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石灰岩的白云岩化作用因能形成较好的储层而备受关注,以往学者开展大量的分析和研究工作,但对白云岩的次生灰化作用的研究和认识程度均较低。次生灰化是发生在碳酸盐岩中重要的成岩作用类型之一,对储层的储集性能具有显著的影响作用。分析鄂尔多斯盆地东南部宜川—黄龙地区奥陶系马家沟组马五段次生灰岩岩石学特征及其形成的成岩阶段,并对次生灰岩的成因及主控因素进行探讨,指出古地貌低洼部位有利于白云岩次生灰化作用的发生,裂缝体系也是次生灰化作用的控制因素之一,泥晶含膏白云岩在低温条件下易于发生次生灰化作用。这些认识在碳酸盐岩风化壳储层预测方面具有理论指导意义,在油气勘探实践中具有重要的应用价值。
Dolomitization of limestone has attracted much attention for its ability to form better reservoirs. In the past, scholars carried out a great deal of analysis and research work, but the research and awareness of secondary ashing in dolomite were relatively low. Secondary ashing is one of the important types of diagenesis occurring in carbonate rocks and has a significant effect on the reservoir performance. The petrological characteristics and formation of diagenetic stages of the secondary limestone of Ma5 member of the Ordovician Majiagou Formation in the Yichuan-Huanglong area, southeast of the Ordos Basin, are analyzed. The origin and controlling factors of the secondary limestone are discussed. It is pointed out that the paleogeomorphology The low-lying parts are favorable for the secondary ashing of dolomite. The fracturing system is also one of the controlling factors for the secondary ashing. The clay-bearing dolomite is prone to secondary ashing at low temperature. These understandings are theoretically instructive in the prediction of carbonate weathering crust reservoir and have important application value in oil and gas exploration.