Pore-pressure diffusion during water injection in fractured media
Pore-pressure diffusion during water injection in fractured media
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DOI：
10.1190/geo2019-0169.1
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发表时间：
2020
期刊：
影响因子：
3.3
通讯作者：
Y. Rao;Yanghua Wang
中科院分区：
文献类型：
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作者：
Y. Rao;Yanghua Wang
对于低渗透、低孔隙度的裂缝性油藏，在采油过程中往往需要注水。我们已经开发出精确模拟注水过程中孔隙压力扩散的方法，并从复杂的裂缝网络中评估扩散通量。我们提出了各向异性扩散的显式标量系数，而不是每个晶格上的扩散张量，并以椭圆形式分配这些标量系数，长轴与断裂方向一致。基于这些系数，推导出计算裂缝网络中孔隙压力扩散通量的数学方程。延长注水时间扩散的各向异性数值模拟表明，注水初期主要沿单个裂缝影响孔隙压力分布，但逐渐影响裂缝周围介质的孔隙压力，改变裂缝介质的物性。
For fractured reservoirs with low permeability and low porosity, water injection is often needed during hydrocarbon production. We have developed methods to accurately simulate pore-pressure diffusion during water injection and to evaluate the diffusion flux from a complex fracture network. We proposed explicit scalar coefficients of the anisotropic diffusion instead of a diffusion tensor at each lattice, and we assigned these scalar coefficients in an elliptical form, with the major axis aligned with the fracture orientation. Based on these coefficients, we derived mathematical equations for calculating the flux of the pore-pressure diffusion in fracture networks. Numerical simulation of the anisotropic characteristic of diffusion with a prolonged water injection time revealed that although water injection affects pore-pressure distribution mainly along the individual fractures during the early stage, it gradually affects the pore pressure of the media surrounding the fractures and changes the physical property of fractured media.