bluuebunny/crossref_metadata_2025 huggingface dataset:
CO2 Sequestration in the Arbuckle Group: Flow Simulation in Osage County, Oklahoma
Authors: Hamzat A. A. , Milad B. , Moghanloo R. G.
Published: October 2023

This paper provides a valuable foundation for the potential establishment of a carbon dioxide (CO2) sequestration project in Osage County, Oklahoma. Given the current global climate crisis and the resultant efforts to reduce atmospheric CO2 levels, these types of initiatives are expected to increase in frequency and scale. This study focuses on the Arbuckle Group, a saline aquifer and carbonate rocks that has been identified as a potential large-scale CO2 storage reservoir in a previous publication by Milad et al. (2023).

A 3D geological model was constructed integrating core and well log data, allowing for the estimation of stratigraphic and petrophysical properties of the Arbuckle Group in Osage County. A 30-year injection period of over 50 million metric tons of CO2 was then simulated, incorporating the permeabilities and porosities from the geological model.

This process involved building a compositional simulation model with one injection well, with the formation divided into 10 layers and injections occurring in the bottom four. These layers were chosen based on the depth of existing injection wells, as well as the existence of natural fractures that enhance the permeability distribution, thus supporting large-scale CO2 injection at low pressure. A subsequent 50-year post-injection study was also conducted to monitor pressure buildup and CO2 plume evolution.

The formation was found to have an average porosity of 6%, variable permeability distribution, and an average reservoir thickness of about 940 ft. These properties make the Arbuckle saline aquifer an ideal candidate for CO2 sequestration, with ample storage capacity. We discovered significant potential for large-scale CO2 sequestration, owing to the natural fractures in the Arbuckle's lower section, and determined that a single well could feasibly store tens of millions of metric tons of CO2. This capacity could be significantly augmented by increasing the number of injection wells. We observed a positive correlation between the formation's permeability, particularly in the lower Arbuckle, and the volume of CO2 that can be stored. The study confirms the potential feasibility of safe and efficient carbon sequestration in the formation, with potentially minimal risks risking fracture or contamination of underground potable water sources, particularly if CO2 is injected deep in the formation. The less permeable upper Arbuckle, ranging from 0.0001mD to 2.5mD, could offer an additional protective layer. The dominant CO2 trapping mechanism was structural trapping in 3 of 4 simulation cases considered, with an increase in residual trapping at the end of the injection period.

The results of this study can serve as a valuable resource in the potential deployment of CO2 injection in the Arbuckle Group. Moreover, this study could aid decision making during field development in this formation and contribute to efforts to promote a sustainable future.
Laboratory Evaluation of Reversibility Feature of Physico-Chemical Water Shut-Off Agent for Enhanced Gas Recovery
Authors: Sergeev V. , Abe M.
Published: October 2023

A paper presents laboratory research conducted to evaluate technological properties of the nanoparticle-induced water shut-off agent and to assess its potential for gas recovery enhancement in geo-physically complicated reservoir conditions. The studied water shut-off agent is an inverse emulsion generated through the synergy of physico-chemical reactions between natural and artificial surfactants with silicon dioxide nanoparticles (NPs). Ultra-hydrophobicity and stability of the nanoparticle-based emulsion (nano-emulsion) conveys game-changing technological properties, resulting in a high performance of the water shut-off agent. Introduced in this paper research program was specifically developed to meet an inquiry of gas-condensate fields operator for an efficient physico-chemical or chemical water shut-off technology with zero secondary damage to reservoir. Therefore, the research program aimed to evaluate technological properties of the emulsion system with nanoparticles (ESN) in the tight sandstone formation conditions 8990 psi and 230°F. Firstly, rheometric study and tests in an autoclave were conducted to measure rheology, stability, compatibility and floating property of the ESN water shut-off agent under heavier polymer-clay fluid. Secondly, core flooding tests were conducted on four sets of natural low-permeable sandstone core columns to assess reversibility feature of the ESN water shut-off agent and a threshold pressure of the gas-condensate breakthrough. Rheology of the investigated water shut-off agent characterized by the share thinning behavior, i.e., viscosity drops under rise of the share rate and the other way around. The pseudoplastic behavior of the ESN perfectly suits applications in gas wells because it improves processes of preparing and pumping the water shut-off fluid downhole, does not float under heavier process fluids and self-controllable in-situ. It was learned that the ESN is compatible with reservoir and process fluids, and stable at reservoir conditions 230°F and 8990 psi. The ESN's blockage reversibility feature was confirmed in core floods. Overall, the research results confirmed innovative properties of the ESN water shut-off technology with its wide-range compatibility and high stability properties.
Best Practices of Flowback and Deliverability Analysis in the Canadian Unconventional Montney for Enhanced Treatment Stage Design and Reservoir Characterization
Authors: Virues Claudio , Robertson Alexandra , Sendecki Bruce
Published: October 2023

In September 2021, the Alberta Energy Regulator (AER) through a new pressure and deliverability testing directive issued new guidance for inline testing to align with the current practice for conducting these tests. Best practices of these techniques are presented for calculations for industry-submitted inline testing for flowback analysis and industry-submitted Absolute Open Flow deliverability analysis. Results are compared to previously published best practices in the Canadian Unconventional Montney.

The new approach is based on obtaining dynamic fracture dimensions such as fracture half-length and height, conductivity, associated matrix permeability, and well productivity index estimates. This information is supporting evaluation on reserves and near wellbore communication. Analytical and numerical method descriptions are provided that has proven to have significant implications for treatment stage design and reservoir characterization. Complete governing equations are provided and flowback and deliverability techniques are described in detail to permit readers to replicate all results.

80 field case studies are presented for multi-stage hydraulic fractured horizontal wells in the Canadian Unconventional Montney. Comparisons are also provided for Inline testing and deliverability- derived productivity index. The most significant new findings are the variability of fracture dimensions, conductivity, matrix permeability and productivity index impacting reservoir characterization. This is important for well spacing and bench-related reserves assessment at the pad level. For AER it also means an enhancement on reserves assessment of the Montney for its flagship report ST-98 by conducting Rate Transient Analysis (RTA) using rate and bottom-hole pressure information. The findings have direct practical implications for operators in the Canadian Montney shale play and analogous shale plays in USA and elsewhere. Accurate production and pressure data is needed for calculating linear flow parameters, effective surface area, fracture length / height and for optimizing well spacing and frac design. It could be used for input for Rate Transient Analysis (RTA) for resources / reserves assessments in similar unconventional plays.

The novelty of the new approach is in the ability to develop best practices in inline testing and analysis in the Canadian unconventional Montney, focus of significant short-term investment impacting royalties and solve non-uniqueness and/or uncertainty for well testing / completions/ production / reserves in reasonable time using the newly aligned engineering processes.
Importance of Thermal Modelling in CO2 Storage
Authors: Chidambaram P. , Yakup M. H. , Mohd Ali S. , Tewari R. D. , Tan C. , Tiwari P. K. , Das D. P. , Widyanita A.
Published: October 2023

Carbon dioxide sequestration in geological formations involves injection of carbon dioxide (CO2) into a reservoir. Irrespective of the phase of injected CO2 at the well head, there will be a change in temperature of CO2 as it travels from wellhead all the way up to its final storage destination in the reservoir. Such temperature changes affect the fracture gradient of the reservoir and the caprock. Thus, changing the maximum allowable injection pressure and consequently changing the storage capacity of the reservoir. Understanding and accounting for temperature changes is critical in providing a robust estimate of CO2 storage capacity.

A depleted gas reservoir in Central Luconia field, located offshore Sarawak, was evaluated for future CO2 storage. Conventional dynamic modelling is typically isothermal, since it is assumed that reservoir temperature changes during production are minimal and its impact on rock and fluid properties is negligible. But, during CO2 sequestration in geological reservoirs, there could be significant change in temperature of injected CO2 starting from wellhead all the way to the final storage location within the reservoir. Some of the reasons for change in temperature of injected CO2 are a) temperature difference between reservoir and injected CO2; b) geothermal effects as CO2 travels in the wellbore from wellhead to bottom of wellbore; c) Joule-Thompson effect when injected CO2 expands as it enters the reservoir; d) geothermal effects as CO2 migrates through the reservoir to its final storage location. These temperature changes are significant enough to affect the rock and fluid properties. Thus, altering fracture pressure and seal strength. Hence thermal modelling that accounts for changes in temperature has been utilized to estimate storage capacity and CO2 plume migration in the reservoir.

Thermal modelling results show significant cooling near wellbore and all the way up to caprock vertically above injection point. A temperature change of up to ~150 °F has been observed near wellbore and a temperature change of up to ~70 °F has been observed at the caprock. The temperature remains mostly unchanged as we move away from the injector. But the temperature changes observed near caprock directly above injection point is important since this reduces the caprock fracture gradient by as much as ~700 psi. This has a significant impact on storage capacity due to reduction in caprock injection pressure limit. Storage capacity from the thermal model is lower by as much as 10% compared to storage capacity from isothermal model.
Tailored Metal Oxide Nanoparticles-Based Fluids in Acid Restimulation Treatments Reverses Long-Term Hydrocarbon Decline: A Pilot Study in Wolfcamp (A) Formation
Authors: Dalamarinis P. , Radwan A. , Ramanathan R. , Ellafi Abdulaziz , Khanal Suman
Published: October 2023

Multi-fracture horizontal wells suffer from high hydrocarbon decline and water-cuts after initial flow back. This behavior is in part because of near/far field-fracture conductivity damage. Re-fracturing operations (acid or proppant) can mitigate these problems yielding a good cleanout performance and stable oil recovery trends. This paper details a successful pilot to improve long-term well performance using acid stimulation aided by a pioneering tailored metal oxide (TMO) nanoparticles-based fluid in Wolfcamp (A) formation.

Seven wells (in two different areas) with similar designs, same geological landing zone, located within 1 mile from each other were selected to be re-stimulated with different surfactant blends. These wells were producing an average of 4,500 bwpd at a 96% water cut. Acid stimulation programs with a total treatment volume of about 2,000 barrels was designed to stimulate each well. Regular surfactant was added to the treatment fluid in 5 wells, while 2 wells implemented the TMO Nanofluid. The TMO Nanofluid had previously been shown to improve production rates and reduce water cuts with specific focus on long-term performance.

Water cuts, gas-oil ratios (GOR), and hydrocarbon decline rates were monitored daily to observe any significant differences between the well production behaviors. The surfactant-injected wells demonstrated an average of 40% production decline in the 1st six months. The TMO Nanofluid-injected wells showed a reverse trend with a production decline of 5% in the 1st month followed by a production improvement of 10% in the 2nd month and less than 10% production decline after 6 months. This type of behavior is consistent with previous field experiences with the TMO Nanofluid where the production improvement had been sustained over time. The water cut in all wells decreased to about 96%. The TMO Nanofluid worked by providing a unique long-term wettability alteration, reducing the interfacial tension, allowing the chemicals to be retained in the fracture/reservoir phase. It also functions to remove near-wellbore organic formation damage via the structural disjoining mechanism. Overall, this results in better stimulated wells for long-term performance.

The unique characteristics of the TMO Nanofluid in acid stimulation treatments can help restore well/reservoir conductivity and remove near-wellbore formation damage, resulting in improved long-term performance characteristics and improved production decline rates.
Lab Study of High WAT Wax Deposition Reduction with Wax Inhibitors and Dispersants
Authors: Bian Y. , Chiang P. T. , Kiran S. , Wiebe D. , Oswald D.
Published: October 2023

Canadian crude oil and pigged wax from the Montney formation show high wax appearance temperatures (WAT) and experience severe deposition issues during production and transportation. Several commercial wax inhibitors and wax dispersants were studied in the crude oil and reconstituted oils (pigged wax added back to the crude oil and dodecane model system), to minimize the wax deposition by a systematic lab screening protocol. Suitable wax inhibitors (WI) and dispersants were selected and formulated at optimized dosage to efficiently reduce the wax deposition at close to field condition.

The crude oil and reconstituted oils were utilized to study the high WAT wax performance with different types of wax inhibitors and dispersants. This included ethylene vinyl acetate (EVA), alkylphenol formaldehyde resin (AFR), acrylic copolymer (AC), α-olefin maleic anhydride copolymer (AOMAC) and several surfactant-based wax dispersants (WDs). A pour point tester was employed as the initial screening tool to determine the pour point and detected wax appearance temperature (DWAT). Multiple Light Scattering (MLS) was used to evaluate the dispersions of wax in the oil. Dynamic wax deposition tests by capillary flow through (CFT) and dynamic flow loop (DFL) systems were used to verify the wax deposition reduction efficiency, and to study the effect of the test parameters on wax deposition.

The reconstituted oils had higher WAT (>55 °C) than produced oil. The screening tests showed that EVA significantly reduced the DWAT and pour point of the crude oil but was not very efficient in the reconstituted oil. Both AFR and AC reduced the DWAT and pour point but were not as efficient as AOMAC. AOMAC provided the lowest DWAT in the reconstituted oil. It was interesting to find that surfactant-based dispersants also reduced the DWAT of the reconstituted model oil. The top performing WIs and dispersants were then tested by CFT wax deposition system at a flowrate of 1.5 cm3/hr. For the crude oil at 10 °C, 225 ppm AOMAC WI was needed to efficiently reduce the wax deposition in the CFT system. A lower dosage was required in the DFL system. It was also found that wax inhibitor and dispersant together further reduced the reconstituted model oil wax deposition in the CFT system. MLS and bottle tests showed that the WDs helped to disperse the wax in both oil and aqueous phases.

From this systematic WI study on kinetic and dynamic behaviors of high WAT wax deposition, a synergy was observed between wax inhibitors and dispersants. Further investigation is needed to understand how they work together. The specially designed laboratory screening protocol helped to understand the structure and performance relation, efficiently formulate the WIs/dispersants, and optimize the treatment dosages. The inclusion of surfactants/dispersants with WIs could further mitigate wax deposition and be a more cost-effective approach.
Reconsider Your Unpreserved Core: Resurrecting Impactful Data via Closed Retort Thermal Extraction
Authors: Zumberge J. A. , Piper N. C. , Milovac J.
Published: October 2023

Over the past decade and spanning many disciplines, significant progress has been made in the discovery and understanding of unconventional hydrocarbon plays, both through laboratory studies and in-situ analysis. As a result, most operators and researchers still have access to large amounts of residual core material in various states of preservation (wax sealed, foil wrapped, chilled, unpreserved, etc.). This core was originally collected to answer specific questions related to the assets being evaluated, but there is now growing interest in reusing and reexamining this legacy material to explore new ideas, opportunities, and understandings, as well as to increase the potential for enhanced oil recovery. In this study, we show the potential of legacy unpreserved core material providing resurrected datasets via advancements in core extraction methodologies (e.g. closed retort). Results from these preserved/unpreserved core comparison experiments demonstrate the impact that running legacy rock volume can have in terms of additional learnings, calibration and knowledge gain.
Deformation, Damage, And Fracture in Hot Dry Rock of Geothermal Reservoir Under Uniaxial and Diametrical Compression Using 3D-DIC
Authors: Nath F. , Aguirre G. , Vazquez E. C. , Portillo O. , Gindic R. , Cuellar A.
Published: October 2023

Geothermal resources have attracted global attention because of their renewability, cleanliness, and universality. The U.S. Department of Energy estimates that harnessing just 0.1% of the Earth's geothermal energy can power humanity for 2 million years. An improved geothermal system (EGS) efficiently extracts heat from deep hot dry rock (HDR). However, EGS is battling to assure safe drilling and appropriate fracturing to extract heat potential. Conventional laboratory techniques cannot detect fine-scale variability in HDR structures during loading. Due to its inherent heterogeneities, it is especially crucial to characterize deformation and frac-face damage during induced fracturingto unlock heat energy from HDR. This study uses three-dimensional digital image correlation (3D-DIC) to examine damage and deformation in HDR samples.

HDR samples from the DOE Utah FORGE project's Well 16B(78)-32 were studied under uniaxial and diametrical compression using a precise 100kN electro-mechanical load frame with a continuous displacement of 0.05mm/min. The samples had a wide range of minerals. During the uniaxial and diametrical compression tests, a3D-DIC image capture system was set up to watch the samples without touching them at a rate of 5 frames per second. A black-and-white speckle pattern is affixed to the specimen to monitor its deformation under load. The 3D-DIC system is used for image processing, visualization, and analysis of the HDR damage process under various load circumstances.

Our preliminary results of DIC-generated quantitative full-field strain maps (tension, compression, and shear) exhibiting all sequences involved in the damage process of HDR samples. To evaluate the sample damage, damage factors are measured using DIC maps; the tension-compression ratio is obtained at 5%-10%. The damage evolution process of HDR specimens is separated into four stages, which are evaluated by damage variables: initial damage stage, linear elastic, elastic-plastic, and plastic damage stage.

The findings have a major impact on our ability to predict the damage process in EGS. DIC outperforms micro-Computed Tomography(µ-CT), Scanning Electron Microscope (SEM), andAcoustic Emission(AE) in terms of test range, affordability, accuracy, and monitoring of the entire field. This method overcomes the laboratory limitations for evaluating HDR damage heterogeneity. This image-based algorithm is better at understanding anisotropic and heterogeneous HDR fragmentation and predicting stimulated reservoir volume (SRV). Thus, the results of this study will enhance the effectiveness of hydraulic fracturing in HDR and heat recovery from EGS.
In-Reservoir Mixing Dynamics Over Geologic Time of Separate Gas and Oil Charges in Well-Connected Reservoirs
Authors: Mohamed Tarek S. , Kristensen Morten , Pan Shu , Wang Kang , Betancourt Soraya S. , Torres-Verdín Carlos , Mullins Oliver C.
Published: October 2023

Many reservoirs experience separate gas and oil charges that can lead to a variety of different outcomes of fluid type and distribution. There has been fundamental uncertainty even as to which charge fluid can arrive first, let alone what fluid dynamic processes can result over geologic time. For high-pressure basins such as the Gulf of Mexico, this mixture can lead to increased solution gas, large GOR gradients and sometimes cause formation of viscous oil and tar at the oil-water contact, impacting aquifer support. In some reservoirs, the present-day outcome of oil and gas mixing over geologic time is clearly established by detailed chemical evaluation of reservoir fluids from many reservoir locations. Our objective is to understand the dynamics of the gas and oil mixing processes. Chemical measurements show that the extent of mixing includes thermodynamic equilibration in young reservoirs by 1) FHZ equation of state (EoS) asphaltene gradients and cubic EoS modeling of solution gas for reservoir fluids, 2) analysis of liquid-phase geochemical biomarkers, and 3) methane carbon isotope analysis. Specifically, in the common charge of primary biogenic gas and oil into reservoirs, methane isotope analysis is unequivocal. We employ reservoir simulation of a point gas charge into oil with various geometries and charge rates to establish parametric conditions which lead to excellent mixing vs those conditions that lead to large, disequilibrium gradients. The roles of compositional diffusion vs. momentum diffusion induced by forced convection are explored both in simulation and overall fluid mechanics analysis, which helps both to validate the results and extend the range of applicable parameters. Modeling results and simple fluid mechanics estimates also establish that there is no possibility that these reservoirs could have a gas charge followed by an oil charge; in the selected reservoirs, oil must have arrived first, followed by a biogenic gas charge. Seismic images of gas chimneys offer guidance regarding how the latter process can take place. Second, modeling results clearly establish a surprisingly wide range of charge conditions that can lead to excellent mixing and equilibration even for a point gas charge. Modeling results also show that for a very fast charge, results are consistent with those expected for CO2 injection and sequestration. The evaluation of geodynamic processes of separate biogenic gas and oil charges into reservoirs has rarely been accomplished. Even the result that biogenic gas charge must occur after oil charge challenges widely-held conventional thinking. In addition, the rapid and thorough mixing (less than 2 million years) of gas and oil charges is unexpected yet readily reproduced by reservoir simulation. The ability to connect CO2 sequestration to a wide range of reservoir studies is a novel way to constrain CCS modeling.
Machine Learning Based Automatic Marker Clustering
Authors: Katole Atul Laxman , Abubakar Aria , Hoekstra Edo , Ryali Srikanth , Zhao Tao
Published: October 2023

Accurate information pertaining to the markers or well tops is critical to define the key formation boundaries in the regional stratigraphic frameworks. The information with respect to the markers in larger basins is spread across multiple sources as the various tools utilized in the Oil and Gas industry, public data repositories and the well logs provided by data vendors. Collaboration across such multiple sources of information is essential if we need to develop subsurface models for the larger basins. However, such collaboration is non-trivial and is accompanied by challenges. The well tops information is interpreted uniquely by interpreters across different organizations, probably using different stratigraphic columns. The multitude of well top information sources, interpreters and stratigraphic columns introduce inconsistencies in the well top information.

We propose deep learning based unique interpretation of the various marker log patterns which can consistently map them across the wells in a region. The transformer model is trained using a self-supervised learning approach to predict the randomly masked well log values in the input. This allows the transformers to learn the feature hierarchy in the marker log patterns which is manifested in the latent space representations. The proposed approach utilizes transformer latent space to represent markers in a lower dimensional feature space which are further projected using Uniform Manifold Approximation and Projection (UMAP) to two dimensional embeddings. We apply Gaussian Mixture Models (GMM) based probabilistic clustering on the embeddings to automatically separate the marker representations. We evaluate the transformer latent space based automatic marker separation models using Bakken open-source dataset and choose six markers for the evaluation. We find that the proposed approach can separate the markers with very high accuracy, giving us excellent precision and recall for all analyzed markers. This approach enables automatic separation of the marker patterns and maps them consistently across the wells in a basin.
Research on the Method of Multi-Agent and Multi-Slug Combined to Achieve the Reservoir Equilibrium Displacement
Authors: Chen Xin , Li Yiqiang , Zhang Jian , Li Xianjie , Liu Zheyu , Liu Shun
Published: October 2023

The reservoir and fluid properties determine that a single injected fluid will inevitably undergo channeling during displacement. Whether it is water flooding, gas flooding, or steam flooding, it is necessary to control the injection-production profile. This paper aims to design the multi-agent and multi-slug combination displacement to achieve the equilibrium production of reservoirs. Considering the heterogeneity and median permeability of the reservoir, six three-parallel core models were designed. Polymers, hydrophobic association polymers, microspheres, and PPG are multi-agent profile control systems. The displacement equilibrium factor (DEF) was established by comprehensively considering the profile improvement, oil increase, and oil recovery. The optimal switching time can be determined according to the relationship between DEF and the variation coefficient of oil recovery of each layer. Finally, the five-parallel cores displacement experiments were used to verify the EOR effect under the guidance of DEF. Three-parallel core flooding experiments show that the best EOR efficiency can be obtained by plugging from the high permeability layer to the low permeability layer based on fully producing high-permeability layers. Water flooding - associated polymer flooding - microsphere flooding can increase oil recovery by 25.8% after water flooding. Calculate the DEF of 24 single-slug displacements, and draw a scatter diagram with the variation coefficient of the three layers’ oil recovery. The chart has an obvious inflection point that when the DEF is lower than 45%, the difference in the oil displacement effect is enhanced. Therefore, DEF reduced to 45% is the best time to switch the injection slug. The five-parallel core flooding experiments with the DEF<45% as the switching guidance can increase the oil recovery by 17.79% based on association polymer flooding, which is 9.68% higher than that of the conventional profile control method. Slugs combination mode and switching time of each slug are critical problems in applying multi-agent and multi-slug combination displacement. This work forms a combination idea of prioritizing the full use of high-permeability layers and then plugging them step by step. Meanwhile, a method of using DEF to dynamically guide the switching timing of each slug is formed. This paper can provide theoretical and experimental support for the optimal design of polymer injection parameters in oilfields.
An Application of Superhydrophilic Coating to Enhance the Water Film Retention for Core Annular Flow
Authors: Wang W. , Li Z. Z. , Wang X. L. , Xue Q. , Liu M. R. , Yang J. , Wang P. X. , Ding K. , Sun X. Z.
Published: October 2023

The tremendous viscosity of heavy oil presents significant challenges to the pipeline transportation and efficiency improvement of oil gathering systems, thus prompting the execution of numerous studies that aim to reduce drag. The core annular flow is regarded as one of the most efficient and eco-friendly methods for drag reduction, but its commercial application is limited by the inadequate stability of the water film. In this work, a concept of water film retention enhancement at the pipe wall through superhydrophilic coating is presented, to increase the stability of core annular flow in heavy oil flowlines. Furthermore, a novel measuring method that efficiently evaluates the water film retention enhancement performance of superhydrophilic coating using a rheometer is proposed. This method is more effective, oil-saving, and sensitive compared to conventional flow loop tests. The influence of temperature, shear rate, and water film thickness on water film retention are studied. It was found that the viscosities measured with superhydrophilic coating decreased by approximately 40% at 50 °C and showed a reduced temperature-dependence, compared to the inherent viscosities of heavy oil. This decrease in viscosity was attributed to the lubrication provided by the water film. The viscosities measured with coating were also found slightly decrease with increasing shear rates from 10 to 120 s−1, indicating that the water film retention is enhanced by coating and the emulsification of heavy oil and water film is prevented even under strong shear. Moreover, it was observed that the water film thickness had a negligible impact on the measured viscosities as long as the water was sufficient to fully wet the coating. These results verify the feasibility of using superhydrophilic coating to enhance water retention and show a promising possibility of practical application of superhydrophilic coating in core annular flow for transporting heavy oil.
Statistical Aggregation - A Simple Tool in the E&P Industry for Estimating the Economic Value of a Complex Project
Authors: Khan I. , Aslam M. A. , Hasan A. , Palekar A. H.
Published: October 2023

Economic evaluation is an important decision-making tool for drilling an exploratory well. The paper is focused on a well drilled in the Mesopotamian basin in Iraq. Before its drilling, it needs to be passed through the technical and commercial gates. The prospect contains multiple (five) reservoir targets. To properly evaluate its technical and commercial potential, it was prudent to give weightage to each reservoir. To assess the Expected Monetary Value (EMV) of the prospect, a total of 32 economic cases needed to be built in the decision tree which makes the working & decision complicated for the management.

It may be noted that in Iraq most companies operate under Service Contracts which itself is not common in the industry to assess commerciality. To cater for the above, a statistical aggregation methodology was adopted in which hydrocarbon volumes (HCIIP) and the chance of success (CoS) of five individual reservoirs were transformed into one number. Accordingly, the economics was performed on this number and the corresponding prospect EMV is calculated. The results were presented to the technical and commercial gates and were accepted by the management and approval was granted.

It may be noted that results from statistical aggregation were rechecked by performing the economics on 32 cases and both results were found comparable. Therefore, this technique was used to quickly assess the EMV of a complex project for decision making and the same technique can be helpful in commercial decision-making of any scale.

The fit-for-purpose approach was utilized in view of the complexity of the project. This work will serve as a reference for statistical aggregation in the oil industry, to evaluate the commerciality of the project with multiple reservoirs. The findings can also be used to gauge the feasibility of any farm-in block where multiple leads and prospects are available, and a quick decision is required to ascertain its value.
Consistent EUR Forecast in Permian Multiphase Unconventional Reservoirs with Pressure Normalized Rate Method
Authors: Xie Xueying , Liu Shunhua
Published: October 2023

Consistent Estimated Ultimate Recovery (EUR) forecasting has been a much-studied topic for the development and reserves estimation of unconventional resources. It is widely known that unconventional well EUR forecasts using Arp's Decline Curve Analysis (DCA) are not very accurate in early time. This is because Arp's empirical equations were originally defined for constant operating pressure and unconventional wells have significant early-time variations in operating pressure. Consequently, EURs based on early DCA are often overestimated. This paper develops the Pressure Normalized Rate Decline Curve Analysis (PNR DCA) method and demonstrates its ability to provide consistent EUR forecasts for Permian multiphase unconventional wells through multiple case studies and dynamic reservoir simulation.

The authors developed PNR DCA method by normalizing actual oil rate to a rate at constant flowing pressure (PNR) and then applying decline curve analysis using the PNR to forecast EUR of Permian unconventional wells with limited production history. This method was first developed for a single-phase gas reservoir, the Haynesville shale (Xie et al., 2012). Lacayo and Lee (2014) introduced this method to forecast wells in four different shale plays (Eagle Ford, Woodford, Marcellus, and Bakken) for more accurate early forecasts, mostly for single-phase oil or gas reservoirs. This paper describes how the method was modified for more complicated Permian reservoirs, in which the resource contains mobile water and many wells feature early gas/oil ratio (GOR) increases, resulting in multiphase flow in the reservoirs.

The method was validated with the data from over 100 wells with significant history (1-5 years) in the Bone Spring, Spraberry, and Wolfcamp formations in both the Midland and Delaware basins. The EUR estimated using the PNR DCA method was also found consistent with forecasts using history-matched dynamic reservoir simulation. The validation results show the PNR DCA method can provide relatively consistent EUR forecasts with limited production data, whereas Arp's DCA method can only forecast consistent EUR after flowing pressures stabilize, which can take a year to achieve. Results indicate that the PNR DCA method works for several sub-regional areas of the Permian Basin, including areas where water cut is as high as 80-90%.
Evaluation of Synergetic Rheological Behaviour of Polymer and Silica Nanofluids for Enhanced Oil Recovery
Authors: Joshi D. , Maurya N. K. , Mandal A.
Published: October 2023

Reservoirs with partially hydrolyzed polyacrylamide (PHPA) aqueous displacing injected fluids improve the amount of oil produced noticeably. However, the medium's temperature and salinity significantly impact the viscosity of these fluids, which is critical in specific reservoir conditions for oil recovery. Thus, adding nanomaterials in PHPA solutions to prepare nanofluids has been shown to be a promising alternative to increase viscosity and improve performance in enhanced oil recovery. The dispersion of NPs in the aqueous polymer solution was characterized by DLS and zeta-potential measurements for stability. The contact angle measurement was also performed of silica nanofluid for examining the ability to wettability alteration. In the rheological studies, it was observed that there was an improvement in the viscosity by adding Silica Nanoparticles in the polymeric solution by 20%. Along with the improvement, silica polymer nanofluid also reduces the viscosity losses at reservoir temperature over 28 days. The experimental results showed that Silica Core flooding experiments were performed to observe the synergetic efficacy of the nanofluids with polymer in barea sandstone core at 90°C. The Silica NPs Assisted Polymer EOR Agent exhibit superior stability characteristics, to a lesser extent, viscosity losses after ageing and good stability, which are desirable for functional application in enhanced oil recovery (EOR) processes, which was confirmed by the result of EOR core flooding with maximum Incremental Oil Recovery of 28 % after water flooding.
Impact of Vancomycin trough levels monitoring on uncomplicated methilcillin-resistant Staphylococcus aureus bacteremia in chronic kidney disease on hemodialysis, retrospective cohort
Authors: Osorio Julian Felipe Ramirez , Velez-Hernandez Juan Esteban , Castaño Nathalia Fernández , Hernandez David Felipe Rojas , Barragan Fabian Jaimes
Published: October 2023

Background
CKD patients on hemodialysis (HD) with Staphylococcus aureus (SA) bacteremia present high morbidity, mortality and increased risk of MRSA. Vancomycin is the antibiotic of choice in these cases, it has a narrow therapeutic margin and inadequate narrow therapeutic margin and inadequate dosage generates a risk of toxicity, therefore, they recommend that its dosage be guided through measurement of serum levels.
Methods
This is a retrospective cohort study in 3 hospitals of third level of complexity in the city of Medellin in which there were differences in the measurement and implementation of vancomycin25 dosage based on trough levels (VL) in patients with chronic kidney disease on hemodialysis (CKD- HD) with uncomplicated bacteremia based infection by methilcillin-resistant Staphyloccocus aureus (MRSA). The primary outcome was the composite of hospital mortality, clinical response (fever, hemodynamic instability and altered consciousness), complications associated with bacteremia or bacteriological response failure (positive cultures at first week follow-up) at 7 days, and the composite variables were analyzed individually as secondary outcomes.
Results
The main unadjusted outcome (OR 1.3, CI 0.6–2.7) and adjusted for age, Charlson index, loading dose, initial dose, dosing frequency and MIC to vancomycin (OR 1.2, CI 0.5–2.7). Regarding adjusted secondary outcomes: clinical response (OR 1.4 CI 0.3–5.8), death (OR 1.3 CI 0.3–4.6) and complications (OR 0.9, CI 0.37–2.2).
Conclusions
We conclude that the measurement of trough levels in patients with HD-CKD does not modify the composite outcome. The main limitation is the sample size and type of study, so that preferably randomized studies are required to confirm the results presented.
Training Status Levels as a Non-Pharmacological Therapeutic Tool for Blood Pressure Control in Hypertensive Older Adults
Authors: Silva Roberta , Reia Thaís , Jacomini André , Souza Thiago , Nicoletti Rafael , Zago Anderson
Published: October 2023

Deficiency in nitrite (NO2−) concentration and angiotensin-converting enzyme (ACE) activity can contribute to the high incidence of hypertension. Conversely, physical exercise has been shown to counteract these effects. Thus, the purpose of the study was to verify the effect of physical exercise programs lasting 12 weeks on the training status level (TS), plasma NO2−concentrations, ACE activity, and systolic and diastolic blood pressure (SBP / DBP) in hypertensive older adults. After 12 weeks of intervention, participants classified initially with weak TS-level obtained an improvement only in the general functional fitness index (GFFI). Regular TS-level group presented an increase in GFFI and a decrease in ACE activity (34.18 ± 17.82 / 29.73 ± 16.51, p = 0.039 / Δ=-4.44) and SBP (132.15 ± 13.14 / 125.37 ± 12.89, p = 0.006 / Δ=-6.77). Good TS-level group presented improvement in the concentration of NO2−(0.134 ± 0.04 / 0.160 ± 0.42, p = 0.001 and Δ = 0.026) and SBP (127.23 ± 11.97 / 122.52 ± 14.55, p = 0.013 and Δ=-4.70). Additionally, the analysis of functional fitness components individually did not influence the BP control variables. These results suggest that changes in the TS (regular or good) provide a positive effect on such variables in hypertensive older adults, however weak TS did not have enough intensity to generate positive changes in BP control variables.
An 8-week injury prevention exercise program combined with change-of-direction technique training reduces change-of-direction knee joint loading without compromising performance
Authors: Mohr Maurice , Federolf Peter , Heinrich Dieter , Nitschke Marlies , Raschner Christian , Scharbert Julia , Koelewijn Anne
Published: October 2023

Knee ligament sprains are common during change-of-direction (COD) maneuvers in multidirectional team sports. This study aimed to compare the effects of an 8-week injury prevention exercise program containing COD-specific exercises and a similar program containing linear sprint exercises on performance- and injury-related variables during a 135° COD task. We hypothesized that the COD-specific training would lead to more effective reductions in the peak knee abduction moment (H1) as an indicator for knee injury risk and more effective improvements in COD performance, i.e., lower COD completion time (H2) and sharper executed angle (H3). Twenty-two sports science students (40% female) completed biomechanical assessments of COD movement strategies before and after participating in two supervised 25-minute training sessions per week over eight weeks. In partial support of our hypothesis, the COD-specific training but not the linear sprint training led to reduced peak knee abduction moments (significant ‘training*group’ interaction, p = 0.034) compared to baseline. At the same time, the COD-specific training did not lead to a significant performance detriment. In conclusion, a generic knee injury prevention program combined with COD-specific exercises has the potential to prevent knee sprains in multidirectional team sports more effectively than generic programs alone without compromising COD performance.
Interactive effects of elevated CO2 concentration and drought stress on some physio-morphological and biochemical characteristics of Quercus brantii seedlings
Authors: Yousefvand parvaneh , Pilehvar Babak , Nasrolahi Ali Heidar
Published: October 2023

The elevated atmospheric CO2concentration is expected to increase plant growth and productivity and improve water use efficiency. Hence, elevated CO2is considered to mitigate to some extent the adverse effects of drought. We aimed to investigate physio-morphological and biochemical responses of 2-year-old Persian oak (Quercus brantiiLindl.) seedlings to the elevated CO2concentration and drought alone and when combined. Persian oak seedlings were grown in growth chambers at two CO2concentrations (ambient; 380 ppm and elevated; 700 ppm) and two water regimes (well-watered; 100% of field capacity and water stress; about 50% of this value) for one growing season (8 months). The results showed elevated CO2concentration significantly increased collar diameter, shoot height, leaf area, biomass production, root volume, photosynthetic traits, leaf pigments (chlorophyll and carotenoids) content, and relative leaf water content. While, it decreased total N content of leaves, proline content, electrolyte leakage, Malondialdehyde content, and antioxidant enzymes (catalase, peroxidase, and ascorbate peroxidase) activity in comparison to ambient CO2concentration. However, the root length was unaffected in response to elevated CO2. In contrast, drought had an adverse effect on the studied traits except for root length. These effects were alleviated by the presence of CO2, as apparent in physio-morphological and biochemical traits. Our findings suggest that in different proposed climate change scenarios, Persian oak trees may tolerate drought in the presence of elevated CO2.
A Novel Nomogram Based on Multi-Detector Computer Tomography Radiomics of Pectoral Muscle for Predicting Prone to Acute Exacerbation in COPD
Authors: Zhu Tingting , He Qian , Yang Xiao , Li Zhichun , Li Xinghui , Lei Yan , Tang Wei
Published: October 2023

BackgroundDeveloping and validating a radiomics nomogram to predict prone to acute exacerbations in chronic obstructive pulmonary disease (COPD) patients.Methods118 patients prone to acute exacerbation of COPD (PAECOPD) and 92 patients with relatively stable COPD (SCOPD) were split into a training cohort (n=146) and a validation cohort (n=64). Radiomics features of the pectoral muscle (PM) were extracted from the cross-sectional image above the level of the aortic arch on the chest unenhanced multi-detector computer tomography (MDCT) images. We constructed a radiomics signature and calculated a radiomics score (Rad- score). Combination of Rad-score and clinical factors (including quantitative indicators of PM on MDCT) associated with PAECOPD, a radiomics nomogram was constructed with a multivariate logistic regression model. We evaluate the performance of the radiomics nomogram concerning discrimination, calibration, and clinical usefulness.ResultsThe radiomics signature model was built with twelve features. The radiomics nomogram displayed better discrimination capability (P< 0.05) both in the training cohort (area under the curve(AUC), 0.932; 95% confidence interval (CI), 0.891–0.973) and the validation cohort (AUC, 0.896; 95% CI, 0.816–0.975) compared with the clinical factor and radiomics signature, and displayed excellent calibration in the training cohort. According to the decision curve analysis (DCA), the radiomics nomogram demonstrated better clinical usefulness than the clinical factors and radiomics signature alone.ConclusionThe radiomics nomogram based on MDCT combines radiomic signature and clinical factors for predicting acute COPD exacerbations non-invasively with favorable predictive efficacy.