【作者】 刘学锋；

【导师】 孙建孟；

【作者基本信息】 中国石油大学 ， 地质资源与地质工程， 2010， 博士

【摘要】 岩石物理实验费用高,周期长。针对复杂储层,岩石物理实验遇到了诸多困难,如疏松岩心处理存在困难和裂缝发育的碳酸盐岩难以取到代表性的岩心等。同时,岩石物理实验无法定量研究储层微观参数对岩石宏观物理属性的影响。因此,在三维数字岩心基础上开展岩石物理数值模拟实验将弥补上述不足。本文通过两种方法建立三维数字岩心。一是利用X射线CT建立真实岩样的三维数字岩心,并提出了孔隙度与渗透率相结合选择最佳扫描分辨率的方法。二是基于岩石二维信息构建三维数字岩心。首先结合过程法和模拟退火算法的优点,提出了基于岩石二维图像重建三维数字岩心的混合法。重建三维数字岩心的均质性和孔隙连通性与通过X射线CT建立的三维数字岩心相似。然后利用过程法构建具有不同储层参数的三维数字岩心,用于定量研究储层微观参数对岩石物理属性的影响。在三维数字岩心基础上,利用数学形态学方法和有限元方法模拟岩石的电阻率、地层因素和电阻率指数;利用有限元方法模拟岩石的体积模量和剪切模量;利用格子玻尔兹曼方法模拟岩石的绝对渗透率,并结合有限元方法计算不同含水饱和度下的岩石电阻率。基于利用X射线CT建立三维数字,岩心的岩石声电特性和渗透率的数值模拟结果与岩石物理实验结果相符,验证了数值模拟方法的准确性,为开展数字岩石物理实验奠定了基础。在具有不同储层微观参数的三维数字岩心的基础上,利用数值模拟方法研究其对岩石物理属性的影响。模拟结果系统展示了储层微观因素对岩石宏观物理属性的影响。揭示了粘土含量和微孔隙是形成低阻储层的重要原因。岩石润湿性对孔隙流体分布有重要影响,油湿储层的饱和度指数明显大于水湿储层。岩石孔隙尺寸分布影响岩石电性,不同尺寸孔隙的导电网络相互连接,导致岩石电性的非阿尔奇现象。不同的岩石颗粒粒径导致不同的岩石微观孔隙结构,并影响岩石宏观物理属性。在相同孔隙度下,随着岩石粒径的增大,岩石电阻率和弹性模量减小,而渗透率增大。裂缝对岩石的电性影响显著,其影响规律取决于裂缝孔隙度、宽度和方向。岩石弹性模量不但与孔隙度有关,而且与岩石孔隙形状密切相关。微分有效介质模型适用于具有结构泥质的泥质砂岩,而自洽模型和微分有效介质模型相结合适用于具有分散泥质的泥质砂岩。更多还原

【Abstract】 Petrophysics experiment is costly and time consuming. It encounters difficulties applying it to the rocks from the complex reservoir, such as the unconsolidated rock and carbonate sample with fracture that can not be obtained easily. Furthermore it is hard for petrophysics experiment to study the effects of micro-factors on the macro petrophysics properties. The digital petrophysics experiment is numerical simulation of petrophysics based on 3-D digital core. It will overcome the weakness of the petrophysics experiment mentioned above.The 3-D digital cores are generated by two kinds of methods. Firstly we obtain them by X-ray CT based on real rock samples and proposed a new method, which combines porosity and permeability of rock, to determine the best resolution of scanning. The other method to generate 3-D digital core is the reconstruction method based on 2-D information of rocks. We propose a hybrid method to reconstruct 3-D digital core. It inherits the advantages from process-based method and simulated annealing method. The homogeneity and pore connectivity of reconstructed digital cores are similar with those of 3-D digital core from X-ray CT. In order to study the effects of micro-factors of reservoir process-based method is applied to generate 3-D digital core with different grain radius.Based on 3-D digital cores derived from real samples, numerical methods are applied to simulate the petrophysics properties, such as mathematical morphology and the finite element method (FEM) for resistivity, FEM for elastic moduli, and lattice Boltzmann method for permeability. Those methods were also applied to the 3-D digital cores with different micro-factors to study their effects on petrophysics.For the 3-D digital cores of real samples, the numerical results are consistent with the experimental results. It validates the accuracy of numerical methods and the X-ray CT scanning. It will help us build the digital petrophysics experiment. The 3-D digital cores with different micro-factors are built to study the effects of those factors on the resistivity, elastic moduli and permeability by numerical simulation. The results indicate that those factors have great effects on macro petrophysics properties. The clay and micro pores are the main reasons to form the reservoir with low resistivity. The wettability has great effect on the fluid distribution in pore space. The saturation exponent of oil-wet rock is much larger than that of water-wet rock. For the rock with large scale in pore size there is Non-Archie phenomenon, where the saturation exponent varies with the water saturation. It is induced by the connection style of different pore network. The grain radius of rock affects its pore structure, which has effect on macro petrophysics. For a given porosity, as the grain radius increase the resistivity and elastic moduli decrease, while the permeability increases. The fracture affects the resistivity greatly. The effect depends on its volume fraction, width and direction. The elastic properties of rocks are not only determined by porosity, but also determined by the shape of pore, which is defined by aspect ratio of pore. The differential effective medium model can be applied to shaly sand with structured clay, while the combination of the self-consistent approximation and the differential effective medium model is fitted with the shaly sand with dispersed clay.更多还原