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岩石的渗流特性决定了石油开采效率,对于储层的定量评价具有重要意义。为了解岩石中孔洞裂缝以及不同介质对其渗流性能的影响规律,利用显微红外光谱成像技术,对岩石样品进行光谱成像试验,根据样品的光谱图像和吸光度A值,将该岩石截面划分为孔隙裂缝区域、孔隙与岩石介质过渡区域、白云岩介质区域;据此建立能够精确表征真实岩石结构的有限元模型,对其微观渗流特性进行数值模拟研究。研究结果表明:(1)该岩石样品的特征吸收波段为2 500~2 700 cm~(-1),说明样品介质主要为白云岩;(2)同一平面的二维流动中流体的动力黏度越大,流体在孔道中的流动速度越小;(3)多孔白云岩介质的渗透率较小时,流体主要以沿裂隙孔道的自由流动为主,而介质中渗流运动较弱;随着介质渗透率的增大,多孔介质中的流体渗流运动逐渐明显;(4)孔喉尺寸较小的孔道,毛细管阻力较大,孔道中流体不发生流动;孔喉尺寸扩大后,优势水流路径数量增加,岩石截面中流体流动范围增大,流动速度变大。此研究结果可以为石油开采中储层改造方案的制定提供科学依据,从而有效提高石油开采效率。
The seepage characteristics of rocks determine the efficiency of oil exploration, which is of great significance for the quantitative evaluation of reservoirs. In order to understand the influence of different cavities on the seepage behavior of rock, the rock imaging samples were subjected to spectral imaging using microscopic infrared spectral imaging technique. According to the spectral image and absorbance A of the samples, the rock sections were divided into pores The fracture area, the transition zone between pore and rock medium and the dolomite zone. Based on this, a finite element model is established to accurately characterize the real rock structure, and its microscopic seepage characteristics are numerically simulated. The results show that: (1) The characteristic absorption band of this rock sample is 2 500 ~ 2 700 cm -1, indicating that the sample medium is mainly dolomite; (2) the dynamic viscosity of fluid in two-dimensional flow in the same plane (3) When the permeability of porous dolomite medium is small, the fluid is mainly free flowing along the fissure channel, but the seepage motion in the medium is weak. With the increase of medium permeability (4) The pores with smaller pore throats have larger capillary resistance and no fluid flow in the pores. When the pore throat size is enlarged, the number of dominant water flow paths increases and the rock Cross-section of the fluid flow range increases, the flow rate becomes larger. The results of this study can provide a scientific basis for the formulation of reservoir reconstruction programs in oil exploration so as to effectively improve the efficiency of oil exploration.