bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Response Study of Stability Analysis of Conductor Pipe in Shallow-Water Field
Authors: Abimbola Fatai Akorede , Yang Jin , Adetowubo Adenike Yeside
Published: November 2024

Maintaining a vertical position of conductor pipe during drilling and non-drilling operations remains a challenge in shallow-water fields. In Tianjin shallow-water field, a conductor pipe left for evacuation was found displaced on resumption for drilling operation. This prompts the need to address the problem by investigating the stability of the conductor pipe and to prevent its future occurrence. In this work, a governing equation is presented to study the mechanical behavior of conductor pipe in a shallow-water field under combined effect of soil, waves, current, and wind. The displacement response equation of the conductor pipe was solved numerically from which other responses were obtained. Various influencing factors such as internal fluid, top-weight, and wall thickness are analyzed for the conductor pipe. Modal analysis carried out shows that the part of the conductor pipe in the soil tends to vibrate for higher modes which thus threatens the stability of the conductor. Results show that significant displacement occurs for the conductor part in water which indicates that combination of waves and current on the conductor prevails over the top free-boundary condition effect. Analysis results also show that drilling mud of higher density in conductor with applied top-weight on it improves the stability of conductor. The results have been validated using Abaqus simulation.
Lowering the Uncertainties with Innovative Practices for Enhancing the Performance Evaluation of Ultra-Sour Tight Reservoirs
Authors: Ahmad Zeeshan , Leguizamon Javier Antonio , Albadi Mohamad Mubarik , Al Haj Al Hosani Abdulla Ahmed , Ahmad Mubashir , Dike Nnamdi , Ali Siddiqui Muhammad , Agarwal Anubhav
Published: November 2024

Exploration of new zones has always carried risks and uncertainties because of the limited geological data of the reservoirs and potential for hydrocarbons. In the study of an unconventional reservoir through several vertical pilots, with minimum horizontal stresses between 8600 & 10000 psi (0.86 – 1 psi/ft) and permeabilities around 1 md, innovative methods were tested to establish and determine the productivity/injectivity in the high stress sections. Such techniques included Advanced perforation systems, and advanced stimulations with customized fluids and specialized Coil Tubing (CT) tools, all of them constrained by the surface and subsurface equipment capacities to maintain integrity.

The Advanced Gas Fracturing System was examined as new technology which showed the ability to produce gas with very high pressure reaching 32,000 to 46,000 psi. For an Unconfined Compressive Strength between 16000 psi and 26000 psi observed in the subject reservoir, the high-pressure gas surpassing it by 2 to 3 times, is expected to create lateral mega to macro-fractures around the well for up to 98 ft diameter pool in 9 - 12 millisecond, with maximum gun size. The Advanced Perforation system in conjunction with optimized acid system were designed for the for the highest rock strength sections to achieve and maintain maximum connectivity between reservoir and wellbore, becoming a great alternative to hydraulic fracturing. Advanced stimulation techniques including the use of tailored emulsified acids, with Abrasive Jetting tool application to improve placement and productivity, were evaluated in ultra sour tight reservoirs.
Group Optimization and Modeling of Mechanized Wells Operating in Intermittent Mode
Authors: Yudin E. V. , Piotrovskiy G. A. , Smirnov N. A. , Petrushin M. A. , Isaeva S. M. , Zamakhov S. V. , Popravko K. A. , Kherson E. Y.
Published: November 2024

Intermittent mode is one of the most efficient methods of managing low-rate ESP wells. However, this approach implies defining optimal working parameters of the wells. So, there is a demand for complex algorithms that can perform simultaneous joint optimization of power consumption and modeling tasks for the groups of wells operating in periodic regime. Besides, it must consider work/idle cycles synchronization to minimize effect of the pressure fluctuations occurring in the oil gathering chain. The mathematical model of the «tubing–annulus-reservoir" system is used, with boundary conditions defined at the submersible equipment intake by mass conservation equations.The simultaneous joint optimization of power consumption is based on existing approaches for steady-mode wells modified to suit intermittent working regimes. Special tools are developed to consider intracycle parameter dynamics and synchronize the on/off cycles, minimizing negative impacts on the infrastructure.Optimal parameters are determined using the adaptation results of complete nonstationary processes model, while potential scenarios are calculated using simplified methods. Finally, the result is refined by recalculating it using the most complex model.As a result, the algorithm was developed that provides functionality for simultaneous joint optimization of ESP well groups operating in both intermittent and steady modes. It can determine the optimal parameters of the system considering geological, technological and regulatory constraints. Besides, it supports two types of optimization scenarios aimed at either maximizing production or decreasing lifting costs. The optimization is built around existing model of non-stationary flow in the well which can calculate dynamics of production, hydraulic and electrical parameters. On top of that, to bring the performance of new algorithms close to those used for steady modes, a set of simplified models was created based on the full physically driven mathematical model. This technique was the key for achieving sufficient algorithm speeds necessary for increasing the scenarios update frequency by using sequential calculations with model complexity enhancement.In addition, the results of numerous calculations are presented. They were compared with actual data from the production fields to verify their predictive ability. This analysis was performed for all types of models, as well as their combinations and covered both group and individual optimization cases. The developed algorithms were tested on pilot fields and the results were confirmed by process engineers.
Integrated Workflow with Static and Dynamic Geomechanical Modelling for Fault Critical Re-Active Stress Evaluation
Authors: Pei Zhansong , Liu Mingtao , Huang Xingning , Xu Hanbing
Published: November 2024

The Songliao Basin, a vast sedimentary basin located in Northeast China, extends in a north-northeast direction, covering the Heilongjiang, Jilin, Liaoning provinces, and the Inner Mongolia Autonomous Region. It spans approximately 750 kilometers in length and 330-370 kilometers in width, encompassing an area of 260,000 square kilometers. The internal topography of the basin predominantly features uplifted areas to the north, northeast, southeast, and southwest, a gentle slope to the west, and a significant depression in the central region. Cenozoic sedimentary rocks in the Songliao Basin have a cumulative thickness exceeding 6000 meters, with Cretaceous deposits being particularly thick and widespread. The basin's geologic structure is complex and heavily faulted, enriched with geothermal, solar, and mineral resources, hence presenting a favourable environment for inducing seismic activity. Therefore, assessing the stress characteristics and susceptibility to sliding of geological structures in the Songliao Basin holds paramount importance for earthquake mitigation and disaster prevention. This study involved statistical analysis of data from 19 boreholes, 65 hydraulic fracturing experiments, and 44 stress relief measurements from the basin and adjacent areas. The study also discusses fault slip potential and seismic hazards based on fault mechanical theories such as the Byerlee-Anderson theory. Results indicate a shift from compressive (thrust) to transcurrent (strike-slip) stress regimes, aligning with the distribution of high-angle right-lateral NNE-trending reverse faults within the region. The dominant orientation of the maximum horizontal principal stress ranges between N45° and E60°. Preliminary inversion results suggest a primary compressive stress regime with localized strike-slip characteristics, which corroborates the inversion results from focal mechanism studies. The average friction coefficient of the faults in the region is calculated at 0.41, indicating a state of stability and low susceptibility to fault slipping. Additional analyses, interpolating lateral pressure coefficients and stress accumulation indicators, uniformly suggest a low general predisposition for fault slipping, although localized higher levels of stress accumulation are observed in shallow fault zones. Our comprehensive analysis infers that faults are more likely to slip in a NW-SE orientation.
Novel Application of Modified Enzymatic Fluid System for Freeing Stuck Pipe in Gas Wells
Authors: Abuelzm Ehab. , Ghosh D. , Ghosh B. , Mohammed A. R.
Published: November 2024

While Enzymatic treatment is considered safe for downhole tools and an effective technique for the removal of biopolymer-based drilling mud cake formed during drilling, a novel application of enzymatic system has been developed and successfully utilized to release stuck pipe while drilling. An enzyme's function is intrinsically linked to its three-dimensional structure, defining how it achieves substrate binding, catalysis, and regulation. Stuck pipe contingency especially in horizontal/multilateral wells demands large volumes of harsh chemicals like acid, solvents, and other chemicals potentially damaging to the reservoir and downhole tools. This paper aims to demonstrate the function of a robust all-enzyme system that can break down the biopolymer mud cake responsible for stuck pipes at harsh downhole conditions.

Freeing stuck pipe jobs executed in cooperation with one of the largest National Oil Company in Asia in an exploratory well drilled located in the North-Eastern fields. The 8 ½″ hole was drilled deep with logging-while drilling tool. Later the logging-while drilling tool was assembled with a rotatory BHA assembly and lowered for pipe conveyed logging. While lowering this tool at around 10000 ft, stuck was observed and multiple unsuccessful attempts for freeing string were carried out. A mud-acid job was carried out followed by HSD spotting and string shots, without any apparent success. Given the severity of the problem joint operation teams including the product designer, decided on the pilot application of this advanced Recombinant Enzyme H system. A pre-flush solution was pumped before pumping the enzymatic solution at the stuck region. After allowing a minimum soaking time the working on the string was carried out. The drill pipe was freed within 5 hours of enzymatic solution soaking after a loss of about 9 rig days. The drill collar severing job plan was canceled, and expensive logging tools were successfully retrieved. Drilling continued in the same section as planned. The enzyme application dissolved the friction causing cake acting around the stuck region and reduced surface area of contact to release all the differential stuck. This was a novel approach by the Operator showcasing the potential of this technology in freeing stuck pipes quickly and economically.
Enhancing Photorealistic 3D Model Accuracy with Underwater Positioning
Authors: Coffey R. , Beier M.
Published: November 2024

The adoption of photorealistic 3D modelling and digital twins for inspecting and documenting the state of physical assets is gaining momentum across various industries. However, the uptake of these technologies for underwater assets has been notably slower due to the challenges associated with scanning underwater; the limited number of service providers, and the costs and risks involved. Despite these inhibitors, there is a burgeoning interest in developing precise digital replicas of underwater assets.

A critical factor in producing accurate and measurable 3D models of underwater assets is accurate positioning, particularly when creating larger models. The absence of satellite GNSS signals means other methods are needed to estimate the position of moving objects underwater.

This study explores the influence of accurate positioning on the quality of underwater 3D models. It assesses two positioning techniques, comparing an acoustic triangulation method, which can achieve sub-decimeter accuracy with traditional approaches. The study also seeks to find cost effective solutions to the challenge of underwater photogrammetry as this is perceived by the authors to be holding back the adoption of this technology.

The findings highlight the potential improvements in model accuracy through enhanced positioning techniques generated by cost effective solutions, offering significant implications for various industries.

The research has been conducted by a company specialising in advanced vision based underwater 3D scanning and modelling technologies.
Opportunities for Renewable Oxygen Utilization from Electrolysis Plants
Authors: Biyikli Lukas
Published: November 2024

Oxygen is a versatile industrial gas and plays an important role across several industries, including steel, cement, pulp and paper, wastewater treatment, food and beverage, etc. Today, more than 500 million tons per annum (mtpa) of oxygen is consumed by industry globally. Around 90% of this is produced conventionally via cryogenic air separation units (ASUs) and 10% via pressure swing absorption (PSA). Over the coming decades, ASUs will likely continue to serve as the dominant method of oxygen production. However, the impending build out of electrolyzer plants to meet green hydrogen demand is opening a new low-cost production avenue that can be capitalized on.

This paper explores opportunities for renewable oxygen utilization from electrolyzer plants and discusses important considerations for compression. Making a commercial case for oxygen utilization requires evaluation of many different variables, including plant size, location, tax frameworks, available subsidies, etc. In cases where dedicated oxygen pipelines are close by, a compelling business case can be made for oxygen capture and compression. To illustrate the potential return on investment (ROI), the paper evaluates a hypothetical 500 megawatt (MW) electrolyzer plant. For these projects, selection of the compression technology is critical, as it represents a significant portion of the oxygen plant's total cost of ownership.
Upper Lekhwair (Lower Cretaceous) Depositional System and Reservoir Characterization in a Frontier Area, Southeastern Abu Dhabi
Authors: Whitcomb Nick , Bose Sweta , Seyedolali Abbas
Published: November 2024

The Lekhwair Formation, a prominent geological unit within southeastern Abu Dhabi, has recently been established as an oil-bearing reservoir outside of the traditional giant fields in the region. This study utilizes petrography and petrophysical evaluation to understand the Upper Lekhwair relationship between the reservoir quality and depositional environment. Variability in the thin Upper Lekhwair units creates challenges in predicting reservoir quality while drilling horizontal wells, identifying prospects, and optimizing hydrocarbon recovery efforts. This study will expand on the regional understanding of the Upper Lekhwair depositional system and reservoir characteristics to an oil-bearing area not previously investigated.

The Lekhwair Formation was deposited on a wide carbonate ramp setting, with depositional environments ranging from proximal mid-ramp to intertidal. Well log observations across the area show variability in porosity and thickness in most of the reservoir units but little variability in the intraformational seals known as ‘Dense’ zones. Reservoir variability is predominately related to the dynamic nature of the inner-ramp shoal system, which has sub-regionally displayed rapid facies changes between grainstones and mud-dominated packstones within the same zone over short distances (e.g. 2 km). The study noted high abundance of laterally inconsistent grainstones and rudists in the upper most reservoir units. The relationship between these rapid lateral changes between inner ramp mud-dominated and grain-dominated sediment is likely related to local build-ups on the inner ramp. Unlocking this relationship will unlock new exploration strategies.
Offshore Early Production Platform Proposal to Overcome Caspian Sea Constraints
Authors: Seddik Sameh , Chatterjee Prabir Kumar
Published: November 2024

This paper highlights the constraints for installation of early production facilities in the Caspian Sea region due to land-locked geography and non-availability of suitable marine construction vessels. Additionally, high risk for investment exists in the offshore Turkmenistan fields due to the concern of marginal field reservoirs. To address the concern, a removable jacket concept is provided that can be constructed and installed quickly and relocated at other locations in case of commercially unviable well flow rate.

This paper proposes a minimum structure to drill and appraise two oil wells without installing a full-fledged structural jacket and deck. The jacket will be connected to the seabed by temporary skirt piles. In case of a positive drilling outcome, the jacket will be piled and a deck with minimum topside facilities will be installed. A flexible pipeline will also be installed to connect with the nearest subsea/onshore tie-in point to carry out prolonged well testing (for months) and subsequent production operation. The existing and the new decks will be joined offshore. The conceptual design has a provision for four future wells.

Numerical studies show that the skirt-piled structure at 30m water depth can withstand up to 1-year return period environmental loads. The final structure after installing the permanent piles can withstand 100-year environments loads. Structural design is performed using API RP2A working stress design method. The results show the adequacy of the structure and prove that the investment risk can be considerably reduced by carrying out appraisal drilling before installing the full production facilities.
Key Well Construction Strategies for Productivity Improvement Under Integrated Services Projects
Authors: Davila Andres Nunez , Barrera Edison , Presniakov Mikhail
Published: November 2024

Nowadays across the Oil and Gas industry, there is a continuous requirement to find feasible solutions to unlock the oil reserves that were not accessible before. For this purpose, different techniques and technologies were implemented, facilitating the access to oil pools. The present paper will describe the integration models and contracts implemented in different projects, to unlock the oil reserves for diverse Operators.

The contractual model was set within different Oil and Gas Operators, based on the success criteria for each individual project, the environment complexity, and associated risks, considering the specific requirements and historical performance. Accelerating production is one of the main field development strategies, therefore, major technologies were evaluated and selected in accordance to deliver this requirement.

Geosteering services, open hole gravel pack, alternative well architecture designs, swellable packers, cementing innovative slurries, optimize directional trajectories were part of the new and critical services and technologies implemented to succeed while achieving the targets. This paper presents the methodology required to apply new technology, contractual agreement and risk assessment associated to deliver successful operations execution.

Different Integrated Projects supported the production enhancement initiatives by implementing innovative solutions during drilling and completions stage. A collaboration culture was created and validated by the Operators, with the purpose to identify optimization opportunities and expedite the learning curve throughout the project timeline, in line with the production enhancement.
Multi-Layer Reservoir Mapping in Low Resistivity, Low Contrast Clastic Reservoir Using Integration of Ultra-Deep Azimuthal Resistivity 1D and 3D Inversions
Authors: El-Khamry Ayman , Taher Ahmed , Fouda Mohamed , Bikchandaev Eduard
Published: November 2024

The use of modern ultra-deep azimuthal resistivity (UDAR) tools along with other Logging While Drilling (LWD) sensors increases horizontal well placement efficiency, improving net-to-gross and maximizing reservoir contact. The depth of investigation (DOI) of electro-magnetic (EM) resistivity-based technologies depends on multiple factors: frequency of the EM wave transmitted by the tool, spacing between the transmitter and the receiver antenna, conductivity of the surrounding formation and contrasts between layers. Although the first two factors are relatively controllable, the performance of EM resistivity tools in very low resistivity formation has always remained a challenge, limiting the signal propagation and hence the DOI. This paper presents a novel workflow for utilizing EM resistivity-based reservoir mapping logging while drilling (LWD) technologies for successful well placement and multi-layer mapping in very low resistivity, low contrast and thinly laminated clastic reservoirs.

The major challenge for mapping low resistivity low contrast reservoirs is the reduced investigation of the EM wave propagation combined with the weak signal response from the surrounding layers. Resolving multiple layers around the well trajectory then becomes difficult. Pre-well modeling has been performed prior to the start of operations using data from existing offset wells to identify the best configurations and basic settings (spacings, frequencies) for confident reservoir mapping in real time. A novel near-bit UDAR transmitter design was utilized along with a new optimized inversion algorithm was introduced to allow 1D inversion models to map the multiple layers all around the well. This has enabled critical real-time decision making while drilling to steer the well based on petrophysical properties, thicknesses, and structural dip of the target layers. This customized setup was designed specifically for geo-steering and geo-mapping in an extremely low resistivity low contrast environment that is not favorable for the EM resistivity tools.

The new workflow has been utilized in multiple wells with low resistivity and low contrast to adjacent beds. The selected tool configuration design optimized the signal to noise ratio (SNR). As a result, and despite the very low resistivity, both 1D and 3D inversions mapped boundaries more than 20ft away, delineating layers that are less than 0.5 Ohm-m. In places, the technology mapped up to 7 thin layers at a distance. Although structural displacements have been encountered while drilling, horizontal wells were successfully placed in the target layers providing maximum reservoir exposure and great improvements in effective net-to-gross (NTG).

This paper demonstrates a novel tool setup and workflow to expand the application of UDAR tools for well placement and reservoir mapping in very low resistivity low contrast environments.
Rig Electrification to Hit Decarbonization Target Even More
Authors: Al Hadidy Khaled , Segui Emmanuel , Abdulhamid Osma , Abdelhamid Seddik , Al Jabri Bashaer , Al Hosani Suad
Published: November 2024

Global warming is setting the whole world in a real challenge to select between, global economy and industry growth or environment protection. A commitment was set forth via COP organization requesting all countries to show progress and quantify decarbonization efforts. As opportunities always arise through difficulties and challenges, oil and gas industries in UAE found a series of innovative approaches where we can sustain our growth while meeting the decarbonization target.

As drilling Rigs are representing one of the main diesel consumptions in oil field and hence Co2 emission, series of initiatives driven to pilot fit for purpose application to substitute diesel driven generator(s). Any initiative that leads to diesel consumption reduction will represent a building block toward the objective. However, most of them have been short to meet the decarbonization target set by UAE leadership (25% reduction by 2030).

Solar energy and power storage batteries are on top of the pilots conducted but with limitations. Solar power generation requires a fixed setup / assets where nature of land rig is mobile however its very efficient and robust for fixed central camps. Power storing batteries are still limited to provide required range of energy to operate rigs independently or even partially. Dual fuel (Diesel and natural gas), biofuel and Hydrogen been on radar screen and assessed as well in this paper.

Quick and low hanging fruit initiative where this case study about is to screen the existing power grid in our mature fields, quantify the spinning power per each power line and map the drilling location for the upcoming business plan hence evaluate the feasibility to connect rig directly to those power lines utilizing available spare power per each power line providing no future infrastructure or production facility is planned for this spare power.
Innovative Solutions for Enhancing ESP Performance: Addressing Gas Lock Issues Through Flowback Loop Technology and Packer Removal
Authors: Al Manthari M. , Ali A. , Ferdiansyah E. , Al Mahrouqi A. , Al Hashli M. , Al Zaabi A. , Al Gheilani H. , Ji P.
Published: November 2024

This paper aims to address and mitigate the exacerbated ESP gas lock issues in packer completion operations, in Microporous reservoirs in North West Oman, that hinder fluid lifting, reduce production rates, and cause frequent ESP trips. By introducing an innovative solution for packer removal, it seeks to enhance ESP performance, prolong run life, and significantly reduce deferment, particularly in microporous/tight reservoirs with limited water injection support. Packer removal is considered justified under the company's well integrity management practices if a well cannot flow naturally within three days. To evaluate this, flowback tests were conducted in the field to assess natural well flowing capability within this timeframe. Multiple campaigns successfully demonstrated free-flow capability under ambient conditions. Additionally, Dynamic Transient Simulation analysis was used to predict natural flow following ESP shut-ins under atmospheric backpressure conditions. Model validation and sensitivity analyses were performed to evaluate ESP shut-ins and restarts without activating the ESP. The correlation between simulation results and flowback test findings reinforced the reliability of the conclusions. The implementation of flowback loop technology has shown substantial practical benefits. Based on flowback loop and dynamic transient modeling, the inaugural campaign of packer removal from four wells significantly reduced ESP trips, improved operational efficiency, and decreased oil deferment. In 2023, packer removal where feasible led to a net oil deferment reduction of approximately 22,000 barrels. By 2024, extending packer removal to 18 wells further reduced deferment by around 750 bbl/d. This technology not only improves production by allowing gas to escape, preventing gas lock conditions, but also ensures well integrity compliance without the adverse effects of traditional packer use. This dual benefit showcases a forward-thinking approach to managing ESP gas lock issues. The adoption of flowback loop technology combined with dynamic modeling represents a significant strategic advancement. This solution enables real-time evaluation of a well's natural flow capacity within the critical initial 72-hour period post-installation. This approach aligns with well integrity management standards, providing a proactive solution to prevent future gas lock issues and enhancing overall operational efficiency.
Concept of Inverted Jacket for Brown Field Extension of Offshore Platforms in Shallow Water
Authors: Chatterjee Prabir Kumar
Published: November 2024

This paper proposes a new concept of installing an inverted jacket with battered legs to connect with an existing fixed offshore structure for brown-field projects that require significant amount of additional deck space for new facilities. Use of an inverted jacket will allow more spacing between legs at the top of the jacket implying a larger deck space to accommodate more equipment. However, piles are separated from the legs to avoid convergence of the piles within the seabed. Piles will be driven through separate long sleeves and the annulus between the pile and the sleeve will be grouted before installation of the deck. Rigid/welded connections between the new and the existing deck structure helps in reducing the number and diameter of the new piles.

Numerical studies demonstrate the cases of two real-life structures with inverted jacket extensions at 28m and 35m water depths. Results show that a 2-level deck of size 30mx30m can be safely connected to the existing structure to withstand all gravity and environmental loads applicable for the two sites. The extended deck space can accommodate up to 700 MT of equipment and other facilities. The extended structure has adequate strength and the required minimum reserve strength. The proposed design requires considerably less structural steel compared to the conventional jackets to create the same amount of deck space.
AI-Driven Solar-Powered Digital Fencing for Enhanced Oil & Gas Field Security
Authors: Yousef Ahmed , Bukhamseen Raid
Published: November 2024

This paper introduces an AI-driven digital fencing system, designed to revolutionize security in oil & gas fields. The main objectives are to improve security and safety of oil & gas facilities while addressing the limitations of legacy physical barriers, reduce false alarms, and eliminate the dependability on the grid to renewable energy for continuous, reliable monitoring of operational information like temperature, wind speed, and humidity as well as the continuous monitoring to all security and safety aspects.

As per a PwC report (AI, 2018)1, The Middle East, particularly Saudi Arabia and the UAE, is poised to benefit significantly from AI, with an estimated economic impact of $320 billion by 2030. AI technologies are expected to contribute over $135.2 billion to Saudi Arabia's economy, equivalent to 12.4% of its GDP, about 14% of the UAE's GDP and close to 8% of Egypt GDP with contribution expected to reach $42.7 billion. The adoption of AI in the region is driven by substantial investments in technology and innovation, positioning these economies as leaders in the global AI landscape.

In this paper, we cover the integration of AI-driven Solar-powered fencing cameras, highlighting their potential to enhance security resilience and reliability in the oil & gas industry.
Advances in Underwater Robotic Inspection
Authors: Bancroft Jonathan
Published: November 2024

Advanced Non-Destructive Testing (NDT) technologies are the most effective tool in our ongoing fight to ensure the integrity of our offshore assets and subsea infrastructure against corrosion and other damage mechanisms. Over fifty years have passed since the first rigs appeared off the coast of California, in the North Sea, across the Gulf of Mexico, and around the globe. Much of the original structures and associated infrastructure remain in use today.

Operating far beyond their intended lifespans, these structures, pipelines, and other subsea equipment are increasingly vulnerable to aging-related issues, with corrosion being the primary threat among various potential failure modes, including weld cracking. Since the early days, we have witnessed continuous, steady advancements. New materials have been introduced, pipeline designs now better account for the seabed terrain, and the construction, operation, and maintenance of structures and pipelines have become significantly more efficient.

Despite improvements in corrosion protection, mitigation, and inspection technologies, the reality is that the longer a subsea asset has been in service, the more time corrosion or other defects have to develop. This is especially true for older assets installed before the availability of these advanced construction methods. Additionally, the marine environment is harsh and unforgiving, making the monitoring and maintenance of subsea assets integrity crucial, regardless of their age.
Application of Multi Objective Whale Optimization Algorithm for Solving Lift Gas Allocation Problem and Production Enhancement in Oil & Gas Industry
Authors: Kenoth Sasidharan Adiyodi , Paul Samuel Henry , Menon Biju , Kottappuram John , Nair Ajay , Maryam Dashtebayaz
Published: November 2024

Gas lift is one of the most commonly used artificial lift method in oil producing wells. The technique requires constant Optimization of injection gas quantity in the well to maximize oil production. High pressure Lift Gas allocation is an important step in optimization process to reduce the investment on costly and scarce lift gas and maximize oil recovery. In this work, an attempt is made to optimize a group of wells with application of an innovative metaheuristic algorithm. The objective function can be either the generated profit or total produced oil as a function of injected gas.

To achieve maximum recovery from gas-lifted wells, it's essential to identify the optimum injection rate for specific facility constraints, including gas availability, maximum injection depth, and compression capabilities. Normally, these parameters are unchangeable because of prior selection and installation, except when optimization techniques are implemented in the design phase. The Gas Lift Performance Curves (GLPC) are the main design element used for optimized gas injection. These curves are generated by modelling wells in a multiphase steady-state simulator. After building model, sensitivity analysis is run, and the curves are generated. In this work, the common workflow to generate GLPC is followed. Then, a new correlation for GLPC is suggested with help of a bio-inspired meta heuristic Whale Optimization Algorithm (WOA). The correlation is then used to formulate a case study for few wells located in Caspian Sea. R-score and Root Mean Square Error (RMSE) values compared. Wells and PVT models are used to create a simulation. The optimization problem is mathematically formulated using stochastic optimization techniques. The new correlation is used to fit the GLPC with WOA. A set of Pareto Optimal solutions are derived. Results of WOA is compared with other two potential algorithms such as Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) to obtain the global optimum of the distribution of a limited gas lift quantity. The advantages of WOA over PSO and GA is discussed, and the optimum gas allocation is obtained. The correlation outperforms all other models and also bring an injection gas saving of 10-15% and improved oil production to the extent of 5-10% with an automated WOA algorithm application. Compared to the traditionally applied numerical methods for gas allocation and optimization, AI meta-heuristic algorithms are considered as revolutionary methods, offering more solutions to gas allocation problems, which can solve non-linear multi-objective optimization problems quickly and more accurately with fast convergence. WOA is simpler, faster and outperforms PSO and GA and yield maximum production at minimum cost.
Application of Self-Supervised Autonomous Agent Framework for Digital Transformation of Elder Well Potentials Discovery
Authors: Chen H. , Zhao Q. , Lu W. , Gu S. , Jin W. , Liu G. , Lin X.
Published: November 2024

Objectives/Scope

The manuscript presents an innovative agent-based framework aimed at enhancing the reassessment of elder oil and gas wells. By integrating diverse generative artificial intelligence (AIGC) models, this framework harnesses self-supervised feedback mechanisms to continually enhance the reasoning prowess of large-scale models, thereby facilitating curve reconstruction, horizon forecasting, and potential layer interpretation for existing wells. Notably, this approach demonstrates the feasibility of agent-driven AI-native applications in bridging various oil and gas industry contexts without necessitating extensive fine-tuning.

Methods, Procedures, Process

The proposed methodology introduces a novel Explainable Self-Supervised Agent Group Framework (ESSA), which constructs an agent cluster to facilitate seamless interaction among business systems, AIGC models, and scenario-specific models. The ESSA's three-tiered agent system operates within a closed-loop configuration, leveraging continuous feedback and self-supervision agent frame as its core mechanism for aiding reinforced learning to deal with the complex task. This architecture encourages iterative refinement of AIGC models, mitigating issues such as inaccuracies, fabrications, and misleading information, while facilitating precise model selection, content generation, and refined evaluations of aged wells.

Originality

The manuscript underscores the novelty of its platform architecture through two primary contributions: (1) The synergy between the agent ensemble and AIGC models yields an AI-native solution capable of tackling multi-faceted, scenario-spanning challenges in the oil and gas sector. (2) The multi-agent framework fosters a closed-loop ensemble that promotes collective intelligence through self-learning and optimisation, selecting optimal models to continually refine well reassessment processes, significantly curbing operational costs in practical deployments.

Reuslts

To validate the framework's efficacy, we analysed a dataset comprising 50+25 elderly wells, all exceeding 30 years in age, located across two distinct geological blocks. Our evaluation encompassed model selection accuracy, logging curve reconstruction fidelity, horizon classification (encompassing oil, water, gas, sandstone, mudstone, and oil-water coexistence zones), and the capacity to recommend potential horizons. The outcomes underscore the framework's robust agent ensemble organisation, enabling AIGC models to unlock their full potential through self-supervised prompting engineered within the proposed agent framework. With human-in-the-loop interactions, the framework achieved horizon classification and potential horizon prediction accuracies ranging from 50% to 80% for the mature wells under assessment.
Nitrogen level determines arbuscular mycorrhizal fungi nitrogen uptake rate of Stipa purpurea in alpine steppe
Authors: Sun Jiahui , Tang Yu , Chen Keyu , Ren Shijie , Shi Hailan , Dong Qiang , Dong Junfu , Zhang Lin , Cui Xiaoyong , Wang Yanfeng , Ji Baoming , Zhang Jing
Published: November 2024

Background and aims Roots and mycorrhizal fungi, especially the Root-pathway and Myc-pathway, represent two alternative strategies for plants in the process of soil nutrient foraging. However, the concurrent carbon (C) economy associated with resource acquisition through root and mycorrhizal pathways remains unclear, particularly across the nitrogen (N) enrichment gradient.
Methods Using experimental microcosms with a dominant plant of alpine steppe, Stipa purpurea, and inoculated with native arbuscular mycorrhizal fungi (AMF) in combination with 15N and 13C dual-labeling, we quantified the direct N transfer to the host plant through both pathways, as well as the C allocated to the fungi and roots by the same plant, across three N addition treatments (control (0 kg·N ha-1 yr-1), low N (50 kg·N ha-1 yr-1) and high N (150 kg·N ha-1 yr-1)).
Results We found that, under the low N treatment, extraradical hyphae of AMF proliferated extensively, and the plant exhibited significantly positive mycorrhizal responses in terms of biomass and nutrient foraging. The contributions of N foraging through the Myc-pathway to S. purpurea were 13.85%、48.28%、30.59% across the N addition gradient, respectively. Especially under the low N addition, plants preferred the Myc-N pathway over the Root-N pathway. However, the C allocation to AMF by plants under different N levels showed no significant difference.
Conclusion Upon comparing the ratios of N benefit to C cost, we believe that the low N addition can maximize the function of native AMF in N foraging for alpine plants.
Geoelectrical evidence of fluid controlling slow and regular earthquakes along a plate interface
Authors: Nakamura Hayato , Ichihara Hiroshi , Goto Tada-nori , Matsuno Tetsuo , Tada Noriko , Kuroda Manaka , Sato Shinya
Published: November 2024

Shallow subducting plate interfaces, as sites of both destructive and “slow” earthquakes, resulting from rapid and slower fault slips, respectively, present a major scientific and disaster mitigation challenge. Although understanding the different slip mechanisms and their spatial relationships is critical, the role of a key factor, pore fluids, is understudied. Here we present clear observational evidence from Hyuga-nada, southwestern Japan, that the pore-fluid distribution correlates with fault rupture behavior. A 3D electrical resistivity model derived from marine magnetotelluric survey data reveals distinct resistive and conductive anomalies along the plate interface that reflect areas of scarce pore fluid and high concentration area of pore fluids sourced from subducting seamounts (Kyushu–Palau Ridge), respectively. The wet area corresponds to the slow slip area whereas dry and the transition areas correspond to areas of fast fault slip. These findings highlight the influence of the pore-fluid distribution on fault processes and underscore its importance in earthquake and tsunami risk assessments.
Transcriptome Sequencing Reveals Significant RNA Variation in Human Sperm Samples
Authors: Chen Weiming , Yu Lei , Jia Zhenyu , Zhu Jianguo
Published: November 2024

As spermatocytes mature, they shed substantial cellular material, resulting in sperm cells that primarily contain DNA. Sperm cells variation in RNA has not been addressed in the literature. We analyzed semen samples from 83 males, with normal sperm motility and asthenospermia, a condition characterized by reduced sperm motility. Using the conventional quality criterion for RNA sequencing, 15 samples (set 1) met these standards, 22 samples (set 2) approached these standards, remaining samples failed library construction. We hypothesize the samples that did not pass the conventional RNA quality standards represent the mature and functional sperm with reduced RNA, these samples have been ignored in previous studies. We have made the RNA sequencing data publicly available in the GSA-Human database, under accession numbers HRA006250 and HRA006906, respectively. These datasets will provide insights into the role of RNA in sperm generation and facilitate the development of (1) new RNA quality standards for sequencing the sperm transcriptome and (2) identification of residual RNA in mature sperm cells and genetic role in influencing offspring phenotypes.
Association of premenstrual disorders during preconception with perinatal depression: an analysis of the perinatal clinical database of a single Japanese institution
Authors: Ohsuga Takuma , Egawa Miho , Tsuyuki Kaori , Ueda Akihiko , Komatsu Maya , Chigusa Yoshitsugu , Mogami Haruta , Mandai Masaki
Published: November 2024

Background
Recent studies have identified premenstrual disorders (PMDs) as a risk factor for postpartum depression. However, routine screening for preconception PMDs is not yet common in Japan. This study investigated the association between preconception PMDs and perinatal depression in a single tertiary care setting.
Methods
We analyzed data from pregnant women who delivered at Kyoto University Hospital between April 2020 and October 2023. PMDs during preconception was assessed using the Premenstrual Symptoms Screening Tool, whereas perinatal depression was measured using the Edinburgh Postnatal Depression Scale (EPDS) during pregnancy and at 1 month postpartum. EPDS cutoff values were set at 12/13 during pregnancy and 8/9 at 1 month postpartum.
Results
Of 789 women analyzed, 54 had preconception PMDs. Univariate and multivariate logistic regression analyses revealed that preconception PMDs was associated with an EPDS score of ≥ 13 during pregnancy, with a crude odds ratio (OR) of 5.64 (95% confidence interval [CI]: 2.64–11.5) and an adjusted OR of 3.63 (95% CI: 1.51–8.14). For an EPDS score of ≥ 9 at 1 month postpartum, the crude OR was 3.22 (95% CI: 1.72–5.85) and the adjusted OR was 2.10 (95% CI: 1.01–4.20).
Conclusions
Our findings indicate that preconception PMDs is a significant risk factor for both depression during pregnancy and postpartum depression. These results support the implementation of preconception PMDs screening during antenatal checkups to identify women in need of early mental health care and preventive measures.
Ultra-lightweight carbon nanocomposites as microwave absorber with high absorbing performance derived from flour
Authors: Zhong Yiming , Long Yunchen , Sun Yinuo , Qin Jiachen , Li Yongxin , Liang Gemeng , Zou Jinshuo , Xie Peitao
Published: November 2024

Carbon materials, known for their lightweight properties, are widely utilized in electromagnetic wave absorption applications. In order to overcome the limitations of effective absorption of electromagnetic waves by a single carbon material, magnetic cobalt nanoparticles were incorporated into a carbon network derived from flour, resulting in the development of Co/C nanocomposites with a porous structure through fermentation. The research results show that the electromagnetic wave absorbing material prepared in this way has advantages such as being thin (1.80 mm), lightweight, having a wide effective absorption frequency range (8.07 GHz), and high electromagnetic wave absorption capacity (-61.6 dB).The electromagnetic wave absorption capability of the material originates from the multi-level interfaces in Co/C nanocomposites, the porous carbon structure formed during flour fermentation, and the dielectric relaxation generated during the polarization process. The excellent electromagnetic wave absorption performance is mainly attributed to impedance matching and attenuation factor optimization. The presence of a small amount of amorphous carbon in the carbon network reduces the condensation and oxidation of magnetic cobalt nanoparticles, thus enhancing the impedance matching. By adjusting the Co/C ratio inside the nanocomposites, the impedance matching of the Co/C nanocomposites is improved, and the absorption capacity of the CO /C nanocomposites is improved. This article reports the method of determining the ideal content of absorbent in flour based composites and the principle of optimizing the electromagnetic wave absorption capacity of nanocomposites.