Publications

Maximising the volume of oil recovered is a goal in the life cycle of an oil field. This, coupled with a move towards green applications has lead to renewed interest in Microbial Enhanced Oil Recovery (MEOR). This paper discusses a mathematical model built to replicate previously acquired experiment results from adding indigenous bacteria Bacillus sp. and Bacillus polymyxa to oil samples from X-Field in Indonesia. The experiment performed by Bitticaca (2009) was a cultivation of those bacteria adapted in a Stone Mineral Salt Solution (SMSS) with 0.01% (m/v) NPK + 20% (v/v) oil sample. The growth of bacteria was recorded every 24 hours for 7 days. The best inoculum ratio was found by looking at relationship between this ratio and physical characteristics of the oil, such as viscosity and interfacial tension (IFT). Alteration of these characteristics is due to biosurfactant production. Hence, bacteria growth and biosurfactant production were modeled by mathematical equations coupling logistics-growth and a modified predator-prey model. The equations were then solved using analytical and finite difference methods. Since every bacterium has its own special growth rate, carrying capacity, and toxicity constant, these equations are beneficial for the optimization of inoculum of Bacillus sp. and Bacillus polymyxa. The experiment revealed that a mixed culture of bacteria (1:1) performs better than synthetic surfactant. A simple equation was later numerically developed to predict the recovery factor due to MEOR and validated with Priharto’s laboratory data (2009) of bacterial coreflooding using an artificial sandstone core with 7 days incubation (shut-in period), 0.88 cc/minute injection, overburden pressure 100 psi, and 55 C temperature. Thus, this investigation contributes to knowledge about implementing eco-friendly Enhanced Oil Recovery via MEOR to mature sandstone-dominated reservoirs. Keywords: Microbial Enhanced Oil Recovery (MEOR), Biosurfactant, Sandstone Core, Mathematical Model