INFLUENCE OF METHANE ON THE PHASE-BEHAVIOR OF OIL PLUS WATER PLUS NONIONIC SURFACTANT SYSTEMS

The phase behavior of oil + water + nonionic surfactant systems has be en thoroughly studied. The oil had been commonly represented by a sing le long-chain hydrocarbon. In this work, the influence of methane on t he phase behavior of the system decane + water + 2-butoxyethanol is pr esented. Mixtures of methane and decane describe the oil. The methane concentrations in the oil mixture were 0, 5, and 10 wt % (respectively 0, 30, and 50 mol %). The investigated temperature range was from 278 to 365 K, and the studied pressure range was from 10 to 100 MPa. Ln t he temperature, pressure, and methane concentration range investigated in this work, the phase transition with increasing pressure at a cons tant temperature was always found to be (2) over bar-->3-->(2) under b ar. For the systems containing 10 wt % methane in the oil mixture the formation of gas hydrates could be observed for low surfactant concent rations and low temperatures.