大型内陆坳陷湖盆低渗储层富油理论与实践

Petroleum enrichment theory and practice for low permeability reservoir in large continental basin

以鄂尔多斯盆地陇东地区三叠系延长组低渗透砂岩油藏为例,基于大量基础地质、地球物理和地球化学分析资料,指出鄂尔多斯盆地陇东地区延长组石油富集主要受稳定构造背景、低孔渗储层与高效优质烃源岩良好配置等多种因素控制。以长7油页岩为主、多层段有效烃源岩的高效生烃是石油富集的基础,低渗储层与高效烃源岩的直接大面积接触及烃源岩的异常高压驱动下的高效排油是低渗储层石油富集的关键;稳定的构造背景和低渗透储层的强烈非均质性是石油保存的根本。在延长组储层普遍致密的背景下,有效烃源岩的排烃范围和有效储层的分布共同控制了石油富集地区。勘探实践已表明,大型内陆坳陷湖盆低渗储层富油理论可有效指导油气勘探,已发现了亿吨级大油气田。

This paper, taking the low permeability reservoir in the Yanchang Formation of the Triassic in Longdong Region of Ordos Basin as an example, demonstrates the forming mechanism of low porosity and permeability reservoir, based on the comprehensive analysis of general geological, geophysical and geochemical data. The effective source rocks are in different strata, major from Chang 7 oil shale, and are characterized by the high efficient genetic potential. The key factors controlled the petroleum enrichment are the excellent source rock directly contacting low permeability reservoir in a large area and the high efficient oil drainage. The abundant petroleum reserved in low permeability reservoir is based on the stable tectonic setting and reservoir heterogeneity. The abundant petroleum accumulation in low permeability is controlled by the drainage area of effective source rock and the occurrence of low permeability reservoir. Thus, several large oilfields have been found in low permeability reservoir in Ordos Basin under the guidance of the new ideas of forming mechanism of low permeability reservoir.