bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility of Bulk CO2-Foam Screening for Carbon Storage Evaluations at Reservoir Conditions
Authors: Yu Ying , Hanamertani Alvinda Sri , Korsah Paa Kow , Jiao Zunsheng , McLaughlin Jonathan Fred
Published: April 2022

Utilizing foam techniques in carbon storage projects is of recent interest, yet whether the optimized bulk foam screening method could also identify the optimal foam formulation that improves the CO2 storage potential remains under-studied. This study demonstrates the feasibility of the bulk foam test as a screening stage to select a proper foaming agent for carbon storage by investigating the consistency of the results obtained from bulk foam properties measurements, dynamic foam performance evaluations in porous media, and the quantification of CO2 storage potential at the reservoir conditions. Different foaming agents were initially screened based on their abilities to generate ample and stable foam at 13.79 MPa and 90°C. The CO2 storage potential was studied based on the CO2 breakthrough deceleration and water displacement efficiency, while the dynamic performance of supercritical CO2-foams stabilized by these selected surfactants was then evaluated in Berea sandstone using the CO2/surfactant co-injection method. Among the tested surfactants in bulk CO2 foam experiments at high pressure and temperature conditions, a sultaine-based zwitterionic surfactant was identified to exhibit the highest foamability and foam stability. In flooding experiments, the selected surfactant was able to provide decent foam generation ability that leads to the best performance in improving the CO2 storage potential by two-fold magnitude, compared to the brine-saturated core case. Besides, an immediate foam generation was observed, providing high flow resistance for the injected CO2 and, therefore, resulting in controlled CO2 mobility and improved CO2 sweep efficiency. The result coherency from CO2 storage potential evaluations and foam performance assessments both in bulk and inside porous media shows the feasibility of the bulk foam screening method for the carbon storage studies. The initial identification of high-performing surfactants based on their bulk foaming properties can provide countable insights for CO2 storage potential improvement.
Heavy Oil Reservoir Management - Latest Technologies and Workflows
Authors: Aydin Hakki , Nagabandi Nirup , Temizel Cenk , Jamal Diyar
Published: April 2022

Successful heavy oil reservoir management practices, are built on analyzing and accurately predicting the reservoir behavior over time. To enable these practices, the critical component that assures their success is a thorough understanding of reservoir physics. Given the complex nature of heavy oil reservoirs including geomechanical properties, fluid flow behavior, etc., there is a need to develop a repeatable technique that can account for these complexities within an acceptable margin of accuracy. The objective of this study is to conduct a comprehensive review of all the latest technologies and workflows developed for heavy oil reservoir management, so that, it can be used as a single source of reference for the industry.

The latest technologies for heavy oil reservoir management, their underlying principles, along with the advantages and limitations for each of the methods in real-world applications, have been reviewed from different parts of the globe. Based on this review, conclusions have been drawn that help select the best criteria for using the latest heavy oil reservoir management techniques.

The primary component of successfully applying heavy oil reservoir management methods, lies in accurately representing the reservoir physics. These components include petrophysical properties, fluid flow and geological properties of a given formation. In addition to outlining each of these components, an emphasis has been given to highlight the important criteria that enable the successful application of these methods to a given area. As such, the study will be an information repository catered to assist in developing robust reservoir management workflows for heavy oil reservoirs.

While there are other reference, with examples, on heavy oil reservoir management; the uniqueness of this study lies in summarizing key lessons learned from real-field applications of these methods. Within a single source or reference, this study has given the specific focus on summarizing various aspects that are important to successful heavy oil reservoir management processes.
Continuum Modelling of Cyclic Steam Injection in Diatomite
Authors: Smith J. Torquil , Sonnenthal Eric L. , Milliken William J.
Published: April 2022

Objectives/Scope

Steam injection in diatomite reservoirs results in permeability changes owing to fracture propagation, and compaction as a result of thermal effects and pressure changes during injection and production. The purpose of this work is to evaluate these coupled thermal, hydrological, and mechanical (THM) processes over several years of cyclic steam injection and production. A single well model in a diatomite reservoir was created to evaluate these processes at a higher resolution near wellbore than used in a 3-D reservoir-scale model.

Methods, Procedures, Process

Simulations include tensile failure, shear failure with simultaneous shear on multiple planes, coupling of porosity and permeability changes with multiphase flow, and diatomite compaction with temperature and effective stress. Initial isotropic horizontal stresses are 1.0375 of vertical (azimuthal average, part of San Joaquin Valley). Injection interval (437-528 m) pressure is fixed, 6.3 MPa, 930 psi (injection), and ~4 MPa (production), with a soak period between injection and production. Three degree dilation on shearing is assumed. To the extent that fracture opening is tensile, fractures close on fluid pressure drop, but shear components remain. Permeability changes due to mechanical failure are simulated using a cubic law.

Results, Observations, Conclusions

During injection over multiple cycles, the diatomite surrounding the well is heated to over 250 °C and pressurized by the injected steam. During soak (shut-in) and subsequent production, pressure drops, dropping the boiling point, inducing further vaporization. Geomechanical changes show tensile opening accompanied by a greater amount of shearing. Total shearing increases with each injection cycle, resulting in a greater porosity increase from shearing than tensile opening. Fracture propagation was limited to the diatomite reservoir and did not penetrate the caprock.

Novel/Additive Information

Inclusion of an empirical effective stress/temperature diatomite compaction law together with porosity and permeability changes due to mechanical failure more closely models the mechanics of cyclic steaming of diatomite.
An Unconventional Approach to Model a Polymer Flood in the Kalamkas Oilfield
Authors: Sagyndikov Marat , Seright Randall , Tuyakov Nauryzbek
Published: April 2022

This article describes the main features of an unconventional approach to model a polymer flood in the Kalamkas oilfield. This non-standard simulation method is based on specially performed inter-well tracer tests, step-rate tests, pressure fall-off tests, dedicated field studies, well monitoring, and lab analysis. Our approach excludes permeability reduction as a mechanism to provide more mobility reduction than expected from rheology measurements (resistance factor) and by improving the recovery during post-polymer water flooding (residual resistance factor). Evidence is presented to support this exclusion for real field applications. Additionally, our approach places a significant emphasis on history matching bottomhole pressures. Our effort accounts well for the decreased mobility of the injected polymer solution and increased rock permeability during a polymer flood. In contrast to most other simulation approaches to polymer flooding, our method incorporates open fractures during polymer injection and their impact on injectivity and sweep efficiency. A literature review (lab tests and field cases) and our laboratory and field studies confirm the validity of our approach and its advantages over other modern simulator modeling of polymer flooding. From viscosity measurements of back-produced polymer solutions from injectors and well tests (inter-well tracer tests, pressure fall-off tests, step rate tests), we proved that polymer flooding induces fractures or fracture-like features and consequently, the polymer solution flows through the fracture with increased injectivity proportional to a resistance factor. Also, incorporated are expectations during a brine post-flush and the absence of the residual resistance factor (i.e., equal to 1). Implementation of these concepts brings our model closer to reality for simulating polymer floods.
Modelling the Impact of Surface Charge on Wettability Alteration in Low Salinity Waterflooding
Authors: Elakneswaran Yogarajah
Published: April 2022

The wettability alteration is the most prominent mechanism for a favorable effect of low salinity water flooding in enhanced oil recovery. It has been accepted that the surface charge at crude oil/brine and rock/brine interfaces significantly influences the interaction of the crude oil with rock surface and thus wettability changes. In this study, the interface characteristics were coupled with a solute transport model to simulate low salinity waterflooding in carbonate and sandstone reservoirs. The ionic transport and two- phase flow of oil and water equations were solved and coupled with IPhreeqc for geochemical calculations. The dissolution and precipitation of minerals were considered thorough thermodynamic equilibrium reactions in IPhreeqc. In addition, a triple layer surface complexation model was employed in IPhreeqc to predict electrokinetic properties of crude oil/brine and rock/brine interfaces. The wettability alteration was calculated based the adsorbed polar components of crude oil on minerals’ surface, which changes the relative permeability. The coupled model able to predict the spatiotemporal variation of ionic profiles, surface and zeta potentials, dissolution and precipitation of minerals, total disjoining pressure, and wettability index in addition to oil recovery for the injection of brines. The validity of the coupled model results was tested against PHREEQC in a single-phase flow without the presence of oil. Moreover, the modelling results were compared with the published experimental data for a single-phase flow in carbonate cores. A very good agreement between experimental data and modelling results was obtained. Furthermore, the coupled model was applied to predict ionic concentration, pH profile, and oil recovery in both carbonate and sandstone cores and verified with experimental data. The modelling results reproduce well the experimental data, suggesting that model captures the geochemical and interface reactions. Finally, the coupled model can be used to optimize brine composition for improved oil recovery in carbonate and sandstone reservoirs.
A Comparative Study of the Impact of the CO2 Properties on the Thermal Output of a Geothermal Well
Authors: Ratnakar Ram , Dindoruk Birol , Livescu Silviu , Gautam Sandarbh
Published: April 2022

The problem of growing carbon footprint calls for the exploitation of cleaner and sustainable energy resources. Geothermal energy is clean, renewable, and in abundant supply underneath the surface of the earth, which makes it one of the most optimum solutions to this problem. With the depletion of hydrocarbon resources, geothermal energy also helps to close the gap between demand and supply of cleaner energy resources reliably, although several problems need to be solved before producing geothermal energy globally. In this study, an effort is made to understand and improve the reservoir heat extraction through a geothermal well.

There are approximately 3 million abandoned wells within the U.S. and this number will only increase in the future. Producing electricity from these abandoned hydrocarbon wells, as the source of geothermal energy, have intrinsic importance in the context of extending the life of the well in the context of energy production and as well as generation of future options for new wells. Whether the costs are sunken or not (for the existing wells), incremental costs for the new potential wells can be minimum to redesign them to fit for future geothermal energy production. Not only the design/retrofitting the wells, but also the selection of right power fluid is crucial to effectively produce the geothermal energy. Using CO2 as the power fluid to generate electricity from low temperature abandoned hydrocarbon wells while sequestering it will help in reducing the well costs to a minimum as well as optimizing the energy production to lower temperature thresholds.

In this paper, a previously developed coupled well-reservoir model (Livescu and Dindoruk, 2022a, for fixed reservoir delivery as successions of steady state) is extended to study the effects of the fluid properties on the thermal output. Specifically, the previous model considered fluids with constant properties. Several correlations and look-up tables are used in this study for pressure- and temperature-dependent fluid properties (i.e., density and viscosity) to explicitly quantify their effect on the thermal balance of the geothermal system. These results are important for understanding the effects of the fluid PVT properties on the physics and economics of the entire geothermal project.

This study is important for the design of closed-loop systems and can be extended to enhanced geothermal systems. For a given reservoir intake conditions, it can also be used to perform economic evaluation for abandoned oil and gas wells to assess their feasibility for geothermal energy production while reducing the overall CO2 footprint. In particular, the novelty and importance lie in

Impact of choice of fluid/fluid PVT properties on the physics and economics of the entire geothermal project. Parametric study of using CO2 as the power fluid to generate electricity from relatively lower temperature abandoned hydrocarbon wells and variants in terms of P&T ranges.
Water Alternating Alkane Injection: A Molecular Dynamics Simulation Study
Authors: Coskuner Yakup Berk , Dean Elio , Yin Xiaolong , Ozkan Erdal
Published: April 2022

In a recent study, we observed that the diffusion coefficient of common hydrocarbons in crude oils are more affected by the presence of different hydrocarbon components than the effect of confinement. Based on our previous observations, in this study, we investigated the efficiency of smaller-chain alkane injection into oil-soaked sandstone pores to dilute the oil with alkane. We used molecular dynamics simulations of C2, C3, C4 and C5 as well as a mixture of C3 and C4 to rank the effects of different alkanes on the diffusion and distribution of oil molecules in pore. As water-alternating-alkane injection would bring water into the pores, our simulations included water. Our results indicate that alkane injection into sandstone reservoirs has a significant potential due to the fact that it effectively dilutes the oil. Water always wets quartz surface relative to the oils. Injection of water therefore should be effective in detaching oil molecules on the surface. Presence of water layers did not affect the diffusion coefficients of oil molecules.
Lab and Pilot-Scale Evaluation of Stable Foam for Drilling in High Temperature Environment
Authors: Griffith Christopher , Linnemeyer Harry , Kim Do Hoon , Hahn Ruth , Zhou Jimin , Upchurch Eric , Malik Taimur , Wileman Angel , Beck Griffin , Bhagwat Swanand , Gutierrez Luis
Published: April 2022

Using foams to drill in low pore pressure reservoirs is attractive because of their low density, high viscosity, and ability to transport cuttings. However, in high temperature reservoirs (240 °F) with H2S gas present, there are concerns with the long-term stability of a foam drilling fluid. In this work, we highlight a lab program to develop a stable drilling foam for drilling in a low pore pressure, high temperature reservoir. The work also includes pilot-scale experiments to evaluate foam performance.

Aqueous nitrogen-in-water foams were stabilized with a preferred foaming surfactant formulation, and the rheology and stability of the foams were measured at representative drilling conditions (temperature and pressure) at the lab and pilot-scale. The foams were also evaluated for their compatibility with current drilling fluids used on site and for stability in the presence of H2S gas (at 1900 psi and 140 °F). The drilling foam was also evaluated using a pilot-scale flow loop comprised of a rheology flow loop and a model drilling wellbore. The experiments included measuring the foam rheology, foam stability in the model wellbore, and gas migration tests to understand how the foam suppresses upwardly migrating gas bubbles.

We successfully developed a surfactant stabilized foam designed for a high-temperature reservoir with H2S gas present. We found that H2S can negatively impact foam stability if proper surfactants are not selected. Our foam showed less than 10% liquid drainage after 12 hours at 240 °F and showed no significant degradation upon contact with 17 mol% H2S gas. Additionally, the foam was compatible with all drilling fluids (both water-based and oil-based) currently used at the drill site and demonstrated good stability in a model pilot-scale drilling wellbore. Interestingly, when the wellbore was angled at 30 degrees from vertical with the eccentric drill pipe rotating at 100 RPM, the foams were susceptible to degradation compared to an equivalent scenario of a vertical wellbore with concentric rotating drill pipe. The gas migration tests at the pilot-scale showed the foam was capable of significantly slowing down an upwardly moving gas bubble with and without pipe rotation.
Enabling Increased Oil Recovery from Deep-Water Viscous Oil Reservoirs by Improved Performance Prediction of Multiphase Viscous Pumps
Authors: De Raeve Karel , Gaillard Xavier , Bibet Pierre-Jean
Published: April 2022

Typical seawater depths for deep-water oil fields range from 1000m to 4000m. For these deep-water oil fields, the most popular and cost-effective technologies for increased oil recovery are water injection and subsea boosting with a multiphase helico-axial pump on the seabed. By installing a pump on the seabed, the well head pressure and thus the bottom hole pressure can be reduced, which will result in an increased well lifetime and thus an increased oil recovery. This contributes to a reduction in CAPEX per produced barrel and hence make the field development economically more interesting.

Viscous multiphase production fluids occur in case of a viscous oil or in case of water-oil emulsions with a high apparent viscosity close to the inversion point. It is known that for viscous fluids the required power and size of the pump are significantly larger than for water-like products, such as low viscous oils. On top of this, due to the poor accuracy of the existing performance prediction models available in literature for viscous conditions, the pumps and the corresponding utility systems have to be significantly over-dimensioned to compensate for the uncertainties. This has a large negative impact on the CAPEX requirements for such field developments up to the point that it becomes economically unattractive to develop the field.

For this reason, TotalEnergies (Operator), Sulzer (OEM) and TechnipFMC (EPC contractor) have launched real-size pump test campaigns in 2012 and 2014 with viscosities up to 3,000 cP in hot fluid and 10,000 cP in cold start-up conditions.

The data obtained from those measurement campaigns have been used to develop a performance prediction model, which allows for accurate sizing of the pumps and corresponding topside utility system.

This model allows for a reduction of the uncertainties and risks related to subsea boosting for viscous deep-water field developments and related to this the overall CAPEX requirements. This enables subsea boosting as a viable solution for increased oil recovery for deep-water fields with viscous multiphase fluids.

This paper presents the test campaign and acquired measurement data. It explains how the effect of viscosity is modeled. It illustrates the match between the pump performance prediction model and the viscous multiphase test data. This allows for a reduction of the uncertainties and thus a more accurate pump selection.
Bioremediation by Indigenous Microbes: A Green Approach to Degrade Polymer Residue
Authors: Liu Songyuan , Lu Bo , Sie Chao-yu , Li Yifan
Published: April 2022

Polyacrylamide-based friction reducer is commonly used in well completion for unconventional reservoirs. However, residual polymer trapped in the near well-bore region could create unintended flow restrictions and could negatively impact oil production. An eco-friendly approach to regain conductivity was developed by stimulating indigenous bacteria for residual polymer biodegradation.

In this work, a series of laboratory experiments were conducted using produced water and oil from Permian Basin, polyacrylamide-based polymer, and a modified nutrient recipe that contained 100 to 300 ppm of inorganic salts. The sealed sample vials containing water, oil, and polymer were prepared in a sterilized anaerobic chamber and then kept in a 160° F incubator to simulate the reservoir condition. Feasibility tests of bacteria growth and biodegradation evaluation of polymer were conducted using an optical laser microscopic system with bacteria tagged with fluorescent dye. Size regression was calculated and applied to a mathematical model based on actual fracture aperture distribution data from shale formation.

The indigenous bacteria were successfully stimulated with and without the existence of the friction reducer. It was observed that the size of polymer particles decreased from over 300 µm to less than 20 µm after 15 days. Under the condition of produced water injection, 140° F reservoir temperature, and anaerobic environment, about 30% of the natural fractures in shale were calculated to be damaged and remediated within 15 days.

This work is a pioneer research on microbial EOR application in unconventional reservoirs with only indigenous bacteria involved. In field applications, only an extremely low amount of nutrient is required in this process which provides great economic potential. Additionally, the nutrients introduced into the reservoirs will be fully consumed by bacteria during treatment, and the bacteria will be decomposed into organic molecules soon after the treatment. Thus, this technique is environmental- and economical- friendly for the purpose of polymer damage remediation to maximize the recoverable.
Impact of Brine Chemistry on Waterflood Oil Recovery: Experimental Evaluation and Recovery Mechanisms
Authors: Aminzadeh Behdad , Chandrasekhar Sriram , Srivastava Mayank , Tang Tom , Inouye Art , Villegas Mauricio , Valjak Monika , Dwarakanath Varadarajan
Published: April 2022

Water floods are typically conducted using the least expensive, easily available, non-damaging brine. Very little attention is given to the possibility of changing brine composition to improve oil recovery. Over the last 20 years, there has been laboratory and field trial evidence that shows changing brine chemistry, especially to low salinity, can sometimes increase the recovery. The various mechanisms of additional oil recovery from changing brine chemistry are not entirely clear. We report here on the effect of using low salinity and divalent altered brines on oil recovery through a variety of laboratory methods and materials. More than twenty corefloods were conducted to evaluate the effect of brine chemistry and initial wettability on incremental oil recovery. We also performed phase behavior tests, contact angle measurements, and wettability index measurements to evaluate recovery mechanisms. Initial wettability of the core was altered by ageing it with different crude oil containing wide range of asphaltene content. The core flood with lowest wettability index (least water-wet) produced about 12% incremental recovery while the most water-wet core only produced ∼ 4% during the secondary low salinity waterflood.
Energy Efficient Steam-Based Hybrid Technologies: Modeling Approach of Laboratory Experiments
Authors: Pérez Romel Antonio , García Hugo Alejandro , Gutiérrez Dubert , Rodríguez Hector Arnoldo , Mehta Sudarshan , Moore Robert Gordon , Ursenbach Matthew , Sequera-Dalton Belenitza , Manrique Eduardo Jose
Published: April 2022

Colombia is evaluating different steam-based hybrid oil recovery technologies as a strategy to face current challenges in the development of heavy oil reservoirs. Oil price volatility, the need for an energy transition, and carbon footprint reduction are factors limiting the commercial deployment of conventional steam injection projects. Ecopetrol evaluates the hybrid steam methods at laboratory scale as one of the different options to overcome current constraints developing heavy oil resources. The ongoing experimental program is supported by numerical modeling as a prior step to upscale the results at the pilot-scale.

This study aims to present history match results and describe the numerical modeling approach of hybrid steam experiments (50 mm diameter × 1.1 m long assembly) and compare it against the baseline steam injection simulation. The first hybrid test involved the injection of steam and flue gas considering consecutive floods that included a saturated steam flood (SSF), a flue gas slug injection, and a second saturated steam flood. The second test was a steam and solvent injection following the same experimental protocol (SSF + solvent + SSF).

The variables matched included produced fluids, pressures, produced gas compositions, and temperature profiles. One important feature is that all three models use the same set of water-oil relative permeability curves obtained from an independent experiment. Also, it was assumed those curves are not a function of temperature, which simplifies the modeling and allows focusing on the physical mechanisms relevant to each experiment. For instance, for the hybrid steam-flue gas test, it was necessary to include an additional set of gas-oil relative permeability curves to account for the presence of the flue gas in the gas phase. The hybrid steam-solvent test was focused on modeling the mixing of the native oil with the injected solvent. The proposed workflow led to a good history match of all variables, particularly total produced fluids, temperature profiles, and injection pressures. Additional recommendations are provided based on laboratory observations to understand important mechanisms such as trapped gas, relative permeability hysteresis, and solvent characteristics.

A new methodology to simulate hybrid steam methods is provided. The proposed numerical approach incorporates novel energy efficiency and carbon intensity indexes to guide the decision-making and identify recovery strategies driven by its efficiency and reduce carbon footprint. Both hybrid tests led to energy efficiency improvements and reduction in carbon intensity up to 20%. These indexes combined with experimental results will be key input parameters for designing and commissioning future pilot tests using numerical simulations at the field scale.
Comprehensive Evaluation of a Novel Recrosslinkable Hyper Branched Preformed Particle Gels for the Conformance Control of High Temperature Reservoirs
Authors: Song Tao , Ahdaya Mohamed , Zhao Shuda , Zhao Yang , Schuman Thomas , Bai Baojun
Published: April 2022

The existence of high conductivity features such as fractures, karst zones, and void space conduits can severely restrict the sweep efficiency of water or polymer flooding. Preformed particle gel (PPG), as a cost-effective technology, has been applied to control excessive water production. However, conventional PPG has limited plugging efficiency in high-temperature reservoirs with large fractures or void space conduits. After water breakthrough, gel particles can easily be washed out from the fractures due to the lack of particle-particle association and particle-rock adhesion. This paper presents a comprehensive laboratory evaluation of a novel water-swellable high-temperature resistant hyper-branched re-crosslinkable preformed particle gel (HT-BRPPG) designed for North Sea high-temperature reservoirs (130 °C), which can re-crosslink to form a rubber-like bulk gel to plug such high conductivity features. This paper systematically evaluated the swelling kinetics, long-term thermal stability and plugging performance of the HT-BRPPG. Bottle tests were employed to test the swelling kinetic and re-crosslinking behavior. High-pressure resistant glass tubes were used to test the long-term thermal stability of the HT-BRPPG at different temperatures, and the testing lasted for over one year. The plugging efficiency was evaluated by using a fractured model. Results showed that this novel HT-BRPPG could re-crosslink and form a rubber-like bulky gel with temperature ranges from 80 to 130 °C. The elastic modulus of the re-crosslinked gel can reach up to 830 Pa with a swelling ratio of 10. In addition, the HT-BRPPG with a swelling ratio of 10 has been stable for over 15 months at 130 °C so far. The core flooding test proved that the HT-BRPPG could efficiently plug the open fractures, and the breakthrough pressure is 387.9 psi/ft. Therefore, this novel BRPPG could provide a solution to improve the conformance of high-temperature reservoirs with large fractures or void space conduits.
A Study of the Impact of Permeability Barriers on Steam-Solvent Coinjection Using a Large-Scale Physical Model
Authors: Sheng Kai , Okuno Ryosuke , Al-Gawfi Abdullah , Nakutnyy Petro
Published: April 2022

This paper presents a solvent-assisted steam-assisted gravity drainage (SA-SAGD) experiment using condensate in a large physical model. The main objective of this research was to study the impact of permeability barriers on the in-situ thermal/compositional flow and the produced bitumen properties in SA-SAGD using condensate.

A pressure vessel of 0.425 m in diameter and 1.2 m in length contained unconsolidated sands and two horizontal shale plates as permeability barriers. The two shale plates were placed at different elevations above the injection well and horizontally staggered so that they could make the main hydraulic paths tortuous during the experiment. The sandpack had a porosity of 0.34 and a permeability of 5.6 D, and it was initially saturated with 95% Athabasca bitumen and 5% deionized water.

After 24 hours of preheating, SA-SAGD with 2.8 mol% condensate was performed at 35 cm3/min (cold-water equivalent) at 3500 kPa for 4 days. The production, injection, and temperature distribution were recorded. Produced oil samples were analyzed for density and asphaltene content. The sandpack was excavated after the experiment to analyze the oil saturation and asphaltene content in the remaining oil at different locations. Results were compared with the previous SAGD and SA-SAGD experiments using the same physical model with a homogeneous sandpack.

Results showed that SA-SAGD was efficient in the presence of permeability barriers with a cumulative steam-to-oil ratio (SOR) that was two to three times smaller than that ofthe homogeneous SAGD case. Temperature data indicated that a steam chamber vertically expanded from the lower part to the upper part through tortuouspaths of lower temperatures.The emerging steam chamber above the shale plates occurred by convective heat from the injection well through lower-temperature hydraulic paths between shale plates. This should have involved light to intermediate solvent components that enabled the steam chamber to expand away from the injection well. This highlights the important role of volatile solvent components in the growth of a steam chamber in SA-SAGD under heterogeneity. The produced bitumen density in this research was closer to the original bitumen than in the homogeneous SA-SAGD case because the bitumen dilution and the solvent retention increased by the tortuous flow regime resulted in efficient drainage of oil at lower temperature.
Modeling of Foam Flow in Porous Media in the Presence of Residual Oil
Authors: Almajid Muhammad Majid , Kovscek Anthony R.
Published: April 2022

Foaming injected gas has the potential to overcome operational challenges encountered with pure gas injection. A mechanistic population balance model that integrates observed pore level events that are responsible for foam generation and coalescence in porous media was developed. The model is integrated in the AD-GPRS framework (Automatic Differentiation-General Purpose Research Simulator). Based on experimental pore-scale observations that show that the Roof snap-off geometric requirement for foam generation is affected due to the presence of residual oil in the pore, we upscale the pore-scale observations to the macroscale. We use experimental coreflood data from the literature to verify the performance of the model developed. The coreflood data are of two experiments that use the same core to perform a foam flood with and without the presence of oil. Pore-scale observations that show the effect of residual oil on the geometric Roof snap-off requirement translate into less germination sites at the macroscale. The generation constant used in the population balance model in the absence of residual oil reduces to one-fourth its original value when oil is present. The model developed was able to describe experimental data with good agreement both in the presence and absence of oil. In the presence of residual oil, all other foam parameters needed for the population balance model were fixed except the generation constant. The results demonstrate that the "hindered snap-off concept is able to describe foam flow when only residual oil is present.
Recent Advances of Alkali-Surfactant-Polymer ASP Flooding in China
Authors: Guo Hu , Lyu Xiuqin , Zhang Menghao , Xu Yang , Meng En , Liu Huifeng , Wang Zhengbo , Fu Hongtao , Zhang Yuxuan , Song Kaoping
Published: April 2022

Alkali-surfactant-polymer (ASP) flooding is very promising chemical enhanced oil recovery (EOR) technique which has drawn lots of attention. Compared with surfactant-polymer (SP) flooding and polymer flooding, ASP flooding incremental oil recovery can be much higher. This has been verified by several field tests in China. Alkali distinguishes ASP flooding and SP flooding. Alkali plays an important role in ASP flooding. How to select the alkali in the ASP flooding involves ASP flooding mechanisms. Although it is generally a consensus that the ASP flooding adopts weak alkali Na2CO3, strong alkali NaOH was also used both in laboratory and many field tests in China. ASP flooding field tests in Daqing oilfields are notable for the largest number and the biggest size in the world. ASP flooding was first put into commercial application in Daqing. Hence, the lessons and learnings from Daqing field practices as well as laboratory studies can help to provide insights into ASP flooding mechanisms. The number of strong alkali ASP flooding (SASP) field pilot projects is three times that of weak alkali ASP flooding (WASP) in Daqing. This was mainly caused by the difficulty to find suitable surfactants that can reduce oil water IFT to ultra-low for Daqing high wax content and low acid value oil. Earlier surfactants can only attain ultra-low IFT in presence of NaOH. The performance of WASP field tests (B-2-X) using surfactant Daqing petroleum sulfonate (PS) was well above expectation, and some SASP blocks had too high rate of corrosion and scaling. This makes WASP feasible and more attractive than SASP. Due to the sharp fall of oil price, how to choose alkali in Daqing oilfield is of great importance for optimum economic benefit. In 2012 and 2013, the first SASP and the first WASP demonstration project were put into operation in Daqing oilfield. In 2014, Daqing oilfield started to promote ASP flooding in an industrialized manner. In 2015, Daqing oilfield's ASP Flooding production accounted for nine percent of the oilfield's total oil production. In 2016, Daqing oilfield's ASP Flooding oil production reached more than 4 million tons, accounting for more than ten percent of the total oil production. This paper investigated the mechanisms of ASP flooding with a focus on alkali effect. The interaction between different chemicals, polymers, alkalis, surfactants were also studied. Surfactants screening has also been reviewed. The surfactants screening process differences between China and the USA were discussed.
Polymer Stabilized Foam Rheology and Stability for Unconventional EOR Application
Authors: Griffith Christopher , Jin Julia , Linnemeyer Harry , Pinnawala Gayani , Aminzadeh Behdad , Lau Samuel , Kim Do Hoon , Alexis Dennis , Malik Taimur , Dwarakanath Varadarajan
Published: April 2022

It has been shownthat injecting surfactants into unconventional hydraulically fractured wells can improve oil recovery. It is hypothesized that oil recovery can be further improved by more efficiently distributing surfactants into the reservoir using foam. The challenge is that in high temperature applications (e.g., 240 F) many of these formulations may not make stable foams as they have only moderate foaming properties (short half-life). Therefore, we are evaluating polymers that can be used to improve foam stability in high temperature wells which has the potential to improve oil recovery beyond surfactant only injection.Surfactant stabilized nitrogen foams were evaluated using a foam rheometer at pressures and temperatures representative of a field pilot well. The evaluation process consisted of measuring baseline properties (foam viscosity and stability) of a surfactant stabilized foam without any added stabilizer. Next, conventional enhanced oil recovery polymers (HPAMs, modified-HPAMs, and nonionic polymers) were added at different concentrations to determine their impacts on foam stability.

Our results demonstrate that inclusion of a relatively low concentration (0.05 wt% – 0.2 wt%) of polymer has a pronounced impact on foam stability. It was determined that reservoir temperature plays a key role in selecting astabilizing polymer. For example, at higher temperatures (>240 F), sulfonated HPAM polymers at just 0.2 wt% more than doubled the stability of the foam. The polymer that was selected from this lab work was tested in a foam field trial in an unconventional well. It is thought that improved foam stability could potentially help improve the distribution of surfactants in fracture network and further improve oil recovery.
Electronic structure, optical and thermoelectric response of lead-free double perovskite BaMgLaBiO6: A first-principles study
Authors: Munir Junaid , Jamil Muhammad , Jbara Ahmed S. , Fatima Kaneez , Murtaza Hudabia , Ain Quratul
Published: April 2022

Electronic structure, optical and transport properties of double perovskite BaMgLaBiO6 have been investigated theoretically with density functional theory (DFT) implemented in WIEN2k code. The structure is optimized to achieve the minimum energy at the ground state and the optimized lattice parameters. The calculated formation energy shows the stability of the compound, which confirms the possibility of synthesizing it. A band-gap of 2.7 eV is calculated with generalized gradient approximation (GGA) and further improvement, i.e., 3.8 eV is achieved with modified Becke-Johnson (mBJ) exchange potential. The electron density plots show both the covalent and ionic nature between the atoms. The calculated total density of states shows a good agreement with the band structure. The optical parameters are also calculated and a good optical conductivity is achieved in the selected energy range. The figure of merit is achieved up to 0.71 with mBJ which shows the suitability of the studied material for alternative energy devices. The overall response of the compound makes it a potential candidate for LED’s, lasers, power switching and thermoelectric applications.
Toxoplasmosis and abortive chlamydia in small ruminant farms in Cameroon: Knowledge, Attitudes, Practices and Perception of zoonotic risks of farmers.
Authors: Nankam Roland Chimi , KOUAMO Justin , NGOULA Ferdinand , BOUKAR Bakari , TCHINZE Grace Jedida TOUKEM , GAPGUEU Sandra Vanessa , Kouengoua Armelle Prudence Kouengoua , NOUMEDEM Ranyl NGUENA GUEFACK , NJAYOU Arouna NGAPAGNA , POUEME Rodrigue NAMEGNI , SIMO Josué
Published: April 2022

Zoonotic abortive diseases represent a significant health and economic risk for livestock farmers and animal health stakeholders in Cameroon. This cross-sectional survey was conducted from April to October 2021 among 200 selected small ruminant farmers in the three northern regions of Cameroon. Data collection was done through semi-structured questionnaires administered by exchange with the herder and responses were coded and recorded on an Excel spreadsheet. The data were then analyzed with R software, version 2.13.0. An ANOVA test was used to assess significant differences in mean KAPP scores between regions. Pearson correlations were used to calculate the association between KAPP scores within regions. Small ruminant farmers surveyed had low mean scores for knowledge of abortive Toxoplasmosis and Chlamydia (0.1 ± 0.2), desirable attitude (0.32 ± 0.07), appropriate practice (0.36 ± 0.13) in managing abortion, and positive perception of zoonotic risks of Toxoplasmosis and Chlamydia in small ruminants (0.12 ± 0.33), respectively. KAPP was significantly (p<0.01) and positively associated with knowledge (r=0.98) and risk perception (r=0.99). However, attitudes (r=0.06), practices (r=0.05) and risk perception of toxoplasmosis (r=0.07) and abortive chlamydia (r=0.08) were not associated with farmers' knowledge. This study revealed significant knowledge gaps, low levels of desired attitudes, and high-risk behavioral practices. These results therefore call for capacity building of health professionals and farmers to better integrate the One Health concept in the management of neglected zoonotic diseases.
Optimizing intra-facility crowding in Wi-Fi environments using continuous-time Markov chains
Authors: Mizuno Shinya , Ohba Haruka
Published: April 2022

Recently, increased measures are being devised to reduce crowdedness as a countermeasure for the spread of COVID-19. In this study, we propose a solution to reduce intra-facility crowdedness based on the usage of Wifi networks. This study maximizes the Wi-Fi logs that are continually generated in vast quantities in the ever-expanding Wi-Fi network environment to calculate the transition probabilities between nodes and the mean stay time at each node. Then, we model this data as a continuous-time Markov chain to obtain the variance of the stationary distribution, which we use as a metric of intra-facility crowdedness. Therefore, to minimize intra-facility crowdedness, we solved the optimization problem using stay rate as a parameter and demonstrated a numerical solution. In the optimization results, we succeeded in reducing intra-facility crowding by approximately 30%. This solution is a realistic approach for reducing intra-facility crowdedness as it makes adjustments to people’s stay times without any changes in their movements. We used the k-means method to categorize Wi-Fi users into a set of classes and documented the behavioral characteristics of each class, which helped implement class-specific measures to reduce intra-facility crowdedness. This enables facility managers to implement fine-grained countermeasures against crowdedness according to circumstances. Herein, we describe our computing environment and workflow for the basic analysis of vast quantities of Wi-Fi logs. Because the data we used are general-purpose, we believe that this research will be useful for both analysts and facility operators.
Computation of gamma radiation shielding parameters of lead monoxide filled polycarbonate composite films
Authors: Kandagal Vijayashri Ashok , Lobo Blaise
Published: April 2022

The gamma radiation shielding properties of lead monoxide filled polycarbonate composite materials for fourteen different filler levels (ranging from 0.25wt% up to 10wt%) have been studied theoretically by computing radiation shielding parameters such as mass attenuation coefficient, linear attenuation coefficient, half value layer and mean free path. The mass attenuation coefficient of gamma rays having specific energies (from 59.54 keV up to 1332.5 keV) has been calculated by using polynomial formula method and also by using two other methods, namely, Lagrangean interpolation method and Logarithmic interpolation method. Other shielding parameters like linear attenuation coefficient, mean free path, half value layer and tenth value layer have been calculated for these composites. The calculated values of mass attenuation coefficients fit well with NIST-XCOM data. The results suggest that, at higher filler levels, PbO filled PC composites can be good gamma shielding materials for ionizing electromagnetic radiation, especially in the low energy gamma or x-ray region.
Engulfment and cell motility protein 1 fosters functional reprogramming of tumor-associated macrophages in colorectal cancer
Authors: Wen Bo , Li Sheng , Ruan Lei , Yang Yanping , Chen Zilin , Zhang Bin , Yang Xin , Jie Haiqing , Li Shujuan , Zeng Ziwei , Liu Sisi
Published: April 2022

Background Functional reprogramming of tumor-associated macrophages (TAMs) is crucial to their potent tumor-supportive capacity. However, the molecular mechanism behind the reprogramming process remains poorly understood. This work aimed to investigate the involvement of engulfment and cell motility protein 1 (ELMO1) in TAM reprogramming in colorectal cancer (CRC).Methods The expression of ELMO1 in CRC was determined by western blots and immunohistochemistry. The biological effects of ELMO1 on TAM reprogramming were evaluated in vitro. The dependence of these effects on Rac1 was assessed using a Rac1 inhibitor (NSC23766). Cell function assays were performed to determine the role of ELMO1-reprogrammed macrophages in the context of CRC progression.Results The expression of ELMO1 in stromal but not epithelial tumor cells was positively associated with advanced clinical stage and poor disease-free survival in CRC. An increase in ELMO1 expression was specifically found in TAMs, but not in other multiple non-malignant stromal cells. Gain- and loss-of-function assays indicated ELMO1 reprogrammed macrophages to a TAM-like phenotype via Rac1 activation. In turn, ELMO1-reprogrammed macrophages were shown to not only facilitate the malignant behaviors of CRC cells but exhibited potent phagocytosis of tumor cells.Conclusion ELMO1 was shown to be a crucial player for TAM reprogramming in CRC. Our work underscores the importance of ELMO1 in determining functional reprogramming of TAMs and may provide new insights on potential therapeutic strategies against CRC.