河套盆地临河坳陷吉兰泰地区基岩裂隙含油特征及评价

Oiliness Characterization and Evaluation of the Jilantai Bedrock Fissures in Linhe Depression of Hetao Basin

为了构建河套盆地深层褶皱基底中高产的基岩油藏模式、探明基岩裂隙含油气性,基于已获得工业油流的临河坳陷吉兰泰地区的测录井数据、结合岩心观察和薄片鉴定,对河套盆地临河坳陷吉兰泰地区的生储盖特征进行了研究。结果表明:临河坳陷吉兰泰潜山基岩储层岩性主要为片麻岩,储集空间主要为深大断裂形成的构造裂缝,原油来自下白垩统固阳组烃源岩,上覆固阳组泥页岩为基岩裂隙油藏提供了良好的封盖,防止油气逸散,形成了埋藏浅、油层厚度大的潜山顶部基岩富集油藏。吉兰泰潜山油藏模式的成功发现丰富了变质岩领域的油气勘探实践,通过对圈—源关系及油气成藏模式综合分析,分层次开展临河坳陷有利区带优选,为变质岩类潜山油气成藏规律研究及有利区圈定提供重要参考。

The logging and mud logging data of the Jilantai with industrial oil flow in Hetao Basin was analyzed to establish the hydrocarbon accumulation mode of bedrock fissure oil reservoir with medium-high productivity in the deep fold basement of Hetao Basin and explore the hydrocarbon-bearing properties of bedrock fissures.The Jilantai source-reservoir-cap properties in Linhe Depression of Hetao Basin were studied by combining with core observation and thin-section analysis.Result indicates that The major lithology of the Jilantai buried-hill bedrock reservoir in Linhe Depression is considered as gneiss.The reservoir space is mainly contributed by the tectonic fractures results from the deep and large-scale faults.The oil mainly comes from the Lower Cretaceous Guyang Formation source-rock.The overlying Guyang Formation mud shale provides a favorable caprock for the bedrock fissure oil reservoir to prevent hydrocarbon escaping,which leads to a bedrock enriched oil reservoir at the top of buried-hill with shallow buried depth and large reservoir thickness.The successful discovery of the Jilantai buried-hill reservoir hydrocarbon accumulation mode enriched the hydrocarbon exploration practice in the metamorphic rock.The favorable zone optimization in Linhe Depression was carried out hierarchically through the comprehensive analysis of the trap-source relationship and the hydrocarbon accumulation mode,which could provide certain reference for the understanding of hydrocarbon accumulation pattern and the favorable zone optimization.