Abstract. This paper presents a numerical simulation study on coreflood scale derived from a laboratory study conducted on light oil and water-wet sandstone samples from fields at Tempino and Kenali Asam, Sumatra, Indonesia. A rigorous laboratory study prompted a specified surfactant type among dozens of screened samples, i.e. AN3NS and AN2NS-M for Kenali Asam and Tempino, respectively. The coreflood scale numerical simulation study was performed using a commercial simulator, on the basis of the results from the laboratory study, at a constant temperature of 68°C, 0.3 cc/min injection rate and under 120 psia confining pressure. To get better recovery, the cores were tested using surfactant and polymer in a blended mode, containing 0.03% w/w polymer diluted in each field brine, which accommodated around 8000 ppm salinity. The most significant variable in the multiphase flow is the relative permeability curve, which is affected by interfacial tension (IFT) during waterflooding and surfactant-polymer (SP) flooding. This study shows that relative permeability will be shifted at ultra-low IFT (10 -3 to 10 -4 mN/m). This shifting phenomenon is governed by the interpolation parameter set, which implicitly represents the capillary number. Further work in matching the numerical results to the coreflood was conducted by changing the interpolation parameters.

Microbial enhanced oil recovery (MEOR) is a method that utilises bacteria or bioproducts to increase oil recovery at the tertiary stage. Clostridium sp. produces biosurfactant that alters rock-fluid properties and increases oil detachment. The interaction between bacteria and surfactant is interesting relation to study. We revisit and develop models for biosurfactantproducing bacteria's growth and the interfacial tension (IFT) response. The biosurfactant-producing bacteria growth model (BBG model) mimics the predator-prey interaction and the IFT response model derived from analogy. Both models form an integrated model called coupled-simultaneous model. We deliver the suitability of these models to experimental datasets by conducting parameter estimation. The decreased number of parameter in BBG model is with the help of rate estimation model. It estimates the bacteria growth rate and biosurfactant production rate. This research introduces a graphical method to narrow parameters initial guess in the IFT model. The method comes with a proposed index to compare surfactant performance called as surfactant performance index (SPI). The paper exposes the logic of each parameter, physics behind the models, and addresses the mathematical artefacts. The significant findings are valuable to anticipate bacterial performance for MEOR.

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Well known use of epoxy-based polymer is to plug a selective layer in completion process. The similar behaviour related to its gelation as a completion fluid is a trigger to ask a question: Is epoxy-based polymer suitable for WSO (water shut-off) application too? Therefore, this paper is aimed to study the applicability of epoxy-based polymer to "reducing excessive produced water treatment" called WSO covering synthesising and core-flood experiment. An epoxy-based polymer is synthesised in various temperature and concentration of reagents those are epoxy and triethylenetetramine which are vary from 6.25% to 50% which diluted in acetone with volume over volume concentration. The polymer is then characterised using Fann-VG to know the rheology and the gelation behavior with respect to the variables above mentioned. A polymer consists of 50% (v/v) epoxy and 50% (v/v) triethylenetetramine is chosen to be applied in core-flood apparatus operating at room temperature, 20 psia injection and 120 psia confining pressure. Sandstone core with various porosity and permeability are tested to reduce its poro-perm due to epoxy-based polymer injection. Variation on concentration has shown that higher concentration gives shorter gelation period. Gelation is defined as a time required to dramatically changing the viscosity profile. These gelation data can be modelled into a simple mathematical model with multivariable consist of concentration and temperature. Sandstone cores undergo a reduction on its porosity over than 54% and permeability upto 100% which means it has potential to resist or even plug a layer with high water cut.

Well and Inflow Performance Relationship, termed TPR and IPR, respectively have been the unfailing methods to predict well performance. It is further to determine the schemes on optimising production. The main intention of the study is to explore TPR and IPR under heating treatment for heavy oil well. Klamono is a mature field which mostly has depleted wells, it produces heavy oil within 18.5 o API (>0.95 g/cc oil density), and therefore, artificial lifting method is necessary. Sucker Road Pump (SRP) and Electrical Submersible Pump (ESP) are the most deployed artificial lifting method in this reservoir. To boost the heavy oil production, the application of Electric Downhole Heater (EDH) in Well KLO-X1 is being studied. Whole Klamono's production is more than 100,000 blpd within 97-99% water cut. By installing EDH, oil viscosity is decreased hence oil mobility ratio will play a role to decrease water cut. EDH is installed together with the tubing joint to simplify its application in the wellbore. The study shows that EDH application can elevate fluid (mixed oil and brine) temperature. Oil viscosity confirms a reduction from 68 to 46 cP. The gross well production is up to 12.2 bopd due optimising its outflow performance and reducing 97.5 to 96.9% water cut. The field data gives an incremental of 4.9 bopd. The computational results only show an attainment of net oil production up to 8.3 bopd (2 bopd incremental). The EDH works to lessen both density and viscosity as we hypothesised for the mechanism of thermally induced oil production improvement. The evaluation study on its economics aspect exhibits good result that is 1.4 USD/bbl additional profit margin according to field data despite the challenging annual rig rent cost. Following the field data, the expected net income through analytical model revealed that this project is financially promising.