氮气快速逐级返排解堵工艺研究与应用

Research and Application of Plugging Removal Technologyby Nitrogen Rapid Stepwise Flowback

在钻井、完井、修井过程中,由于泥质物及钻井液的混入,不可避免地造成储层污染,导致油井低液低效。油井解堵能够提高原油产量,并且保护油气储层。目前国内外的解堵技术为氮气泡沫、水射流和常规返排解堵,对于深井和低压井,三者解堵不彻底且费用昂贵。因此,以孤岛油田为例,借鉴气举排液理论,对解堵机理、返排管柱进行研究,通过测试调整气举阀开启压力,在返排施工管柱上布置多级气举阀,有效组合了气举阀和油管,提高返排压力。经过不等距布阀和氮气快速逐级返排工艺流程的优化,精细实施返排解堵,确保返排过程中逐渐降低井底压力,动液面持续下降,同时增加井底生产压差和解堵动力。返排过程中可以携带大密度的泥质物、高黏原油及高砂比流体,并获得流体性质、地层供液及产量、地层压力、出砂量等参数。该工艺不但可以为新井投产提供技术保障,还可以应用于低液井、大修井、补孔改层等老井。

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.Currently,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 continuous drop in dynamic fluid level,while also increasing the differential pressure at the bottomhole and the unplugging 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.