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.