惠民凹陷商河油田商一区河口坝储层构型精细剖析

惠民凹陷商河油田商一区油气储层经过近40年的勘探开发,挖潜难度越来越大。为了进一步搞清该区剩余油分布规律,充分利用研究区丰富的岩芯、测井等资料,对沙二下亚段三、四砂组河口坝储层的垂向级次划分、单一河口坝识别及发育特征、垂向演化规律等开展精细研究。结果表明:河口坝储层发育5级构型界面,其中五、四级界面的成因类型分别为洪泛泥岩、砂体披覆泥岩,三级界面的成因主要为物性差异沉积、成岩钙质砂岩,并进一步细分为泥质夹层。物性夹层和钙质夹层3类;三级界面中泥质夹层的横向连续性好于物性夹层和钙质夹层,延伸距离为300~800 m,沿河口坝进积方向,在坡折带处夹层倾角最大可达8°,至湖盆内部夹层倾角一般小于2°,沿垂直于砂体推进方向,夹层倾角一般低于1.5°;储层顶面高程差异、坝间沉积、坝缘侧向交错叠置、曲线形态及砂体沉积厚度差异是单一河口坝侧向边界的4种识别标志;基准面的升降变化控制了沉积砂体间叠置关系,决定了河口坝砂体的沉积厚度及储层物性特征。该研究成果对于指导商河油田及相似油田开展后期剩余油分布预测具有借鉴意义。

Detailed Reservoir Architecture Analyses of Mouth Bar in Shangyi Block of Shanghe Oilfield,Huimin Sag

After nearly 40 years exploration, the development of petroleum reservoir in Shangyi block of Shanghe oilfield, Huimin sag becomes much more difficult. In order to find the distribution of remaining oil, based on the abundant core and well logging data, the mouth bar reservoir in the third and the fourth sand groups of the second member of Shahejie Formation was analyzed for many aspects, including the grading system of architecture interfaces, the identification and characteristics of a single mouth bar and the vertical evolution law. The results show that the mouth bar reservoir can be classified into 5 grades architecture interfaces; the origin types of the fifth and fourth architecture interfaces are flood shale and argillaceous layers, respectively; the origin types of the third architecture interface are sedimentary with poor physical properties and diagenetic calcareous sandstone, and can be further subdivided into shale interlayer, calcareous interlayer and transitional interlayer; the shale interlayer has more lateral continuity than the calcareous and transitional interlayers in the third architecture interface, and can extend for 300-800 m; along the progradation direction of mouth bar, the dip angle of interface in the slope break belt can up to 8°, while the dip angle is less than 2° in the flat terrain; along the vertical provenance direction of sandbody, the dip angle of interface is generally below 1.5°; four identification marks recognizing lateral boundary of single mouth bar include that the top surface altitude difference of reservoir, the appearance of interval zone of mouth bar deposits, the fringe of two mouth bars overlapping each other and the existing difference from curves and deposition thickness of sandbody; the fluctuation of base level controls the superimposed relationship of sandbody, and determines the deposition thickness of mouth bar sandbody and the physical characteristics of reservoir. This results have an important significance in guiding prediction of the remaining oil’s distribution in Shanghe oilfield and other similar oilfields.