Development of a multiphase flow metering system, that measures unseparated oil, gas and water flow rates, is one of the key technologies to improve subsea production. The application of a multiphase metering system benefits subsea oil and gas production. Japan National Oil Corporation (JNOC), Yokogawa Electric Corporation, NKK Corporation, Japan Petroleum Exploration Corporation Ltd. and Teikoku Oil Company Ltd. launched a joint project in April 1995 to develop a multiphase flowmeter.

We are developing a multiphase flowmeter, that is safe for both the personnel and the environment, because there is no use of a radioactive source. And it has no moving parts in order to meet the requirement of easy maintenance. The flowmeter consists of two impedance component fraction sensors, venturi-meter and cross-correlation technique with two component fraction sensors.

The performance of this meter was evaluated in both 2[inch] and 4[inch] multiphase flow test loop using lubricant oil or kerosine, tap water, and air or nitrogen as test fluids. Three-phase flow tests were carried out in mixing velocity 3[m/s] with 0.5[MPa] line pressure. The tests for two-phase flow with 0.5[MPa] and 2[MPa] were carried out. Most of the test results show that the total multiphase flow rate error (TM error : specified uncertainty of one phase / multiphase flow rate) of kerosine and water phase are within +/-10[%]. However nitrogen flow rate was under estimated.

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