鄂尔多斯盆地东缘临兴区块页岩气成藏因素分析及富集区预测

Shale Gas Accumulation Factors and Enrichment Area Prediction in Linxing Block,Eastern Margin of the Ordos Basin

结合中联公司前期勘探成果,基于钻井、岩心、测井资料及实验数据,对鄂尔多斯盆地东缘临兴区块本溪组、太原组和山西组泥页岩沉积特征、有机地球化学特征、储层特征以及含气性特征进行了研究,重点讨论了页岩气的富集区。研究成果表明:本溪组和太原组发育潮坪相沉积环境,山西组发育三角洲相沉积环境;整体属于中等-优质烃源岩,太原组烃源岩最好;本溪组和山西组有机质类型主要以腐殖型为主,太原组有机质类型主要以混合型-腐殖型为主;有机质成熟度整体处于成熟-高成熟阶段,具有良好的生烃潜力;储集层微裂隙较发育,属于低孔低渗类型;山西组和太原组的脆性矿物含量在50%以上,有利于后期压裂;研究区泥页岩具有较高的含气量和较强的吸附能力;山西组页岩气富集区主要集中在北部和西南部,太原组页岩气富集区主要集中在北部,且资源潜力最优,本溪组页岩气富集区主要集中在西北部和东北部边缘一小块区域,且资源潜力有限。

Based on preliminary exploration results by the China United Coalbed Methane Co.Ltd.,we studied the drill-core logging and analysis data,the characteristics of sedimentation,organic geochemistry,reservoir and gas content of the Benxi,Taiyuan and Shanxi formations of the Linxing Block,in the eastern margin of the Ordos Basin.We focused on the shale gas enrichment area.Our results show that the Benxi,Taiyuan and Shanxi formations were deposited in a marine-continental transitional environment.The local muddy shale is medium-high-quality source rocks,with the Taiyuan Formation being the best.The organic matter type is mainly mixed-humus,and the organic matter is generally of mature-high maturity with good hydrocarbon generation potential.Local microcracks are well developed and belong to low-porosity and low-permeability type,and the brittle mineral content of the Shanxi and Taiyuan formations is over 50%,which is conducive to later fracturing.The shale gas enrichment area of the Shanxi Formation is mainly concentrated in the north and southwest,whilst that of the Taiyuan Formation is mainly concentrated in the north and has the best potential.Meanwhile,the shale gas enrichment area of the Benxi Formation is mainly concentrated locally on the margin of the northwest and northeast,with limited resource potential.