Numerical simulation of reaction under high pressure conditions for thermal spallation drilling

Abstract

Thermal spallation technology is a drilling method, which is potentially suitable for the exploitation of petroleum in hard rocks with low costs. In this paper, characteristics of reaction are investigated under relatively high pressure in thermal spallation drilling. The Peng-Robinson equation of state and eddy dissipation model are applied in the simulation. Effects of methane and oxygen flow rate, nitrogen fraction on the flow field are studied. Simulation results are validated in experiments that monitor the temperature of the flame jet using thermocouples. Results show that besides a portion of oxygen reacting with the methane, the left oxygen mainly flows towards the boundary of the reactor. The reaction between methane and oxygen mainly occurs at the central part of the reactor. Also, the temperature close to the wall of the reactor is only 1300 K, which can help to protect the reactor wall from damage due to high temperature. Increasing the methane flow rate within a certain range can help to obtain high temperature and high jet velocity simultaneously. Also, injecting mixture of oxygen and nitrogen can prevent too much excessive oxygen from existing in the wellbore during thermal spallation drilling. Results in this paper could provide guidance for field applications.