羌塘盆地隆鄂尼地区油砂矿地质特征及成藏模式

Geology Characterization and Hydrocarbon Accumulation Pattern of Oil Sand in Longeni of Qiangtang Basin

为研究羌塘盆地隆鄂尼地区油砂矿资源潜力,通过剖面地质调查、岩心描述、薄片鉴定、物性测试和含油率测定等方法,对隆鄂尼地区地表及钻井油砂样品的岩性、物性及含油性特征进行分析,结合油砂露头剖面及钻井连井剖面特征,对研究区油砂矿地质特征及油砂矿成矿模式进行分析研究。结果表明,研究区油砂主要以中—细晶白云岩为主,油砂层总体厚度较大,但储层物性较差,属于低孔低渗储层,而含油率较高,属于"B级"油砂矿。隆鄂尼地区油气主要来自布曲组碳酸盐岩和泥岩,为自生自储型古油藏。综合分析认为,羌塘盆地隆鄂尼地区油砂矿由岩性封闭配合构造抬升共同作用形成。研究结果可为进一步勘探该地区油砂资源提供一定的理论依据。

Geology profile survey, core description, thin-section identification, physical property test and oil content tests were used to study the resource potential of oil sand in the Longeni of Qiangtang Basin. The lithology, physical and oil-bearing properties of surface and drilling oil sand samples were analyzed to investigate the geology and oil sand accumulation patterns through combining with the oil sand outcrop and drilling well-tie profiles. Result indicates that the oil sand in this area with relatively large thickness is mainly composed by medium-fine crystal dolomite. However, the oil sand with relatively poor quality and relatively high oil content is considered as the low-porosity and low-permeability reservoir, which is classified as a “Class-B” oil sand. The hydrocarbon in Longeni mainly migrates from the carbonate rocks and mudstones in the Buqu Formation, which is regarded as a self-generation and self-preservation paleo-reservoir. Comprehensive analysis believes that both the lithology sealing and tectonic uplift lead to the oil sand accumulation in Longeni of Qiangtang Basin. This research could provide certain theoretical reference for the further exploration of oil sand resource in this region.