Research and Application of Plugging Removal Technology by Nitrogen Rapid Stepwise Flowback
During the drilling,completion,and workover processes,the inevitable introduction of clay materials and drilling fluids can lead to reservoir contamination,resulting in low fluid production and reduced efficiency in oil wells.Unplugging oil wells can enhance crude oil production while also protecting oil and gas reservoirs.Cur-rently,the main plugging removal technologies used both domestically and internationally include nitrogen foam,water jetting,and conventional flowback.However,these methods are often ineffective and costly for deep wells and low-pressure wells.Therefore,taking the Gudao Oilfield as an example,the plugging removal mechanism and flowback tubing were studied.By adjusting the opening pressure of gas lift valves and arranging multiple gas lift valves on the flowback tubing string,the gas-lift valves were effectively combined with the tubing,which increases the flowback pressure.Through optimizing the valve spacing and process flow,this technique allows for precise implementation of flowback to plugging removal,ensuring a gradual reduction in bottomhole pressure and a con-tinuous drop in dynamic fluid level,while also increasing the differential pressure at the bottomhole and the un-plugging power.During the flowback process,the technique can carry high-density clay materials,high-viscosity crude oil,and high-sand content fluids,providing valuable data on fluid properties,formation supply,production,formation pressure,and sand production.This not only provides technical support for the commissioning of new wells but can also be applied to low-fluid wells,major workovers,and other old wells requiring perforation layer changes.
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