【作者】 秦子桢； 武富礼；

【Author】 QIN Zizhen;WU Fuli;School of Earth Sciences and Engineering, Xi’an Shiyou University, Shaanxi Key Laboratory of Petroleum Accumulation Geology;

【机构】 西安石油大学地球科学与工程学院陕西省油气成藏地质学重点实验室；

【摘要】 鄂尔多斯盆地中部Z区块长4+5属于陆相低-特低渗透储层,致密油藏有效储层下限参数评价对甜点预测及油藏注水开发具有重要指导意义。本文运用该区长4+5大量岩性、薄片、扫描电镜、物性、X衍射、测井资料、压汞等资料,建立了致密油储层有效孔隙度解释方法,确定了适用于Z区快长4+5油层评价的岩性、物性、电性、含油性下限标准。研究结果显示,长4+5储层的主要岩石类型是细粒长石砂岩,其次是岩屑长石砂岩;长4+5储层的主要孔隙类型为粒间孔、长石溶孔、粒间溶孔及岩屑溶孔。目的层孔隙度主要分布在8%～14%,渗透率分布区间为0.039×10^-3μm²～1×10^-3μm²。长4+5储层岩性下限为细砂岩,油迹级为其含油级别下限,渗透率下限为0.2×10-3μm2,根据电阻率及孔隙度交会图版,得出孔隙度下限为9%,含油饱和度下限为40%,电阻率下限为15Ω·m,声波时差下限为226.4μs/m。此外,砂岩厚度与有效厚度呈一定正相关关系,有效厚度与孔隙度也有一定正相关关系,当储层物性较好以及砂层厚度较大,油层厚度较大;反之,当储层物性较差以及砂层厚度较小时,则主要发育差油层。更多还原

【Abstract】 Block Chang 4+5 in Z area of central Ordos Basin belongs to continental low-ultra-low permeability reservoir. The evaluation of effective reservoir lower limit parameters of tight reservoir has important guiding significance for dessert prediction and reservoir waterflooding development. In this paper, the interpretation method of effective porosity of tight oil reservoir is established by using a large number of lithology, thin section, scanning electron microscope, physical properties, X-ray diffraction, logging data, mercury injection and other data in this area. the lower limits of lithology, physical properties, electrical properties and oil-bearing properties suitable for the evaluation of fast-growing 4+5 reservoirs in Z area are determined. The results show that the main rock types of Chang 4+5 reservoir are fine feldspar sandstone, followed by lithic feldspathic sandstone, and the main pore types of Chang 4+5 reservoir are intergranular pore, feldspar solution pore, intergranular solution pore and cuttings solution pore. The porosity of the target layer is mainly distributed in 8% ～ 14%, and the permeability distribution range is 0.039 × 10^-3 μm2 ～ 1 × 10^-3 μm². The lower limit of lithology of Chang 4+5 reservoir is fine sandstone, the oil trace level is the lower limit of oil-bearing grade, and the lower limit of permeability is 0.2× 10^-3μm². According to the resistivity and porosity intersection chart, the lower limit of porosity is 9%, the lower limit of oil saturation is 40%, the lower limit of resistivity is 15 Ω m, and the lower limit of acoustic time difference is 226.4μs/m. In addition, there is a certain positive correlation between sandstone thickness and effective thickness, and there is also a certain positive correlation between effective thickness and porosity. When the reservoir physical property is better and the sand layer thickness is larger, the reservoir thickness is larger; on the contrary, when the reservoir physical property is poor and the sand layer thickness is small, poor oil layers are mainly developed.更多还原