Type curve analysis of multi-phase flow of multi-component thermal fluid in toe-point injection horizontal wells considering phase change

Huge amount of works were done on modeling of wet steam flow in the conventional heel-point injection horizontal wellbores. With the rapid development of technology, new technology of superheated steam - non-condensing gases (SNG) injection coupled with toe-point injection wellbores was adopted in oil field. In this paper, a series of works were done on modeling of SNG flow in a horizontal wellbore with toe-point injection technique. The two-phase flow model was embedded in this SNG model for describing the phase change phenomenon. Firstly, a hydraulics model comprised of mass, momentum and energy conservation equations was developed. Then, coupled with the seepage model in oil layer, a wellbore/formation coupled model was established. Thirdly, straight forward numerical method was adopted to solve the model. Finally, model verification and sensitivity analysis were conducted sequentially. Results show that: (1) The SNG temperature in annuli has an increase at the heel-point due to heat conduction from IT to annuli. (2) When the mass injection rate is kept unchanged, the SNG temperature at a certain place in annuli decreases with increasing of the mass content of non-condensing gases. (3) The SNG in IT undergoes phase change into saturated state at the distance of 150 m. Then, from the distance of 150 m-200 m, the gas content in the mixture system gets an increase and the superheat degree is equal to zero. (4) Phase change occurs again in annuli when the SNG reaches the distance of 110 m where the wet fluid turns into superheated state, after which the superheated degree of SNG increases continuously as SNG is flowing to the heel-point.