电导率和流体分布关系的微观孔隙网络模型研究

MICROSCOPIC PORE NETWORK MODELING OF RELATIONSHIP BETWEEN ELECTRICAL CONDUCTIVITY AND FLUID DISTRIBUTION

关于电导率和流体分布关系的研究还很少,仅有的一项研究是在有机玻璃微观模型上进行的。利用实际Berea砂岩的微CT断层三维图像原型数据,根据Yeong和Torquato提出的两相多孔介质的重构方法,用形状因子控制模型中的孔隙和喉道形状,运用模拟退火方法实现了孔隙岩样的重构过程;给出了模型的统计指标,包括孔隙与喉道大小、孔喉特征半径比等孔隙特征和孔喉形状、配位数等孔隙导通特征。由该模型计算得到的渗流特征和实际实验结果完全吻合,表明了模型的正确性。在此基础上,对电导率和流体分布的关系进行了微观孔隙网络模拟,结果表明随着孔隙形状及分布不同,分布在孔隙中的流体状态也发生变化,导致电阻率发生变化。这些结果可用孔隙中水膜的变化来解释。

Researches of relationship between electrical conductivity and fluid distribution are rarely documented and the only one research was performed on a microscopic organic glass model. Following the reconstruction algorithm proposed by Yeong and Torquato for reconstruction of a two-phase porous medium, simulated annealing algorithm is used to reconstruct porous rock samples, with pore and throat shapes controlled by shape factors, on the basis of the original 3D image data of real Berea sand samples acquired by X-ray micro-tomography. The statistical indexes of the mode are presented, including pore features such as pore and throat sizes and characteristic pore-throat radius ratio and conductivity features of pores such as pore and throat shapes and pore-throat coordinate number. Percolation features calculated with this model coincide well with real experiment results, indicating that the model is correct. Microscopic pore network modeling of the relationship between electrical conductivity and fluid distribution shows that flow status of fluids in pores change along with pore shape and distribution, resulting in change of resistivity. These results can be explained by variation of water film in pore space.