致密砂岩油藏全尺度孔喉分布特征及其微尺度非均质性对流体赋存状态的影响研究

Tight sandstone reservoirs characterized by small pore-throat size, complex pore structure, greater heterogeneity, difficult characterization. In this application,taking the Chang 8 tight sandstone oil reservoir in the Longdong area of the Ordos Basin as an example, based on the background of clear sedimentary and diagenetic evolution., rock mineral types, contents pore types, throat morphology, pore-throat matching relation, pore-throat connectivity, etc will be analyzed and the rock texture and pore-throat structure model will be established; The full-scale pore-throat distribution model will be established by applying the curve splicing theory combined with a variety of advanced testing techniques; The pore-throat micro-scale heterogeneity will be quantitatively characterized based on the information entropy theory in tight sandstone reservoirs;The effect of pore-throat micro-scale heterogeneity on fluid occurring and availability will be illustrated in different rock texture and pore-throat structure of tight sandstone reservoirs;Combining dynamic characteristics analysis of oilfield production, the results of full-scale pore-throat distribution and its micro-scale heterogeneity in tight sandstone reservoirs based on the union between multi-means and multi-science will be verified.It would provide a theoretical basis for the fine evaluation of micro-pore structure of tight sandstone reservoirs and efficient development.

致密砂岩储层孔喉尺寸小、孔隙结构复杂、非均质性强、表征难度大。本申请以课题以鄂尔多斯盆地陇东地区长8致密砂岩油藏为例，开展致密砂岩油藏全尺度孔喉分布特征及其微尺度非均质性对流体赋存状态的影响研究。在明确沉积和成岩演化背景下，分析储层岩石矿物类型、含量、孔隙类型、喉道形态、孔喉匹配关系、孔喉连通性等，构建岩石组构-孔喉结构模型；将曲线拼接理论与多种先进测试技术相结合建立全尺度孔喉分布模式；引入信息熵理论，全面量化表征致密砂岩储层孔喉微尺度非均质性；阐明不同岩石组构-孔喉结构致密砂岩储层孔喉微尺度非均质性对流体赋存状态（数量）与可动用量的影响机制；结合油田生产动态特征分析，对多手段、多科学联合表征的致密砂岩储层全尺度孔喉分布特征及其微尺度非均质性结果进行动态验证。对致密砂岩储层微观孔隙结构精细评价、高效开发提供理论依据。

致密砂岩储层孔喉小、孔隙结构复杂、非均质性强、表征难度大。以鄂尔多斯盆地长8致密砂岩油藏为例，以铸体薄片、扫描电镜、X衍射为手段，构建储层岩石组构-孔隙组合模型；将归一化理论、先验概率、映射理论与高压压汞、恒速压汞实验相结合，建立致密砂岩储层全尺度孔喉分布特征量化表征模型；引入信息熵理论，构建新参数（孔隙均匀度）量化表征致密砂岩储层孔喉微尺度非均质性；结合核磁共振冻融技术，讨论不同岩石组构-孔隙组合类型储层孔喉微尺度非均质性对流体赋存状态（数量）与可动用量的影响机制。研究表明，研究区长8储层岩石组构-孔隙组合类型可分为4类：钙质-溶孔-粒间孔、高软组分-溶孔-粒间孔、低软组分-粒间孔-溶孔以及低软组分-溶孔-粒间孔；不同岩石组构-孔隙组合类型储层的全尺度孔喉分布模式差异主要取决于数据融合过程的映射值；不同类型储层微尺度孔隙均匀度存在明显差异，不同孔隙区间孔隙均匀度与储层物性之间的关系受钙质、溶孔的发育程度控制较为明显；该致密砂岩储层可动流体动用下限值为0.1μm；岩石组构与孔隙组合类型耦合控制着不同孔隙区间内流体赋存状态，软组分高低、溶孔的发育程度对不同孔隙区间内流体赋存状态与可动量的控制尤为显著。从而，为致密砂岩储层精细表征、高效开发提供理论依据。