Abstract
Mathematical programs to simulate two-phase flow in wellbores have been developed for water and/or water-carbon dioxide mixtures. “Bubble rise velocities” in the slug flow regime are estimated using three methods: Orkiszewski (1967), Nicklin et al. (1962) and a modified Nicklin method. The modified Nicklin method uses ∧= 0.1 instead of ∧= 0.2 as in the Nicklin method. A package has been developed to estimate the phase behaviors of the water-carbon dioxide system. The three methods are evaluated by comparing calculated results with measured data from a Japanese geothermal field. Good results are obtained at moderate to large production rates, however there are some differences between the predicted and actual data at low rates. The average absolute deviation of percentage errors between predicted pressure losses and the field data is 6.21, with standard deviation of 5.72, excluding the low rate cases. The simulation program can estimate the following variables: pressure, temperature, specific enthalpy, flashing point, flow regime, carbon dioxide solubility in water, and can give phase diagrams of the water-carbon dioxide system, which includes the carbon dioxide content of the water and gas phases, and the quality of the gas phase.
