摘要

Huge amount of works have been done on wellbore modeling, but most of the researchers focused on saturated thermal fluid, with very little efforts on superheated multi-component thermal fluid (SMTF). In this paper, the authors presented a novel model for predicting thermophysical properties of SMTF in concentric dual-tubing wells (CDTW). Firstly, based on real gas state equation, a novel model comprised of mass, momentum and energy balance equation in the integral joint tubing (UT) and annuli was proposed for CDTW. Secondly, type curves of SMTF flow in CDTW were obtained from the mathematical model mainly by finite difference method and iteration technique. Finally, validation and sensitivity analysis of the model were sequentially conducted. The validation results showed that the predicted results were in agreement with field test results, which proved the correctness of the model. Type curves of SMTF flow in CDTW showed that the injection temperature difference between the UT and annuli has a strong influence on the profiles of temperature and superheat degree in each tubing. According to the sensitivity analysis of the model, the superheat degree in the UT decreases with the increase of injection pressure in the UT, but the superheat degree in annuli does the opposite. The superheat degree in the UT increases with the increase of injection pressure in annuli, but the superheat degree in annuli does the opposite. Both of the temperature and superheat degree in each tubing decreases with the increase of non-condensing gas content. This paper gives the engineers a novel insight into what is the distribution characteristics of thermophysical properties of SMTF in CDTW, and provides an optimization method of injection parameters for oilfield.