裂缝水窜形成的剩余油研究

THE REMAINING OIL FORMED BY WATER BREAKTHROUGH IN FRACTURES

裂缝水窜在注水开发的火山岩、变质岩类块状裂缝型油藏中相当普遍,位于裂缝发育带附近的高产井,常常就是裂缝水窜最严重的井。裂缝性油田一个显著特点就是少数几口高产井控制着全油田多数的储量和产量,开发效果好坏决定全油田的开发成败。以克拉玛依及内蒙古注水开发的火山岩油田为例,研究发现,国内多个火山岩油田,存在相当数量快速水淹的高产井,当这些高产井水窜水淹以后,只要采取及时的停注强排措施,油井产能大部分就可顺利恢复。分析出现这种生产动态的原因,在于裂缝水窜水流形成连续相以后,运动粘度较低的水流形成“水锁”封闭流道中的可动油。据此提出了裂缝与大孔洞水窜机理以及水窜后的剩余油分布模式。

Water breakthrough in fractures is quite commom in igneous rock and metomorphic rock fractured reservoirs developped by water injection, the high yield wells lacated near fractures are, in general,the ones with most serious water breakthrough. The fractured reservoirs are characterized by several high yield wells which determin most of reserves and productivity in all the oilfield. Taking the igneous rock reservoirs in Kelamayi and inner Mongolia, which are developped by water flooding, as an example, research implies there are quite a few high yield wells in igneous rock and metemorphic rock reservoirs flooded by water quickly when the wells are flooded due to water breakthrough, if the measurement stopping water injection and forcing drainage is adapted, the output of the wells will recover a lot. The reason that the dynamic performance of production occurs is that after water breakthrough flow in fractures communicates, the flow with lower mobile viscosity forms 'water lock' to seal the mobile oil in channels. In the view of that, the mechanism of water breakthrough in fractures and vugs and the distribution model of remaining oil after water breakthrough are presented.