Research On High Efficiency Water Injection Technology In Chengdao Oilfield

By investigating the status of water injection in Chengdao oilfield,the efficiency of water injection system,the physical property of reinjection water,separate injection and testadjustment technology is analyzed.Some effective measures are proposed to deal with the problems existed in these links.The guantao formation in Chengdao oilfield is developed by two or three sets of laminar systems,which is mainly based on five-point method and supplemented by four-point method or edge-water injection.Overall the efficiency of water flooding is high and the good adaptability is in the layers.The layer segmentation meets the needs of reservoir development.But there are many problems increasing such as the low qualification rate of water injection layers,the increase of the casing damage well and the deposit corrosion of the oil pipe.The applicability of sewage treatment system of offshore central platform is poor and the processing efficiency cannot meet the design requirements,so that the injected water quality is not up to standard.Meanwhile the long water injection pipe network and the unreasonable configuration results in the low network efficiency.The network efficiency increased by 13.11% while several measures have been taken: optimizing the water injection pipe and the water distribution and improving the water injection system capacity of each central platform through modeling the water injection system efficiency and integrating the motor efficiency,water pump efficiency,network efficiency and the efficiency of other important nodes considering the casing damage,friction and other factors.The water quality is mainly affected by the non-standard offshore wastewater treatment system and polluted along the path.As a result,the injected water quality is not up to standard.The corrosion and scaling characteristics of injection water were evaluated,and the corrosion rate of reinjection water was up to standard,but the scaling trend was obvious.The core damage test showed that the reinjection water was sensitive to low velocity and medium intensity.The qualified water quality is ensured by improving the sewage treatment system on central platform and the water source quality,optimizing the operation of the sewage treatment system and upgrading the water criteria.Through analyzing the technical status of tubing string and water injection tool in injection well,the packer is invalid by the influence of the tubing string peristalsis and water injection string is invalid by the influence of packer leakage,water nozzle failure,backwash valve leakage and the string perforation.Aiming at these problems of the tubing string and tool and integration technology of test and adjustment,some technical and improvement measures are proposed and achieve a good application effect.