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 stud

Subsonic Euler flows in a three-dimensional finitely long cylinder with arbitrary cross section

This paper concerns the well-posedness of subsonic flows in a three-dimensional finitely long cylinder with arbitrary cross section. We establish the existence and uniqueness of subsonic flows in the Sobolev space by prescribing the normal component of the momentum, the vorticity, the entropy, the Bernoulli's quantity at the entrance and the normal component of the momentum at the exit. One of the key points in the analysis is to utilize the deformation-curl decomposition for the steady Euler system introduced in \cite{WX19} to deal with the hyperbolic and elliptic modes. Another one is to employ the separation of variables to improve the regularity of solutions to a deformation-curl system near the intersection between the entrance and exit with the cylinder wall

Stimulated Raman scattering in a non-eigenmode regime

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density 0.25nc when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency, which is no longer the eigenmode of electron plasma wave. Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than