bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of A Process For Domestic Wastewater Treatment Using Moringa Oleifera for Pathogens and Antibiotic Resistant Bacteria Inhibition under Tropical Conditions
Authors: Sané Nini , Laffite Amandine , Serge Stöll , Malick Mbengue , Joh Pote , Philippe Le Coustumer
Published: June 2022

Developing countries are confronted with general issues of municipal wastewater management and treatment. Untreated faecal sludges and wastewaters from septic tanks and traditional toilet are rejected into rivers and sometimes using for urban agriculture without any treatment to reduce the biorisk. Consequently, there are potential environmental and public health risks. In this study, a wastewater treatment plant prototype coupled with Moringa Oleifera seeds treatment was developed to evaluate their effectiveness for the reduction of faecal indicator bacteria and antibiotics resistant bacteria in domestic wastewater. Results indicate that our performed prototype system presents high capacity to reduce bacteria with abatements up to 99.34%. High reductions of bacteria load were obtained after add of Moringa Oleifera seeds into waters, with reductions varied from 36.6-78.8% for E. coli, 28.3-84.6% for Faecal coliform, 35.3-95.6% for Vibrio cholerae and 32.1-92.4% for total flora. Same effects of Moringa Oleifera seeds were noted for reducing antibiotic resistant bacteria, Extended Spectrum Beta-lactamases and Carbapenem-Resistant Enterobacteriaceae with abatements up to 98% for E. coli and faecal coliform, 100% for Vibrio cholerae and 91.96% for total flora. Our results supported high capacity of Moringa Oleifera seeds as an excellent alternative for pathogens and antibiotics resistant bacteria reduction/purification from domestic wastewater
Transport and Nonequilibrium Phase Transitions in Polygonal Urn Models
Authors: Cirillo Emilio N. M. , Colangeli Matteo , Di Francesco Antonio , Kröger Martin , Rondoni Lamberto
Published: June 2022

We study the deterministic dynamics of N point particles moving at constant speed in a 2D table made of two polygonal urns connected by an active rectangular channel, which applies a feedback-control on the particles, inverting the horizontal component of their velocities, when their number in the channel exceeds a fixed threshold. Such a bounce--back mechanism is non-dissipative: it preserves volumes in phase space. An additional passive channel closes the billiard table forming a circuit in which a stationary current may flow. Under specific constraints on the geometry and on the initial conditions, the large N limit allows nonequilibrium phase transitions between homogeneous and inhomogeneous phases. The role of ergodicity in making a probabilistic theory applicable is discussed both for rational and irrational urns. The theoretical predictions are compared with the numerical simulation results. Connections with the dynamics of feedback-controlled biological systems are highlighted.
https://erevistas.uacj.mx/ojs/index.php/decumanus/issue/view/743
Authors: Rodriguez Sosa Marisol , Sánchez Flores Erick , Holguín Ávila Raúl
Published: June 2022

Se presenta un estudio cualitativo que indaga sobre las cualidades de la vivienda social adecuada y habitable. En México, las políticas de vivienda social se debaten actualmente entre la necesidad de promover la ciudad compacta y la adecuación cultural, en respuesta al reconocimiento de las diferencias socioculturales en las formas de habitar. Para estimular la compacidad de un modo sustentable socioculturalmente sin menoscabo de la habitabilidad, es necesario considerar el contexto, las preferencias y estilos de vida de los habitantes, como paso esencial para no solo construir vivienda social, sino además promover comunidades habitables. En ese sentido, se presenta un estudio cualitativo desarrollado a partir de la aplicación de una encuesta, que busca evaluar si es sustentable socioculturalmente el fomento a la densificación, así como identificar criterios de diseño urbano y arquitectónico adecuados a las preferencias de habitar y estilos de vida de los habitantes. Tomamos como caso de estudio los principales conjuntos con tipologías de vivienda vertical social existentes en Ciudad Juárez, la segunda más grande ciudad fronteriza del norte de México, donde las políticas de impulso a la compacidad han sido recibidas con escepticismo, bajo el argumento de que los fronterizos tienen un apego a la vivienda unifamiliar con patio. El aporte del trabajo radica en la contribución al tema de promover comunidades compactas y habitables, desde la consideración de la vivienda adecuada socioculturalmente; lo que puede afinar los mecanismos para adoptar esta estrategia en el marco del programa de vivienda social en ciudades de esta región fronteriza, y en otras localidades donde pueda replicarse el estudio.
Percepción social del servicio de recolección de residuos sólidos urbanos en León, Guanajuato
Authors: Tagle-Zamora Daniel Tagle-Zamora , Rodríguez-González Juan Antonio , Caldera-Ortega Alex Ricardo
Published: June 2022

El objetivo de esta investigación consistió en captar la percepción social del usuario del servicio municipal de recolección de residuos sólidos urbanos (RSU) en el municipio de León, Guanajuato, el cual es uno de los municipios más poblados de México con 1.7 millones de habitantes. En León, el Sistema Integral de Aseo Público de León (SIAP) es un ente público descentralizado responsable de atender los distintos procesos de la Gestión Integral de Residuos Sólidos Urbanos (GIRSU). Una de las actividades fundamentales del SIAP es la recolección de residuos sólidos, la cual tiene implicaciones para la salud pública y el medio ambiente del municipio. El SIAP se apoya en el sector privado a través de la modalidad de concesión, lo que hace necesario conocer la percepción que el ciudadano tiene sobre la prestación del servicio. La investigación fue de tipo mixto, cualitativo-cuantitativo. Se aplicó una encuesta bajo una variante del modelo SERVQUAL para captar la percepción social de los usuarios que reciben el servicio de recolección dentro de la mancha urbana de León. Los resultados señalan que el ciudadano se encuentra muy satisfecho con este servicio público dando confianza a la continuidad del prestador municipal. No obstante, la revisión de la literatura permite identificar que el servicio brindado presenta sesgo con respecto a la GIRSU, destacando que el modelo en León atiende la recolección de basura y no de residuos. Se concluye que es necesario plantear esfuerzos financieros municipales para alinear dicha prestación dentro del esquema de la GIRSU aprovechando la satisfacción del usuario municipal.
Desarrollo y pobreza en México. Los índices IDH y FGT en la primera década del siglo XXI
Authors: Limas Hernández Myrna
Published: June 2022

Bajo las condiciones económicas mundiales de la actualidad se hace necesario analizar la coexistencia, en los ámbitos nacional como regional, de niveles elevados o aceptables de desarrollo con niveles de pobreza preocupantes en amplios grupos de población. México presenta esta paradoja. Pese al proceso de liberalización vigente, algunas entidades y regiones mexicanas continúan presentando niveles de pobreza y bajos índices de desarrollo. Al confirmar, con base en los índices IDH y FGT, que la relación entre las variables desarrollo-pobreza se prevé es inversa para el caso de México, el paso siguiente es revisar el rumbo que habrán de seguir las políticas públicas en pro del desarrollo, conforme a un nuevo modelo social incluyente.
Dinámica demográfica y crisis socioeconómica en Ciudad Juárez, México, 2000-2010
Authors: Martínez Toyes Wilebaldo
Published: June 2022

El objetivo de este trabajo es mostrar los principales cambios demográficos de Juárez en la primera década del siglo XXI. Una década marcada por el impacto significativo de las crisis económicas de Estados Unidos de 2002 y 2008 y por la crisis de violencia e inseguridad derivada de la lucha del crimen organizado por la venta y el trasiego de droga por esta ciudad fronteriza. Los resultados permiten constatar una transformación demográfica –asociada a las mencionadas crisis- de los tres componentes encargados de condicionar el volumen y la estructura de la población, que propiciaron un descenso pronunciado en la tasa de crecimiento demográfico; además se identifica al fenómeno de la migración como el factor más determinante de la nueva realidad demográfica juarense.
Fractional Catastrophe Model considering the Rheological Properties of Slope Faults
Authors: Bao Min , Chen Zhonghui , Nian Gengqian , Zhang Lingfei , Zhou Zihan
Published: June 2022

Fault properties have an important influence on the sliding mode and long-term stability of slopes. In this paper, a cusp catastrophe theoretical model of an open-pit slope is established based on the mechanical model of plane sliding slope instability. The model considers time effects, the rheological properties of fault locking sections, and the strain softening properties of fault softening section. A rheological constitutive model is constructed based on the fractional derivative according to fractional calculus. A slope instability criterion is proposed within catastrophe analysis. The influences of the fault medium length, stiffness ratio, and different orders of the fractional derivative on slope stability are discussed. The critical height and critical safety factor of the dynamic slope instability are derived, and the catastrophe instability time is predicted. The results show that longer softening stages are associated with smaller stiffness ratio values, higher fractional orders, and a greater possibility of slope instability. Slope stability is dynamic under the rheological action of the fault medium.
Experimental Research on the Effect of Bedding Angle on the Static and Dynamic Behaviors of Burst-Prone Sandstone
Authors: Tang Peng , Ma Xiang , Zhao Yang , Jiang Lishuai , Fan Kegong , Hu Xiaoyu , Wang Fangtian
Published: June 2022

In order to understand the mechanism of some unconventional failures such as rockburst caused by deep rock excavation, the failure characteristics of burst-prone sandstone specimens under static and dynamic loads were studied by using the MTS816 rock mechanics testing system and the split Hopkinson pressure bar (SHPB) experimental system, as well as the effects of bedding angle and impact pressure on rock mechanical properties and failure patterns. The uniaxial compression test used a cylindrical specimen with a height of 50 mm and a diameter of 100 mm, and cylindrical specimens with height and diameter of 50 mm were adopted in the SHPB tests. The bedding angles in the tests are 0°, 45°, and 90°. In the dynamic impact test, three different impact pressures were applied to observe the magnitude of impact load on the mechanical behaviors of the burst-prone sandstone specimens. The results show that with the increase in the bedding angle, the uniaxial compressive strength firstly decreases and then increases. When the bedding angle is 45°, the uniaxial compressive strength is the lowest. The uniaxial compressive strength is highest when the bedding angle is 0°. The burst-prone sandstone specimens with different bedding angles had three different failure pattern types. Under the dynamic loading, the stress-strain curves show springback phenomenon; with the increase in impact pressure, the dynamic strength of the burst-prone sandstone specimens with each bedding angle increases; the fracture degree of the bedding sandstone specimens gradually increases. The dynamic strength of the 45° burst-prone sandstone specimen is the lowest, and it has the highest fracture degree.
Vigilancia de la salud de los trabajadores expuestos a plaguicidas en el programa de control de vectores en México
Authors: Ocotzi-Elías María Isabel , Schilmann Astrid , Arenas-Monreal Luz
Published: June 2022

Objetivo. Analizar la interpretación e implementación de las políticas para la vigilancia de la salud de los trabajadores del programa para el control de vectores en México. Material y métodos. Se realizó un estudio transversal con métodos mixtos en cuatro estados de México; se incluyen entrevistas semiestructuradas, recolección de datos sobre los plaguicidas aplicados y los resultados del biomonitoreo realizado a los trabajadores y obtenidos de los registros estatales. Resul­tados. En todos los estados participantes se identificó un uso extensivo y variado de plaguicidas altamente peligrosos. Los procesos para monitorear la exposición ocupacional a inhibidores de acetilcolinesterasa son diferentes en cada uno de ellos y en ninguno se calculan los índices biológicos de ex­posición. Conclusiones. El conocimiento sobre las políticas para vigilar la salud de los trabajadores debe fortalecerse y es necesario mejorar el contenido de las políticas vigentes de modo que abarquen los múltiples plaguicidas que aplican los trabajadores, así como sus posibles efectos combinados y a largo plazo.
Serological follow up of positive SARS-CoV-2 cases
Authors: González-González José Gerardo , Camacho-Ortiz Adrián , Rodríguez-Gutiérrez René , Saldívar-Rodríguez Donato , Ramírez-García Luz Adriana , Sánchez-García Adriana
Published: June 2022

Objective. To describe the humoral response in a cohort with mild and asymptomatic SARS-CoV-2 infection previ­ously identified in a community-based serological survey. Materials and methods. This study was an observational follow up of 193 subjects previously identified with positive anti-SARS-CoV-2 antibodies invited for a second test 112 days after the first sampling. All completed a standardized electronic questionnaire. IgM/IgG antibodies were determined using a qualitative IgM/IgG chemiluminescent immunoassay. Results. Among the 193 eligible subjects, a total of 174 (90%) attended the follow-up visit, and their serum samples were tested. Of the samples, 171 (98.3%) were still positive, and 3 (1.7%) were negative. Also, the cut-off index (COI) value of the immunoassay significantly increased from the first to the second test (P <0.001). Conclusions. Our findings support a sustained humoral response in individuals with mild and asymptomatic SARS-CoV-2 infection up to 112 days after a positive serologic baseline test, accompanied by increasing antibody titers.
Driving Factors for Purity of Withdrawn Hydrogen: A Numerical Study of Underground Hydrogen Storage with Various Cushion Gases
Authors: Wang Gang , Pickup Gillian Elizabeth , Sorbie Kenneth Stuart , Mackay Eric James
Published: June 2022

The central objective of this study is to improve our current understanding of the hydrodynamic processes arising when hydrogen (H2) is stored in subsurface porous media. In this work, we compare the use of two cushion gases, namely carbon dioxide (CO2) and methane (CH4), for H2storage ina synthetic aquifer. The impacts of viscous instability, gravity segregation, capillary trapping, and CO2 solubility in water on the recovery performance are investigated in detail.In the context of H2 storage, wefocus on both the amount and the purity of the H2that is back produced. A series of very fine-scale numerical simulationswas performed in 2D vertical systems using a fully compositional simulator. A simple three-stage operation strategy (cushion gas injection, H2 injection and H2 production) was designed to trigger the flow behaviour of interest. Based onscaling theory, we analysed the impacts of various mechanisms on the H2 recovery performance, from viscous dominated to gravity dominated flow regimes. Viscous instability and permeability heterogeneity may strongly degrade the purity of the back produced H2. No matter whichgas (CO2 or CH4) is selected as the cushion gas, the less viscous H2 infiltrates the cushion gas, meaning that the displacement does not proceed in a piston-like fashion. In the viscous-dominated scenario, H2 may even bypass the cushion gas of CO2, which subsequently leads to early breakthrough of the cushion gas and thus a dramatic reduction in H2 purity during back production. However, this effect does not arise in the case with CH4 as cushion gas. On the other hand, in the gravity-dominated case, the less dense H2 accumulates above the cushion gas and there is no flow infiltration or bypassing occurring in cases studied here. Therefore, the overall H2recovery performance is much better in the gravity-dominated regime than that in the viscous dominated regime. Finally, we demonstrate that it is important to include the solubility of CO2 when used as cushion gas in aquifer systems. This isbecause CO2 dissolution in water may significantly reduce its gas volume and lead to early water breakthrough during back production.
Research Progress and Field Trail of a New Micro-Nano Oil-Displacement System Flooding Technology
Authors: Sun Zhe , Wang Xiujun
Published: June 2022

Although polymer flooding technology has been widely applied. Yet the "entry profile inversion" phenomenon occurs inevitably in its later stage, which seriously affects the development effect. In recent years, the micro-nano oil-displacement system is a novel developed flooding system.

The oil-displacement system consists of micro-nano particles and its carrier fluid. After coming into porous media, it shows the properties of "plugging large pore and leave the small one open" and the motion feature of "trapping, deformation, migration". In this paper, physicochemical properties, reservoir adaptability, oil displacement mechanism of micro-nano oil-displacement system in pore throat is explored by using macroscopic physical simulation and CT scanning technology. Furthermore, the typical field application case is analyzed.

Results show that, micro-nano particles have good physicochemical performance and transport ability in porous media. According to the reservoir adaptability evaluation, the matching relationships between particle size and core permeability is obtained, to provide guidance for field application scheme. By using NMR andCT techniques, its micro percolation law in porous media and remaining oil distribution during displacement process is analyzed. During the experiment, micro-nano particles presents the motion feature of "migration, trapping, and deformation" in the core pore, which can realize deep fluid diversion and expand swept volume. From 3D macro experiment, the sweep volume can be further expanded by injecting MNS and adjusting well pattern structure after polymer flooding. The dual goals of expanding sweep volume and improving oil washing efficiency can be achieved by using binary composite system (MNS and petroleum sulfonate) and ternary composite system (MNS, alkali and petroleum sulfonate). Finally, the micro-nano oil-displacement system conformance control technology has been applied in different oilfields, which all obtained significant oil increment effect.

By using the research methods of interdisciplinary innovative, the oil displacement mechanism and field application of micro-nano oil-displacement system is researched. The research results provide guidance for oil companies to enhance oil recovery significantly.
Synergistic Cooperation with Energy Transition Initiatives of Oil Producing Countries and NOC from IOC Standpoint
Authors: Yonebayashi Hideharu
Published: June 2022

Decarbonizing initiatives are being advanced in the energy sector: not only international oil companies (IOC) and oil consuming nations but also national oil companies (NOC) and oil producing countries. The recent net zero initiatives, declared by several gulf coast countries (GCC), are expected accelerating the progress towards the decarbonized society. The study focuses on the UAE's decarbonization strategy, as a case example, because of the first country releasing the net zero initiative with the most concrete approaches among the GCCs. Each approach of the NOC, aligned with the national initiative, are carefully investigated to give a comprehensive perspective of the strategic grand design. This can bring us an insight of how each piece interacts with others and finally leads to having cooperative ideas from the IOC's viewpoints for achieving the NOC/IOC-common objective of net zero greenhouse gas (GHG) emission society. As a NOC's approach, an electrification of oil fields can reduce CO2 emission with valualizing lower carbon intensity oil. To enhance the effort, IOC can support the future market trading low carbon intensity products as offtaker. From the aspect of expanding the existing technologies, CO2 enhanced oil recovery (EOR) can contribute not only reducing CO2 emission and/or carbon credit trading but also producing clean energy such as ammonia and/or hydrogen, too. To improve CO2 EOR project values, the IOC can provide an advanced CO2 mobility control technology. The study discusses further win-win cooperative potentials such as other CO2 intensity lowering technologies (ex. water shut off, production chemical optimization) and another opportunity of decarbonization (ex. CO2-methanation).
Design and Application Evaluation of Revolutionary Inflow Control Devices Enhanced Bitumen Recovery and Thermal Efficiency in SAGD Process
Authors: Liang Guangyue , Xie Qian , Liu Yang , Liu Shangqi , Zhou Jiuning , Bao Yu
Published: June 2022

Non-uniform steam chamber caused by reservoir heterogeneity, shale interlayer, local mobile water, undulating well trajectories and improper operation, etc., severely restricts oil sands SAGD performance. Inflow control devices (ICD) achieved great success in controlling conventional water or gas coning. Inspired by this, liner and then retrofitting tubing deployed ICD have been tested since 2009 and soared in recent years. Therefore, this paper made a systematic review of ICD design, operation principle and application evaluation.

Different types of ICD applications in dozens of Canadian oil sands projects were comparatively investigated including operating principle, adaptability analysis, liner-deployed or tubing-deployed ICD, early-to-medium SAGD performance. Then a numerical simulation method incorporated the relationship of pressure drop versus mass rate at different conditions and pressure degradation due to erosion impacts is presented. The feasibility analysis of ICD deployed on injector or producer was further evaluated by numerical simulations. Besides, a set of ICD optimization design method is provided including the principles of well selection, reasonable ICD number along horizontal well section, and optimum operating conditions, etc.

Revolutionary ICD technology has become an effective way of greatly improving SAGD performance in recent years. According to the statistical data, most ICD are deployed on producers rather than injectors, which is also explained by numerical simulations of technical feasibility evaluation. In order to deal with uneven steam chamber growth, the number of tubing deployed ICD dramatically increases in recent years. The proportion of liner and tubing deployed ICD is 58% and 42%, respectively. However, there are big differences in SAGD performance of different ICD wells. Some ICD wells is worse in SAGD performance and even damaged by sand production. Based on absorbing the knowledge of field application, the behavior of different types of ICD was compared to guide the selection. Then the workflow of ICD optimization design method was provided by calculating conformance and allocated liquid volume according to the relationship of pressure drop versus mass rate. The operation principle is suggested to facilitate lower subcool but zero subcool not allowed in long term due to sand production risk. On the basis of reasonable well selection, it can easily improve conformance by above 15% and oil production by over 50%. Inspired by this, ICD also applied to several multilateral SAGD well pairs to balance steam or liquid distribution along horizontal wellbore.

This paper first systematically provides various types of ICD behavior, screening criteria, design practices, operation principle and application evaluation in SAGD process. These findings are very useful for ICD design and enhancing both oil recovery and thermal efficiency in heavy oil or bitumen production.
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

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

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

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

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

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

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

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

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

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.