Accurate Modelling of Pore-Scale Films and Layers for Three-Phase Flow Processes in Clastic and Carbonate Rocks with Arbitrary Wettability
Accurate Modelling of Pore-Scale Films and Layers for Three-Phase Flow Processes in Clastic and Carbonate Rocks with Arbitrary Wettability
复制标题
DOI：
10.1007/s11242-013-0144-z
复制
发表时间：
2013-03
影响因子：
2.7
通讯作者：
Adnan Al-Dhahli;M. V. van Dijke;S. Geiger
中科院分区：
文献类型：
--
作者：
Adnan Al-Dhahli;M. V. van Dijke;S. Geiger
三相流是地下油藏中发生的一个关键过程，例如，在采油、封存和提高采收率技术，如注入水交替气体(WAG)时。预测三相流过程，例如，在WAG过程中提高石油采收率，需要对水到油湿岩石中的基本流动物理有良好的了解，以推导出物理上可靠的流动函数，即相对渗透率和毛细压力。在这项研究中，我们使用孔网络模型，一个可靠的和基于物理的模拟工具，来预测流动函数。我们开发了一种新的孔隙尺度网络模型，适用于从水到油湿的各种润湿性岩石。它包括一组受约束的参数，模拟储集层的润湿状态。与其他模型不同，它结合了三个主要特征：(1)一种新的油层形成和坍塌的热力学判据。因此，新模型充分捕捉了原油的润湿膜和层状流动，影响了低含油饱和度时的原油相对渗透率，从而能够准确地预测剩余油。(2)多个位移链，其中在入口处注入一个相会触发整个网络的界面位移链。这允许对特别是在更高级别的WAG洪水期间出现的许多断开的相簇的移动化进行准确的建模。(3)该模型以由孔隙空间重建方法提取的真实三维孔隙网络和CT图像为输入，既保留了样品的拓扑结构，又保留了样品的孔隙形状。对于水湿系统，我们用岩心水淹实验数据验证了我们的模型。对于油湿系统，我们通过比较二维网络模拟和油湿微观模型中WAG洪水的公开数据来验证我们的网络模型。这证明了膜和层流对于后续WAG周期中各相的连续性和剩余油饱和度的重要性。利用全三维模型进行了敏感性分析，预测了不同润湿条件和不同驱油终点条件下WAG周期的三相相对渗透率和剩余油饱和度。
Three-phase flow is a key process occurring in subsurface reservoirs, for example, duringsequestration and enhanced oil recovery techniques such as water alternating gas (WAG) injection. Predicting three-phase flow processes, for example, the increase in oil recovery during WAG, requires a sound understanding of the fundamental flow physics in water- to oil-wet rocks to derive physically robust flow functions, i.e. relative permeability and capillary pressure. In this study, we use pore-network modelling, a reliable and physically based simulation tool, to predict the flow functions. We have developed a new pore-scale network model for rocks with variable wettability, from water- to oil-wet. It comprises a constrained set of parameters that mimic the wetting state of a reservoir. Unlike other models, it combines three main features: (1) A novel thermodynamic criterion for formation and collapse of oil layers. The new model hence captures wetting film and layer flow of oil adequately, which affects the oil relative permeability at low oil saturation and leads to accurate prediction of residual oil. (2) Multiple displacement chains, where injection of one phase at the inlet triggers a chain of interface displacements throughout the network. This allows for the accurate modelling of the mobilisation of many disconnected phase clusters that arise, in particular, during higher order WAG floods. (3) The model takes realistic 3D pore-networks extracted from pore-space reconstruction methods and CT images as input, preserving both topology and pore shape of the sample. For water-wet systems, we have validated our model with available experimental data from core floods. For oil-wet systems, we validated our network model by comparing 2D network simulations with published data from WAG floods in oil-wet micromodels. This demonstrates the importance of film and layer flow for the continuity of the various phases during subsequent WAG cycles and for the residual oil saturations. A sensitivity analysis has been carried out with the full 3D model to predict three-phase relative permeabilities and residual oil saturations for WAG cycles under various wetting conditions with different flood end-points.