Enhanced Oil Recovery Methods

Abstract

Oil and natural gas remain the dominant components of the worldwide energy system. The International Energy Agency (IEA) predicts that global energy demand will increase by at least 30 % over the next 20 years. It is expected that 99.7 million barrels per day will be needed in 2035. Therefore, the world economy depends on the availability of oil and natural gas resources, advances in oil production technologies, the development of alternative energy sources, and the existence of reliable energy supply routes. At present, the average worldwide oil recovery factor after primary and secondary oil recovery is in the order of one third of the total original-oil-in-place depending on the reservoir characteristics; hence, significant amounts of oil are left in the formation. To achieve oil recovery factors higher than 30 % from mature reservoirs, it is necessary to implement enhanced oil recovery (EOR) processes. Consequently, EOR methods will become increasingly important in the future. This chapter presents a brief description of the most common EOR processes as well as information on recent developments and field applications.

The biopolymer produced by Rhizobium viscosum CECT 908 is a promising agent for application in microbial enhanced oil recovery

“…The results demonstrated that the R. viscosum biopolymer and xanthan gum were able to recover their properties immediately after being exposed to shear rates as high as 300 s −1 . These results are in good agreement with previous studies reporting that biopolymers are more stable to mechanical degradation due to shear stress under real injection conditions compared to synthetic polymers such as HPAM [13].…”

“…A shear-thinning behaviour favours (bio)polymer application in EOR, because during their injection in the oil reservoir, they undergo high shear rates (≥ 100 s −1 ) in the near-wellbore region, which results in low viscosity values, improving their injectivity and preventing damage to the oil formation. Once transported away from the near-wellbore region, the shear rate experienced by the (bio) polymer solution is lower (about 1 to 10 s −1 ), allowing the recovery of high viscosity values, required for a favourable mobility control and, consequently, an efficient oil displacement [9,13]. However, the high shear rates achieved during the injection of the (bio)polymer solution can result in the mechanical breakdown of the molecules due to the high shear stress values achieved [3,14].…”

“…Moreover, in some cases their application is limited by their instability at the oil reservoir conditions. For instance, the viscosity of HPAM solutions is considerably reduced at high salinities and temperatures, and high shear rates result in the degradation of the polymer [13,14]. Due to the high flexibility of HPAM chains in aqueous solutions, they begin to fold irreversibly, particularly at high temperatures and high salinities, resulting in a significant loss of viscosity [14].…”