Research And Application Of Gas Lift Production And Supporting Tools For Complex Structure Wells In Oilfield A

Oilfield A is an integrated oilfield invested by CNPC and operated by buying oil to recover investment.The oilfield is a large carbonate reservoir in the Middle East.Under the circumstances of political turmoil and high security risks,the oilfield is in urgent need of large-scale rapid production and recovery of investment.At present,continuous gas lift is the main replacement lifting method in the oil field.The main technical problems in production process include:(1)The well structure is complex and the output fluid has high asphaltene content with strong corrosiveness;(2)The production in the single well is high,and there is no matching gas lift tool in China.In order to promote the large-scale application of continuous gas lift technology in oilfield A,it is urgent to carry out the optimization design research of continuous gas lift and the development of matching tools.Considering the gas injection and lifting process of continuous gas lift wells,the calculation method of annular gas injection pressure and the calculation method of wellbore temperature and pressure were established respectively.On this basis,the design method of continuous gas-lift pressure reduction is optimized.Taking vertical wells and horizontal wells in target oilfields as examples,sensitivity analysis of tubing size,gas injection pressure,gas injection depth,water cut and wellhead pressure is carried out,and dynamic analysis and optimization design of continuous gas lift wells are realized.A method for calculating the radius of curvature of wellbore and the allowable maximum length of tool is deduced for complex structure wells.As a guide,the large-scale gas lift tool and the supporting wire fishing tool are developed.A gas-lifting completion string that integrates various functions such as gas lift production,chemical injection,well washing and no-pressure well is formed.At present,the technology has successfully applied in 54 wells in oilfield A,the construction success rate is 100%,and the commissioning success rate is 100%.The initial production stage is stable,which lays a foundation for the large-scale promotion of the continuous gas lift process in oilfield A.