bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer Containing Produced Fluid Treatment for Re-Injection: Lab Development to Field Deployment
Authors: Pinnawala Gayani Wasana , Subrahmanyan Sumitra , Alexis Dennis Arun , Palayangoda Sujeewa Senarath , Linnemeyer Harold , Matovic Gojko , Kim Do Hoon , Theriot Timothy , Malik Taimur , Dwarakanath Varadarajan 
Published: April 2022

Abstract
Chemical Enhanced Oil Recovery operations involve injecting polymer and surfactants for enhanced recovery. Some of the polymer and surfactant are produced in the form of emulsions. The emulsions need to be treated to recover the oil and reuse water for mixing new polymer for injection. New treatment methods are required to effectively break these emulsions. While chemical treatment and other methods are effective in breaking emulsions formed by electric submersible pumps (ESP's), these methods are not successful in breaking emulsions formed by injected chemicals for CEOR.
Reuse of produced water is important in off-shore as well as some on-shore fields. Produced water re-injection requires mixing of fresh polymer with fluid containing produced polymer and traces of oil, which can cause potential incompatibility. Ideally, removal of all produced polymer using a viscosity reducer followed by injection of fresh polymer will improve facility reliability and uptime.
Sodium hypochlorite (NaOCl or bleach) was evaluated as a viscosity reducer (VR). Bleach can reduce the viscosity of any HPAM by breaking down the polymer. Polymer destruction fortuitously causes a breakdown of emulsions which releases oil from water and results in improved water quality. After destruction of HPAM, excess bleach was neutralized by chemical means using a neutralizer. After neutralization, the resulting water is free of excess bleach and can be reused for mixing fresh polymer for injection without the risk of degradation of newly mixed polymer. Activating the VR (acidic VR) by pH adjustment can enhance the performance of VR dramatically. Improved oil separation as well as polymer removal can be realized using this technique.
Selective Crystallization - En Route to In-Situ Deep Conformance Control
Authors: Binabdi Ali , Ayirala Subash , Gmira Ahmed , Solling Theis 
Published: April 2022

Abstract
We have investigated the interfacial properties at a brine-hydrocarbon boundary with the prospect of understanding the crystallization process that takes place when certain electrolytes are present in the brine and when certain surfactants are present in the hydrocarbon phase. This was done in an optical force tensiometer setup with a so-called buoyant droplet configuration. It is only specific combinations (that is not all surfactants not all electrolytes) that form crystals and we aim at utilizing this specificity to form crystal plugs in particular sections of an oil reservoir, for example in zones with high flow that can then be reduced by the crystal plugs. The treatment can potentially be tailored based on the predominant acid-type in a mixture. The current study reveals several (at least three) different modes of crystal formation. The electrolyte-surfactant combination that gives rise to the most clear-cut formation of crystals directly at the interface is involving Zn2+ or Cu2+ and dodecanoic acid (C11H23COOH). Several of the systems under study appears to be forming crystals within the hydrocarbon phase and that these crystals more the likely are a result of the surfactant associated diffusive transfer of cations into the hydrocarbon phase. The next short-term goal is to induce crystals when the hydrocarbon phase is (potentially spiked) crude oil to tailor the discoveries towards the longer-term goal: In-situ deep conformance control field applications.
Gas-Oil Ratio GOR Characterization of Unconventional Wells in Eagle Ford
Authors: Zhao Yajie , Nohavitza Jack , Williams Ryan , Yu Wei , Fiallos-Torres Mauricio Xavier , Ganjdanesh Reza , Sepehrnoori Kamy 
Published: April 2022

Abstract
With the increased exploration and development of unconventional reservoirs, the complicated production mechanisms of unconventional wells have gradually become a hot topic among the oil and gas industry. Due to the ultra-low permeability and porosity, the fluid phase behavior in shale reservoirs significantly differs from the conventional fluid phase behavior, increasing the production forecasting complexity. A substantial effort to better understand the mechanisms is the ability to characterize the unconventional well gas-oil ratio (GOR) behavior. The GOR always plays a critical indicator to help predict long-term oil/gas production trends and develop appropriate production strategies. In this paper, GOR behavior was discussed based on an unconventional parent-child horizontal well set in the Eagle Ford shale formation. Subsequently, fracture hit intensity can be determined through the producing GOR characterization. Afterward, the historical production data were well matched. The long-term GOR trends (20 years) were then predicted with the calibrated reservoir model. Based on the simulation results, an interpretation of the fracture hit impact on GOR behavior, and the well productivity was established. This study provides some key insights into GOR behaviors, especially for the parent-child well GOR trends with considering the impact of fracture hits. The Eagle Ford GOR is strongly influenced by the flowing bottomhole pressure. Meanwhile, the GOR trends of both parent and child wells are extremely sensitive to fracture hits, strong correlations between GOR and fracture hits are observed. Compared to the parent well, the flat GOR period of the child well is much shorter due to pressure depletion. The existence of a child well also reduces the rising speed of the parent well with a lower plateau. In addition, the long-term production prediction shows that fracture hits negatively influenced both well performances, where the child well has a more severe production loss than the parent well. Through the findings presented in this work, a better understanding of the unconventional well GOR behaviors can be obtained. The analysis approaches proposed in this paper provide valuable insights into GOR characterization and contribute to the production forecasting from unconventional plays. The results can help to improve the efficiency of reservoir management, field development, and economic valuation in future projects.
Understanding Foam Flow in Rough Carbonate Fractures
Authors: Radhakrishnan Anuradha , Gigliotti Alex , Johnston Keith P. , DiCarlo David , Prodanovic Maša 
Published: April 2022

Abstract
Foams are used to improve the sweep efficiency during oil recovery in carbonates. Carbonates have high permeability fractures and vugs which can alter the foam structure, potentially changing the flow and sweep efficiency of the foam. In this paper, we investigate how the roughness of fractured carbonates affects the foam structure stability. The behavior of foam in a rough and saw-cut fractures was observed experimentally and with simulations using Lattice Boltzmann method to qualitatively assess their structure. In the experiments, it was observed that a fracture with a rough surface decreased the collapse of foam lamella and increased apparent viscosity in comparison to the saw-cut fracture. In the temperature range of 40°C to 60°C, foam structure was more stable at lower ends of this temperature range. In the simulations, we observed that the foam bubbles in the smooth fracture tended to undergo Ostwald ripening. This led to a more heterogeneous distribution of bubble sizes inside the smooth fracture. Whereas the average size of the polygonal bubbles was fairly small and uniformly distributed across the rough fracture, leading to more stable foams.
A Molecular Level Study of Water-Oil Interface in the CO2 EOR Under Low Pressure Condition
Authors: Chang Qiuhao , Huang Liangliang , Wu Xingru 
Published: April 2022

Abstract
In this study, molecular dynamics simulations have been performed to study the interfacial properties between water and oil with different mole fractions of CO2 under 8 MPa and 345 K. Simulation results show that with the increase of CO2 mole fraction, more CO2 got adsorbed in the water-oil interface region. Such CO2 increase weakened water and oil interactions at the interface, resulting in a decrease of the interfacial tension (IFT). Moreover, the water-oil IFT decreased significantly from 0 to 0.40 CO2 mole fractions. But the change was small for higher CO2 mole fractions of 0.40 to 0.80. From those calculations, we conclude that in the CO2-EOR, the volume of injected CO2 needs to be at least more than 0.4 mole fraction (to the oil) to achieve a decent reduction of the water-oil IFT. This study can provide a molecular level reference for implementing the CO2-EOR in the oil field under a low-pressure condition.
Surfactant Enhanced Oil Recovery from Tight Carbonates: Core-Scale Experiments to Reservoir-Scale Modeling
Authors: Shi Yue , Mohanty Kishore 
Published: April 2022

Abstract
Most carbonate reservoirs are oil-wet/mixed-wet and heterogenous at multiple scales. Majority of the injected water flows through the high permeability regions/fractures and bypass the oil in the matrix due the high negative capillary pressure (Pc). To enhance oil recovery from such reservoirs, the sign of the Pc should be changed by wettability alteration (WA) or the Pc should be reduced by lowering interfacial tension (IFT). In this study, surfactants which can either alter wettability or develop ultra-low IFT were identified through laboratory measurements for the target carbonate reservoir. The performance of these two types of surfactants was systematically evaluated at the core scale and scaled-up to the reservoir scale. A reservoir-scale model was developed to simulate injection-soak-production (ISP) tests and evaluate performance of the selected surfactants at the field scale. Experiments showed that quaternary ammonium cationic surfactants have excellent WA ability, while a series of propoxy sulfate anionic surfactants showed intermediate WA and ultra-low IFT. Spontaneous imbibition tests showed that WA surfactants have fast initial oil production, while ultra-low IFT surfactants has low initial oil rate but higher final oil recovery, which was validated by mechanistic simulation. Low IFT results in low Pc and slow imbibition, but also triggers gravity-driven drainage. For ultra-low IFT system, gravity drainage is more dominant than WA, and Pc-alteration is less important than relative permeability (Kr) alteration. As reservoir thickness increases, Kr-alteration is more important than Pc-alteration. Gravity drainage is expected to be scaled up by length of matrix (L), while Pc-driven imbibition is scaled by L2. Field-scale simulation showed that low-IFT surfactant has better injectivity than WA surfactant during injection phase. In soaking phase, spontaneous imbibition by WA surfactant is much more significant than that by low-IFT surfactant. In production phase, post-waterflood achieved higher oil recovery from low-IFT surfactant treated matrix due to its low residual oil saturation and high oil relative permeability.
Screening of Topside Challenges Related to Polymer Presence in the Back Produced Fluids – Casabe Case Study
Authors: Mouret Aurélie , Blazquez-Egea Christian , Hénaut Isabelle , Jermann Cyril , Salaün Mathieu , Quintero Henderson , Gutierrez Mauricio , Acosta Tito , Jimenez Robinson , Vargas Nadine 
Published: April 2022

Abstract
Polymer enhanced oil recovery (EOR) pilots were implemented in various mature oilfield reservoirs in Colombia with encouraging results. That chemical EOR technology is often considered as a promising process to faster recover oil. To increase the chance of success of such an industrial project it is important not to neglect the potential impact of residual polymer in back produced effluents. The objective of this work is to highlight the impact of back-produced EOR polymer at the laboratory scale on various topside equipment before deploying the polymer injection at wider scale in a heavy oil field (18° API).
A topside facility review was first performed to collect operational conditions and parameters, to identify applied treatment technologies and to define relevant sampling locations for the laboratory study. The impact of the residual acrylamide/ATBS ter-polymer selected for the future polymer implementation was then explored in a set of experiments as part of a dedicated laboratory workflow representing the whole surface treatment chain. The scope of the study has covered primary separation, static gravity water clarifying, deep-bed filtration and heater fouling. Large residual polymer concentration and water cut ranges were investigated to anticipate some produced fluid composition change over time.
In the case studied, the selected polymer does not stabilize tight water-in-oil emulsions, but it has a negative impact on the water quality. Some compatibility issues are observed with incumbent demulsifiers, which seems to be sensitive to both polymer concentration and water cut. The fouling risk of heat exchanger is very low in the testing conditions. In the water de-oiling side, filtration and gravity settling performance are reduced but the right chemical and equipment combination enables to obtain a better water quality and to meet injection specifications targets.
Novel/Additive Information: This work illustrates that management of produced fluid containing EOR polymer has to be considered as early as possible in the project implementation. It also points out that laboratory experiments are useful to better appraise and mitigate the potential operational issues. All the results obtained in such a study are valuable guideline and input data for treatment facilities upgrade studies. In polymer flooding roadmap implementation, it is key to bond operational conditions and laboratory parameters in order to be as close as possible to the field conditions as each case is unique.
Predictive Model for Relative Permeability Using Physics-Based Artificial Neural Networks
Authors: Yoga Hanif Farrastama , Purswani Prakash , Johns Russell Taylor 
Published: April 2022

Abstract
Hysteresis of transport properties like relative permeability (Kr) can lead to computational problems and inaccuracies for various applications including CO2 sequestration and chemical enhanced oil recovery (EOR). Computational problems in multiphase numerical simulation include phase labeling issues and path dependencies that can create discontinuities. To mitigate hysteresis, modeling Kr as a state function that honors changes in physical parameters like wettability is a promising solution. In this research, we apply the state function concept to develop a physics-informed data-driven approach for predicting Kr in the space of its state parameters.
We extend the development of the relative permeability equation-of-state (kr-EoS) to create a predictive physics-based model using Artificial Neural Networks (ANN). We predict kr as a function of phase saturation (S) and phase connectivity (χ^), as well as the specific S−χ^ path taken during the displacement, while maintaining other state parameters constant such as wettability, pore structure, and capillary number. We use numerical data generated from pore-network simulations (PNM) to test the predictive capability of the EoS. Physical limits within S−χ^ space are used to constrain the model and improve its predictability outside of the region of measured data.
We find that the predicted relative permeabilities result in a smooth and physically consistent estimate. Our results show that ANN can more accurately estimate kr surface compared to using a high-order polynomial response surface. With only a limited amount of drainage and imbibition data with an initial phase saturation greater than 0.7, we provide a good prediction of kr from ANN for all other initial conditions, over the entire S−χ^ space. Finally, we show that we can predict the specific path taken in the S−χ^ space along with the corresponding kr for any initial condition and flow direction, which makes the approach practical when phase connectivity information is not available. This research demonstrates the first application of a physics-informed data-driven approach for prediction of relative permeability using ANN.
Evaluating the Effect of Carbonate Impurities on Wettability Alteration Using a Geochemical Model
Authors: Hao Xingjuan , Abu-Al-Saud Moataz , Ayirala Subhash , Elakneswaran Yogarajah 
Published: April 2022

Abstract
Wettability alteration considered as the principal mechanism has attracted more attention for low salinity waterflooding effect. It was significantly affected by electrokinetic interactions, which occurred at the interfaces of rock/brine and crude oil/brine. The mineral impurities of natural carbonate releasing ions have an important impact on the electrokinetics, which could lead to wettability shift subsequently. In this study, the effect of dolomite and anhydrite as the main impurities in natural carbonate, which caused wettability alteration, was evaluated using triple-layer surface complexation and thermodynamic equilibrium models coupled with extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The electrokinetics of crude oil and carbonate in brines were predicted by the triple-layer surface complexation model (TLM) based on zeta potential, while thermodynamic equilibrium model was mainly used for analyzing the carbonate impurities on wettability alteration. The equilibrium constants of reactions were determined by successfully fitting the calculated zeta potentials with measured ones for crude oil and carbonate in different solutions, which were validated for zeta potential prediction in smartwater. The disjoining pressure results show that there is a repulsion between crude oil and carbonate in Na2SO4 brine (Brine3) or smartwater (Brine4) equilibrating with calcite when comparing to that in MgCl2 (Brine1) and CaCl2 (Brine2), indicating the water-wet condition caused by the presence of sulphate ions. Moreover, the equilibrium of carbonate impurities with smartwater increases the repulsion between oil and carbonate. When the sulphate ion concentration in the adjusted smartwater exceeds a certain value, the effect of carbonate impurities on wettability alteration is not significant. Finally, the influence of smartwater pH on the interaction between oil and carbonate was evaluated with or without considering the equilibrium of carbonate impurities.
Polymer Injectivity Enhancement Using Chemical Stimulation: A Multi-Dimensional Study
Authors: Chandrasekhar Sriram , Alexis Dennis Arun , Jin Julia , Malik Taimur , Dwarakanath Varadarajan 
Published: April 2022

Abstract
Chevron injected emulsion polymer in the Captain field, offshore UK in the last decade at various scales (Poulsen et al., 2018). Pilot horizontal wells had exhibited faster than designed injectivity decline and Jackson et al. (2019) documented the causes to include oleic phase damage from a) injection of produced water containing crude oil after imperfect separation, and b) entrainment of injected emulsion polymer’s carrier oil. The wells were remediated with a surfactant stimulation package (Alexis et al., 2021; Dwarakanath et al., 2016). The remediation boosted the water relative permeability near wellbore which enhanced injectivity and allowed higher processing rates for subsequent continuous polymer injection.
In this work, we conducted a set of core floods in slabs of surrogate rock of varying dimension and patterns to demonstrate the beneficial effect of near wellbore stimulation in the general case. 0.04 PV of the remediation package was injected and we show consistent injectivity enhancement across the experiments. We demonstrate the dominant effect of well skin treatment on the pressure drop profile compared to flow resistance from a) residual oil saturation and b) viscous fingering. The result is an important reminder for injectivity maintenance for high polymer flood processing rates for the life of the project. Clean injection fluids were demonstrated to maintain injectivity. We show applicability of stimulation for injectors into viscous oil reservoirs with adverse viscosity ratio. The robust nature of the remediation package developed by Alexis et al. (2021) is also shown, working to efficacy on viscous oil, as well as in situ phase separated polymer. We estimated skin and stimulation depth for a line drive case with low chemical dosage finding that 0.04 pore volumes of surfactant injection at 0.33 oil saturation units gave injectivity improvement of 31%. Surfactant stimulation is thus broadly applicable to wells with oleic phase skin.
Design of Surrogate Oils for Surfactant-Brine-Oil Phase Behavior
Authors: Park Jaebum , Mohanty Kishore 
Published: April 2022

Abstract
Many conventional surfactant-brine-oil phase behavior tests are conducted under ambient pressure conditions without the solution gas. It is known that the solution gas lowers the optimum salinity. Researchers often mix toluene (or cyclohexane) with the dead oil and form a surrogate oil to mimic the live oil. The objective of our work is to study the effect of gas and toluene on phase behavior, and to provide the proper amount of toluene to be mixed to mimic the live oil. Effects of toluene in surrogate oil and solution gas in live oil are examined by hydrophilic-lipophilic difference and net average curvature (HLD-NAC) structural model simulation and the equivalent alkane carbon number (EACN). Experimental values from literature and our experiments are also examined to compare those with the simulation results. For the simulation, both the mole fraction and mass fraction were used to calculate mixture EACN and examine the effect of additional components. HLD-NAC simulation results showed that the mass fraction-based simulation is more accurate (~7% error) than mole fraction-based simulation (~19% error) with a toluene EACN of 1. For larger molecules like toluene in surrogate oil, EACN using mole fraction also works with a toluene EACN of 5.2. The EACN of the surrogate oil should match the EACN of the live oil to determine the proper amount of toluene in the surrogate oil.
Small Scale EOR Pilot in the Eastern Eagle Ford Boosts Production
Authors: Bozeman Tim , Nelle Will , Nguyen Quoc 
Published: April 2022

Abstract
Low primary and secondary recoveries of original oil in place from modern unconventional reservoirs begs for utilization of tertiary recovery techniques. Enhanced Oil Recovery (EOR) via cyclic gas injection ("huff ‘n puff") has indeed enhanced oil recovery in many fields and many of those projects have also been documented in industry technical papers/case studies. But the need remains to document new techniques in new reservoirs. This paper documents a small scale EOR pilot project in the eastern Eagle Ford and shows promising well results.
In preparation for the pilot, full characterization of the oil and injection gas was done along with laboratory testing to identify the miscibility properties of the two fluids. Once the injection well facility design was completed a series of progressively larger gas volumes were injected followed by correspondingly longer production times. Fluids in the returning liquid and gas streams were monitored for compositional changes and the learnings from each cycle led to adjustments and facility changes to improve the next cycle.
After completing five injection/withdrawal cycles in the pilot a few key observations can be made. The implementation of cyclic gas injection can be both a technical and a commercial success early in its life if reasonable cost controls are implemented and the scope is kept manageable. The process has proved to be both repeatable and predictable allowing for economic modeling to be utilized to help determine timing of subsequent injection cycles. A key component of the success of this pilot has been the availability of small compressors capable of the high pressures required for these projects and learning how to implement cost saving facility designs that still meet high safety standards.