bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immiscible and Near-Miscible Gas Flooding in Tight Chalk: Laboratory Experiments and Compositional Simulation
Authors: Mirazimi Seyedamir , Olsen Dan , Stenby Erling Halfdan , Yan Wei 
Published: June 2022

Abstract
History matching methods are widely used to extract relative permeability curves as well as other uncertain parameters, which cannot be measured accurately through laboratory analysis. This study presents the results of gas flooding experiments in composite chalk cores and seeks a systematic approach toward overcoming the challenges encountered during history matching of the performed experiments.
Two vertical core flooding experiments are conducted on tight chalk composite cores at two different pressures providing immiscible and near-miscible conditions for the natural gas and live oil used. An EoS (equation of state) model tuned with routine PVT tests as well as swelling data is used to simulate the experiments by Eclipse compositional simulator E300. Difficulties encountered in the process of history matching are addressed, and a proper method to be implemented to resolve each of the problems is proposed and investigated in detail.
A common drawback in compositional simulation of gas injection processes is the excessive vaporization of oil into gas due to local equilibrium assumption, which leads to over-predicting the oil production. It is shown that using a proper technique such as the Sorm method (available in Eclipse via SOR keyword) can be an efficient solution to overcome this issue. It is also established that in the absence of enough reliable data for absolute and relative permeability, these parameters can be subjected to modification and improvement based on experimental observations such as gas breakthrough time and the pressure difference across the core. Furthermore, the change of relative permeability due to the reduction of IFT (interfacial tension) at near-miscible conditions is studied in detail, and the contradicting findings in this area reported by various authors in the literature are elaborately discussed. Different approaches for correcting the relative permeability of the wetting and non-wetting phases are examined in the history matching process and the obtained results are evaluated by being compared to the experimental results of this study.
The findings of this work can help to identify and resolve some of the most common problems in compositional simulation of gas injection processes. These results should specifically be taken into consideration in upscaling the reservoir characteristics and performing field-scale simulations in order to obtain reliable results for the future performance of the field.
The Effect of Core Wettability on Oil Mobilization, Capillary Forces and Relative Permeability in Chalk
Authors: Pinerez Torrijos Iván Darío , Strand Skule , Puntervold Tina , Kahlbom Wathne Agnes , Harestad Amalie , Radenkovic Katarina , Andersen Pål Østebø 
Published: June 2022

Abstract
Rock wettability is of utmost importance when assessing reservoir recovery processes, because it controls key transport properties of fluid flow in porous media. The effects of wettability on capillary forces, fluid distribution, and oil mobilization are of great interest for understanding waterflooding and water-based EOR processes such as Smart Water injection.
Two strongly water-wet and three reduced water-wet chalk cores containing Swi = 20% and 80 % non-wetting mineral oil were used in this study. Spontaneous imbibition (SI) experiments were used to assess the wettability of restored core material and forced imbibition (FI) tests were carried out to capture fluid flow behavior under a viscous force dominated environment. Oil recovery and pressure drop profiles, start and endpoint core saturations and pressure drops were collected in front of and during FI tests with formation water (FW) as injection fluid to avoid any chemical induced wettability alteration. The SI oil recovery results showed that the cores exposed to crude oil possessed reduced water wetness compared to the strongly water-wet reference cores. The FI oil recovery results showed only small differences in oil production profiles and ultimate recoveries. The oil recovery profiles displayed a piston-like displacement indicating that oil recovery was controlled by capillary forces at the injection rate used.
SENDRA was used to simulate the effect of wettability on relative permeability and capillary pressure curves for the strongly to reduced water-wet cores from FI processes. On average, higher oil relative permeability end points and lower water relative permeability end points were measured for the strongly water-wet cores compared to the cores reduced in water-wetness. The core scale simulation with SENDRA indicates continuous production of water and oil taking infinite time to reach residual oil saturation, however, the end of production was reached at a finite time in the experiments. A history matching approach based only on single rate injection did not yield reliable results, partly, because the capillary and viscous forces cannot easily be separated in the history matching process. This affects estimates of residual oil saturation and water end points of relative permeability.
Can Reasonable Certainty be Assessed from Disclosed Proved Reserves Revisions?
Authors: Morales Enrique , Lee John 
Published: June 2022

Abstract
If properly estimated, technical revisions to disclosed proved reserves can be used to establish the reasonable certainty of both proved developed and undeveloped reserves. The trends in these technical revisions are important because they should result in overall positive revisions in EUR within a representative time period. If this criterion is not met, then the proved status of the reserves disclosed becomes questionable with the implications that this may have in depreciation, profit and loss, impairment tests and other reserves indicators where proved reserves are used.
Unfortunately, in our review of the annual proved reserves revisions of developed and undeveloped proved reserves disclosed by companies to the SEC, we identified different interpretations and inconsistencies in the annual changes of proved reserves. We used data from annual reports issued between 2010 and 2020 by 141 companies, complemented by hundreds of comment letters issued by the SEC during this period, and found that companies did not apply the regulations and standards consistently, highlighting the limited effect the SEC comment letters have had in improving clarity and understanding in this important area of reserves estimation and categorization.
We identified several issues which, if not carefully considered, may lead to incorrect interpretations and conclusions regarding the reliability and comparability of the disclosed proved reserves annual changes and their embedded level of certainty. The paper highlights different interpretations of key definitions and the different approaches and practices that seem to exist in companies when evaluators estimate, categorize, and disclose annual proved reserves changes due to revisions, improved recovery and extensions and discoveries, with special focus on isolating the technical revisions. We also show that the approach that some companies use to estimate the impact of changes due to changes in economic factors in the disclosed proved reserves leads to incorrect estimates and distorts the overall results or comparisons between companies.
The evidence shown in the paper calls for improved and systematic official guidance if the proved reserves disclosures are to be used in a practical and useful manner. In the absence of such official guidance, this paper provides a simple project-based framework that may be used to properly analyze and extract value from the disclosed annual changes of proved reserves to improve the alignment, consistency, and proper interpretation of the disclosed proved reserves information and ensure that annual reserves changes do not end up being useless, impractical, or unreliable.
Key Innovation Technologies and Practice Effect of Polymer Flooding Field Application
Authors: Zhu Youyi , Fan Jian 
Published: June 2022

Abstract
Chemical flooding technique is the dominating EOR technique in China. Polymer flooding has entered into industrialized applications and has been applied on a large scale in Daqing sandstone reservoir. Now polymer flooding is expanding to other reservoirs such as conglomerate reservoir, complex fault block reservoir and high temperature and high salinity reservoir. The good EOR effect achieved by polymer flooding is closely related to the key innovation technologies.
Recent progress of field tests and application of polymer flooding enhanced recovery (EOR) in China was summarized in this paper. Key technical innovations and field application effects was introduced. The challenges faced and the development direction of polymer flooding technology was discussed.
Polymer flooding has been applied in Daqing Oilfield from medium-high permeability reservoirs (type I reservoirs) to medium-low permeability reservoirs (type II reservoirs) with poor petrophysical properties. In addition, polymer flooding solution was prepared by dilution of produced water instead of fresh water. 13% incremental oil recovery in average has been obtained. Polymer flooding has expand apply to conglomerate reservoir in Xinjiang Oilfield, complex fault block reservoir in Dagang Oilfield and high temperature and high salinity reservoirs in Shengli Oilfield, the application results was also successful by solving bottleneck technical problems. A series of technologies have been developed for industrialization application of polymer flooding during tests and application. The key innovations are: polymer product evaluation and molecular weight optimization techniques; development of numerical simulation software and optimization of field test scheme; high efficient injection equipment and process; profile modification during polymer flooding; separated layer injection technique; separated molecular weight and pressure injection technology; anti-eccentric wear lifting technology; fracturing and injection technology; dynamic tracking and adjustment technology; produced liquid treatment technology. These innovative techniques ensure good results of polymer flooding in field applications. The key points and practical application of these technologies are illustrated with examples.
Polymer flooding is the leading EOR technology for medium and high permeability reservoirs. Polymer flooding has been applied on a large scale and is being extended to more complex reservoirs. Facing new technical challenges, it is necessary to continuously strengthen the research and development of new functional polymers, research of reservoir adaptability and continuously technological innovation of supporting technology for different types of reservoir application.
Sustaining Wormholes Mechanical Stability in Weak Acidized Carbonates Using Consolidants
Authors: Desouky Mahmoud , Mustafa Ayyaz , Aljawad Murtada , Solling Theis , Dvorkin Jack 
Published: June 2022

Abstract
Matrix acidizing is implemented to increase the productivity of carbonate reservoirs by creating wormholes. An optimal matrix acidizing job creates conductive wormholes that are mechanically stable. However, over-acidizing and non-optimal wormholes (i.e., face dissolution) weaken the rock rendering it more susceptible to collapse under stress. Therefore, mineralogy alteration agents were employed in this research to change the carbonate rock prevalent mineral into a harder one to enhance rock strength and consequently the wormhole stability.
Treatments of zinc sulfate (ZnSO4) and diammonium phosphate ((NH4)2HPO4) are applied in 1.5 in × 3 in Austin chalk and Indiana limestone plugs. First, acid was injected using a coreflooding setup to create wormholes fully penetrating the sample. The acidized plugs’ hardness was assessed by two non-destructive techniques (i.e., impulse hammer and acoustic measurements). Then, the plugs were flooded again by 4-5 pore volumes of one of the agents at 80 °C with a pumping rate of 1 cc/min, keeping the confining and back pressure at 1,000 psi and 400 psi, respectively. The samples were kept in the same agent solution for three days at the same temperature. The hardness measurements were repeated for all plugs after the consolidation treatment.
A treatment is deemed successful if a noticeable increase in the rock hardness is achieved. On the one hand, zinc sulfate solutions of 0.1M and 0.2M concentrations increased the hardness of Indian limestone by 16% and 10%, respectively, by forming smithsonite on the plug surface. Also, a diammonium phosphate solution of 0.5M induced a 30% improvement in Indiana limestone hardness by developing a hydroxyapatite layer on the surface. On the other hand, the weaker Austin chalk plugs showed better strengthening outcomes. It showed a remarkable 4-fold increase in the hardness when treated with 0.5M diammonium phosphate solution.
Improving the rock hardness of acidized carbonate rocks can sustain the long-term wormhole permeability. This is especially important when acid softens the rock or in ductile rocks, prone to wormhole collapse. To the best of our knowledge, this is the first study to suggest improving the mechanical properties of wormholed weak carbonates through consolidation.
Study on Blockage and Fluid Diversion Behaviors of Polymer Microspheres
Authors: Wu Dejun , Liu Yongsheng , Lu Xuejiao , Hou Jian , Zhou Kang , Wei Bei , Du Qingjun , An Zhibin , Zheng Haoyu 
Published: June 2022

Abstract
Polymer microsphere (PM) flooding is a deep fluid diversion technology that is suitable for high water-cut oilfields to further enhance oil recovery. It has been successfully applied in some oilfields in China. However, the flow characteristics of polymer microspheres in porous media are very complex, involving blockage, elastic deformation, and remigration. On this account, we used microfluidic tests and core flow experiments to investigate how polymer microspheres block pore throats and promote fluid diversion.
Two types of microfluidic chips are first used to study the flow behaviors of polymer microspheres at the pore scale. The blockage and migration behaviors are observed through a single microchannel, and the real-time inlet pressure is monitored by a precision pressure sensor. To explore how polymer microspheres divert fluid, the unequal-diameter dual microchannel model tests are carried out. On this basis, the capacity of polymer microspheres to adjust the shunt flow in high and low permeable cores was investigated by a parallel sand-packed pipe flow experiment from a macroscopic level.
The results of the single microchannel model tests show that when the particle size of the polymer microspheres is smaller than the inner diameter of the microchannel, the microspheres can freely pass through the microchannel. When the particle size of the microspheres is larger than the inner diameter of the microchannel, the microspheres may first be blocked in the microchannel, and then deform and migrate through the microchannel; correspondingly, the inlet pressure first increases and then decreases. When multiple large-sized microspheres are bridging and blocking the microchannel, it may be difficult for the microspheres to enter and pass through the microchannel, and the inlet pressure shows a rising trend. The results of dual microchannel model tests show that the polymer microspheres can divert flow direction by alternately blocking wide and narrow microchannels. The results of the parallel sand-packed pipe shunt flow experiment show that the polymer microspheres can cause fluid diversion by blocking high permeable cores so that more subsequent fluid can enter the low permeable cores. The variation of the shunt flow rates in the two sand-packed pipes directly reflects the fluid diversion capacity of polymer microspheres from a macro perspective.
Polymer microspheres flooding breaks the shackles of the traditional idea of using homogeneous displacing fluid to increase oil recovery. As a novel aspect, this paper further interprets how polymer microspheres block pore throats and promote fluid diversion, which is the key mechanism for enhanced oil recovery of this heterogeneous particle suspension.
Artificial Intelligence Approach for Predicting the Shale Brittleness Index - A Middle East Basin Case Study
Authors: Mustafa Ayyaz , Tariq Zeeshan , Mahmoud Mohamed A. , Abdulraheem Abdulazeez 
Published: June 2022

Abstract
Brittleness Index (BI) of rocks can help target the most suitable formation for the hydraulic fracturing stimulation in the tight shale reservoirs. The two most widely used approaches in the petroleum industry are based on mineralogical composition and elastic parameters for the BI estimation. However, these approaches may not be applied for all wells for BI determination due to the scarcity of mineralogical-composition and shear wave slowness data.
This paper presents a machine learning (ML) approach to predict the BI using readily available well logs. Well log data were collected from three different wells that encompass a total of 2000 ft thick interval of potential shale gas formation in one of the middle eastern basins. Mineralogical composition of shale formation revealed that the shale intervals are comprising of alternate high brittle and low brittle zones and mainly composed of quartz, clay, feldspar, and mica. Feed-forward artificial neural network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) were employed to develop the predictive model for the BI.
The proposed model was tested and validated to check the consistency of the model. The reliability of the proposed AI model was reflected by the correlation coefficient (CC) ‘0.97’ between predicted and actual brittleness indices. The root mean squared ‘RMSE’ and average absolute percentage error ‘AAPE’ of the predicted brittleness were observed as 3.78 percent and 1.98 respectively for the ANN model. AAPE and RMSE for ANFIS predictive model were 3.51 and 1.81 respectively. The coefficient of determinations (R2) for ANN and ANFIS models were 0.945 and 0.951 respectively.ANN was found to be better than ANFIS by giving high accuracy. The proposed model was then compared with widely used models in the industry such as Jarvie et al., (2007) and Rybacki et al., (2016) on a blind dataset.
The predictive model was also validated by comparing with two widely used mineralogy-based approaches. The developed approach can be applied to identify the brittle layers/zones within the shale gas reservoirs to optimize the hydraulic fracturing stimulation treatment. Results showed that the proposed model outperformed previous models by giving less error.
Doxycycline post-exposure prophylaxis for prevention of sexually transmitted infections among Kenyan women using HIV pre-exposure prophylaxis: study protocol for an open label randomized trial
Authors: Stewart Jenell , Bukusi Elizabeth , Sesay Fredericka A , Oware Kevin , Donnell Deborah , Soge Olusegun O , Celum Connie , Odoyo Josephine , Kwena Zachary , Scoville Caitlin W. , Violette Lauren R , Morrison Susan , Simoni Jane , McClelland R. Scott , Barnabas Ruanne , Gandhi Monica , Baeten Jared M 
Published: June 2022

Abstract
Background: Women in Africa face disproportionate risk of human immunodeficiency virus (HIV) acquisition, accounting for more than half of new infections in Africa and similarly face a disproportionate burden of sexually transmitted infections (STIs). Very high STI prevalence is being observed globally, especially among people taking pre-exposure prophylaxis (PrEP) for HIV prevention. Doxycycline post-exposure prophylaxis (dPEP) has been proposed as an STI prevention strategy to reduce chlamydia, syphilis, and possibly gonorrhea, and trials are ongoing among cisgender men who have sex with men (MSM) and transgender women who are taking PrEP in high-income settings. We designed and describe here the first open label trial to determine the effectiveness of dPEP to reduce STI incidence among cisgender women.Methods: We are conducting an open-label 1:1 randomized trial of dPEP versus standard of care (STI screening and treatment and risk-reduction counselling without dPEP) among 446 Kenyan women aged ³18 and £30 years old women taking PrEP. Women are followed for 12 months, with quarterly STI testing, treatment, and adherence counselling. The primary trial outcome will be the combined incidence of Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum, compared between the randomized groups. We will also assess dPEP acceptability, tolerability, safety, impact on sexual behavior, adherence, and occurrence of antimicrobial resistance (AMR) in N. gonorrhoeae and C. trachomatis isolates. Finally, we will estimate cost per incident STI case and complications averted accounting for nonadherence and benefits relative AMR or side effects.Discussion: The results of this trial may have immediate implications for the global epidemic of STIs and sexual health. If effective, dPEP could put STI prevention into women’s hands. While dPEP may be able to prevent STIs, it carries important risks that could counter its benefits; global debate about the balance of these potential risks and benefits requires data to inform policy and implementation and our study aims to fill this gap.Trial registration: https://clinicaltrials.gov/ct2/show/NCT04050540
An experimental framework for quantifying the degree of intraguild predation in a three-species omnivorous food web in the field
Authors: Hsu Gen-Chang 
Published: June 2022

Abstract
Intraguild predation (IGP) is common in natural and human-managed systems and plays a critical role in food web dynamics. Although studies have documented the occurrence of IGP across a wide range of predator taxa, quantitative understanding regarding the degree/intensity of IGP remains lacking. I propose an experimental framework combining controlled feeding trials and stable isotope analysis to quantify the degree of IGP in a three-species omnivorous food web (top predator + mesopredator + shared prey) in the field. The degree of IGP is defined as the proportion (in number) of mesopredator consumed in the total diet (shared prey + mesopredator) of the top predator. Feeding trials along with stable isotope analysis are used to construct a standard curve of the relationship between top predator’s diet and shift in its nitrogen isotope signatures. The nitrogen isotope signatures of field-sampled top predator individuals are then analyzed and interpolated to the curve to estimate the degree of IGP in the field. The proposed framework leverages the strengths of different experimental approaches to studying trophic interactions, providing a tool for quantifying IGP in a more accurate (controlled feeding trials and standard IGP curve) and realistic (stable isotope analysis of field samples) fashion. The current framework can be further extended to food webs involving more complex interactions (e.g., cannibalism and multiple shared prey) and complemented with other approaches (e.g., molecular gut content analysis) to capture a more complete picture of IGP dynamics in the field.