bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring and Quantification of Trapped CO2 in Porous Media: A Low-Field Online NMR Investigation on CO2 Flooding And Sequestration of Low Permeability Reservoir
Authors: Zhang Zheng , Rui Zhenhua , Liu Yueliang , Zhao Yang 
Published: February 2025

Abstract
Low-field online Nuclear Magnetic Resonance (LF-NMR) technology has been extensively used to describe hydrogen content in pores during CO2 injection. However, spatial migration and existence form of injected CO2 in porous media are still unclear. NMR combined with micro-gas measurement was used to quantify CO2 of different states to evaluate the capacity and security of CO2 sequestration. Moreover, fluid-rock interactions and mass transfer were considered to reveal the migration and evolution mechanism of injected CO2. In this work, quantitative CPMG scanning was done and T2 distribution of hydrocarbon in porous media was obtained and CO2 produced was measured to quantify CO2 in free and dissolved state during constant rate CO2 injection. Considering pressure variation from injectors to producers in reservoir condition, pressure-dependent CO2 injection was designed to obtain CO2 migration law and mass transfer in pores of different radius. On the other hand, depressurizing experiment was done to simulate CO2 exsolution from hydrocarbon and determine dissolubility trapped CO2.
For low permeability rock sample, CO2 first occupied medium pores and macropores after injection, and then expanded to micropores with smaller radius. It was shown that injection pressure is the main factor that controls the direction of CO2 migration because pressure condition reflects phase behavior of CO2. For gaseous CO2 (pressure lower than critical point), only large pores were swept. When the system pressure is much higher than supercritical pressure, micropores were activated for CO2 sequestration. More interestingly, the volume of CO2 in free state increased rapidly when gaseous CO2 was transforming to supercritical phase. Compared with free state CO2, dissolved CO2 in liquid phase depends on saturation pressure. When the pressure was much higher than saturation pressure, solubility trapping in porous media showed great stability. As the pressure was decreased to a value lower than saturation pressure of fluid in pores, CO2 started to exsolve from liquid phase in large volume. Moreover, CO2 preferentially exsolve from micropores first. This work proposes a method to quantify the states of CO2 exists in porous media and illustrates that injection pressure was dominant to control migration and evolution of CO2. In this work, equipped with NMR technology, CO2 injection and depressurizing experiments were done to monitor and characterize dynamic dissolution and exsolution of CO2 in different pores.
Analysis of Acoustic Signals Generated by Proppant Slurry Flow Through Perforations-Experimental Study
Authors: Chen Jiayue 
Published: February 2025

Abstract
This study explores the acoustic signal generated when a water-sand slurry flows through perforations in the frequency domain. The goal is to identify the proppant/sand presence on distributed acoustic sensors (DAS), and therefore to allocate sand concentration during a multi-stage fracture treatment using DAS monitoring data. We have studied whether sand-related signals can be distinguished from a water flow signal in the frequency domain, what are the frequency components of the proppant signal, and how proppant concentration or other parameters affect the proppant-related signals.
In limited entry design, water-sand slurry flows through perforations with a high injection rate and a high-pressure drop across the perforations. This high flow velocity generates the acoustic signal. It is believed that when solids (sand) pass the perforation, the frequency domain responds differently than just liquid flow. To prove the concept, we conducted an experimental study simulating this process at the lab scale. The experimental setup consists of a core with a hole drilled in the middle as a perforation. A steel plate placed at the inlet of the core serves as perforated casing. The injection rate of single-phase flow (water only) and two-phase flow (water-sand slurry) was designed to mimic the field condition to generate enough pressure drop from the flow through perforation. A microphone was used to provide acoustic measurements for the experiments. The apparatus used in this research has only one perforation, which allows us to build correlations between acoustic signals with known water flow rates and proppant concentrations.
With acoustic signals collected, signal processing methods including the Fast Fourier transform method and Yule-Walker method were applied to analyze the acoustic amplitude spectrum in the frequency domain. The spectra obtained for slurries with different concentrations were compared. Theoretical modeling started with understanding the acoustic signal generated by the collision of a single solid particle with a metal surface. Starting with the single collision model, signal processing was applied to the superposition of multiple signals in the time domain to explore the effect of sand concentrations on the spectrum function of the acoustic signal. Results from theoretic modeling were used to confirm the experiment data.
Sand-related signals can be distinguished from water flow sounds in the frequency domain. Certain frequency band picks up when sand is introduced to the system. This characteristic of the frequency becomes higher in amplitude when the concentration of sand increases, but the characteristics of the frequency band remain the same. With regression analysis, sand concentration and acoustic signal amplitude were determined to be linearly related.
This study provides a new correlation to interpret proppant placement in individual perforation clusters from high frequency DAS measurements.
Dissolvable Frac Plug with BIP Design for Hydraulic Proppant Fracturing in Unconventional Wells
Authors: Zhu Yunyang , Gao Xiang , Chen Huan , Chen Zhongsiao 
Published: February 2025

Abstract
In the gas and oil industry, efficiency optimization within unconventional reservoirs persists as a crucial and formidable challenge. As the exploration and development of these reservoirs advance, horizontal wells are being drilled to increasingly greater depths. Plug and perf (P&P), serving as the principal approach for reservoir stimulation, entails the execution of multiple stage hydraulic fracturing procedures subsequent to fracturing. A newly engineered dissolvable plug, which disintegrates following the main fracturing operation and thereby obviates the necessity for milling, substantially augments efficiency, curtails costs, and diminishes carbon emissions. Nevertheless, it typically requires 20 to 30 minutes and the pumping of 300 to 400 barrels of water to propel the ball downward and seal the plug inner bore to form isolation.
The modification of the wire line adapter kit (WLAK) to be commensurate with the dissolvable frac plug, along with the alteration of the ball drop method to ball in place (BIP), comprehensively resolves this predicament. It eradicates the ball chasing process for down hole isolation, truncates the operation time by 13% during the overall single stage stimulation, and conserves 300 to 400 barrels of water per stage. Through the assessment of the performance of the dissolvable plug in unconventional reservoirs, and in adherence to the PDCA model, the deployment process is streamlined, and the mechanical stability is fortified to preclude post plug and perf operations for the dissolvable plug, thereby diminishing non-productive time.
Streamlining Horizontal Well Deployment in Unconventional Najmah MFS Formation through the Integration of Spectral Gamma-Ray and High-Resolution Imaging Technologies: North Kuwait
Authors: Al Ajmi Saad , Al-Azmi Mejbel , Al Otaibi Fahad , Joshi Girija , Pattnaik Chinmaya , Issa Dania , Danash Tarek , Vican Kresimir , Abdulkarim Anar 
Published: February 2025

Abstract
The Najmah Marine Flooding Surface (MFS) in northern Kuwait, recognized for its significant organic-rich clay content (2-30% total organic carbon, i.e TOC), offers considerable promise for gas, condensate, and light oil production. Nonetheless, geosteering challenges arise from limited seismic resolution and stratigraphic uncertainties, leading to lateral variations in petrophysical properties and pay-zone thickness. The formation is characterized by porosity levels ranging from 2-6% and permeability values from 0.01-1.5 mD, with the flow behavior dependent on a natural fracture network.
A comprehensive logging operation was conducted utilizing advanced logging-while-drilling (LWD) technology, integrating spectral gamma ray (SGR) measurements and ultra sonic-high-resolution imaging (UHRI). The SGR analysis facilitated a detailed evaluation of the formation's mineralogical composition by breaking down total gamma ray (GR) responses into their key elements—potassium (K), uranium (U), and thorium (Th). This process is essential for accurately distinguishing organic-rich zones from other lithologies, laying the groundwork for effective geosteering in future operations.
The integration of UHRI in the lateral section provided high-resolution imaging, enabling the accurate identification of fractures and other geological features that influence reservoir dynamics. A total of 60 features were identified, including 41 fractures and 19 bedding planes. This vital structural information played a crucial role in refining completion strategies and boosting production efficiency.
These findings offer valuable insights for improving future field development strategies and optimizing drilling operations in the Najmah MFS. This methodology is strongly recommended for application in upcoming well profiles with similar characteristics, contributing to improved resource management in the unconventional reservoirs of northern Kuwait.
Estimating Water-Gas Ratio in Producing Gas Wells Through Multi-Fidelity Data Assimilation by Integrating Wellbore Physics and Data-Driven Reservoir Models
Authors: Sinha Utkarsh , Sankaran Sathish , Sabharwal Varad , Ravuri Meher , Zalavadia Hardikkumar , Li Zhuoran 
Published: February 2025

Abstract
Effective management of conventional gas wells relies on timely detection of water breakthroughs, crucial for optimizing reservoir recovery, production, and pipeline operations. Current gas flowmeters struggle to accurately measure water rates, and while methods like well tests and tracers are effective, they are costly and infrequent. Multiphase flowmeters need frequent calibration, and virtual metering approaches depend on pre-known phase ratios. We propose a hybrid model integrating data-driven and physics-based methods for continuous water-gas ratio (WGR) estimation using routine pressure measurements and sporadic WGR data. Our approach combines an optimization framework for data assimilation with a parameterized model for WGR evolution, utilizing gas rate, wellhead, and bottomhole pressures along with multi-fidelity measurements. A weighted loss function minimizes errors in bottomhole pressure (BHP) and WGR estimates. Applied to an offshore mature gas field, our method demonstrated good accuracy, with an average error in BHP of 23 psia across 40 wells over 7 years of production. Water breakthroughs were detected in 20% of wells, validated by increased water rates at the processing platform. This hybrid approach enables proactive reservoir management by merging engineering principles with data-driven modeling.
Analysis of Seepage Pattern of CO2 Intensified Fracturing-Flooding Water Injection Development in Deep Low-Permeability Heavy Oil Reservoirs
Authors: Luo Chen , Liu Huiqing , Li Xiang , Gai Pingyuan , Zhang Zhaoxiang , Yin Fanghao 
Published: February 2025

Abstract
Fracturing-flooding (FT) is a sophisticated fracture-driven enhancement technology designed to optimize hydrocarbon storage and recovery. Particularly effective in deep low-permeability heavy oil reservoirs, this method revitalizes the reservoir structure, enhances reservoir utilization, and substantially improves the crude oil recovery rate. Additionally, the integration of CO2 injection within the FT process can significantly augment heavy oil recovery efficiency by enhancing the oil-water relative permeability dynamics.
In this study, we explore the seepage dynamics associated with CO2-intensified fracturing-flooding (FT) water injection strategies in deep low-permeability heavy oil reservoirs. Utilizing a two-dimensional visualization physical simulation apparatus in conjunction with advanced AI-driven image recognition technology, we assess the planar propagation and characteristic behaviors of the CO2-intensified FT water injection. Additionally, we investigate the microscale seepage performance enabled by this technique using micro-nanochip technology. Furthermore, we analyze the enhanced oil recovery effects and the CO2 utilization efficiency to optimize the reservoir's storage capacity.
In low-permeability reservoirs, CO2 injection as part of fracturing-flooding (FT) processes significantly expands the plane wave area and reduces oil saturation when compared to conventional FT water injection alone. The dissolution of CO2 into crude oil reduces its viscosity by swelling the oil phase. Additionally, CO2 mitigates the 'water locking effect', thereby facilitating the transformation of residual oil from clusters into films and droplets, which enhances oil mobilization. Furthermore, CO2 decreases the strength of the oil-water interfacial tension, which helps prevent the coalescence of dispersed-phase droplets upon collision. This action promotes the kinetic stability of the oil-water system and diminishes the flow resistance, thereby improving sweep efficiency. The low-pressure CO2 injection not only enhances the oil displacement efficiency but also increases the utilization rate of CO2 and incrementally elevates the storage capacity within the oil-water system. The proposed development plan for intensified FT water injection with CO2 in deep low-permeability heavy oil reservoirs proved to be effective in improving oil-water seepage capacity and mitigating greenhouse gas emissions.
28in Hybrid Bit Technology Drilling through Complex Offshore Drilling Intervals
Authors: Alvarez O. , Othman M. , Alrowitea M. , Daksuev D. 
Published: February 2025

Abstract
This paper explores the successful application of hybrid bit technology in offshore gas well operations. It details the strategic steps taken to meet the primary objectives, utilizing a 28-Inch hybrid bit technology to tackle the complexities of drilling in challenging offshore intervals. Key aims of the bit design and tool deployment encompassed achieving single-trip completion of the section, enhancing drilling speed and efficiency, and driving cost savings in operations.
Offshore gas drilling presents significant costs and challenges, particularly in large hole sizes. In this specific scenario, the interval comprises highly interbedded formations and a demanding drilling environment, including fluid loss zones, boulders, and hard, abrasive intercalations. The challenging 28-Inch section spans over 4,000 ft of medium to hard dolomites with occasional streaks of anhydrite and interbedded limestone with shales. The conventional approach to drilling such sections involves using two or three roller cone tungsten carbide bits, leading to high drilling costs and instability issues due to prolonged hole exposure.
To address these challenges, multiple wells in the area were meticulously analyzed, examining both time and depth-based logs along with electrical logs. This comprehensive analysis revealed a drilling trend, indicating that hybrid bit cutting structures were best suited for this demanding application. The hybrid bit solution was chosen for its unique capability to shear and crush formations during drilling, combining the durability of roller cone bits with the efficiency of PDC (Polycrystalline Diamond Compact) drill bits. This distinctive drilling mechanism enables hybrid bit technology to efficiently drill through this challenging application compared to traditional drill bits.
In the field-testing phase, the hybrid bit was deployed in two consecutive wells. Although the drilling parameters were controlled to prevent total losses, which impacted the overall average rate of penetration (ROP), the outcomes were remarkable. Both wells successfully completed the section using only the hybrid bit, which was pulled out of the hole in good condition. Furthermore, both wells achieved above-average ROP and saved 3 to 4 days of drilling time compared to the conventional method of using standard roller cone bits.
The 28-Inch hybrid bit technology has proven to be the ideal solution for addressing the demanding offshore gas drilling challenges in this application. It stands out as the only drill bit technology capable of completing this section in a single trip, thereby facilitating the achievement of all performance targets set for the test.
Extending Automated Drilling Capabilities by Enabling Automated Data Aggregation and Drilling Advisory Workflows - Case Study
Authors: Temer Elias , Arabi Hakim , Bisht Sameer , Xu Lina , Casado David , Calligrafi Remy , Rocha Carlos 
Published: February 2025

Abstract
Automation is revolutionizing efficiency in various sectors, notably in oil and gas, by streamlining tasks to enhance speed, safety, and labor reduction. On-target well delivery solution systems integrate automation, advisory systems, and data aggregation, leveraging AI to optimize drilling operations while ensuring compliance with well-construction plans. In drilling edge operations, data aggregation systems collect and manage information from various sources using standardized protocols, addressing challenges such as hardware duplication and network complexity. In this paper we proposed a multi-layered solution through a data aggregation layer and a shared domain service layer, ensuring consistent data management and secure transmission to the cloud using protocols like WITSML, ETP, and Avro for efficient data handling. Using this solution will allow deploying, with less hardware, multiple workflows such as real-time advisory, predictive analytics for risk mitigation, and cross-domain workflow coordination, all aimed at improving operational efficiency and decision-making while maintaining data integrity across diverse workflows.
A New Clean Completion Technology for Soluble Screen Tubes in Ultra-Deep Well with High Temperature and High Pressure
Authors: Liu W. , Gao W. , Zhang H. , Wei B. , Jiang R. , Liang L. , Zhang L. , Xie Y. 
Published: February 2025

Abstract
In response to the problems of insufficient completion fluid replacement and wellbore contamination caused by well killing fluid in the conventional completion process of ultra deep fractured sandstone reservoirs in Tarim Oilfield, a new technology for clean completion with soluble screen tubes has been developed, which includes the configuration of soluble screen tubes and release short joints in the production zone.
Soluble screen tubes, when used as tubing during well completion fluid replacement, can replace high-density well killing fluid in the lower part of the perforation section, ensuring the cleanliness of wellbore for fluid replacement; During reservoir transformation and production, the soluble sieve tube is dissolved in acid and the soluble pore plug is used to reduce fluid flow resistance. The release short section can be repaired and salvaged in sections by shearing the pin under pressure. Through experimental research on tools such as soluble sieve tubes and release short joints under pressure, the reliability of the tools has been verified.
Based on the application research in the laboratory and D304 well site, the effectiveness and feasibility of the new technology of clean completion with soluble screen tubes have been proven. In the perforation section, the soluble screen tube column effectively solves the contradiction between incomplete liquid replacement from the lower part of the column to the middle and upper parts of the perforation section and increased flow resistance from the lower part of the perforation section. Comparing the two types of tubing structures, namely tubing completion and soluble screen clean completion, it is found that the soluble screen clean completion process has significant advantages in fluid replacement, high-pressure gas flow, drainage area, daily production, etc., and the process is simple and easy to operate on site.
This technology has been applied in over 10 high-pressure gas wells in the ultra deep fractured sandstone reservoir in front of Kuche Mountain in Tarim Oilfield, with a success rate of 100%. At the same time, this technology has the advantage of integrating completion fluid replacement with well repair and salvage, providing important reference for the selection of completion technology for similar wells.
ИНСТИТУЦИОНАЛЬНЫЙ ПОДХОД К ИССЛЕДОВАНИЮ КАТЕГОРИИ «НАЛОГОВЫЙ ПОТЕНЦИАЛ»
Authors: Шемякина М.С. 
Published: February 2025

Обосновано, что налоговый потенциал является одним из видов налоговых институтов. Автором разработана институциональная модель налогового потенциала, раскрыта её структура. Доказано, что в основе формирования налогового потенциала лежит институт собственности, характеризующий трансформацию налогооблагаемых ресурсов при воздействии налогового механизма в налоговые доходы. С позиции институционализма дано авторское определение категории налоговый потенциал. Выделены формальные и неформальные институты, на которых базируется институт налогового потенциала .
Introduction. Economic development of regions and municipalities is impossible without an adequate assessment of fiscal capacities. In this regard, the study of a kind of safety bag - fiscal capacity, on which the sustainable development of public-law entity depends, seems to be highly relevant. The goal of the study is to develop the theoretical positions in terms of determining the nature of tax capacity through the use of an institutional approach. To achieve this goal, the following tasks are defined: to analyze the totality of dissertation (PhD) researches, monographs, and periodical materials devoted to the problem of determining the nature of tax capacity and assessing the tax capacity in order to classify the approaches to reveal the essence of the category of tax capacity from the standpoint of the institutional approach to determine its structure to develop an institutional model of tax capacity. Results. Institutionalization of the category of tax capacity is analyzed, four stages in its development are revealed, and their brief description is given. A detailed analysis of the literature allowed to classify the approaches to the interpretation of tax capacity and to identify resource, reproduction, effective, and institutional approaches. It is substantiated that tax capacity is one of the types of tax institutions. The author has developed an institutional model of tax capacity and justified its structure. It is proved that the basis of formation of tax capacity is the institution of property, which characterizes the transformation of taxable resources when tax mechanism is exposed to tax revenues. From the standpoint of institutionalism, the authors definition of the category of tax capacity is given. Formal and informal institutions on which tax capacity institution is based on are identified. Conclusion. The results of the study show that the use of the institutional approach to determine the nature of the category of tax capacity is much broader and allows to synthesize the approaches already known, and also opens up new directions for further research.