Current Status of Research and Performance Analysis of Depressure Tools for Jet Pump

According to the experience of oil/gas drilling,ROP in well drilling can be improved significantly when the bottom hole pressure drops,chip hold down effect of cuttings was reduced,and under balanced condition was achieved.This paper summarized the structure features,depressurization capacities,and the current status of researching and developping jet pump,jet pump joint and jet pump bit based on the depressure principle of jet pump.The key factors that affect the depressurization capacity were analyzed.Annulus jet pump is actuated by a jet pump.It can reduce the equivalent circulation density about 0.16-0.52 kg/L.The depressure ability of the jet pump joint is lower than that of jet pump,and there is almost no pressure drop when the outlet of the jet pump is two meters off the bottom hole two meters.The clearance between bit and borehole wall is critical to the depressure ability of the jet pump bit.When the bit clearance is 1 mm,about 1.86 MPa is reduced;however,when the bit clearance is increased to more than 3 mm,the pressure is almost unchangeable.The results can provide the theoretical guidance for the development of the jet pump depressure tools.