致密油评价新方法及其应用——以鄂尔多斯盆地延长组长7段致密油为例

New Tight Oil Evaluation Technology and Its Application——A Case Study of Chang7 Tight Oil Reservoir in Yanchang Formation,Ordos Basin

利用高分辨率场发射扫描电子显微镜、微米及纳米级CT扫描、恒速压汞及核磁共振等先进技术方法，对鄂尔多斯盆地延长组长7段致密油储层微观孔喉结构特征及致密油赋存状态进行定量深入研究。首先对致密油赋存的微观孔隙结构进行分析．认为孔隙大小决定致密油储层的储集能力，喉道大小是储层物性主要制约因素。长7段致密油储层孔隙平均半径为10—15μm，喉道半径主要分布范围为0．3～0．9μm；其中半径为0．1～0．5μm的喉道控制了储层中60％的可动流体；并建立了孔隙、喉道及孔喉配置结构三维立体模型。定量评价致密油微观赋存状态，将其分为乳状、簇状、喉道状、颗粒状、薄膜状及孤立状6种赋存状态，定量测得储层中致密油以乳状和薄膜状为主要赋存状态，占致密油总量的70％以上。致密油赋存状态的定量研究，为科学开展致密油储层评价及实现致密油有效动用提供可靠依据。

Using the technology of leading field emission scanning electron microscope, micro-nano grade CT scanning technology, the technology of constant pressure mercury, the nuclear magnetic resonance technology, and other advanced technology, quantitative research was done about the reservoir pore-throat and tight oil occurrence state of Yanchang tight oil reservoir of Yauehang Formation in Ordos Basin. First of all, the micro-pore structure of tight oil in the reservoir was analyzed. It was believed that pore size determined tight oil reservoir capacity, and the size of pore throat was a main factor restricting reservoir property. The radius of porosity was around 10μm to 15μm, throats distribute between 0. 3μm and 0. 5μm, and the throats of the range 0. 1μm and 0. 5μm controlled 60% of movable fluid of reservoir. And 3D models of pore, throat and pore-throat structure were established. On the basis of quantitative evaluation of micro occurrence state, tight oil was divided into six types, i. e. thin film form, cluster form, throat form, emulsion form, particle form and isolated form. Emulsion form and thin film form were main types, and the content of emulsion form and thin film form accounted for about 70% of total. Quantitative research on micro occurrence state provided a reliable basis for evaluating tight oil reservoir and making effective use of tight oil.