鄂尔多斯盆地陕北地区延长组长9深部层系油气成藏特征研究

Hydrocarbon Accumulation Characteristics of Deep Stratigraphy of Chang-9 Oil Reservoir of Yanchang Formation in Northern Shaanxi,Ordos Basin

为剖析陕北地区长9深部油气成藏特征,总结其成藏模式,针对其成藏要素及油藏类型有待明确等问题,运用岩心观察、铸体薄片、扫描电镜、生物标志化合物对比等方法进行研究,得出以下结论:陕北地区延长组长9段主要发育三角洲前缘和浅湖沉积亚相;长9顶部所发育的浅湖亚相黑色泥页岩为研究区东南部的长9油藏提供油源供给;研究区长9储层主要为三角洲前缘水下分流河道砂体,物性显示长9整体为低孔、低渗储层;形成于印支期的裂缝和局部高渗砂带为研究区长9油气疏导体系;油藏类性主要包括构造—岩性油藏和岩性油藏两大类;发育上生下储和自生自储式两类成藏模式。结论为陕北地区延长组深部油气进一步勘探开发提供科学依据。

In order to analyze the hydrocarbon accumulation characteristics of Chang-9 reservoir in northern Shaanxi and summarize its hydrocarbon accumulation model, in view of the problems of reservoir elements and reservoir types to be clarified, core observation, casting thin sections, scanning electron microscopy, biomarker compound comparison and other methods were used to be studied in this paper. Those studies have drawn the following conclusions： The delta front and shallow lake sedimentary surfaces were mainly developed in Chang-9 formation in the study area. The black shale at the top of Chang-9 provides oil supply for Chang-9 reservoir in the study area. Chang-9 reservoir is mainly distributary channel sand body of delta front which physical property shows that Chang-9 reservoir is low-porosity and low-permeability. The fractures formed in the Indosinian period and the local high-permeability sand belt are the oil drainage system of Chang-9 reservoir in the study area. The reservoir types mainly include structural-lithological reservoirs and lithologic reservoirs. Chang-9 reservoir mainly develops two types of hydrocarbon accumulation models. It provides a scientific basis for further exploration and development of deep oil in the Yanchang formation in northern Shaanxi.