bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatically Detected CSES Ionospheric Precursors During Aftershocks of the Wushi MS 7.1 Earthquake on 23 January 2024 in Northwest China
Authors: Li Mei , Yan Hongzhu , Liu Tianyu
Published: September 2024

Launched on 2 February 2018, CSES is the first constellation in China to advance our understanding of seismo-ionospheric influence and lithosphere-atmosphere-ionosphere coupling process in electromagnetic environment during earthquake prediction practice. For this purpose, a software platform developed for automatically searching ionospheric perturbations from the CSES plasma data had been put into service immediately after the Wushi MS 7.1 earthquake occurred on 23 January 2024 to weekly detect possible precursory information before impending aftershocks. Effective ionospheric variations were successfully detected two times during more than four weeks. An ionospheric perturbation with an enhanced magnitude 38.3% was primarily detected on electron density but none on ion density on 24 January 2024 at night orbit 33175 and the corresponding variations in different parameters recorded at the same orbit presented a complex features. There irregularities possibly combined with influence both from three following strong aftershocks with magnitudes over 5.0 during 25–30, January and magnetic storm disturbance due to Kp value once up to 3.7 on 24 January. An electron perturbation with an amplitude 24.6%, as well as an ion one with 27.3%, was successfully searched automatically at the same revisiting orbit 33251 occurred on the revisiting date of 3 February 2024 in a magnetic quiet period. These two plasma variations, as well as ones on other ionospheric parameters, were characterized by highly similar properties, which increases the availability as seismic precursors. However, no obvious variations had been observed at other revisiting orbits or other orbits near the aftershock areas during this period till the occurrence of a magnitude 5.3 earthquake on 24 February and the strongest one 5.8 on 25 February, respectively, 20 days after and 1000 km away.
The Long-term Rate of Repeat Surgery After Optimal Excision Surgery of Endometriosis at a Single Tertiary Referral Center
Authors: Yeung Patrick , Mohan Ayesha , Gavard Jeffrey
Published: September 2024

The primary purpose of this prospective cohort study was to determine if treating endometriosis with optimal excision surgery leads to lower rates of repeat surgery as compared to historical rates of repeat surgery by ablation. A secondary outcome was to examine whether the use of hormonal suppression differed before surgery, depending on the stage of endometriosis found at surgery. Optimal excision was defined as completely excising all areas of abnormal peritoneum, wherever found in the pelvis, having looked systematically with near contact laparoscopy. All surgeries were performed by a single surgeon specializing in optimal excision at a tertiary referral center. The rate of repeat surgery after optimal excision surgery for endometriosis was remarkably low (2.5%, 15/620) as compared to historical rates of repeat surgery by ablation. Additionally, the lack of significant evidence between hormonal suppression use and progression of stage of endometriosis provides implicit evidence that hormonal suppression does not prevent progression of the disease. Further controlled studies are needed to verify these findings.
Assessment of Ghana’s Municipal Solid Waste for Valorization – a Review
Authors: Kissi Stephen Kelly , Bryant Isaac Mbir , Boateng Samuel Nketia , Antwi Godbless Boateng
Published: September 2024

Ghana spends over $4000 (US dollars) annually managing municipal solid waste (MSW) with little improvement in regional sanitation. Energy demand in the country is also on the rise. Therefore, addressing waste problems via the waste-to-energy valorization approach is necessary for dual benefits. This paper thus seeks to comprehensively review Ghana's MSW's proximate and ultimate compositions for biological and thermochemical conversions. Studies between 2011 and 2024 were analyzed. The findings revealed that the organic fraction of Ghana’s MSW is currently about 10.47Kt per day. The proximate analysis reveals a moisture content from 13.55 – 61.9 %, volatile matter ranges from 6.24 - 80.25%, and the calorific value ranges from 14.96-21.46MJ/Kg. The ultimate analysis revealed that the carbon-to-nitrogen ratios range from 24.3-32.2, and the hydrogen content ranges from 5.53-22.8%. The sulphur and nitrogen contents were below 0.6 and 1.7% respectively. Approximately 2,534.65 GWh of electricity is estimated from the organic fraction. Ghana’s MSW is more suited for biochemical conversions.
Political Competition, Resource Availability, and Conflict: A Simulation
Authors: Siemers Troy , Basu Atin , Hentz James
Published: September 2024

This paper explores the dynamics of political competition, resource availability, and conflict through a simulation-based approach. Utilizing agent-based models (ABMs) within an evolutionary game theoretical framework, we investigate how individual behaviors and motivations influence collective outcomes in civil conflicts. Our study builds on the theoretical model developed by Basuchoudhary et al. (2023), which integrates factors such as resource availability, state capacity, and political entrepreneurship to explain the evolution of civil conflict. By simulating boundedly rational agents, we demonstrate how changes in resource availability and state capacity can alter the nature of civil conflict, leading to different equilibrium outcomes. The findings highlight the importance of understanding individual motivations and adaptive behaviors in predicting the stability and resolution of conflicts. This research contributes to the growing body of literature on the use of agent-based models in evolutionary game theory and provides valuable insights into the complex interactions that drive civil violence.
Negotiating Darwin’s Barrier: Evolution Limits Our View of Reality, AI Breaks Through
Authors: Samid Gideon
Published: September 2024

Physics is imagined in the human brain which was formed in Darwin's Evolution by responding to certain threats for the survival of our evolutionary ancestors. The struggle to survive prevented us from wasting resources by paying attention to parts of reality that had no survival impact. These parts are of unknown scope and dimension. Can we negotiate this Darwin's barrier? As to reality within our reach, we suffer from imbalance between information absorption capacity and information analysis capacity which resulted in ignoring the overflow of information to match human capacity to make sense of it. Also James Clerk Maxwell suggested that reality has small scale phenomena beyond our human reach. Since we have no brain other than what Darwin equipped us with, this barrier looked unsurmountable. But lo and behold: much as we have built vehicles to carry us further than our biological legs, so we now build artificial intelligence machines that carry us beyond our Darwinist barrier. Physics may transform to building AI capability to ride on. This capability may require a more universal geometry and material representation to fit AI inference engines. Suggesting Depth Unbound Reality Architecture (DURA). AI connects raw data to its conclusion potential, by-passing a storied theory of nature. The objective of physics ahead may be to build theory-replacement AI machines.
Comparison of Large Language Models Versus Traditional Information Extraction Methods for Real World Evidence of Patient Symptomatology in Acute and Post-Acute Sequelae of SARS-CoV-2
Authors: Thakkar Vedansh , Silverman Greg M. , Kc Abhinab , Ingraham Nicholas E. , Jones Emma , King Samantha , Tignanelli Christopher J.
Published: September 2024

Patient symptoms play a critical role in disease progression and diagnosis, yet they are most often captured in unstructured clinical notes. This study explores use of large language models (LLMs) for extracting patient symptoms from clinical notes, comparing their performance against rule-based information extraction (IE) systems, like BioMedICUS. By fine-tuning an LLM on diverse corpora from multiple healthcare institutions, we aimed to improve symptom extraction accuracy and efficiency with symptoms related to acute and post-acute sequelae of SARS-CoV-2. We also conducted prevalence analysis to highlight significant differences in symptom prevalence across corpora and performed fairness analysis to assess the model's equity across race and gender. Our findings indicate that while LLMs can match the effectiveness of rule-based IE methods, they face significant challenges related to demographic bias and generalizability due to variability in training corpora. This evaluation revealed overfitting and insufficient generalization, especially when models were trained predominantly on limited datasets with single annotator bias. This study also revealed that LLMs offer substantial advantages in efficiency, adaptability, and scalability for biomedical IE, marking a transformative shift in clinical data extraction processes. These results provide real-world evidence of the necessity for diverse, high-quality training datasets and robust annotation processes to enhance LLM’s performance and reliability in clinical applications.
A Three-Phase Novel Angular Perturbation Technique for Metaheuristic-Based School Bus Routing Optimization
Authors: Karema Moses , Tole Fulegnece Mwakondo , Tole Kevin Tole
Published: September 2024

This article introduces a novel three-phase angular perturbation technique for solv- 1 ing the School Bus Problem (SBP), an NP-hard combinatorial optimization challenge. The three 2 phases—initial solution, global and local search, and solution exploration—focus on optimizing 3 school bus routes by minimizing sharp turns and reducing travel distances. The performance of 4 three metaheuristic algorithms (GAACOSA-AP, BFSPSO-AP, RL-AP) is evaluated, and significant 5 improvements in routing efficiency are observed. we evaluated the performance of our hybrid algo- 6 rithm against the industry-leading optimization software, CPLEX, and other optimization techniques 7 across multiple school scenarios. The results show that the GAACOSA-AP algorithm consistently 8 outperforms its counterparts, achieving substantial reductions in travel distances, particularly for 9 complex routes with numerous stops. The integration of Angular Perturbation was key to improving 10 route geometry by, reducing sharp turns, and enhancing overall path optimization by an average 11 reduction of 27.12% compared to 22.37% without Angular Perturbation.12
Associated Gas Recovery Integrated with Solar Power for Produced Water Treatment: Techno-Economic & Environmental Impact Analyses
Authors: Chen Daniel H. , Aziz Fuad Samier , Sargsyan Gevorg
Published: September 2024

Excess associated gas from unconventional wells is typically flared while excess produced water is injected underground. In this work, flare gas recovery is integrated with produced water desalination and a solar pre-heater. The solar module with a beam splitter preheats the produced water. Aspen Plus was used to perform process modeling as well as to estimate capital and operating costs. The Solar-Flare Gas RDcovery- desalination (Solar-FGRD) process can conserve water resources and reduce the brine injection by 77%. The accompanying solar farm results in excess solar electricity for exporting to the grid.
The process burner combustion efficiency (CE) is 99.8% with the destruction and removal efficiency (DRE) of 99.99% for methane as opposed to the flare CE of 80-98% (and a methane DRE of 91-98%). The greenhouse gas (GHG) emissions for CO2 and methane in terms of CO2 equivalent (CO2e) can be reduced by 45 % for US North Dakota & Texas flaring and 13% for North Sea flaring by employing the Solar- FGRD process. The comprehensive financial analysis demonstrates the financial-economic feasibility of the investment project with or without tax credits. Best-case and worst-case scenarios provide a realistic range that investors can consider before making investment decisions.
Exclusive Enteral Nutrition as Induction Therapy for Paediatric Crohn Disease – Efficacy, Outcomes and Predictors of Response over a Ten-Year Period
Authors: Brown Stephanie , Wall Catherine L , Frampton Chris , Gearry Richard Blair , Day Andrew S
Published: September 2024

Background: Exclusive enteral nutrition (EEN) is the recommended first-line induction therapy for pediatric patients with active luminal Crohn’s disease (CD). The primary aim of this retrospective study was to ascertain the efficacy of EEN used as induction therapy for children with newly di-agnosed CD resident in the South Island of NZ over a ten-year period (2010 – 2021). Secondary aims were to assess the clinical impact of EEN therapy on anthropometry, biochemistry, the pro-gression to medical therapies over three time periods, and to identify positive predictors of re-sponse to EEN therapy. Methods: This retrospective clinical case review collected data from children diagnosed with CD at Christchurch Hospital, Christchurch, New Zealand, and prescribed EEN as induction therapy between the years January 1st, 2010 – December 31st, 2021. Descriptive statistics, Spearman’s correlation coefficient, multivariate logistic regression test and standard t-tests were used for analyses. Results: Data were collected for total of 161 children, 128 (80%) children were offered EEN as induction therapy and were included in this analysis. One hundred and twenty-one (94.5%) children successfully completed an eight-week course of EEN, and a de-crease in PCDAI scores ≥ 15 points from baseline to the end of week 8 of EEN treatment was seen in 119 (98.3%). L1 and L4 disease location were positive predictors of response (p
One-X Property Conjecture, Stochastic Orders and Implied Volatility Surface Construction
Authors: Cao Zeyu , Zhao Siqiao , Huang Shaosai
Published: September 2024

In this work, we explore Conjecture 1 proposed in the newly released pioneering paper “Volatility transformers: an optimal transport-inspired approach to arbitrage-free shaping of implied volatility surfaces” by Zetocha Valer, which posits that the “One-X” property is both a necessary and sufficient condition for convex order between non-negative continuous strictly increasing distributions with the same mean. We provide a counterexample demonstrating that the conjecture, as originally stated, does not hold. By examining stochastic orders, particularly the increasing convex order, and the “One-X” property, we propose an enhanced version of the conjecture which is shown to be valid. Furthermore, we discuss the implications of these findings in the context of equity implied volatility fitting and the construction of implied volatility surfaces, highlighting the challenges posed by real-market conditions. In the end, we propose several applications in implied volatility surface construction or simulation.
Real-Time Modelling for Design and Controlling of Material Additive Manufacturing Processes
Authors: Horr Amir M.
Published: September 2024

The use of digital twin and shadow concepts for industrial material processes have promoted new notions to bridge the gap between physical and cyber manufacturing processes. Hence, many multi-disciplinary areas like advanced sensor technologies, material science, data analytics, and machine learning algorithms are employed to create such hybrid systems. On the other hand, new additive manufacturing (AM) processes for metals and polymers based on novel emerging technologies have already shown a promising horizon for manufacturing of sophisticated parts with complex geometries. These processes are going through a major transformation with the emergence of digital technology, hybrid physical-data driven modelling and fast reduced models. This paper presents a fresh look at the hybrid physical-data driven and reduced order modelling (ROM) techniques for digitalization of AM processes within a digital-twin concept. The main contribution is to show the benefits of ROM and machine learning (ML) technology for process data handling, optimization\controlling and their integration into the real-time assessment of AM processes. Hence, a novel combination of efficient data solver technology and architecturally designed neural network (NN) module has been developed for the transient manufacturing processes with high heating\cooling rates. Furthermore, a real-world case study has been presented where the combination of hybrid modelling along with ROM and ML schemes are used for an industrial wire arc AM (WAAM) process.
State Estimation for Quadruped Robots on Non-Stationary Terrain via Invariant Extended Kalman Filter and Disturbance Observer
Authors: Wan Mingfei , Liu Daoguang , Liu Zhigui
Published: September 2024

Quadruped robots possess significant mobility in complex and uneven terrains due to their outstanding stability and flexibility, making them highly suitable in rescue missions, environmental monitoring, and smart agriculture. With the increasing use of quadruped robots in more demanding scenarios, ensuring accurate and stable state estimation in complex environments has become particularly important. Existing state estimation algorithms relying on multi-sensor fusion, such as those using IMU, LiDAR, and visual data, often face challenges on non-stationary terrains due to issues like foot-end slippage or unstable contact, leading to significant state drift. To tackle this problem, this paper introduces a state estimation algorithm that integrates an Invariant Extended Kalman Filter (InEKF) with a disturbance observer, aiming at estimating the motion state of quadruped robots on non-stationary terrains. Firstly, foot-end slippage is modeled as a deviation in body velocity and explicitly included in the state equations, allowing for a more precise representation of how slippage affects the state. Secondly, the state update process integrates both foot-end velocity and position observations to improve the overall accuracy and comprehensiveness of the estimation. Lastly, a foot-end contact probability model, coupled with an adaptive covariance adjustment strategy, is employed to dynamically modulate the influence of the observations. These enhancements significantly improve the filter's robustness and the accuracy of state estimation in non-stationary terrain scenarios. Experiments conducted with the Jueying Mini quadruped robot on various non-stationary terrains show that the enhanced InEKF method offers notable advantages over traditional filters in compensating for foot-end slippage and adapting to different terrains.
Optimizing Power Forecasting Models with Customized Features for Academic and Industrial Buildings
Authors: Cabezuelo David , Lopez-Ramirez Izar , Urkizu June , Goikoetxea Ander
Published: September 2024

Power consumption prediction is a crucial component in enhancing the efficiency and sustainability of building operations. This study investigates the impact of data collection frequency and model selection on the predictive accuracy of power consumption in two distinct building types: an Academic one with 15-minute interval data and an Industrial one with hourly data. Various machine learning models, including Support Vector Machine (SVM) with Radial and Sigmoid kernels, Random Forest (RF), and Deep Neural Networks (DNN), across different data splits and feature sets. Our analysis reveals that higher data collection frequency generally improves model performance, as indicated by lower RMSE, MAPE, and CV values, alongside higher R² scores. The inclusion of more historical power consumption features has also been found to have a more significant impact on the accuracy of predictions than including climate condition features. Moreover, the SVM-Radial model consistently outperformed others, particularly in capturing complex, non-linear patterns in the data. However, the DNN model, while competent in some metrics, showed elevated MAPE values, suggesting potential overfitting issues. These findings suggest that careful consideration of data frequency, features and model selection is essential for optimizing power prediction, contributing to more efficient power management strategies in building operations.
Review on Evaporative Cooling Systems for Application in Buildings in Hot and Dry Climates
Authors: Haile Misrak Girma , Marinez Roberto Garay , Arenaza Ana Macarulla
Published: September 2024

Numerous studies on evaporative cooling systems have been conducted globally, but there is a scarcity of investigations in eastern Africa. The few studies undertaken in this region have primarily focused on their application in food storage and preservation, rather than for building purpose. The goal of this study is to review the most recent advancements in evaporative cooling technology, which would be relevant in eastern Ethiopia and could provide adequate cooling, give adequate thermal comfort, use less energy, and minimize environmental effect in hot and dry areas. There aren't many studies on evaporative cooling systems for building applications in Eastern Africa as a whole, thus this review has taken into account studies conducted in regions with climates similar to eastern Ethiopia. This study covers the classification, operation, and performance of evaporative cooling systems in hot and dry climate. Evaporative cooling systems work well in hot and dry climates, as revealed by this review study.
A participação em eventos científicos dos integrantes de Biologia do Programa de Residência Pedagógica da Universidade Federal de Sergipe
Authors: Marcolan Cintia de Cássia , Nepomuceno Aline Lima de Oliveira
Published: September 2024

O Programa de Residência Pedagógica (PRP) visa aperfeiçoar a formação inicial docente através da articulação entre a universidade e a escola de educação básica. Entre as experiências vivenciadas no programa, o Subprojeto Institucional de Biologia da Universidade Federal Sergipe (UFS) propõe o incentivo à produção e divulgação científica através de diversas ações, como por exemplo, a participação em eventos científicos. Deste modo, visamos caracterizar a participação em eventos científicos dos integrantes do Subprojeto de Biologia do PRP da UFS, de 2018 a 2020. Isto posto, recorremos à análise documental de produções textuais dos residentes e a entrevistas semiestruturadas com os docentes participantes do programa, analisados à luz da Análise Textual Discursiva. No qual, concluímos que a participação em eventos científicos esteve presente em todo o desenvolvimento do programa, objetivando principalmente a formação e aperfeiçoamento dos residentes para a realização das atividades do PRP.
Kesulitan Menulis Aksara Jawa dalam Pembelajaran Luring dan Daring (Studi Kasus di Kelas VIII SMP Negeri 1 Kebakkramat)
Authors: Sariyanti Rissafitri , Sumarwati Sumarwati , Said Dewi Pangestu
Published: September 2024

The problem in this research is motivated by the difficulty of writing Javanese characters in offline and online learning. This research aimed to determine the Javanese language learning process in Javanese characters material offline and online, to describe the difficulties of writing Javanese characters, and to describe the factors causing the problems in writing Javanese characters. This research method uses qualitative descriptive research with a case research approach. The results showed that offline and online learning went well, but difficulties in writing Javanese characters were still found. The challenges in writing Javanese characters that were found include not being able to write quickly in a short time, difficulty determining the exact and correct Javanese characters, difficulty determining the sandhangan and pair of Javanese characters, difficulty distinguishing the form of Javanese characters, and dependence with notebooks. The factors causing the problem of writing Javanese characters come from internal and external factors. Internal factors include less motivation, lack of exercise, no interest, no confidence, and less student response. External factors include differences in the concept of writing latin letters and Javanese script, teacher differences in class levels, less conducive classes, lack of parental control, limited learning time, and changes in offline and online learning systems.
Cerita Rakyat Daerah Pegunungan Kabupaten Karanganyar (Analisis Struktur Naratif dan Fungsi Menurut Alan Dundes)
Authors: Oktivisari Adestya Tahira , Wijaya Fasyeh Paramasari , Khoiriyati Hesti Nabilla , Marfuah Putri Aprihlia Tul
Published: September 2024

Oral literature research on “Dumadine Candi Sukuh” and “Pertapan Cokro Kembang” aims to find out and analyze the series of motifs and functions based on Alan Dundes' theory. The existence of this research is also relevant to the absence of analysis of folklore in the Karanganyar area because mountainous areas are indeed difficult for researchers to reach. This research uses data analysis methods in the form of motifs and folklore functions based on Alan Dundes' theory using data in the form of words and texts. The data acquisition is taken through data collection techniques in the form of interviews, personal notes, photos, and other documents. The results showed that the folklore of “Dumadine Candi Sukuh” and “Pertapan Cokro Kembang” has five dominant motifs, namely 1) lack liquidate, 2) lack, 3) task, 4) task completed, and 5) consequence. Then, function is as 1) an educational tool, 2) increasing the solidarity of a group, 3) sanctions for people to behave well, 4) solace, and 5) social criticism. So it can be concluded that oral literature research on “Dumadine Candi Sukuh” and “Pertapan Cokro Kembang” both have complex storylines.
Elbow Flexion Reconstruction after Traumatic Amputation Using Hinged External Fixator and Muscle Transfer
Authors: Miyaoka Shunsuke , Yamazaki Hiroshi , Hayashi Masanori , Isobe Fumihiro , Abe Yukiho , Sakurai Toshiyasu
Published: September 2024

Case:

A 40-year-old man sustained a traumatic elbow disarticulation without any fracture, accompanied by severe damage of the biceps and brachialis. After replantation, passive elbow motion was used with a hinged external fixator to facilitate elbow joint reduction and mobility. Eight months after the injury, a functional latissimus dorsi transfer for elbow flexion restoration was performed. Ten years postoperatively, he achieved antigravity elbow flexion and 120° of flexion and −15° extension of the elbow.

Conclusion:

This reconstruction technique was useful for reconstructing elbow flexion after traumatic elbow disarticulation.
Land Power in the Littoral: An Australian Perspective
Authors: Nash John
Published: September 2024

The Australian Army is coming to terms with a new strategic direction set by the 2023 Defence Strategic Review (DSR), 2024 National Defence Strategy (NDS), and the Integrated Investment Program (IIP). This article considers how the Australian Army fits into this new direction as a littoral maneuver-focused force providing long-range strike capability. It examines concepts and analyzes how the Australian Army might be used in future scenarios: what it might be required to do in the maritime environment, whether it is contributing to sea control operations, sea denial, and/or intelligence, surveillance, reconnaissance (ISR). In addition, there is the maneuver component and how the Army might use the littorals of the Indo-Pacific as a maneuver space. This article seeks to generate discussion on how a modern land force might adapt to conflict and competition in the Indo-Pacific littoral.
The Effects of Compositional Uncertainties on Phase Behavior Calculations
Authors: Nielsen M. H. , Wanat E. C. , Whitson C. H.
Published: September 2024

Accurate estimates of reservoir mole compositions are important for developing accurate fluid models and fluid initialization. However, because of the limitations of the methods used for compositional analysis, a complex mathematical procedure is used to estimate the reservoir from several other measured and estimated properties. The method for compositional analysis has several potential sources of uncertainties, from measurement errors and calculational errors. Compositional variations can have a significant impact on phase behavior calculations, which can have impacts on downstream estimates. Examples of processes that can be impacted include fluid model development, composition initialization (resulting wrong in place estimates), to surface oil volumetric rates. This article systematically introduces the sources of compositional errors for a wide range of fluid types and shows the impact on the phase behavior calculations. Based on this analysis, qualitative guidelines can be made on what compositional uncertainties have the biggest impact on the different fluid types and phase behavior properties.
Experimental Study to Investigate CO2 Mediated Oil Flow in Nanopores
Authors: Hegazy D. A. , Yin X. , Qiao R. , Ozkan E.
Published: September 2024

To optimize CO2 EOR operations, such as Huff and Puff (HnP), it is necessary to have a good understanding of oil- CO2 transport both at nanopore and at reservoir scales. In this study, experiments were performed to investigate how pore adsorbed CO2 can mediate oil flow in analog nanopore arrays. These experiments quantified how much interfacial CO2 contributed to improving permeability to oil in nanopores, in addition to increasing mobility by viscosity reduction. The experimental procedure involved flowing C10 (decane) with and without CO2 through an Anodic Aluminum Oxide (AAO) membrane at a defined differential pressure and recording flow rate. Viscosity obtained from correlations was then used to calculate membrane pore permeability. Inlet pump pressure was lower than the oil-CO2 miscibility pressure at the test conditions. Pore permeability improvement due to pore wall adsorbed CO2 was computed by isolating the effect of viscosity reduction of the bulk fluid. An overall pore-permeability increase of 15% was observed in the CO2 and C10 mixture experiments compared to the C10-only experiments, due to interfacial CO2. These results lend support to the previous molecular dynamics simulations, which predicted that interfacial CO2 can significantly modulate C10 flow in nanopores up to 10 nm diameter (Moh et al. 2020). Some differences from the molecular dynamics simulations of Moh et al. (2020) observed in the experimental study also verify the potential contribution of other phenomena to the permeability enhancement of the nanoporous membrane in the presence of CO2. Therefore, this study provides further impetus for exploring the unique nanofluidic physics of oil and CO2 transport arising from CO2 at oil-wall interfaces. The demonstrated significance of the unique nanopore phenomena, which have not been observed and incorporated into large-scale flow models, emphasizes the importance of identifying and incorporating nanofluidic physics into commercial reservoir simulators' transport models for better representation of CO2 and oil flow in unconventional reservoirs.
World's Largest Non-Traditional Packer with Extreme Annulus Sealability
Authors: Marhoon Z. Al , Alsharaawi A. , Atiyah A. , Carragher P. , Nasser M. , Dearmon J.
Published: September 2024

The historical use of packers in the oil and gas industry has primarily involved elastomers with hydraulic or mechanical operating systems. Bismuth alloy technology offers an alternative material with a distinct operating system. TDAP stands for thermally deformable annulus packer which is a non-traditional seal that aids in sealing leakages in an annulus with Sustained Casing Pressure as a preventative solution before the pressure is observed at the surface.

The technology was developed with extensive lab, yard, and field testing to prove the reliability of this alloy, particularly for larger annulus spaces, such as 9 5/8″ × 13 3/8″. The objective is to proactively eliminate the risk of Sustained Casing Pressure (SCP) in the production and intermediate casing annuli.

The method used to demonstrate this system's applicability involves having bismuth alloy disks on the exterior of one joint of the 9 5/8″ casing. The joint is positioned to achieve the intended depth for the packer. The packer is set above the 13 3/8″ shoe. After cementing, the disks are turned into a liquid using a heater run inside the 9 5/8″ casing. This heater is precisely controlled for temperature and optimized for heat transfer. When the heat source is removed, the bismuth alloy solidifies between the intermediate and production casing, creating a metal-to-metal annulus seal - steel to bismuth alloy to steel. Bismuth has minor expansion properties which give the packer gas tight qualities. To succeed in the field trial, this system underwent testing under full downhole conditions. The setup mimicked the pressure, temperature, casing design, and the medium in which the alloy is set downhole. The test included the heater deployment, the melting of the alloy, and pressure testing of the system up to 5,000 psi in hydraulic pressure.

A unique sealing mechanism of bismuth alloy proactively prevents SAP B. The paper describes the results of the extensive R&D work undertaken, during which the annular bismuth alloy barriers were tested and withstood up to a 5,000-psi pressure differential, having been formed in drilling fluid, clear brine, and cement.

The success of the implementation in the world's largest offshore field will be described. In particular, the innovative well design and deployment of the annular packer to be set in clear brine for maximum pressure integrity with a gas-tight rated seal will be highlighted.

This is the industry's first downhole utilization of bismuth alloys for this size with this application. Its novelty lies not only in the size but also in the engineering required to achieve optimal heat transfer and alloy melting efficiency for such a large size, which entails carefully studying the behavior of this untraditional alloy.
Eco-Friendly Drilling: Evaluating the Impact of Engineered High-Performance Water-Based Mud on Emissions and Waste
Authors: Bageri Mohammed , Vordick Travis
Published: September 2024

The oil and gas industry are under increasing pressure to minimize its environmental footprint, with drilling fluids being a significant contributor to operational emissions and waste. Traditional Oil-Based Muds (OBMs), despite their effectiveness in drilling operations, pose substantial environmental risks due to their disposal challenges and high carbon footprint. In response, High-Performance Water-Based Muds (HPWBMs) have been developed, promising reduced environmental impact and improved performance. This study aims to evaluate the efficacy of HPWBMs in reducing emissions and waste while maintaining operational efficiency and cost-effectiveness. The primary objective of this research is to compare the environmental and economic impacts of HPWBMs and OBMs through comprehensive field trials and laboratory tests. By analyzing drilling performance, cost-per-lateral-foot, waste management, and emissions, this study seeks to establish HPWBM as a viable and sustainable alternative to OBMs in the oil and gas industry.

Field trials were conducted in North Central Texas and the Permian Basin, involving the drilling of 26 wells—13 using HPWBM and 13 using OBM. The North Central Texas case study focused on an operator's challenge of drilling 10,000-15,000’ lateral wells at TVDs of 3,800-4,800’. In the Permian Basin, Wolfcamp horizontal wells were drilled to evaluate performance. Key performance indicators (KPIs) such as drilling fluid cost, lateral cost per foot, and days per well were measured. Emissions were calculated using a carbon calculator, and laboratory tests assessed rheological properties, lubricity, and thermal stability.

The results indicated that HPWBM systems not only reduced drilling costs by 18.2% but also significantly lowered CO2 emissions and hazardous waste generation. In the North Central Texas case study, the use of HPWBM resulted in cost savings of over $100,000 per well, with significant reductions in disposal costs, OBM logistics, base-fluid costs, motor realignment fees, and pit cleaning expenses. The environmental footprint and carbon emissions were notably reduced, with CO2 emissions for HPWBM wells averaging 386.1 metric tons compared to 710 metric tons for OBM wells. In the Permian Basin, the average fluids cost per foot for HPWBM wells was $6.02 compared to $7.04 for OBM wells, and the average number of lateral days was reduced to 4.92 days compared to 11.50 days for OBM wells.

This study presents a comprehensive evaluation of HPWBMs, demonstrating their superior environmental and economic performance over traditional OBMs. The significant reduction in CO2 emissions and hazardous waste, combined with cost savings and improved operational efficiency, highlights the potential of HPWBMs to transform drilling practices in the oil and gas industry. The findings support the broader adoption of HPWBMs, promoting sustainable and cost-effective drilling operations that align with global sustainability goals.
Gas Flow Rate Estimation with Artificial Intelligence: Bridging Reality Through Computer Vision and Machine Learning
Authors: Santhalingam V. , Abinader A. , Vesselinov V. , Krishna D.
Published: September 2024

Flaring in the oil and gas industry is a critical process where excess gases are burned off through a flare stack. This practice is essential for safety reasons, such as pressure relief during unplanned overpressuring of plant equipment, and for managing gases that cannot be processed economically. However, flaring is also a significant source of greenhouse gas emissions, releasing harmful gases such as carbon dioxide and methane into the atmosphere. The environmental impact of these emissions makes it imperative to monitor and control flaring activities effectively.

Despite the necessity of monitoring, the traditional methods involving flowmeters present significant challenges. These devices, which measure the rate of flow of the gas being flared, are often prohibitively expensive and complex to install, especially in remote or offshore locations. This high cost and complexity can hinder comprehensive monitoring efforts, leaving a gap in effective environmental management practices.

Moreover, the practice among oil and gas operators to rotate available flowmeters across different flare stacks further complicates consistent monitoring. This rotation often results in minimal monitoring—sometimes only sufficient to meet the bare minimum of legal reporting requirements. Such practices underscore the need for more robust and continuous monitoring solutions.

To address these challenges, in this paper we explore an innovative approach to estimate flaring emissions using a more accessible and cost-effective technology. By leveraging a simple system composed of a camera and an edge computer, this method uses visual data and advanced computing techniques to estimate the volume of gas flared. This approach not only reduces the economic burden associated with traditional flowmeters but also enhances the feasibility of continuous monitoring across various operational settings in the oil and gas domain. Through this paper, we aim to demonstrate the effectiveness of this system and discuss its potential implications for environmental monitoring and regulatory compliance in the industry.
A Systematic Approach to Interpreting Cement Bond Logs
Authors: Harris K. L. , Shine J. M.
Published: September 2024

To achieve a more consistent and disciplined approach, and to achieve a higher rate of accurate conclusions, a cement bond log interpretation method has been organized and applied to hundreds of operations around the world. This method approaches the bond log from a "cementing perspective" and when applied to previously interpreted logs, resulted in an accuracy increase from approximately 30 % to greater than 90 %. This study of three-hundred and twenty five wells also showed that the most common error was the misinterpretation of logs for wellbore sections containing a microannulus.

This paper details a five-step process, including an example of the numerous observations and decisions that are typically made, and introduces forty-three wellbore effects that may be key to accurate bond log interpretation. Besides accuracy, the vast majority of cement bond logs have been "under-interpreted," lacking important details. This new integrated approach to bond log interpretation is designed to provide a full interpretation, hence the zonal isolation summary, the nature and cause of any cement defects, and recommendations for remediation or future improvements, are all key parts of the final interpretation.
Unveiling the Imprecision in Well Test Data: A Guide to Improve Accuracy of Water Cut Measurement
Authors: Rois Muhammad Amin
Published: September 2024

Well test in Banyu Urip (BU) field employs 2-phase Test Separator equipped with Coriolis Meters to measure gross liquid rate and density for water cut calculation. As BU matures, obtaining water cut data during well test is crucial for well surveillance and scale management. However, there are challenges to precisely and accurately measure water cut as it evolves. This paper shares insights to improve precision and accuracy of water cut measurement during well test.

The well test accuracy is validated by comparing produced water (PW) rate from process flow meter at Primary Separators with those derived from Coriolis Meter at Test Separator. The process flow meter's accuracy is ensured through range adjustments following actual rate. In early year, water cut data from Coriolis Meter was inaccurate as indicated by significant PW balance gap. This finding prompted investigation through High-Pressure High-Temperature (HPHT) test analysis, collaboration with manufacturer, and process simulation. Lab test emerged as the primary method to measure water cut by manual sampling at inlet Coriolis Meter during well test.

Upon increasing PW rate, discrepancies between PW rate derived from well test manual sampling and process flow meters showed an upswing, reaching 27% gap. This swing was mainly caused by inconsistency in obtaining homogenous oil-water mixture from sampling branch. Hence, examination of Coriolis Meter's accuracy was imperative as it can precisely capture representative sample.

An investigation uncovered gas entrainment in preserved liquid sample by testing it in HPHT. The gas lowered actual density from Coriolis Meter below than reference density at the same pressure and temperature, resulting into significant PW balance gap during low water cut operation. Two potential root causes were identified: gas carry under and gas flashing. Vessel sizing verification confirmed adequacy of existing Test Separator in preventing gas carry under, leading to conclusion that gas flashing due to friction loss was the root cause.

To address this, the water cut calculation was modified by incorporating an empirical correction factor for gas entrainment, including operation strategy to minimize it. This proved pivotal to improve well test accuracy, reducing PW balance gap to 5%. The improved PW rate precision and accuracy contributed to benefits for well allocation, Voidage Replacement Ratio management, and scale inhibitor effectiveness.

Typical gas entrainment issue can be found at liquid leaving separator in saturated condition, thus effecting meter accuracy. Adjusting liquid level upwards can mitigate gas flashing by providing additional static head to compensate friction loss. However, this poses the risk of high-high liquid level trip, especially for slugging well. Therefore, addressing gas entrainment issue by good Test Separator operation strategy and reliable water cut calculation is critical to get accurate and precise well test data.
Advanced Downhole Flow Detection through Acoustic and Temperature Sensing in Combination with Geochemical Testing; A holistic Approach
Authors: Hashim Qassim , Khnaifir Waleed , Rowaie Mohammad , Malyazin Alexey
Published: September 2024

As the need for energy increases, drilling and completion of new deep natural gas wells is also increasing. Commonly, gas wells are monitored through real-time surface readings. Government regulations and environmental considerations mandate the safe operation of all producing assets. A measure of well health is the annuli readings. Normally, each outer casing annulus should read zero pressure. However, due to a number of factors, the annuli can sometimes exhibit positive pressure. Once a well exhibits abnormal annuli pressures, it must be investigated and actioned accordingly. As the casings can cover a long section of footage, it is necessary to run a downhole detection tool to identify the fluid flow. This paper describes the best practices to detect fluid outflow through temperature and acoustic logging in combination with geochemical laboratory testing and provides field applications.

Conventional bleed-off/build-up cycles are used to check the sustainability of the pressure build-up in the annuli. Once that pressure is confirmed to be sustainable, a slim downhole tool conveying high-definition spectral noise and temperature sensors is run to determine the fluid flow location. The high-definition acoustic survey is conducted on the stations using a wide frequency range acoustic sensing platform that can record within a 15 ft radius of investigation. The acoustic survey produces a high-definition power spectrum that can reveal and characterize flow activity within the well system, including the tiniest of noises generated by fluid movement. This was combined with high-precision temperature surveys and analysis.

To identify the feeding zone, fluid is sampled via pressurized cylinders at the surface and dispatched to a laboratory for geochemical isotopic fingerprinting analysis. Carbon isotopes were measured using gas chromatography connected to an isotope ratio mass spectrometer.

Downhole logging composed of High Precision Temperature and High-definition Spectral Noise Logging was combined with surface pressure reading analysis to provide a complete assessment of the casing fluid outflow. Logging showed clear signs of downhole fluid movement while gas isotope analysis identified sample origin. Carbon isotope compositions were compared to other endmembers. Carbon isotopic profile plots were used to fingerprint the origin of the moving fluid.

The novel suggested methodology and procedure of downhole fluid movement detection in combination with geochemical testing provides comprehensive and highly accurate analysis that helps to reveal the truth of fluid movement and enables for fit for purpose preventative workover operation.