A model for predicting thermophysical properties of water at supercritical state in offshore CDTW. (August 2018) - Sun, Fengrui
Highlights: A model is proposed for simulating supercritical water flow in wellbores. The wellbore structure is concentric structure. Effect of flowing seawater on SCW heat loss is considered. Type curves in wellbores are obtained with straight forward numerical method. Sensitivity analysis of various injection parameters are analyzed. Abstract: Thermal methods have been widely used for heavy oil recovery. In this paper, a mathematical model is proposed for estimating the key water properties in offshore concentric dual-tubing wells (OCDTW) at supercritical state. Firstly, based on the pipe flow theory, a governing model, comprised of the energy and momentum balance equations, is established for supercritical water (SCW) flow in the vertical tubes. Then, the effect of heat loss to seawater as well as formation is taken into consideration of the mathematical model. The thermophysical properties of SCW are calculated through interpolation method from the pressure-temperature based tables. Besides, the heat exchange between the the integral joint tubing (IJT) and annuli is also considered. Results show that: (a) Seawater and the thermal exchange inside the offshore wellbores are two main factors contributing to the profile change of thermophysical properties in IJT and annuli. (b) Different from the heat and mass transfer characteristics of wet steam flow in wellbore, SCW possesses some unique features. For instance, the pressure is not sensitive to temperature while the temperature is sensitive to heat loss.