Injection of alkaline (A), polymer (P), and surfactant (S) chemicals in enhanced oil recovery (cEOR) processes increases output by changing the properties of the injected fluid. In this work, micellar fluid interactions were studied via microemulsion rheological analysis. Crude oil and stimulated brine with ASP or SP was used for bottle testing. The results revealed that no microemulsion was produced when ASP (Alkaline, Surfactant, and Polymer) or SP (Surfactant and Polymer) was left out during the bottle testing phase. The addition of ASP and SP led to the formation of microemulsions—up to 29% for 50% water cut (WC) ASP, and 36% for 40% WC SP. This shows that the addition of ASP and SP can be applied to flooding applications. The results of the rheological analysis show that the microemulsions behaved as a shear-thinning micellar fluid by decreasing viscosity with increase in shear rate. As per the power-law equation, the ASP micellar fluid viscoelastic behavior shows better shear-thinning compared to SP, suggesting more efficiency in fluid mobility and sweep efficiency. Most of the microemulsions exhibited viscoelastic fluid behavior (G’ = G”) at angular frequency of 10 to 60 rad s⁻¹, and stable elastic fluid behavior (G’ > G’’) below 10 rad s⁻¹ angular frequency. The viscosity of microemulsion fluids decreases as temperature increases; this indicates that the crude oil (i.e., alkanes) was solubilized in core micelles, leading to radial growth in the cylindrical part of the wormlike micelles, and resulting in a drop in end-cap energy and micelle length. No significant difference was found in the analysis of viscoelasticity evaluation and viscosity analysis for both ASP and SP microemulsions. The microemulsion tendency test and rheology test show that the addition of ASP and SP in the oil-water interface yields excellent viscoelastic properties.

Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new CI molecules focusing on their application condition as a prediction or screening process before the physical empirical assessment. In this work, the adsorption inhibition efficiencies of two monomer surfactants (2B and H) and their respective Gemini structures with the addition of different spacers (alkyl, benzene, ester, ether, and ketone) are investigated using DFT calculation and MD simulation method in 3% sodium chloride (NaCl), and 1500 ppm acetic acid solutions. In DFT calculation, 2B-benzene molecules are assumed to have the most promising inhibition efficiency based on their high reactivity and electron-donating ability at their electron-rich benzene ring region based on the lowest bandgap energy (0.765 eV) and highest HOMO energy value (−2.879 eV), respectively. DFT calculation results correlate with the adsorption energy calculated from MD simulation, where 2B-benzene is also assumed to work better as a CI molecule with the most adsorption strength towards Fe (110) metal with the highest negative adsorption energy value (−1837.33 kJ/mol at temperature 323 K). Further, diffusion coefficient and molecular aggregation analysis in different CI concentrations through MD simulation reveals that only a small amount of Gemini surfactant CI is needed in the inhibition application compared to its respective monomer. Computer simulation methods successfully predict and screen the Gemini surfactant CI molecules that can work better as a corrosion inhibitor in acetic acid media. The amount of Gemini surfactant CI that needs to be used is also predicted. The future planning or way forward from this study will be the development of the most promising Gemini surfactant CI based on the results from DFT calculation and MD simulations.

In recent years, numerous research work has been conducted in order to find the most practical and cost-effective solution for corrosion issues in the oil and gas industry. Several studies have revealed that fatty hydrazide derivatives are the most suitable corrosion inhibitor for the application in the said industry. These compounds can also act as effective corrosion inhibitors in acidic medium with inhibition efficiency greater than 95%. This review summarizes and discusses the recent corrosion inhibitor development in acidic media from 2017 until 2021, focusing on fatty hydrazide derivatives. The significant findings and mechanisms of inhibition have been elucidated. In addition, intake on the computer simulation studies of fatty hydrazide inhibition properties is also included in this review. Finally, some suggestions for future research on corrosion inhibitors have been recommended.

Alkaline Surfactant Polymer (ASP) flooding has been identified as one of the best EOR methods to further recover the trapped oil in Malaysian maturing fields. ASP flooding application promises a huge incremental recovery factor based on recent successful implementation on offshore fields in other part of the world. The application of ASP flooding has been identified for pilot in North Sabah reservoir which is currently flooded with seawater since March 2011. Despite the promising recovery factor from the pilot laboratory and simulation study with incremental recovery of >80% above waterflood, the ASP flooding success always comes with risks and challenges. Two major challenges behind the success of ASP flooding are the formation of scales near wellbore due to the high pH of the alkaline in the injection fluid and the tight micro-emulsion which produced back in separator vessel which contains surfactant breakthrough. The identified pilot North Sabah reservoir which is currently been flooded with seawater is expected to further worsen the scaling effect due to the high divalent cation concentration (i.e. Ca2+ and Mg2+) in seawater. In addition, the high seawater cut causes a very tight micro-emulsion which is very difficult to manage. These challenges cause formation damage which impact injectivity and flow assurance issue to the production facilities as well as impair the crude quality and sellability. This paper will discuss in great detail on the lab test results which was designed based on the reservoir simulation ASP flooding study in North Sabah reservoir. Based on the in-situ produced water and chemical breakthrough simulated, this paper describes the extent of emulsion and scale severity at various ASP to water ratio, extensive performance tests evaluating the demulsifier and the scale inhibitor and discusses on the challenges in finding the suitable demulsifier and scale inhibitor at the simulated breakthrough condition.

More aggressive reservoir conditions, such as higher concentrations of CO2 corrosive gases, have a massive effect on corrosion. Moreover, additional aqueous species, such as organic acids, have complicated the conditions and enhanced corrosion to the maximum rate. This study investigates and screens three commercial corrosion inhibitors on their performance in mitigating corrosion at welded areas of carbon steel in high CO2 conditions with the presence of organic acids. These investigations were conducted via chemical elucidations to study the functional groups present in the compounds that affect the inhibition performance and the electrochemical measurements to evaluate the inhibition activities and efficiency of these commercial inhibitors under extreme conditions of high CO2 and organic acids. The results indicated that only CT5727 and CT17906 gave a high inhibition efficiency of 90% in the absence and presence of organic acid, with CT5727 giving the lowest corrosion rate of 0.038 mmpy in the absence of organic acid, while CT17906 gave the lowest corrosion rate of 1.00 mmpy in organic acid condition. On the other hand, D4305 gave the worst inhibition performance under both conditions. The elucidation of these inhibitors also found that specific functional groups such as hydroxy, carboxylic acid, alkyl and alkene presence in the structure were believed to affect the inhibition performance of these commercial inhibitors in mitigating corrosion. These could be used as a future reference for the new development of corrosion inhibitors in similar conditions.