Recently, a new type of carbonate reservoir, the fault-karst carbonate reservoir has attracted lots of attention, which usually develops large-scale karst caves, vugs, and high-angle fractures along the strike-slip fault zones. Despite containing plenty of hydrocarbon resources, the complex geological structure and the strong heterogeneity make it difficult to develop this kind of reservoir effectively and economically. To perform water-drive experiments and investigate the production performance under different well patterns and injection-production modes, two 2D visualized physical models were designed and fabricated based on the typical geological structures of the fault-karst carbonate reservoir in the vertical and horizontal directions, respectively. According to the experimental results, the average oil recovery can reach 62.96% for the vertical model and 58.18% for the horizontal model. In fact, gravity effect due to density differences can greatly improve the displacement efficiency of oil by water in the vertical direction; hence, the horizontal heterogeneity would have a relatively greater impact on waterflooding development. When water is injected into the reservoir from the middle section, a large amount of un-swept oil will remain at the bottom fractures. Thus, the Bottom Injection & Top Production (BI & TP) mode should be adopted in all well patterns to increase recovery. If non-inverted well patterns are employed, dominant water channeling would form quickly in the horizontal direction, and the swept area will be hugely limited. Therefore, the Center Injection & Edge Production mode (inverted well patterns) is recommended for water-drive applications. It is also found that the water breakthrough time negatively correlates with the effective flooding time for the vertical model and the total oil recovery is more impacted by water breakthrough for both models. Additionally, the oil-water exchange ratio is introduced to evaluate the utilization efficiency of injected water. Calculation results have shown that the BI & TP mode is optimal in terms of either total recovery or oil-water exchange ratio in the vertical direction, but the well pattern layout in the horizontal direction could impact the oil recovery and oil-water exchange ratio, which, in turn, affect the project economics. This study provides novel insights for optimizing well patterns and waterflooding measures in actual fault-karst carbonate reservoirs.

近年来，一种新型碳酸盐岩储层——断层—岩溶碳酸盐岩储层备受关注，其沿走滑断裂带通常发育大型溶洞、孔洞和高角度裂缝。尽管油气资源丰富，但地质构造复杂、非均质性强，难以有效、经济地开发该类储层。为开展水驱试验，研究不同井网和注采方式下的生产动态，基于断层岩溶碳酸盐岩储层垂直和水平方向的典型地质结构，设计制作了两个二维可视化物理模型，分别。根据实验结果，平均采油率可达62。垂直模型为 96%，水平模型为 58.18%。事实上，由于密度差异产生的重力效应，可以大大提高水在垂直方向上的驱油效率；因此，横向异质性对注水开发的影响相对较大。当从中段向储层注水时，大量未波及的油会留在底部裂缝中。因此，所有井网都应采用底注顶采（BI&TP）模式，以提高采收率。如果采用不倒转井网，将在水平方向迅速形成优势水窜，波及面积将受到极大限制。因此，中心注射& 建议在水驱应用中使用边缘生产模式（倒置井网）。还发现，垂直模型的水突破时间与有效驱油时间呈负相关，两种模型的总采收率受水突破的影响更大。此外，还引入了油水交换率来评价注入水的利用效率。计算结果表明，无论是总采收率还是垂向油水交换率，BI&TP模式均最优，但水平方向井网布局会影响采收率和油水交换率，这反过来又会影响项目的经济性。