Study On Measure Methods And Applications Of Oil Gas Water Three-Phase Flow On Oil-Field Ground

Multiphase flow exists in various kinds of fields, such as petroleum, chemistry and metallurgy. And its parameter measurement plays an important role in resource exploration, production safety and industrial process control. A great deal of attention has been paid to this field, which has become a leading subject both home and abroad. Since multiphase flow is a complex process, it is quite difficult to measure its parameters. According to characteristics of multi-phase flow, the gas/liquid separating methods, flow rate measuring methods and water ration measuring methods are deeply investigated.Based on principle analyzing of gravity and ratation separating measure methods, the problems of low separating officiency and big volume on gravity separator and big pressure lose for big entry rate on circle cylinder separator are confirmed. Multi-cycle spiral tube gas liquid separating method is studied. The dynamic formula is derived. And the boundary conditions of gas liquid separating are given. The numerical simulation is done.A compound optimazation separator structure combined gravity with spiral centrifugal power is developed. The entire design rules and structure parameters calculating methods are given. The test separator is developed.The fuzzy-PID control system of separator's level is designed. The experiments show the performance of this separator is good. The separating efficiency is 2.5 times of that of same shape size gravity separator.Considering there are some liquid drops in gas phase. There are some problems for measuring wet gas flow with standard orifice plate, such as the rangeability being 3:1, big pressure loss and liquid aggregation near the upstream orifice plate. So, it is necessary to improve the structure of the standard orifice plate. A tapered tube variable area ring orifice device for wet gas measure is developed. It combines a tapered tube, an inner circle-shaped movable baffle, a precision spring and a displacement sensor. Flow equation is given, with distance displacement for pressure difference. The rangeability can be as large as 15:1 in the case that the area ratio of the variable flow path is designed to be 5:1. The hydromechanical numerical simulation results indicate that both speed field and pressure field inside the device are stable and the pressure loss is one-third of the standard orifice plate. Further, the problems of liquid aggregation and pressure ducts block are avoided..Considering there are still some bubbles in liquid phase,the measurement of liquid phase is still three phase measurement. The multi-sensor methods for three-phase measurement are well used. A method combined elbow tube and conductance sensor is developed. The measure models of flow rate, water ratio and gas ratio are given. Experiments show that the relative error of flow rate is less than 0.5%, the relative error of water ratio is less than 2.5%, the error of measuring gas ratio is less than 2%, on the conditions of flow rate range being 0.4-4m/s,gas volume ratio being 5%, water volume ratio being 50%-90%。Aiming at gas existing in liquid, capacitance and short wave methods for water content ratio measurement are studied. Based on uniformity model and H-B formula, the water content ratio measure formula of capacitance and short wave for oil gas water three phase flow is given. The influnces of temperature and mineralization is analysed. Aiming at temperature changing, the temperature equalized formula forγray water content meter is given. The experimental results accord with the theory conclusions.