Analytical Study on Feasibility of Applying Vapor Extraction Method for Sudanese Heavy Oil Reservoir

Abstract

World’s conventional oil reservoirs are depleting on an alarming rate and alternative sources must be found to keep the supply undisturbed. Currently the best alternative is the heavy oil which can be extracted by applying techniques which are different from the conventional methods. Sudan have large amount of heavy oils which aren’t extracted yet, and need the applications of new technologies to be extracted. In this research reservoir and crude oil properties data has been collected and analyzed to study the feasibility of applying vapor extraction process (VAPEX) to Sudanese heavy oil field. In vapor extraction process a pair of horizontal wells will be drilled one on the top of the other, and vapor of light hydrocarbon solvent are to be injected into the upper horizontal well. The vapor diffuses into the heavy oil causing reductions in viscosity, and makes it easier for oil to flow by gravity to the lower horizontal well. This research attempts to provide some initial understanding and evaluation tool for the potential of applying VAPEX process in heavy Sudanese crude oil reservoirs. Based on the results obtained it could be possibly applied. Butler and Mokrys analytical model of VAPEX process had been applied in the area of study to predict the initial oil rate from VAPEX process. New technologies such as Cyclic Steam Stimulation (CSS) and Multifunctional Chemical Agent (MFCA) also had been applied before in the area of study. Then the results of VAPEX process had been compared with the previous results of new technologies (CSS and MFCA), the result obtained from the VAPEX process was promising from technical point of view. While from an economical point of view it should be taken into account that in the CSS and the MFCA implementation was on the existing wells no need for drilling new wells. Regarding the VAPEX process it need to drill a pair of horizontal wells or to drill horizontal well and convert vertical wells to injectors. So the additional cost should be taken into account. The Recovery factor of the field can be enhanced significantly by applying the VAPEX process technology compared with the other technologies which were already been applied. Finally the optimum pilot area for applying the VAPEX process was proposed according to the simulation results