The effects of fluid transport on the creation of a dense network of activated fractures in a porous medium
The effects of fluid transport on the creation of a dense network of activated fractures in a porous medium
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流体传输对多孔介质中激活裂缝致密网络的影响
DOI：
10.1017/jfm.2018.313
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发表时间：
2018
影响因子：
3.7
通讯作者：
Koch, D.L.
中科院分区：
文献类型：
--
作者：
Alhashim, M.G.;Koch, D.L.
分析了低渗透岩石中注入流体时激活裂缝簇的形成。裂缝性岩石被模拟为双孔隙介质，其由不断增长的活化裂缝簇和岩石的固有孔隙度组成。在开发中的裂缝群的流体压力的积分微分方程被引入到占的压力驱动流通过集群，流体的损失到多孔基质和集群的渗透率和孔隙度的演化作为裂缝被激活。讨论了由渗流理论导出渗透率和孔隙度与流体压力关系的条件。它示出的积分微分方程承认流体压力的相似性解决方案，并在两个制度的集群半径增长作为一个幂律的时间：（i）短时间制度，当许多裂缝被激活，但压力驱动的网络中的流动仍然占主导地位的流体损失;和（ii）长时间制度，当流体损失占主导地位。在这两个政权的幂律指数的函数的欧几里德维数的集群，渗流普适指数和注射协议。该模型预测，在两个相似区域中，流体性质对所形成的网络形态的影响是不同的。例如，在流动主导状态下，随着时间增加注入速率产生比通过以恒定速率注入流体形成的更小的活化裂缝群。然而，在滤失量占主导地位的情况下，提高注入速率会产生更大的聚集。
The formation of a cluster of activated fractures when fluid is injected in a low permeability rock is analysed. A fractured rock is modelled as a dual porosity medium that consists of a growing cluster of activated fractures and the rock’s intrinsic porosity. An integro-differential equation for fluid pressure in the developing cluster of fractures is introduced to account for the pressure-driven flow through the cluster, the loss of fluid into the porous matrix and the evolution of the cluster’s permeability and porosity as the fractures are activated. Conditions under which the dependence of the permeability and porosity on the fluid pressure can be derived from percolation theory are discussed. It is shown that the integro-differential equation admits a similarity solution for the fluid pressure and that the cluster radius grows as a power law of time in two regimes: (i) a short-time regime, when many fractures are activated but pressure-driven flow in the network still dominates over fluid loss; and (ii) a long-time regime, when fluid loss dominates. The power law exponents in the two regimes are functions of the Euclidean dimension of the cluster, percolation universal exponents and the injection protocol. The model predicts that the effects of the fluid properties on the morphology of the formed network are different in the two similarity regimes. For example, increasing the injection rate with time, in the flow dominant regime, produces a smaller cluster of activated fractures than that formed by injecting the fluid at a constant rate. In the fluid loss dominated regime, however, ramping up the injection rate produces a larger cluster.