塔河缝洞型碳酸盐岩油藏因缝洞单元多,压力系统多以及渗流单元多,使得油水关系复杂,水体能量分布不平衡。针对封闭底水单缝单洞油藏弹性驱动单元油井开展在见水前出现水侵过程研究。封闭底水单缝单洞单元存在相连的水体,流体在溶孔中发生弹性膨胀,随着开采时间进行,开采过程因油藏压力衰减导致水侵是不可避免的,某个时期开始有水侵发生,基于缝洞型油藏特征,将侵入水简化为底水处理,继续发生弹性水驱以补充地层能量的亏空。根据泊稷叶定律公式揭示油井见水前溶洞压力、溶孔中累产油增量速率随时间都呈指数递减关系,早期递减快后期递减缓慢规律,并结合油藏工程改进的物质平衡方法计算出见水前弹性驱动时期水侵量。通过分析TH12523井为例,在弹性开采阶段发生水侵,弹性与水体共同驱动,整体开采过程实测累产油量增量速率、溶洞压力随时间变化结果与油藏动态预测结果一致。

As Tahe fractured-vuggy carbonate reservoir has many fractured-vuggy units, pressure systems and seepage units, its oil-water relation is complex and the water body energy distribution is unbalanced. Therefore, studies on the water intrusion process before water seepage is conducted for the elastic drive unit oil wells in single fracture and single hole reservoir with closed bottom water. There exists a connected water body. The fluid expands elastically in the dissolved hole. As time goes on, the water intrusion is inevitable due to the pressure decay of the reservoir during the mining process and begins at some point. Based on the characteristics of the fracture-cavity reservoir, the intrusion water is considered as the bottom water, and the elastic water flooding continues to supply the insufficient of the formation energy. According to the Poiseuille’s equation, the pressure of the karst cave before water breakthrough and the incremental rate of the cumulative oil production in the dissolved pores both decrease exponentially with time, following the rules of rapid in the early stage and slow down in the later stage. Meanwhile, combining the improved material balance method of reservoir engineering to calculate the water influx during the elastic driving period before water breakthrough. Taking well-TH12523 as an example, water intrusion occurs during its elastic mining stage, and the elasticity and the water body drive together. The actual measured incremental rate of the measured oil production and the karst pressure varied with in the whole mining process are consistent with the dynamic prediction results of the reservoir .