基于多点统计法构建三维数字岩心的研究

发布时间：2018-07-04 11:44

本文选题：三维数字岩心 + 多点统计法　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：面对巨大的能源需求,人们开始更多地关注非常规石油天然气资源。非常规油气储层岩心致密,非均质性强,导致岩石物理性质变化规律复杂,制约了储层评价精度。同时,非常规储层岩心取芯成功率低且驱替困难,仅通过岩石物理实验难以准确定量揭示变化规律,而基于三维数字岩心的岩石物理数值模拟已发展成为岩石物理研究的重要手段。由于非常规储层岩心的非均质性,适用于均质岩心的三维数字岩心建模技术难以直接应用,仅通过X射线CT无法准确描述岩石的微观孔隙结构,且难以建立某一储层参数连续变化的三维数字岩心。因此,在岩石二维信息基础上,采用重建算法建立与真实岩心微观结构相似的三维数字岩心具有重要的理论意义和应用价值。首先,基于单张二维图像采用多点统计法重建三维数字岩心,定量计算了重建三维数字岩心的自相关函数、局部孔隙度分布函数和平均渗流概率函数,与真实岩心进行比较,评价重建结果的准确性。然后,改进多点统计法中硬数据添加规则、搜索树建立方法和条件概率分布函数耦合算法,在三张正交二维图像基础上,重建了枫丹白露砂岩和高岭石填隙物三维数字岩心。最后,将孔隙中轴线与多点统计法相结合,在归纳孔隙中轴线特征基础上,采用多点统计法重建孔隙中轴线,通过四参数法模拟孔隙生长过程,建立三维数字岩心,并评价其准确性。通过编程实现上述重建算法,重建结果表明:基于单张二维图像重建三维数字岩心与真实岩心具有相似的孔隙度和均质性,但孔隙连通性差异较大,且呈现明显的各向异性;基于三张正交二维图像重建三维数字岩心,由于将三个方向概率分布作为约束条件,所以改善了孔隙的各向异性,孔隙连通性与真实岩心接近,为采用扫描电镜建立亚微米尺寸三维数字岩心奠定了基础;基于孔隙中轴线,利用多点统计法重建的三维数字岩心在孔隙大小、分布及均质性与真实岩心类似,且重建岩心在连通性方面与真实岩心更加接近,为建立具有孔隙结构参数连续变化的三维数字岩心提供了一种新方法。
[Abstract]:In the face of huge energy demand, people begin to pay more attention to unconventional oil and natural gas resources. Unconventional oil and gas reservoirs have dense core and strong heterogeneity, which leads to complex rock physical properties and restricts the accuracy of reservoir evaluation. At the same time, the core core of unconventional reservoirs is low in power and difficult to drive, only through rock physics experiments. The numerical simulation of rock physics based on the three-dimensional digital core has developed into an important means of rock physics. Because of the heterogeneity of the unconventional reservoir core, the 3D digital core modeling technique suitable for the homogeneous core is difficult to be directly used, and the rock can not be accurately described by the X ray CT. It is difficult to establish a three-dimensional digital core with a continuous change in the parameters of a reservoir. Therefore, on the basis of the two-dimensional information of the rock, it is of great theoretical significance and application value to establish a three-dimensional digital core similar to the real core microstructure by the reconstruction algorithm. First, a multi point statistics method based on a single two-dimensional image is adopted. The three-dimensional digital core is reconstructed, the autocorrelation function, the local porosity distribution function and the average percolation probability function are quantitatively calculated, and the accuracy of the reconstruction results is evaluated by comparing with the real core. Then, the rules of adding hard data in the multi point statistics method are improved, and the method and the conditional probability distribution function of the search tree are established. The coupling algorithm, on the basis of three orthogonal two-dimensional images, reconstructs the three-dimensional digital core of Fontainebleau sandstone and kaolinite fillings. Finally, the axis axis of the pore is combined with the multi point statistics method. On the basis of the characteristics of the axis axis, the multi point statistics method is used to reconstruct the axis of the pore, and the pore growth process is simulated by the four parameter method. Three dimensional digital core is established and its accuracy is evaluated. The reconstruction algorithm is realized by programming. The reconstruction results show that the three-dimensional digital core based on a single two-dimensional image has similar porosity and homogeneity with the true core, but the pore connectivity is different and shows the obvious anisotropy; based on the reconstruction of three orthogonal two-dimensional images The three-dimensional digital core, due to the three directional probability distribution as a constraint, improves the anisotropy of the pore, and the pore connectivity is close to the true core. It lays a foundation for the establishment of a three-dimensional digital core with a scanning electron microscope for the establishment of a submicron size three-dimensional digital core. The size, distribution and homogeneity of the gap are similar to the true core, and the rebuilt core is closer to the true core in connectivity, which provides a new method for the establishment of a three-dimensional digital core with continuous changes in the pore structure parameters.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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