Perpustakaan Digital ITB

A Toe-to-Heel Air Injection (abbreviated as THAI) process is regarded as a promising method in heavy oil and extra heavy oil recovery. Numerical simulations, together with laboratory experiments, were employed to investigate coke zone evolution. The time window of interest focuses on the interval from the commencement of oil production to that of air breakthrough. The simulation results show good history match in local temperature profile, cumulative oil production and produced gas concentration. For the purpose of quantitative assessment, new parameters named coke volumetric sweep efficiency (Esw) and volumetric expansion speed (Ssw) are proposed. Coke zone was first generated around the ignitor and then propagated forward and upward due to the effects of gravity drainage and displacement. The gravity effect makes a major contribution to sustaining a stable state especially in the early to middle term of the THAI process, which is also identified with the generation of a significant faster increase of Ssw. An evenly developed of coke zone with oval shape both in thickness and concentration is also accounted in this period (4 h ? t ? 9 h). Then changes occur in coke zone with stronger heterogeneity, and the peak value of Ssw occurring at the 9th hour generally infers the maximum oil drainage effect. When the Ssw decreases to around 0.02, an unstable combustion state happens. The characterization method of the coke zone construction proposed in this work and the combination of simulating tools such as CMG software can be beneficial in guiding the future work of ISC.