Trial Research On Nozzle Adjustable Surface Jet Pump System For Water Injection

With the further development of offshore oil field,the oil production has entered the stage of water flooding,thereinto the energy consumption of the water injection system is huge,which accounts for the proportion of the total energy consumption of the offshore oil field up to 30%?40%.The offshore platform achieves water flooding development by an intensive way,multi water injection wells are injected by some single high-pressure water.The difference of formation properties of different injection wells leads to different injection pressure,the injection pressure of the rest of the wells must be reduced by valve throttle in order to ensure the injection of the highest pressure well.This kind of way is bound to cause a large number of energy consumption.A new idea is put forward to reduce the energy consumption of water injection by using the adjustable jet pump to replace the wellhead valve.A series of research work has been done for the adjustable jet pump.Both the research and application status of energy saving water injection and jet pump domestic and overseas were analyzed.The design theory of jet pump was introduced,and the water flooding situation of some a platform in Bohai was analyzed.The design index that the injection pressure arranges from 1.4MPa to 4.0MPa and the injection flow rate arranges from 500m3/d to 800m3/d was determined according to the characteristics of the platform.Then an adjustable jet pump was designed.After that the strength of the structure was analyzed to satisfy the demand of strength and the jet pump can be manufactured.Due to uncertainty of some structure dimensions,the CFD numerical simulation method of the adjustable jet pump for water injection was used to obtain the optimized structure dimensions,the nozzle-throat clearance Lc is equal to 19.5mm which is 1.50 times of the throat diameter,the throat length Lk is equal to 98mm.The simulation of water injection rate under 16 different degrees of opening was carried out,results show that the design of the adjustable jet pump can satisfy the demand of variable water injection pressure and variable water injection flow rate in the water injection platform.A whole structure dimension was determined according to the results of optimal simulation and strength check,and then an adjustable jet pump was manufactured.Subsequently an external characteristic experiment scheme was designed and the test bench was set up.The experiment results show that the design of the adjustable jet pump can almost satisfy the demand of variable water injection pressure and variable water injection flow rate in the water injection platform.The experimental results were used to modify the simulation value,and the modified q-h equation of the jet pump was obtained.The energy saving effect of the adjustable jet pump for water injection was briefly analyzed,which can save about 715,000 kw·h per year.Compared with the current water injection style at offshore platform,the jet pump water injection style has obvious energy saving effect.Finally,the energy saving water injection system based on adjustable jet pump was designed,and the working process of the system was briefly described.