量-渗透率耦合控制的富集高产模式,其中埋深小于1 000 m的原生裂隙发育区为自生自储型富集高产模式,埋深大于1 000 m的次生裂隙发育区为内生外储型富集高产模式,并建立了该区深层煤层气富集高产选区评价指标体系,优选出4个富集高产有利区,为气田精细排采和上产稳产提供支持,并为其他深层煤层气区块勘探开发提供借鉴。

The production effect of the deep coalbed gas field in Yanchuannan area at Southeastern Ordos is better than expected,in which the No.2 coal seam of the upper Permain Shanxi formation as the main coal seam is built and commercially produced,revealing that the deep coalbed methane has a great exploration and development potential.Through the systematic analysis of structural features,reservoir characteristics and controlling effects on the CBM enrichment and high-yield of the main coal seam,combined with the dynamic production data of the gas field,it is considered that the model of deep CBM enrichment and high-yield in Yanchuannan area is gas content-permeability coupling control,of which in the primary fissure development zone with buried depth less than 1 000 m,it is self-generated plus self-storage type,while in the secondary fissure development zone with buried depth greater than 1 000 m,it is endogenous generated plus exogenetic-storage type.Upon this basis,the index system of deep CBM evaluation and selection is established,then four favorable areas of gas enrichment and high-yield are optimized,which support for the fine drainage and stable production of the gas field,also provide reference for the exploration and development of other deep CBM areas.