Waterflooding Under Dynamic Induced Fractures: Reservoir Management and Optimization of Fractured Waterfloods

Abstract

It is well established within the Industry that water injection mostly takes place under induced fracturing conditions. Particularly in low-mobility reservoirs, large fractures may be induced during the field life. This paper presents a new modeling strategy that combines fluid-flow and fracture-growth (fully coupled) within the framework of an existing 'standard' reservoir simulator. We demonstrate the coupled simulator by applications to five-spot pattern flood models, addressing various aspects that often play an important role in waterfloods: shortcut of injector and producer, fracture containment, reservoir sweep. We also demonstrate that induced fracture dimensions can be very sensitive to typical reservoir engineering parameters, such as fluid mobility, mobility ratio, 3D saturation distribution (in particular, shockfront position), positions of wells (producers, injectors), and geological details (e.g. flow baffles). The results presented in this paper are expected to also apply to (part of) EOR operations (e.g. polymer flooding).

An Improved Embedded Discrete Fracture Model with Fracture Growth for Water-Induced Fracture Simulation in Low Permeability Reservoirs

“…However, because of the relatively low accuracy in traditional EDFM, a novel Boundary Element Method (BEM) model with higher early accuracy is used in our model to calculate the geometric factor instead of the average normal distance [30]. Equations (10) and (11) give the final expression.…”

“…(1) Firstly, assume that the fracture propagates in the direction of the maximum principal stress. The preprocessing program includes grid division and fracture division, Figure 1 shows the schematic of a grid-fracture system in which fractures are cut by grid boundary for BEM discussed in Equations ( 10) and (11). To simulate fracture propagation, a slight fracture is connected to the injection well to initialize the water-induced fracture as is shown in Figure 2(a).…”

“…de Souza et al [10] combined injection with fracture propagation pressure (IFPP) with a commercial reservoir simulator to evaluate the displacement efficiency of different vertical well patterns and horizontal well patterns; The Net Present Value (NPV) was also calculated considering different fracture behaviors to predict oilfield benefits. Besides, some scholars dealt with fracture propagation problems during the waterflooding process in a similar way, respectively [11][12][13]. In recent years, the discrete fracture model (DFM) was used to realize the dynamic changes of fractures [14,15] but was limited to the complexity of grid division.…”

Development theory and practice of water injection induced fractures in ultra-low permeability reservoirs

“…姜瑞忠 等 [34] 提出了两种动态裂缝模拟方法: 一是通过定义 油藏不同方向的渗透率级差来表征注水动态裂缝引 起的平面非均质性; 二是通过模拟裂缝的扩展来表 征方向性裂缝的特点. van den Hoek 等 [35] , Hustedt 等 [36] 通过评价裂缝尖端的应力强度因子, 判断不同时 间步诱导裂缝是处于静止, 闭合还是延伸状态, 实现 对裂缝的动态表征. 吴侃 [37] 基于对流体在裂缝中渗 流规律的分析, 建立了裂缝扩展模型, 模拟裂缝扩展 对注水开发采出程度的影响.…”

Integrated Approach to Managing Formation Damage in Waterflooding

“…The above requirements for fractured injection can be defined with modelling tools that simulate the induced fractures growth over time: "PWRI-FRAC" [5,6] and "FRAC-IT" [7,8].…”