博文
关于含启动压力梯度低渗透储层渗流控制方程的讨论
||
关于含启动压力梯度低渗透储层渗流控制方程的讨论
Advances in Geo-Energy Research, 2018, 2(3): 245-259原文网址：http://www.astp-agr.com/index.php/Index/Index/detail?id=69
通常认为低渗透油藏存在启动压力梯度。低渗透油藏研究中较多使用一维和径向流动的含启动压力梯度的渗流控制方程。刘文超的研究表明，使用直角坐标系的含启动压力梯度的渗流控制方程单井数值模拟的压力分布不符合径向对称的规律。此外，文献中报道的直角坐标系下的含启动压力梯度渗流控制方程与其圆柱坐标系下的径向流动的方程不相容。
本文根据三维空间含启动压力梯度渗流本构方程，导出了各向同性储层直角坐标系的含启动压力梯度渗流控制方程及圆柱坐标系径向流动的方程，分析表明两者是相容的。讨论了各向异性储层启动压力梯度的表征方法，得出需要使用二阶张量表示的结论。基于启动压力梯度对渗流的阻碍指向渗流速度负方向的假设，得到了一般形式的渗流启动条件和各向异性储层含启动压力梯度渗流控制方程，他们能够退化到各向同性储层的情形。本文的研究对于低渗透油藏数值模拟具有重要的应用价值。
Discussion on seepage governing equations for low permeability reservoirs with a threshold pressure gradient
Guofeng Han, Yuewu Liu, Kumar Nawnit, Yingfang Zhou
(Published: 2018-06-14)
CorrespondingAuthor and Email: Guofeng Han, hgf_xg@126.com
Citation: Han, G., Liu, Y., Nawnit, K., Zhou, Y. Discussion on seepage governing equations for low permeability reservoirs with a threshold pressure gradient. Advances in Geo-Energy Research, 2018, 2(3): 245-259, doi: 10.26804/ager.2018.03.03.
ArticleType: Original article
Abstract：
Low permeability reservoirs account for an increasing proportion of oil production. Threshold pressure gradient is an important factor that governs the flow in low permeability porous media. The 1-D seepage governing equation (SGE) for low permeability porous media can be derived from the 1-D core flooding experimental rule. In the literature, for isotropic porous media, the SGE with a threshold pressure gradient (TPG) in Cartesian and cylinder coordinate systems are incompatible to each other. In addition, irrational results were found in simulation using SGEs in the Cartesian coordinate system. In this study, 3-D SGEs with a TPG in the Cartesian coordinate system and for radial flow in the cylindrical coordinate system are derived from the vector form of the seepage velocity in 3-D domain which is transformed from the 1-D seepage velocity vector. The 1-D equation degenerated from the 3-D SGE of low permeability media is in accordance with the 1-D SGE. The derived SGE of low permeability porous media in Cartesian coordinate systems is consistent with that in cylindrical coordinate systems. So, the contradiction of SGEs with a TPG in literature is resolved. For anisotropic reservoirs with a TPG, with the assumption that the impeding of a TPG to flow in porous media occurs in the opposite direction of the seepage velocity vector, the general seepage initiation condition for anisotropic porous media with a TPG is derived. The SGEs for anisotropic porous media with a TPG under a specific condition in Cartesian coordinate systems and for radial flow in cylindrical coordination the systems are derived, and then are degenerated to isotropic cases. It is found that a simple form of the SGE in anisotropic porous media with a TPG can only be derived when the flow is radial. So, it is suggested that numerical simulations for anisotropic porous media with a TPG should use the equation set composed by the pressure and seepage velocity vector. The analysis also indicates that a TPG of anisotropic reservoirs is a two-order tensor, and cannot be represented by a vector. However, the current form of effective pressure gradient requires further investigation.
Keywords: Low permeability, flow in porous media, governing equation, non-Darcy, threshold pressure gradient.
PDF下载：5b284a62d452f.pdf
https://blog.sciencenet.cn/blog-549881-1128269.html
上一篇：Zara-Bolucan地区周围始新世地层的古沉积环境及生物标志特征
下一篇：多孔介质自吸与加压自吸的自模解
