The heat and mass transfer characteristics of superheated steam coupled with non-condensing gases in horizontal wells with multi-point injection technique

In this paper, a series of works are conducted to study the heat and mass transfer characteristics of superheated steam & non-condensing gases (SNG) flow in horizontal wellbores with multi-point injection technique. Firstly, the energy and momentum balance equations of SNG flow in both of the inner tubing (IT) and annuli are established. Then, coupled with the S-R-I( real gas model and formation heat transfer model, a comprehensive model is established. The model is solved with finite difference method on space and the predicted results are compared against field data and previous models. The results show that: (a). The model is applicable to wide ranges of SNG pressure, temperature and mass friction of non-condensing gases. (b). Formation heat absorption rate can be monitored or adjusted at heel or toe point. Uniform steam absorption can be achieved when proper injection pressure at heel point is selected. (c). The mass friction of non-condensing gases is a double-edged sword. The advantage of increasing of formation SNG absorption rate can be offset by the decrease of SNG enthalpy. Laboratory test should be conducted to investigate the oil displacement mechanisms of non-condensing gases or superheated steam before selecting the mass friction for each component. (C) 2017 Elsevier Ltd. All rights reserved.