注氮气驱油技术在雷64-28-K22井的应用

雷64区块为巨厚块状稀油油藏,自2008年注水开发至今,地层亏空加大,含水上升速度较快且水窜严重,而通过水井停注或下调配注控制含水上升的效果并不明显。为此,针对水驱效果较差问题,开展了老井再利用注氮气气顶驱试验。研制了1种注氮气完井管柱。该管柱主要使用了Y521封隔器以满足井底注气压力较高的需求。管柱坐封后,在油套环空内灌清水至井口以下100 m左右,起到平衡封隔器下压差作用;此外,严格对老井进行套管试压及固井质量检查,尽可能避免试注过程中的安全隐患。现场应用结果表明,该管柱性能可靠,注氮气试验期间井口始终无刺漏,受效油井单井增油可达9 t/d,初步实现了稳油控水的目的,为后期注氮气驱试验及设计提供了可靠的依据。

Application of nitrogen displacement technique in Lei 64-28-K22 Well

Lei 64 Block is thick-layer massive thin-oil reservoir. Since water flooding development in 2008, it has been faced with increasing formation depletion, faster water cut rising rate and serious water channeling. Water injection well shutdown and injection allocation reduction are implemented to control the water-cut increase, but the effect is limited. Therefore, a nitrogen injection gas-cap drive experiment is implemented against the poor water flooding effect. The new developed nitrogen injection completion string mainly uses Y521 packer to meet the requirement for high bottom-hole injection pressure. After the packer setting of pipe string, clean water is injected through casing annulus up to 100 m below the wellhead to balance the differential pressure below the packer. Besides, the casing pressure test and cementing quality inspection on old wells were performed strictly to avoid the potential safety hazards in the injection process as far as possible. The field test shows that the pipe string has a stable performance during the nitrogen injection, with no leakage at wellhead. For the affected production wells, the single well gets an average daily increased oil production of 9t. This primarily achieves the goal of oil production stabilizing and water cut control, and provides guidance for future nitrogen injection tests and design.