Disscusion on double throttling process to prevent hydrate freeze plugging in Mahu oilfield

Objective For the special hydrate freeze plugging prevention and control problem of high gas-bearing oil wells in Mahu oilfield, a study on hydrate freeze plugging prevention, production regulation, the release of spray and unblock was conducted by using downhole and wellhead dual throttling nozzles.

Methods Based on PIPESIM software, the pressure and temperature of tubing and nozzle were calculated. The effects of downhole nozzle on hydrate freeze plugging in downhole tubing and wellhead tubing were studied. The effect of wellhead nozzle on production adjustment was studied.

Results The double throttle nozzle diameter polar difference has a direct impact on hydrate prevention and production adjustment. Increasing the double throttle nozzle diameter polar difference can significantly reduce the risk of hydrate occurrence, and reducing the double throttle nozzle polar difference can improve the production adjustment ability of the wellhead nozzle. The downhole nozzle can reduce the adverse impact of wellhead release unplugging on the reservoir.

Conclusions The field test results show that while the wellhead nozzle maintains the production regulation capacity, the downhole nozzle has the dual function of hydrate freeze plugging prevention and blowout unplugging, which improves the development efficiency of high gas-bearing wells in Mahu oilfield.