Assessment of Imperfect Heater Contact due to in-situ Pyrolysis of Oil Shale

Oil shale, known as one of the unconventional oil sources, has world reserve of an equivalent to 3.2 trillion barrels of crude oil. Oil shale is a kerogen rich fine sedimentary rock which can be converted into crude oil via a heating process called as pyrolysis. In in-situ pyrolysis of oil shale, a resistive electric heater is installed in a wellbore and it is known as heater-well system. The heating element itself does not actually touches the wellbore which creates imperfect heater contact. In this project, the imperfectness of heater contact will be quantified and an assessment on the effect of air gap on in-situ pyrolysis of oil shale in between the electric heater and wellbore will be done. In that, the thickness of air gap in the heater-well system will be identified and the heat transmission performance between a perfect heater and an imperfect heater contact will be analysed through simulation. In this simulation, Green River Formation oil shale will be heated up to conversion temperature of 3200C and above. The amount of oil shale converted will be compared for both perfect and imperfect heater contact by interpreting the temperature profile obtained from the simulation. The targeted oil shale layer will be in between 281 meters to 540 meters in depth with the starting temperature of 250C. At the same time, parameters that affects the heating process and its weight as well as sensitivity will be identified. Based on the result of this project, the air gap does affect the performance of in-situ pyrolysis of oil shale. It is observed that the thicker the air gap the lesser the oil shale converted. Furthermore, the present study also identifies that the input temperature of heater and the duration of heating are the most influential factors on distance of oil shale converted due to in-situ pyrolysis. The quality of oil shale and the initial temperature of air gap which have also been investigated has negligible effect on this study