Abstract
Chemical flooding is known as one of the Enhanced Oil Recovery (cEOR) methodology to increase recoverable oil from the aging reservoirs, so that: several successful chemical injection projects were done worldwide for the past decade.
Previous studies in screening of EOR methods for the Sudanese oil fields show that Heglig Main oil field is suitable candidate for cEOR operation; the Stock Tank Original Oil in Place (STOOIP) for this field is about 577.95 MMSTB where only 22.2 % was produced through naturally depletion.
The objective of this research is to select the optimum pilot area and to design the cEOR pilot in Heglig Main oil field through a dynamic simulation modeling study; this model was constructed and run in advanced Thermal/Chemical simulation software. The scope of work of the pilot study is; a) to ascertain the alteration in oil saturation, injectivity, chemical absorption, and chemical breakthrough time for cEOR in this field, and b) to obtain pilot results in order to further refine to the cEOR full-field model.
The advantage of pilot model study is; reducing the cost by utilizations of existing wells and also minimizing the operating constraints by selecting the poor/medium performing wells.
According to the current study, a sector model with the well spacing of 200-350 m which is main factor for choosing the "pilot well area" could be properly implemented to check the flooding behavior, continuity, predict the production performance and incremental oil recovery, as well as to predict cEOR response and breakthrough time.
In this paper, pilot area as a sector model extracted from Heglig main field and a dynamic simulation model was constructed. Accordingly, seven (7) scenarios of 5-spot pattern were prepared and run in advanced Thermal/Chemical simulation software. Sensitivity analysis and optimization were also done to achieve the best scenario of the chemical flooding.
The results show that a combination of 0.4wt% of Alkaline, 0.1wt% of Surfactant, and 0.1wt% of Polymer in an ASP flooding process can increase the recovery factor of Heglig main up to 43.54%.