bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tar Origin and Prediction in an Offshore Oil-Field Abu Dhabi
Authors: Peralta E. , Cajas L. , Al Jawhari M. , Carr C. , Alaminos A. , Buhindi H. , Al Harbi H. , Ibrahim L. S. , Escobar R. , Liu Y. , Anurag A. K. , Grimmer J. O. 
Published: October 2023

Abstract
This study shows the successful integration of analyses performed in an oil field offshore Abu Dhabi to explain the origin and distribution of a Tar zone. These analyses were performed at different scales and led us to propose a hypothesis that helps to optimize well placement and reservoir development.
The study was executed in five overlapping phases starting with a geochemical characterization (Tegelaar et al., 2021) to describe the nature of the Tar found in the field using rock and fluid samples. The second phase was a structural analysis (Needham., 2021) focused on understanding the chronology and role of the faults and structural deformation on the migration process and Tar deposition. In parallel, detailed petrographic analyses (Rossi., 2021) were performed to establish the Diagenetic and oil charge history; fluid inclusion data were of key importance to the final conclusions. Petroleum systems modelling (Grimmer et al., 2022) was performed using input from the preceding phases to validate concepts. Finally, an integration phase was performed to bring together ideas from each component and conclude with a unique description for the tar distribution and corresponding uncertainty.
There are two types of Tar found in an Upper Jurassic Formation of this offshore Abu Dhabi field. Tar Type 1 occurs as massive or patchy and mainly in the Mid-Lower reservoir, commonly in coarser grained lithology where it occludes porosity. Tar Type 2 (stylobitumen) occurs in non-reservoir facies (mainly micrite and stylolite) in the Lower Reservoir. The study highlighted that the field was exposed to a paleo-temperature peak higher than the current reservoir temperature that transformed both types of tar into pyrobitumen, a solid carbon form with no potential for exploitation.
Predicting the distribution of Tar type 1 is important to the field development as it occurs within the producing zone. The proposed concept of flocculation indicates that it was created mainly during Eocene times. Two conceptual models where presented, both leading to similar predicted tar distributions that allow the optimization of future well locations.
The study proposed a new description of the tar found in this field offshore Abu Dhabi and a novel concept that has already proven valuable in the well planning process of the wells drilled since the study was completed.
Enhancing Production From Low-Permeable Reservoirs With Advanced Hydraulic Fracturing Monitoring Techniques
Authors: Fesina Yulia , Smirnov Dmitrii , Uralsky Stanislav , Skitin Vasilii , Butaev Artur , Ghadna Sulaimi , Hadhrami Abdullah , Alkhattab Mahrooqi 
Published: October 2023

Abstract
Hydraulic fracturing is an important technology that can improve the production of oil and gas from low-permeable reservoirs, but it can also be challenging and requires ongoing monitoring and assessment to ensure that the fractures are performing as expected. The height of the fracture can significantly affect the efficiency of production. Spectral noise logging and tracer analysis are two methods that can be used to determine the height of the fracture and assess its performance. The Tracer analysis technique involves mixing a tracer material with the hydraulic fluid used during the fracturing process. The subsequent monitoring of the radioactivity level versus depth provides information about the fractures' placement and extent along the wellbore. On the other hand, a passive spectral acoustics survey will record the acoustic signal that is generated by the flow through the fractures during production, thus enabling the exact determination of the fractures' position and their active heights along the wellbore axis. By combining these techniques with temperature and hydrodynamic modelling, it is possible to calculate the specific performance of each fracture.The results from three wells' surveys confirmed the effectiveness of this methodology. Both Tracer and Passive spectral acoustic methods were able to determine the location of the fractures along the wellbore axis. However, the spectral noise determination is a lot more informative due to the nature of the measurement, which responds properly to the contributing or active height of each fracture whilst the GR response opposite the Tracer represents the physical extent of the fracture along the wellbore. One more point; the Tracer fluid can migrate away from the fractures due to poor cement bonding, etc. which could confuse the interpretation by falsely indicating a fracture extent at a certain depth.In addition to the findings described above, this methodology allows the pinpointing of the fracture depths behind the casing, away from the fracturing ports. The coupling of these measurements with a High Precision Temperature sensor and with Temperature Modelling allows the determination and quantification of the flow rates inside and outside the wellbore, thus providing a full and comprehensive picture of the downhole flow profile.
Importance of Benchmarking, Parametric Assessment for Capacity Enhancement
Authors: Sivanandam Surendarbabu , Al Marzooqi Fauzeya 
Published: October 2023

Abstract
It is very important to benchmark the plant performance and check existing unit adequacy in detail to ensure integrity and operating flexibility for the potential capacity enhancement. In this study 110% capacity enhancement of existing acid gas removal unit and NGL units are targeted with higher ethane recovery and the study is conducted to identify any bottlenecks / limitations. The digital twin model is developed in performing the adequacy checks with digital databank of the existing facilities.
Bench marking simulations and parametric study is carried out to clearly demonstrate the plant performance in terms of product quality, major equipment performance, duty, utility (refrigerant, steam requirement) and available margin on equipment. The detailed process simulation model developed with rigorous modelling of Column internals, Exchangers, compressors, expanders, steam turbines, pumps etc. The calculation routines for adequacy check of all type of separators, molecular sieves beds, piping, inline instruments are built in the excel digital twin concept. The approach of rating mode of simulation and results transfer from HYSYS to excel digital twin completes adequacy check quickly in details.
Based on one-year operating data, processing capacity limits of process trains are established for different range of feed compositions anticipated. Process simulation and detailed equipment level adequacy checks has been performed for benchmarked plant performance as well as increase in feed gas throughputs to the maximum limits in steps. The parametric study identified the potential capacity enhancement of existing AGRU and NGL units is possible up to 110% compared to original design for various compositional cases simulated. The study established the maximum CO2 concentration in the treated gas from acid gas removal unit shall be limited less than 1% to avoid potential freezing issues in NGL unit for the targeted ethane recovery level. NGL unit capacity and ethane recovery levels are limited by the richness of the gas, a nomogram is developed indicating the maximum through put that could be achieved with respect to C2+ content in the feed gas for the targeting ethane recovery levels. The propane refrigerant compressors in the unit were limiting the process capacity for the targeted recovery levels. Few minor debottlenecking measures were identified in AGRU units to ensure the plant safe operating limits.
The detailed study ensured safe operation, integrity and no HSE concerns. This study helped in maximizing overall asset utilization and supporting the revenue stream in terms of more gas throughput and higher NGL recovery. The detailed digital twin modelling approach adopted along with the simulation data integration to perform calculations helped to do the detailed study to complete quickly with all the necessary information.
Exploring the Potential of Offshore Green Hydrogen Production: A Concept Study for a Large-Scale Installation
Authors: Dzhusupova Rimma , Vis Ron 
Published: October 2023

Abstract
Green hydrogen production involves the use of renewable energy sources such as wind, solar, or wave power to produce hydrogen. As the demand for large quantities of hydrogen continues to increase, it is necessary to scale up green hydrogen plant designs to the gigawatt scale. One of the main advantages of offshore green hydrogen production is the availability of more consistent and stronger wind resources, which can be directly connected to hydrogen production in the area. Unlike onshore production, offshore production does not require expensive infrastructure such as offshore HVDC substations or large volume of subsea cables to collect and transport electrical energy to shore. Additionally, offshore production can help to reduce the visual impact of renewable energy infrastructure on land and can provide opportunities for co-location with other offshore activities such as aquaculture or shipping. Due to the inability of the existing electrical grid in West Europe to support numerous hydrogen projects, offshore production near renewable wind energy sources will become necessary for countries in that region, such as the Netherlands, Germany, and Denmark (NSWPH, 2022).
However, offshore green hydrogen production also presents some challenges. The cost of building and maintaining offshore infrastructure can be higher than onshore, and the harsh marine environment can increase maintenance costs and reduce the lifespan of equipment. Additionally, the transportation of hydrogen from offshore production sites to onshore markets can be more complex and expensive.
Currently, there are no large-scale green hydrogen installations operating offshore. However, there are several projects under development, including the recently announced plan of the European Commission to develop the North Sea as a green power plant for Europe, targeting offshore wind power generation of at least 65 GW by 2030 and 150 GW by 2050. This will contribute to large-scale offshore production of green hydrogen, where the target is to reach 20 GW production capacity already by 2030 (NSWPH, 2022).
Given the growing demand for green hydrogen, industry recognizes the need for innovative solutions that address the challenge of scaling up production while minimizing environmental impact. To achieve this, we are exploring in details an offshore green hydrogen production installation at large-scale.
In this study we combined McDermott's significant experience in onshore green hydrogen production and offshore complex process platform engineering designs. The concept for Offshore Green Hydrogen Production is developed by McDermott's Subject Matter Experts (SMEs) from various engineering disciplines and based on commercially available Electrolyser Package information. The concept offers a total electrolysis capacity of 480 MW. Moreover, AI-based technology has been assessed to ensure efficient and autonomous process control of the plant in the long run.
Multi-Objective Schedule Optimization for Intermittent Pumping Wells Based on NSGA-II
Authors: Sun Y. , Zhang X. , Zhao R. , Wang C. , Shi J. , Zhang X. , Zhao H. , Ma G. , Yi H. , Yu C. , Zuo Q. , Sun D. , He J. , Xu M. , Chen S. , Chen G. 
Published: October 2023

Abstract
Intensive production over time can lead to wells with low productivity and efficiency in oil wells. To address this issue, intermittent pumping has become a popular solution, involving temporary cessation of production to allow for fluid level recovery and achieve optimal submergence depth before resuming pumping. However, determining the appropriate schedule for intermittent pumping wells is challenging. This paper proposes a multi-objective schedule optimization method for intermittent pumping wells using the non-dominated sorting genetic algorithm II (NSGA-II). The method considers multiple objectives such as production rates, electricity costs, and the solar energy utilization. Two case studies are presented, optimizing schedules with stepped electricity tariffs and integrating solar power. The results demonstrate significant reductions in electricity costs by 13.5%, while maintaining production rates. With the assistance of solar energy, the proposed method achieves over 45% reduction in electricity costs and a solar energy absorption rate exceeding 90%.
Cement Bond Logging; A Generational Review of Technologies & Log Interpretation
Authors: Kamgang Sebastien , Hanif Amer , Neupane Rakesh , Goralczyk Matthew 
Published: October 2023

AbstractSuccessful placement and curing of cement behind casing is critical for the environment, operational safety, economics and lifespan of any oil and gas well. Cement bond logging technologies have evolved, from basic CBL, to include different measurement physics, sensor technologies and deployment options. Add to that, a better understanding of downhole conditions now enables us to interpret the measurements in a more insightful manner. We will present a modern review of the cement logging technologies including current and best practices in log interpretation.Introduced in the oil and gas industry in the mid-1950’s, Cement Bond Log (CBL) tools have stood the test of time despite the continuous development of increasingly sophisticated technologies. Where used by itself, CBL technology presents several inherent limitations, however, when used together with modern measurements, it frequently provides valuable complementary information. Our methodology consists of using a collection of recent case examples, using multiple technologies and measurement physics, and review both the weaknesses of a standalone CBL and the value it brings when integrated with new methods.Initially designed and tested in laboratory conditions, cement slurries are expected to achieve certain downhole performance with respect to curing time and compressive strength. The casing is also expected as centralized, in good borehole, surrounded by a uniform cement sheath for zonal isolation. A deviation from the ideal conditions, can impact the interpretation of cement logs and lead to erroneous decision making. Low density and or contaminated cements, unexpected downhole pressure and temperature, gasified borehole fluid, enlarged and or rugose open holes, casing eccentricity, multiple concentric casings, fast formations, micro-annulus, etc. are all real-life conditions which influence the condition of cement, as related to both coverage and strength, and challenge the interpretation of the logs. However, a majority of these challenges are effectively overcome, through integration of technologies, as will be demonstrated through presented field examples.Advancement in cement evaluation technologies, over the last 70 years, and our increased understanding of downhole conditions makes the case of an all-encompassing, modern review of cement bond logging. Log responses are easy to understand in extreme conditions of "free" or fully bonded pipe. However, as downhole conditions start to differ from ideal conditions, the log responses can often be misunderstood. This paper proposes to provide a comprehensive and additive information on interpretating the time-tested CBL all the way to modern services in use today. This will lead to unambiguous evaluation of downhole cement status and confident decision making by practicing engineers.
A Case Study to Recover LP Steam from Deheptanizer MP Steam Condensate
Authors: AlGhailani Mi , Sajjad Saqib 
Published: October 2023

Abstract
In pursuit of energy efficiency and sustainability, this study explores the untapped potential of recovering low-pressure (LP) steam from medium-pressure (MP) steam condensate in Plant A's Train-4 Deheptanizer reboiler. By harnessing the power of LP steam recovery, significant fuel savings, emission reductions, and revenue generation can be achieved. This study aims to assess the technical feasibility and economic viability of this proposed solution.
Employing a comprehensive methodology, we gather data from multiple sources, including design specifications, operational figures, and advanced thermodynamic models. The proposed modification to the system enables the recovery of LP steam from the MP condensate, paving the way for remarkable gains in energy efficiency.
Through systematic analysis, it has been determined that the waste heat recovery of the LP steam from the MP steam condensate in the Deheptanizer Reboiler has significant technical feasibility. This recovery process involves necessary modifications and additions to the existing infrastructure, enabling the recovery of LP steam and resulting in a substantial increase in energy efficiency.
Moreover, the cost savings achieved through LP steam recovery, along with the revenue generated by surplus steam, contribute to its economic viability. This investment demonstrates a short payback period, positive net present value, and a high internal rate of return, all indicating its financial attractiveness.
Furthermore, embracing LP steam recovery has a positive environmental impact, specifically in terms of reducing fuel consumption and greenhouse gas emissions. ADNOC Gas's commitment to environmental stewardship is underscored by this solution, as it aligns seamlessly with their sustainability goals.
Our findings reveal a promising opportunity for Plant A to unlock enhanced energy efficiency, reduce environmental impact, and achieve substantial cost savings by recovering LP steam from MP steam condensate in the Train-4 Deheptanizer reboiler.
Well Control Optimization with Output Constraint Handling by Means of a Derivative-Free Trust Region Algorithm
Authors: Hannanu M. , Silva T. L. , Camponogara E. , Hovd M. 
Published: October 2023

Abstract
The Derivative-Free Trust-Region (DFTR) optimization is well-suited for reservoir engineering problems where gradient information is often unavailable, unreliable, or unacceptably costly to obtain by numerical means. As opposed to direct search methods, the DFTR method is known to exhibit early convergence due to its capability to capture function curvatures with approximation models, which is important for simulations with long run-time. In this paper, we propose a new DFTR optimization algorithm which is capable of handling output constraints in well control problems.
The method relies on building polynomials using interpolation points generated from the simulation runs to model the objective function and constraints that are valid within the region around an incumbent solution. The models are subject to improvement when appropriate to ensure good geometry and accuracy of the approximation. The algorithm utilizes the models to find the next optimum iterate and introduces safeguards to ensure improvement in both the objective function and the constraints violation.
The algorithm is open source and has a clear interface with capability for integration to different reservoir simulators. The method is tested on the SPE10 benchmark model for reservoir simulation with realistic output constraint scenarios. The result of this study shows that the DFTR algorithm can achieve optimal operating points that improve the objective function in well control optimization problems while still honoring the constraints within a reasonable number of iterations. A comparison study is also conducted with two other derivative-free methods: NOMAD and COBYLA, where it is shown in the case studies that the proposed DFTR algorithm performs better in terms of the objective function value, number of function evaluation, and the feasibility of the solutions.
This paper addresses the handling of output-constraints by introducing an algorithm called Derivative-Free Trust-Region Filter Sequential Quadratic Programming (DFTR-FSQP) that can handle black-box type of simulators. This allows a non-intrusive optimization routine that can be naturally added into any reservoir modeling frameworks in order to handle practical operational limitations typical of field operations that can be expressed as constraints on acceptable solutions, such as water production and topside capacity. Further, using this method, one may express constraints independently from the simulators if the information is available. While reservoir simulators may be able to impose such restrictions internally, it introduces discontinuities in the cost function by control-variables switching and therefore could jeopardize the consistency of the dynamics and therefore the optimality of the solution.
Analysis of the Japanese Depleted Gas Fields’ Prospect for Underground Hydrogen Storage
Authors: Safari A. , Sugai Y. , Sarmadivaleh M. , Imai M. , Esfandyari H. , Haghighi M. , Moradi M. , Zeinijahromi A. 
Published: October 2023

Abstract
A method for reducing power peak is to store hydrogen (H2) underground in depleted gas reservoirs (hereafter UHS). In contrast to alternative solutions, like salt caverns or aquifers, the availability of depleted gas reservoirs gives a greater storage capacity. But choosing the right gas field for the UHS and carrying it out are tricky. As a result, the goal of this work is to characterize the UHS in the chosen field and rank Japanese gas fields for it.
To begin with, we ranked and screened potential H2 storage locations in Japan using the Analytical Hierarchy Process (AHP). The best locations for UHS, according to our calculations using the AHP approach, are Sekihara, Kumoide, Katakai, Nakajo, Kubiki, Shiunji, Iwafune-oki (gas), and Minami-Nagaoka. These fields’ high flow capacity, depth, current reservoir pressure, and dip angle are the causes of their elevated position. Then, based on a volumetric reservoir, we studied the H2 injection, storage, and withdrawal capacity at the chosen site in the Niigata Prefecture using the CMG reservoir simulator.
For the first time in Japan, this work offers a framework for evaluating and ranking potential depleted gas reservoirs as a UHS option. It also includes a reservoir simulation study to comprehend the impact of various parameters such as hysteresis trapping, number of injection and withdrawal cycles, and type of cushion gas on the efficiency of H2 storage and withdrawal in a volumetric gas reservoir.