深海浊积砂岩油田高效注水策略及实践

以尼日尔三角洲盆地典型的深海浊积砂岩油田AKPO为研究目标，剖析了浊积水道和朵叶的储层特征，以注采井组间砂体连通方式为基础，结合生产动态特征评价了注采井组间的连通性，确定油田在无水采油期的注水策略。基于时移地震揭示了不同储层类型的水驱波及特征，形成了油田注水突破后的注水以及控堵水策略，建立了适宜油田不同开发阶段的高效注水策略。在无水采油期阶段，基于注采井组间砂体的连通方式应用以“控制压力”为重点的注水强度优化策略，实现不同井组的分级配产配注；在中低含水阶段，基于储层沉积类型应用以“提高波及”为重点的注水强度优化方法，即依靠水动力学方法来改善水驱波及系数，水道储层注采井组采用周期注水提高“纵向”波及系数；朵叶储层注采井组采用改变液流方向提高“平面”波及系数；在高含水阶段，应用适宜深海油田的“低成本”分段控堵水方法，实现深海油田经济有效的控堵水。上述深海浊积砂岩油田高效注水策略经AKPO油田实践，实现AKPO油田高峰采油速度达到5.5%，连续7 a实现稳产，预测油田采收率达到53%。系统形成深海浊积砂岩油田在不同开发阶段的高效注水策略，该策略简单易行、经济有效，可以指导同类深海油田的注水优化。

Strategy and Practice of High Efficient Water Injection in Deep Sea Turbidite Sandstone Oilfield

The reservoir characteristics of turbidite channel and lobe in AKPO Oilfield, a deep-sea turbidite sandstone oilfield in the Niger Delta Basin, are analyzed. It also evaluates its dynamic production behavior based on the connectivity of sand bodies between injectors and producers to determine the water injection strategy during the zero water-cut production period. Based on time-lapse seismic imaging, after-breakthrough water control and plugging strategies are established from the flooding characteristics of different reservoir types. Thus, efficient water-flooding strategies at different production stages are constructed. In the zero water-cut production stage, the optimized water injection strategy focusing on controlling pressure is applied based on the connectivity of sand bodies between injector and producers. In the low and medium water-cut production stage, the water injection scheme focuses on increasing sweep efficiency based on sedimentation type. Therefore, hydro-dynamic method is implemented to improve the water-flooding sweep coefficient. Periodic injection scheme is applied for injector-producer well groups in the channel reservoir to increase the vertical sweep coefficient and the areal sweep coefficient for injector-producer well groups in the lobe reservoir is enhanced by changing the fluid flowing direction. In the high water cut production stage, "low-cost" sectional water control and plugging technique suitable for deep sea oilfield is applied to achieve economic and effective production development. Through the practice in the AKPO Oilfield, high efficient water injection strategy has achieved in the deep-sea turbidite sandstone oilfield. The stable production has continued for 7 consecutive years with a peak oil recovery rate at 5.5% and ultimate oil recovery rate at 53%. This water injection optimization strategy has worked well in the AKPO Oilfield and can be implemented to similar deep sea oil fields, which is convenient, economic and effective.