The invention discloses a method for accurately metering oil input of an
oil field united
station, which is used for the metering of
crude oil of the
oil field united
station. In the method, a
differential pressure method is adopted, the temperature of a
pressure pipe is kept equal to that of a
sedimentation tank by arranging the
pressure pipe inside and outside the tank, and all absolute oil and all water in an entire
oil tank are considered as two wholes; a liquid level is supposed to be constant, only the variation of the absolute oil in the
sedimentation tank is measured by using a dehydrator
differential pressure metering device without measurement of the total amount of oil and water in the
sedimentation tank. The method consists of a sedimentation tank
differential pressure metering method, a
buffer tank differential pressure metering method and a dehydrator differential pressure metering method or consists of a sedimentation tank differential pressure method, a
buffer tank differential pressure method and a dehydrator differential pressure method and is implemented through a sedimentation tank differential pressure method device, a
buffer tank differential pressure method device and a dehydrator differential pressure method device. The device consists of a differential
pressure sensor, a
pressure pipe, a liquid level meter, a computer, a multidirectional pressure valve, a multidirectional pressure
valve seat and a multidirectional pressure valve faucet, wherein the differential
pressure sensor is connected with the pressure
pipe through a
screw thread; the multidirectional pressure valve is connected with the pressure
pipe through a
screw thread; and the multidirectional pressure
valve seat is in tolerance fit with the multidirectional pressure valve faucet. The method solves the problems of high labor intensity and big metering error existing in a conventional method and can be widely applied to
crude oil metering operation of the
oil field united
station.