Adiabatic behavior of gas wells due to natural reservoir fines migration: analytical model and CFD study

The adiabatic behavior of natural gas production well is frequently neglected in the reservoir formation damage study. The temperature of surrounding formation contributes to the smooth flow of natural gas in the wellbore. The heat transfer from the formation and geothermal gradient plays vital role in the efficient transport of gas in the subsurface formation and wellbore. But, fine particles which are attached to the rock surface migrate and are trapped in the pore throats, and as a result, there is deterioration in the permeability. The detachment of fines occurs due to high reservoir temperature and gas internal energy and temperature. Therefore, this paper conducts theoretical and numerical investigations on the adiabatic behavior of natural gas production well due to in situ reservoir fines migration. Firstly, an analytical model is developed and then, numerical models were constructed using CFD simulation tool to study the adiabatic nature of a gas well. A total of 24 cases were run in simulation, and input temperatures such as 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C were given for modeling. The results revealed that there was no sign of heat transfer from the wellbore to the surroundings. There was a heat circulation only within the wellbore. During the adiabatic state, the pressure in the central zone of the gas well is moderate, but rises linearly on the radial sides.