沁水盆地横岭区块深部煤层气地震相控反演及有利区预测

Seismic facies controlled inversion of deep coalbed methane in Hengling block of Qinshui Basin and favorable area prediction

随着浅部煤层气已探明可动用储量的减少,深部煤层气受到越来越多的关注。以沁水盆地东北部横岭区块为例,利用地震相控反演技术,采用厚度标定、有效储层厚度分析、多尺度边缘检测和岩性识别等方法,对横岭区块储层空间分布、煤层厚度、含气性、储层特性等进行预测,结果表明:相控非线性随机反演的方法在目的储层反演中取得显著效果。区块内确定的3个煤储层小层地震波特征与测井结果一致;15号煤层厚度在4~7 m,分布为NNE方向,全区厚度分布稳定,最厚处位于西北部,最薄处位于中西部;15号煤层在区块中部和北部含气特征明显,有效储层厚度最高可达4.5 m;15号煤孔隙度分布整体较均匀(4%~6%);煤层厚的区域孔隙度较大,含气高部位对应的孔隙度发育较好,煤层裂隙主要分布在区块西部,断层发育的破碎带裂隙发育好,裂隙密度随着深度增加逐渐减少。同时,根据以上研究成果,并结合实际开发经验,圈定了15号煤层有利区4处,煤层气综合有利区4处。

With the decrease of proved reserves of shallow CBM,more and more attention has been paid to deep CBM.Taking Hengling block in Northeast Qinshui Basin as an example,the spatial distribution of reservoir,coal seam thickness,gas bearing property and reservoir characteristics in Hengling block are predicted by using seismic facies controlled inversion technology and by means of thickness calibration,effective reservoir thickness analysis,multi-scale edge detection and lithology identification,the results show that:The method of facies controlled nonlinear random inversion has achieved remarkable results in the inversion of target reservoir.The seismic wave characteristics of the 3 coal reservoirs determined in the block are consistent with the logging results;The thickness of No.15 coal seam is between 4~7 m,and the distribution is NNE direction.The thickness distribution of the whole area is stable,the thickest part is in the northwest,and the thinnest part is in the Midwest;The gas bearing characteristics of No.15 coal seam are obvious in the middle and north of the block,with the maximum effective reservoir thickness of 4.5 m;The porosity distribution of No.15 coal is uniform,ranging from 4%to 6%;The area with thick coal seam has larger porosity,and the porosity corresponding to the high gas content part is well developed,The coal seam fractures are mainly distributed in the west of the block,The fracture zone with developed faults has well developed fractures,and the fracture density gradually decreases with the increase of depth.At the same time,according to the above research results and the actual development experience,4 favorable areas of coal seam 15 and 4 comprehensive favorable areas of coalbed methane are delineated.