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An integrated approach to simulate fracture permeability and flow characteristics using regenerated rock fracture from 3-D scanning: A numerical study
Gas Science and Engineering Pub Date : 2018-03-11
W.A.M. Wanniarachchi, P.G. Ranjith, M.S.A. Perera, T.D. Rathnaweera, C. Zhang, D.C. Zhang

Fluid flow in a rock fracture bounded by two rock surfaces with surface asperities is a complex phenomenon to study. However, precise knowledge of the flow characteristics through a real rock fracture is essential in order to design and estimate the efficiency and production of unconventional oil and gas exploration and geothermal energy extraction projects. The aim of this numerical study, is therefore to incorporate a rock fracture in the modelling platform using a pre-processing procedure and to couple it with the flow parameters. 3-D scanning technology was used to obtain the rock fracture surfaces and to generate the fracture profile in a grid matrix form. In addition, the generated fracture profile was imported in to the COMSOL Multiphysics software package to simulate the flow characteristics of the rock fracture. The COMSOL model was validated using experimental permeability results conducted under triaxial conditions. According to the results, the COMSOL numerical model can simulate the flow characteristics through the rock fracture with more than 90% accuracy compared to the experimental data. The numerical results also reveal that the pressure gradient through a rock fracture is nonlinear and depends on the fracture profile. Furthermore, the nonlinearity of pressure gradient varies on different sections of the fracture, confirming the heterogeneity nature of the fracture. In addition, the results illustrate that the entire fracture width does not contribute to the final flowrate and that it is essential to consider the effective fracture width in flow calculations.



中文翻译:

使用3-D扫描中的再生岩石裂缝模拟裂缝渗透率和流动特征的综合方法:数值研究

由两个具有表面凹凸的岩石表面界定的裂隙中的流体流动是研究的复杂现象。但是,对于设计和估算非常规油气勘探和地热能开采项目的效率和生产,必须准确了解通过实际岩石裂缝的流动特性。因此,此数值研究的目的是使用预处理程序将岩石裂缝合并到建模平台中,并将其与流动参数耦合。3-D扫描技术用于获取岩石裂缝表面并以网格矩阵形式生成裂缝轮廓。此外,将生成的裂缝剖面导入到COMSOL Multiphysics软件包中,以模拟岩石裂缝的流动特性。使用在三轴条件下进行的实验渗透率结果验证了COMSOL模型的有效性。根据结果​​,与实验数据相比,COMSOL数值模型可以模拟流过岩石裂缝的流动特性,其准确性超过90%。数值结果还表明,通过岩石裂缝的压力梯度是非线性的,并取决于裂缝的轮廓。此外,压力梯度的非线性在裂缝的不同部分上变化,从而确认了裂缝的非均质性。此外,结果表明,整个裂缝宽度对最终流速没有贡献,在流量计算中必须考虑有效裂缝宽度。根据结果​​,与实验数据相比,COMSOL数值模型可以模拟流过岩石裂缝的流动特性,其准确性超过90%。数值结果还表明,通过岩石裂缝的压力梯度是非线性的,并取决于裂缝的轮廓。此外,压力梯度的非线性在裂缝的不同部分上变化,从而确认了裂缝的非均质性。此外,结果表明,整个裂缝宽度对最终流速没有贡献,在流量计算中必须考虑有效裂缝宽度。根据结果​​,与实验数据相比,COMSOL数值模型可以模拟流过岩石裂缝的流动特性,其准确性超过90%。数值结果还表明,通过岩石裂缝的压力梯度是非线性的,并取决于裂缝的轮廓。此外,压力梯度的非线性在裂缝的不同部分上变化,从而确认了裂缝的非均质性。此外,结果表明,整个裂缝宽度对最终流速没有贡献,在流量计算中必须考虑有效裂缝宽度。数值结果还表明,通过岩石裂缝的压力梯度是非线性的,并取决于裂缝的轮廓。此外,压力梯度的非线性在裂缝的不同部分上变化,从而确认了裂缝的非均质性。此外,结果表明,整个裂缝宽度对最终流速没有贡献,在流量计算中必须考虑有效裂缝宽度。数值结果还表明,通过岩石裂缝的压力梯度是非线性的,并取决于裂缝的轮廓。此外,压力梯度的非线性在裂缝的不同部分上变化,从而确认了裂缝的非均质性。此外,结果表明,整个裂缝宽度对最终流速没有贡献,在流量计算中必须考虑有效裂缝宽度。

更新日期:2018-03-12
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