Numerical evaluation on multiphase flow and heat transfer during thermal stimulation enhanced shale gas recovery

A fully coupled thermo-hydro-mechanical model in multiphase shale gas reservoirs is first developed and is then validated with analytical solutions and experimental result. Subsequently, the coupling responses are investigated to addressing mechanisms of gas recovery enhancement. Finally, a series of parameter sensitivity analyses are implemented to investigate the effect of parameters on gas recovery. The results indicate that gas production is strongly dependent on heating temperature, while the economic benefits should be evaluated further. The heating treatment for shale gas reservoirs not only rapidly desorbs the adsorbed gas, but also quickly evaporates the water in the pores within the shale, which removes the water lock effect and makes the desorbed gas produced smoothly. The parameters such as permeability, thermal conductivity, bottom-hole pressure, Langmuir volume, and entry capillary pressure also affect thermal recovery, which should be considered comprehensively to evaluate thermal recovery efficiency. Hydraulic fracturing enhances gas recovery at early-stage, and formation heat treatment can promote gas source supply at later-stage. Therefore, the combination of the two techniques can extend the life of shale gas wells and achieve effective and sustainable development of shale gas. © 2020 Elsevier Ltd