核磁共振技术定量表征致密砂岩气储层孔隙结构——以临清坳陷东部石炭系—二叠系致密砂岩储层为例

发布时间：2018-03-20 23:40

本文选题：核磁共振T_谱　切入点：孔隙结构　出处：《石油学报》2017年08期 　论文类型：期刊论文

【摘要】：核磁共振技术能够实现岩石微米—纳米级孔隙高精度、快速、无损测量,为致密砂岩孔隙结构定量表征提供新的手段。基于压汞数据刻度核磁共振T_2谱的方法,针对致密砂岩压汞进汞饱和度不足100%而造成的测不准问题,提出采取压汞曲线和T_2谱从右边界的最大孔隙向左侧小孔隙累加,选定右累加曲线中压汞测量的孔喉半径范围作为核磁共振孔喉半径的可对比区间,利用纵向插值法和最小二乘法构建T_2谱转换的孔喉半径分布曲线。选择临清坳陷东部石炭系—二叠系致密砂岩气储层为研究对象,利用改进方法获得核磁共振T_2谱和孔喉半径转换系数及孔喉半径分布,定量研究了储层孔隙结构特征,并结合岩石薄片、扫描电镜观察,探讨了致密砂岩孔隙结构差异成因及储层有效性。结果表明,利用改进方法得到的核磁共振孔喉半径曲线与压汞曲线吻合度高,显著提高了致密砂岩核磁共振测试的准确度。研究区石炭系—二叠系致密砂岩孔喉半径主要分布于0.002~2μm,总体为亚微米—纳米级孔隙,但不同类型砂岩孔喉半径分布具有明显差异:岩屑石英砂岩富硅质、贫塑性岩屑和杂基,总体以亚微米级孔喉为主,含微米级孔喉;岩屑长石砂岩和长石岩屑(富石英)砂岩石英含量高、塑性岩屑和杂基含量较低,为亚微米—纳米级孔喉(纳米级占优);而长石岩屑(富岩屑)砂岩和岩屑砂岩贫石英、富塑性岩屑和杂基,主要是小于0.05μm的纳米级孔喉。微观岩石学组分是控制孔隙结构差异和储层有效性的关键因素,储层质量宏观上可能受控于沉积微相,粗粒和细粒的点砂坝/河床滞留微相岩屑石英砂岩是最有利储层,细粒的点砂坝微相岩屑长石砂岩、分流河道和障壁砂坝长石岩屑(富石英)砂岩是较有利储层,而潮坪相长石岩屑(富岩屑)砂岩、岩屑砂岩均是孔、渗性极差的无效储层。
[Abstract]:Nuclear magnetic resonance (NMR) technology can achieve high accuracy, fast and nondestructive measurement of pore size in micrometer and nano-scale rock, and provide a new method for quantitative characterization of pore structure in dense sandstone. In view of the uncertainty caused by the mercury injection saturation of tight sandstone is less than 100%, the mercury injection curve and Tap2 spectrum are accumulated from the maximum pore in the right boundary to the small pore on the left side. The range of pore throat radius measured by mercury pressure in the right accumulative curve is chosen as the comparable interval of the nuclear magnetic resonance aperture throat radius. Using the longitudinal interpolation method and the least square method to construct the pore throat radius distribution curve of T _ 2 spectrum conversion, the dense sandstone gas reservoir of Carboniferous and Permian in the eastern part of Linqing depression was selected as the research object. By using the improved method, the NMR T _ 2 spectrum, the conversion coefficient of pore throat radius and the distribution of pore throat radius were obtained, and the pore structure characteristics of reservoir were quantitatively studied. The origin of pore structure difference and reservoir effectiveness of tight sandstone are discussed. The results show that the NMR pore throat radius curve obtained by the improved method is in good agreement with the mercury injection curve. The accuracy of nuclear magnetic resonance (NMR) measurement of dense sandstone is significantly improved. The pore throat radius of the Carboniferous to Permian tight sandstone is mainly distributed in 0.002 渭 m, and the total pore size is submicron and nanometer. However, the distribution of pore throat radius of different types of sandstone has obvious differences: lithic quartz sandstone is rich in silicon, poor in plastic cuttings and complex bases, generally dominated by sub-micron pore throat, including micron pore throat; Lithic feldspathic sandstone and feldspar lithic sandstone (rich in quartz) contain high quartz content, while plastic lithic sandstone and complex base contain relatively low content, which is sub-micron and nanometer-sized pore throat (nanoscale dominated), while feldspathic sandstone (rich in lithosphere) and lithic sandstone are poor in quartz. Plastic cuttings and heterogeneity are mainly nanoscale pore throats of less than 0.05 渭 m. Microscopic petrological components are the key factors to control pore structure difference and reservoir validity, and reservoir quality may be controlled by sedimentary microfacies macroscopically. Coarse grain and fine grain point sand dam / bed retained microfacies lithic quartz sandstone is the most favorable reservoir, fine grain point bar microfacies lithic feldspar sandstone, distributary channel and barrier bar feldspar lithic (quartz rich) sandstone are more favorable reservoirs. In the tidal flat facies feldspar (rich in lithic) sandstone, the lithoclastic sandstone is an invalid reservoir with very poor permeability.
【作者单位】：中国石油大学地球科学与技术学院;中国科学院地质与地球物理研究所中国科学院油气资源研究重点实验室;北京大学信息科学技术学院量子电子学研究所;中国石油化工股份有限公司胜利油田分公司勘探开发研究院;
【基金】：国家自然科学基金项目(No.41372151) 国家重大科技专项(2017ZX05008-004) 国家重点基础研究发展计划(973)项目(2015CB250902)资助
【分类号】：P618.13

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