Optimization of Carbonate Heavy Oil Reservoir Development Using Surfactant Flooding: from Laboratory Screening to Pilot Test

Abstract

Bashkirian reservoir is a heavy oil fractured carbonate reservoir. It has a low temperature (23 ℃) and an ultra-high salinity (217.5 g/L). The low injectivity is the main problem that limits the efficient development of this reservoir. Hot water injection has been tried to solve this problem, but it did not work. The purpose of this work is to find an effective surfactant system for high salinity condition to increase the injectivity during water flooding. This paper presents the whole process from laboratory screening and numerical simulation to pilot test. In laboratory, ten surfactants were evaluated by measuring interfacial tension (IFT) and wettability change. For each surfactant, three concentrations were studied to obtain the optimal surfactant formulation. The optimal surfactants were used for filtration experiments to evaluate the effect of surfactant on the injectivity and oil displacement efficiency. The effect of the best surfactant was assessed by reservoir numerical simulation at the field scale. Eventually, the pilot test was implemented to test the effectiveness of surfactant injection. According to the ability to reduce IFT and change the wettability, oil displacement efficiency, the capacity of reducing injectivity, and production performance, as well as considering the cost and accessibility of surfactant, one nonionic surfactant was eventually chosen for pilot test in the oilfield. The pilot test results show that this nonionic surfactant shows a very good effect on improving water injectivity. After the injection of surfactant, the wellhead pressure and downhole pressure were reduced from 40 at and 171.5 at to 24 at and 153.4 at), respectively. Surfactant injection increased additional oil production of about 1094 tones. The good effect of this nonionic surfactant showed in pilot test makes it a good candidate for wide application under high salinity condition to improve well injectivity as well as oil displacement efficiency in the case of complex heavy oil carbonate deposits.

Screening of Surfactants for Flooding at High-Mineralization Conditions: Two Production Zones of Carbonate Reservoir

“…An example of wettability measurement photos is shown in Figure 5. down to values of 10 −2 mN/m, as in previous works for reservoirs with similar conditions [30,31].…”

“…The results show the dependence of the viscosity and density of oil from different horizons on the IFT value: most of the values for (B) turned out to be lower, except for Composition-2, where the difference in the IFT value is insignificant for both production zones. Comparing the obtained results of IFT values with other works, it can be concluded that the selected surfactants are able to reduce IFT effectively down to values of 10 −2 mN/m, as in previous works for reservoirs with similar conditions [30,31].…”

“…Energies 2021, 14, x FOR PEER REVIEW 8 of 15 down to values of 10 −2 mN/m, as in previous works for reservoirs with similar conditions [30,31].…”

Novel Nonylphenol Polyethoxylated Based Surfactants for Enhanced Oil Recovery for High-Mineralization Carbonate Reservoir

“…Additionally, it was observed that wettability alteration from oil-wet/mixed-wet to water-wet becomes more difficult in very high salinity and vice versa [15]. Some laboratory screening and field applications of surfactants for carbonate reservoirs with high salinity water were conducted [16][17][18]. Many types of surfactants were reported, Energies 2022, 15, 961 2 of 14 including anionic, cationic, and nonionic [19,20], as well as newly created ionic-nonionic, such as guerbet alkoxy carboxylate surfactant [21][22][23].…”