Multi-Physics Simulation of Tar-Rich Coal In Situ Pyrolysis with a Multiregion Homogenization Treatment

The macroscopic multi-physics simulation of tar-rich coal in situ pyrolysis (TCISP) is conducted, in the fractured porous zone, by coupling heat transfer, fluid flow, and chemical reaction. A novel TCISP pattern of gas injection between fractured zones is proposed by treating the fractured porous zone as a homogeneous porosity gradient descending region. In this case, nearly 11,500 kg of oil can be produced within 6 months from a 10*10*1 m³ area. The influence of the fractured zone and porosity are investigated. The results indicated that gas injection between fractured zones is more conducive to rapid production, compared with the traditional case where the gas injection is in the center. The temperature field is more uniform, which is conducive to maintaining the same reaction conditions and producing appropriate products. Inlet velocity has a positive effect on the increase of heat transfer rate but has a negative effect on heat transfer uniformity. There is an optimal inlet temperature of 973 K for the fastest heating rate. With the increase in temperature, the heat transfer uniformity gets worse. Increasing the height of the fractured zone is beneficial for the heating rate and heat transfer uniformity.