bluuebunny/crossref_metadata_2025 huggingface dataset:
Innovative Molecular Sponges: Next-Generation Direct Air Capture Technology Enabled by Metal-Organic Frameworks
Authors: Cruz A. J. , Parrella I. , Wenz G. , Storey J. , Husk J.
Published: October 2023

Direct air capture (DAC) is an engineered atmospheric carbon dioxide (CO2) removal technology aimed at mitigating climate change impacts, as emphasized by the United Nations Framework Convention for Climate Change (UNFCCC). With only a limited number of currently deployed units globally, DAC technology is still at its embryonic stage. To improve its acceleration, the DAC system needs to be tackled holistically – including but not limited to (1) sorbent selection and performance improvement, (2) scaling of manufacturing from laboratory to industrial segments, and (3) integration of the engineered contactor design. Metal-organic frameworks (MOFs), with their interesting properties, such as record-breaking specific surface areas, crystallinity, and chemical versatility, are identified as one of the most promising materials for solid DAC applications. Baker Hughes recently acquired Mosaic Materials to scale its next-generation DAC technology. In this work, Mosaic's breakthrough will be used as a case study, building on its proprietary MOF, process optimization, and engineering design, and the journey from lab-scale work to systems-level programs. Policy, sustainability, and knowledge-sharing will play critical roles as prime agents to accelerate DAC deployment enabled by advanced materials such as MOFs.
Research on Geophysical Response Analysis and Geostress Prediction Technology Based on Seismic Azimuthal Anisotropy
Authors: Wang Chang , Shi Xuewen , Wu Jianfa , Zhang Dongjun , Liao Maojie , Zhang Ruhua
Published: October 2023

The exploration and development potential of shale gas reservoirs in Sichuan Basin is enormous, however it also faces difficulties such as complex structures, strong heterogeneity and unclear geophysical response characteristics. Fine prediction of geostress is an important part of shale gas exploration and development, which directly affects the implementation effect of reservoir evaluation, well trajectory design and fracture reconstruction. The existing geostress prediction techniques lack high precision seismic data constraints, making it difficult to accurately reflect the planar distribution characteristics of the geostress in block with rapid changes in complex tectonic zones. At the same time, the geophysical response characteristics of geostress in Sichuan Basin are unknown, the geostress seismic prediction technology lacks theoretical basis. This paper combines numerical simulation and physical experiments, and defines the characteristics of geophysical response of shale gas reservoir in Sichuan Basin changing with stress field, and technical countermeasures for geostress seismic prediction are established to provide technical means for accurate prediction of geostress field in shale gas block. Based on the geostress sensitive parameters obtained from prestack seismic inversion, the geostress field prediction of a Shale gas work area in Sichuan Basin is realized.
Combining Machine Learning and a Multiphase Flow Model for Hybrid Virtual Flow Metering
Authors: Gryzlov A. , Safonov S. , Krasnopolsky B. , Arsalan M.
Published: October 2023

Virtual flow metering is a technology for indirect estimation of multiphase production rates. The most straightforward approach to obtain virtual measurements is to apply machine learning models, which enable fast but not necessarily accurate prediction of flow rates. In order to overcome any related limitations machine learning methods can be combined with physical conservation laws of mass, momentum and energy. The resulting hybrid virtual flow metering approach strongly relies on the capabilities of underlying physical simulator.

In this work various approaches of combining measurements with multiphase flow models are investigated. It is demonstrated that a wellbore flow model has a central role in any type of hybridization scheme which connects the available measurements to the target flow rates. Due to specific requirements of the virtual flow metering applications, this simulator has to be fast and accurate enough to qualitatively describe flow in wellbores and pipelines. In this work, such a simulator is presented, which is based on a one-dimensional formulation for mass and momentum conservation, but contrary to other commercially available options, the current development is based on a drift-flux approach, which is less demanding on the interfacial closure terms and can be more easily tuned with field data. The performance of the simulator has been evaluated using a set of transient benchmark scenarios, where the reasonable match against the reference data has been demonstrated.

The simulator is applicable to a wide range of multiphase flow problems of practical interest and uses advanced numerical algorithms to ensure robustness and performance. The closure relationships can be adjusted to improve the performance for a particular well. In addition, a dedicated graphical user interphase enables user-friendly interaction for setting up the computational case and processing the output production data.
Rock Type-Based Geosteering in a Multilayered Reservoir by Combining LWD NMR Measurements and Ultradeep Azimuthal Resistivity Images
Authors: Al-Otaibi A. , Osman H. , Van Steene M. , Santoso G.
Published: October 2023

Deep-azimuthal resistivity images are widely used to place wells accurately inside of a target reservoir structure. However, the resistivity measurement does not provide much sensitivity to the reservoir quality, particularly in carbonates, where large pore-size variations are often encountered. For optimized well placement, combining the deep-resistivity images with logging-while-drilling (LWD) nuclear magnetic resonance (NMR) measurements establishes the link between reservoir structure and rock types while drilling.

Factor analysis is the technique used to reduce the large NMR data set to a smaller number of underlying, porofluid components. These components are clustered into groups called porofluid facies, which reflect the most common combinations of pore volume and fluid NMR properties. Based on the NMR data, four petrophysical rock types are generated while drilling: RT-1 has good porosity and long T2 components, indicating large pores; RT-2 also has good porosity but medium T2 components, indicating smaller pores; RT-3 has medium porosity and long T2 components, while RT-4 has medium or low porosity and medium or short T2 components, indicating the poorest facies.20

The NMR-based rock typing technique and ultra-deep resistivity images were combined in three laterals drilled back-to-back in a thin-carbonate reservoir where pore size variations were expected. In the first lateral, targeting layer 10, fair (RT-2) rock type was present over the first half of the lateral. Only a small part of the drilled footage encountered the best rock type RT-1. The decision was then made to explore layer 11 under layer 10. The NMR showed that layer 11 was mostly of the poorest quality (RT-4). Based on the first lateral results, the second lateral targeted layer 10. Layer 10 was found to be of excellent quality in which most of the rock was RT-1 type, with some sections of RT-2; hence, no change of layer was required in this lateral. The third lateral explored layer 5. The first half of the section encountered RT-2 and RT-4 types. After having observed that a resistivity increase corresponded to a poorer rock type, the second part of the lateral was completed in one layer that intersected RT-1 and RT-2.

Combining NMR rock typing with reservoir delineation by means of deep-azimuthal resistivity images while drilling is a new methodology that combines the strengths of both techniques to optimize well placement and reservoir understanding. One example is a well that has three laterals, which illustrates this technique; each lateral was placed not only in the best rock type, but also in the target structural location.
An Integrated Geomechanical Approach in Mud Loss Pressure Prediction in a Giant Oil Field in Offshore Abu Dhabi
Authors: Tsusaka K. , Toma M. , Goraya Y. G. I. , Fujita K. , Nakayama S. , Saito S. , Fukuda K. , Toki T. , Matsubuchi H.
Published: October 2023

In a giant oil field in offshore Abu Dhabi, the intermediate hole section has suffered from borehole instability in highly laminated shale, mud loss in leaky carbonate and high reservoir pressures. Appropriate control of equivalent circulation density (ECD) is a key for safer drilling to the target reservoir. The present study aimed at analyzing the mud loss pressure in the leaky carbonate which is the allowable limit of ECD in the hole section. The study investigated spatial distribution of mud losses and variation in ECD at mud loss based on review of drilling operation in nearly 560 boreholes. The geomechanical models were built in five key locations. The area in which vuggy and fractured carbonates are distributed was interpreted based on the seismic interpretation. The mud loss pressure in the carbonate formation was analyzed based on the comparison of formation breakdown pressure and the minimum in-situ stress (S3) with ECD applied in drilling. The study proposed a map of mud loss pressure in the leaky carbonate in the six regional divisions in the studied field. The P90 and P50 values of the mud loss pressure in each region were analyzed by using the geomechanical models. The P90 value was analyzed by comparing ECD at mud loss with the magnitude of S3 in each region. Mud losses are highly likely to be prevented by controlling ECD under the P90 value in each of the regions. The P50 value was estimated by analytical solution which considers the effect of natural stress cage due to stress redistribution and thermal stress due to cooling effect by drilling fluid in near-borehole wall area. The P50 value was represented in a polar plot since regional variation in the rock mechanical characteristics and in-situ stresses and borehole direction were considered. The map functions as a guide for the design of mud weight in the ongoing drilling campaign. The P90 value is applied to the standard design. The P50 value is referred to as the upper limit in the case that excessive borehole instability in the shale or kick in the reservoirs is expected by applying the P90 value. If ECD above the P50 value is expected, additional casing should be considered to secure the loss zone before penetrating collapsing shale and high-pressure reservoirs.
Plunger Lift Application in Packer Wells – Success Stories, Challenges & Lessons Learnt
Authors: Khan Z. H. , Hafeez Q. , Ahmed R. , Memon S. A. , Khan R. A.
Published: October 2023

This paper focuses on the effective application of plunger lifts in gas wells with packer completions. Such wells present unique challenges, and the study aims to shed light on the successful use of plunger lift under these conditions. The paper delves into the complexities encountered during operations and emphasizes the opportunities to optimize recovery rates by reducing abandonment thresholds. The study also highlights the key lessons learned throughout the entire process, providing valuable insights to industry professionals working in similar contexts.

The deployment of plunger lifts as a project within the current portfolio was undertaken to optimize gas recovery from pre-existing fields. An all-inclusive approach was taken to meticulously determine the wells suitable for potential installation, resulting in 17 such installations. These cases illustrate the obstacles encountered during the installation process and the methodologies employed to surmount them. The efficacy of plunger lift in wells utilizing packers is influenced by several variables, including the need for a high gas-liquid ratio as compared to packer-less completions, sole reliance on tubing energy for plunger cycling, the avoidance of severe slugging flow regimes, and the lack of casing pressure monitoring.

Following initial trials in 2021 and 2022, a total of 17 plunger systems were installed, yielding highly favorable outcomes in terms of production resurgence, amounting to approximately 5-6 MMCFD from load-up and shut-in wells, coupled with an additional 6.5 BCF of gas and 50 MBC of condensate reserves. Project economics indicate a net present value of approximately 9.7 MM USD, versus a capital expenditure of approximately 1.5 MM USD. The case studies featured in this work underscore the effectiveness of plunger lift systems that utilize packer completions, emphasizing the criticality of precise design and operation of the system for optimal performance. Furthermore, this research outlines several post-installation challenges, including rapid inflow, insufficient energy for plunger cycling, large liquid slugs, and the necessity for plunger lift monitoring and mitigation. Overall, this study offers valuable insights into the design and operation of plunger lift systems in conjunction with packer completions, underscoring the continued requirement for research and innovation in this area to improve gas production in these wells.

An innovative aspect of this research is creating selection criteria for packer completions, which underwent further refinement based on insights gleaned from installations. These criteria include DAGLR, velocity profile, flow regime, slug volume, fluid level, and wellbore restrictions. In addition, shut-in pressure trends and plunger arrival data were employed to monitor and optimize plunger lift performance. However, monitoring plungers in packer completions remains an area of study for effectively enhancing plunger lift performance.
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

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

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

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

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

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

Successful 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

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

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

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.
Design of Limited-Entry Completions Using Near-Wellbore Simulator for Effective Acid Stimulation of Heterogeneous Carbonates
Authors: Bedewi M. , Andreev A. , Khoriakov V. , Mogensen K. , Burke R.
Published: October 2023

Limited-entry liners (LEL) have predominantly been deployed in carbonate formations with only moderate variation in reservoir properties. In this work, a detailed numerical analysis was applied to investigate how the hole-spacing design can be tailored for effective stimulation of heterogeneous carbonate formations completed with long laterals. The base case is a well with a 10,000 ft reservoir section with a permeability of 1mD completed with a 4.5in LEL with 3mm and 4mm holes pre-drilled at variable hole spacing.

A commercial near-wellbore simulator was used during this work, coupled with a new interface module, to study the flow distribution for a number of scenarios. The new interface module calculates a hole spacing which provides a desired acid coverage for each reservoir compartment, while honoring operational constraints such as not exceeding formation fracturing conditions, allowable surface pressure, maximum pump rate, as well as the number of joints with pre-drilled holes available onsite. Additionally, the module is designed to deliver a hole spacing promoting deeply penetrating wormholes from each hole in the liner. Finally, because stimulation takes place under transient conditions in the reservoir, a transient inflow model for horizontal wells was deployed to capture the reservoir response accurately. Skin reduction due to the acid-rock interaction is not considered at this point.

The scenarios simulated demonstrate that swellable packers significantly dampen the impact of permeability variation by reducing annular flow. The initial hole spacing estimated for uniform reservoir properties in general does a good job of choking flow into high-perm zones, especially if the base line permeability is 10mD (higher reservoir quality). A high-perm zone at the toe has a larger effect than a high-perm zone at the heel because of the larger hole density. The 1mD base case design can accommodate reservoir pressure gradients of 500 psia without compromising the outflow profile, whereas a 10mD base case cannot. In the latter case, either the pump rate must be increased, or the stimulation must be postponed until the pressure gradient has reduced.

The authors strongly believe that this work will help expand the operational envelope towards other reservoirs by providing physics-based guidance on how and when to modify the hole spacing for achieving an effective stimulation.
Utilizing Innovative Nanolime-Geopolymer as a Cement for Gas Wells
Authors: Mario A. , Salem S. , Tantawy M. , Rammah S.
Published: October 2023

This paper introduces the formulation of an innovative nanolime-geopolymer NLGP and its application in gas wells as a replacement for traditional cement. The new mix is composed of nanolime NL, fly ash, sodium hydroxide, and sodium silicate. Various NLGP products are formulated using different molarities and ratios of its components. The compressive strength of these products is measured and compared. For competency, NLGP is compared to cement fly ash CF then a new cement type. Finally, "deep water horizon" incident will be used as a case study to indicate the applicability of NLGP as a stable material against gas channeling.
Fragility Analysis of Fixed Offshore Platform in Malaysia Under Earthquake Effect
Authors: Azlan F. S. , Wahab M. M. A. , Ramli M. Z. , Rahman A. Abdul
Published: October 2023

In Malaysia, the oil and gas industry contribute significantly to its economy over the past decades. Currently there are over 250 offshore platforms in Malaysian waters. These platforms may be vulnerable to earthquake effects coming from near and far fields since seismic loading was not considered during the design stage for all offshore structures within all three (3) offshore sectors in Malaysia waters, including Sabah. Contrary to common belief that Malaysia is located outside the Pacific Ring of Fire of recent incidents and research is proving the opposite. In this study, seismic vulnerability assessment for fixed offshore platform in Sabah water is performed. Non-linear static (Pushover Analysis) and non-linear dynamic analysis (Incremental Dynamic Analysis or IDA) were performed prior to obtaining the fragility curve. Pushover analysis shows the seismic capacity through determining the drift ratio of the structure. The outcome of the analysis will then be classified into different damage levels according to Federal Emergency Management Agency (FEMA) categories; Operational Procedure (OP), Immediate Occupancy (IO), Damage Collapse (DC), Life Safety (LS) and Collapse Prevention (CP). Incremental dynamic analysis was performed by series of non-linear response histories which enabled PGA values to be systematically scaled. The maximum displacement and drift ratio were computed and compared with the drift ratio from pushover analysis to be classified into FEMA defined damage levels. Then, the mean and standard deviation of the PGA values were computed and substituted into fragility curve equation. The curve describes the probability of damage of the fixed offshore platform under earthquake effects. From the result, the vulnerability of the fixed offshore platform in Sabah water for an earthquake was concluded to be having a low probability of damage, i.e., 6.4% OP and 4.86% IO associated to Sabah PGA value of 0.28g.
Evaluating the Robustness of Autonomous Inspections in the Energy Industry with a Quadruped Robot
Authors: Fiorucci M. , Schillaci G. , Tannous M. , Bianchi L. , Salusti L. , Cioncolini S. , Politano A. , De Magistris G.
Published: October 2023

This pilot work evaluates a robotic solution for automating inspection activities on a mineral lube oil console used to lubricate gas turbines. A series of autonomous inspection missions have been carried out at the Baker Hughes site in Florence (Italy). A quantitative analysis of robot performances in tasks that are critical for accomplishing routine autonomous missions – such as locomotion, step climbing, visual inspection, recharge and docking - has been conducted and discussed. To assess the robustness of the quadruped robot, pre-programmed autonomous missions have been carried out to perform robotic visual inspection activities on the package of a gas turbine. The walkway was characterized by different ground conditions including climbing up and down steps throughout the path. We evaluated the robot's performance by measuring self-localization precision estimated with QR tags, robustness under different environmental conditions, locomotion quality, and success rate in step climbing behaviors. We carried out 40 autonomous missions, which lasted on average 5’36". Robot climbed steps successfully at the first attempt in 99.16% of cases (down: 99.16%, up: 98.30%). Average localization errors were on average 1.8 cm. Results indicate that this technology is robust enough to perform the autonomous inspection on energy assets with low mitigation action requirements.
Accurate aging clocks based on accumulating stochastic variation
Authors: Schumacher Björn , Meyer David
Published: October 2023

Aging clocks have provided one of the most significant recent breakthroughs in the biology of aging. Such clocks allow the determination of chronological and increasingly also biological age, which is a prerequisite for assessing the effectiveness of interventions in the aging process and preventive treatments of age-related diseases. The most advanced aging clocks are based on age-dependent changes in DNA methylation pattern. The reproducibility of such changes over the life course has reinvigorated the debate whether a programmed process underlies aging. A programmed aging process, however, is incompatible with the evolutionary theory of aging. Aging occurs as a consequence of a vanishing force of selective pressure post-reproduction as no fitness benefit is provided by immortality of the soma. In fact, stochastic events have been observed to increasingly occur during the aging process. Here, we test whether aging clocks could be built with entirely stochastic variation. We find that accumulating stochastic variation is sufficient to accurately predict chronological and biological age. Moreover, current aging clocks are entirely compatible with random alterations in the methylation or transcriptomic patterns. Our analysis unifies the clock measure of aging with the evolutionary theory of aging and predicts that any set of data that have a ground state at the age zero with accumulating stochastic variation could be used for building accurate aging clocks.
Convoluted Micellar Morphological Transitions Driven by Tailorable Mesogenic Ordering Effect from Discotic Mesogen-Containing Block Copolymer
Authors: Li Xiaoyu , yang Huanzhi , Luo Yunjun , Chi Chumeng , Jin Bixin
Published: October 2023

Solution-state self-assemblies of block copolymers (BCPs) to form nanostructures are tremendously attractive for their tailorable morphologies and functionalities. While incorporating moieties with strong ordering effects may introduce highly orientational control over the molecular packing and dictate assembly behaviors, subtle and delicate driving forces can yield slower kinetics to reveal manifold metastable morphologies. Herein, we reported the unusually convoluted self-assembly behaviors of a liquid crystalline (LC) BCP bearing triphenylene discotic mesogens. They underwent unprecedented multiple morphological transitions spontaneously, driven by their intrinsic subtle LC ordering effect. Meanwhile, LC orderedness could also be instantly built by doping the mesogens with small-molecule dopants, and the morphological transitions were dramatically accelerated and various exotic micelles were produced. Surprisingly, with high doping levels, the self-assembly mechanism of this BCP was completely changed from intramicellar chain shuffling and rearrangement to nucleation-growth mode, based on which self-seeding experiments could be conducted to produce highly uniform fibrils.
Prediction of 30-Day In-Hospital Mortality in Elderly UGIB Patients Using a Simplified Risk Score and Comparison with AIMS65 score
Authors: Xue Zaiyao , Che Hebin , Xie Deyou , Si Quanjin , Ren Jiefeng
Published: October 2023

Background: Upper gastrointestinal bleeding (UGIB) in elderly patients is associated with substantial in-hospital morbidity and mortality. This study aimed to develop and validate a simplified risk score for predicting 30-day in-hospital mortality in this population.
Methods: A retrospective analysis was conducted on data from 1899 UGIB patients aged ≥65 years admitted to a single medical center between January 2010 and December 2019. An additional cohort of 330 patients admitted from January 2020 to October 2021 was used for external validation. Variable selection was performed using five distinct methods, and models were generated using generalized linear models, random forest, support vector machine, and k-nearest neighbors approaches. The developed score, "ABCAP," incorporated Albumin <30 g/L, Blood Urea Nitrogen (BUN) >7.5 mmol/L, Cancer presence, Altered mental status, and Pulse rate >100/min, each assigned a score of 1. Internal and external validation procedures compared the ABCAP score with the AIMS65 score.
Results: In internal validation, the ABCAP score demonstrated robust predictive capability with an area under the curve (AUC) of 0.878 (95% CI: 0.824-0.932), comparable to the AIMS65 score (AUC: 0.827, 95% CI: 0.751-0.904). External validation yielded an AUC of 0.799 (95% CI: 0.709-0.889) for the ABCAP score, slightly outperforming the AIMS65 score (AUC: 0.743, 95% CI: 0.647-0.838). The ABCAP score effectively stratified mortality risk into low (0-2 points), moderate (3 points), and high (4-5 points) categories. This score exhibited consistent accuracy across variceal and non-variceal UGIB subgroups.
Conclusions: The ABCAP score incorporates easily obtained clinical variables and demonstrates promising predictive ability for 30-day in-hospital mortality in elderly UGIB patients. It allows effective mortality risk stratification and showed slightly better performance than the AIMS65 score. Further cohort validation is required to confirm generalizability.