致密油孔隙结构表征方法——以川中致密油储层岩心为例

发布时间：2018-11-05 13:05

【摘要】：致密油孔隙结构表征是该类储层评价的核心,直接制约其规模开发。由于传统方法的局限性,文中运用医用CT、场发射扫描电镜、微米CT和纳米CT 4种技术相结合的方法,从毫米级、微米级和纳米级3个尺度综合描述致密油孔隙结构。以川中致密油岩心为例进行研究,结果表明,川中致密油储层具有多尺度多类型孔隙连续分布的特征。基于医用CT扫描分析,储层连通性较差,孔隙空间分布也极度分散,其孔隙度主要分布范围在0.5%以下;在SEM图像上,观察到大量的微米级粒间残余孔道和纳米级粒内溶蚀孔道,但孔隙网络重建表明,基质孔道在微纳尺度的连通性都很差;除基质孔道外,在渗透率较高的岩心SEM图像中观察到粒间缝和方解石颗粒解理缝2类微裂缝,其存在能较好地改善储层连通性。实验分析认为,在孔隙结构表征中,开展微米级孔道和微裂缝的基础研究是致密油规模勘探开发的关键。
[Abstract]:Pore structure characterization of tight oil is the core of reservoir evaluation, which directly restricts its scale development. Because of the limitation of the traditional methods, this paper describes the pore structure of dense oil from millimeter scale, micron scale and nanometer scale by combining medical CT, field emission scanning electron microscope, micron CT and nanometer CT. Taking the dense oil core in central Sichuan as an example, the results show that the tight oil reservoir in the middle of Sichuan has the characteristics of multi-scale and multi-type continuous distribution of pores. Based on the medical CT scanning analysis, the reservoir connectivity is poor, the pore space distribution is extremely dispersed, and the main porosity distribution range is below 0.5%. On SEM images, a large number of residual microparticle channels and nanoscale dissolution channels were observed, but the reconstruction of pore network showed that the connectivity of matrix channels at micro- and nanoscale scale was very poor. In addition to matrix channels, two types of microfractures, intergranular fractures and calcite granular cleavage fractures, were observed in SEM images of cores with high permeability, and their existence can improve reservoir connectivity. The experimental analysis shows that in the characterization of pore structure, it is the key to develop micrometer pore channel and micro fracture in the exploration and development of tight oil scale.
【作者单位】：中国石油勘探开发研究院;北京大学地球与空间科学学院;中国地质大学(北京)能源学院;
【基金】：中国石油天然气集团公司科研项目“油气开发新技术、新方法研究”(2014A-1003)
【分类号】：P618.13

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