bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydraulic Fracturing Challenges and Solutions for the Development of a Low Permeability Oil Reservoir – Case History from Offshore West Africa
Authors: Tassone Gianluca , Giammancheri Michele , Banoori Saadoun , Parziale Sabino , Mittiga Vincenzo , Ilyasov Robert , Dupouy Nicolas , Reilly Brett
Published: March 2022

The operator in West Africa embarked upon the "N" field offshore development in 2016 with 13 multi-stage horizontal wells being fracture-stimulated in Phase-I, with further wells being planned in next development phases. Due to the complex nature of the reservoir, which is a multilayered sandstone characterized by high heterogeneity and low permeability, wellbore connections are often located in structurally altered areas with high presence of faults. The unpredictable local re-orientation of the stresses has resulted in complications for the fracturing operations with multiple fractures being induced. This paper presents the challenges and solutions implemented for delivering more consistent fracturing execution and well productivity improvements.

The horizontal wells in the "N" field were hydraulically fractured using the "plug-and-perf" method with up to four fractured intervals. The quality of the near-wellbore connection and the observations of complex near-wellbore fracture geometries have hindered far-field proppant distribution and limited maximum proppant concentration inside the fracture. When fracturing this tight formation, controlling the opening of the pressure-dependent multiple fractures was identified as a critical issue. An engineering breakdown process and adapted frac strategy was implemented to minimize the multiple fractures generated at the formation.

For the early hydraulic fracture treatments performed, conservative treatment designs were applied in order to avoid premature screenout with the consequence of increasing operative time. Implemented solutions have shown to improve the near-wellbore connections and increase well productivity. The successful outcomes are attributed to the implementation of improved perforating strategies, the optimization of fracturing fluid performance, an engineered fracturing breakdown process, and the development of a frac decision tree for improved decision making. The hydraulic frac strategy has been tailored well-by-well depending on the reservoir conditions (e.g. faults, permeability thickness, contacts), and on the operational conditions interpreted from the diagnostic injection tests (e.g. near wellbore tortuosity, net pressure). The holistic implementation of these new concepts for hydraulic fracturing and field development have delivered positive production results beyond initial expectations.

For the horizontal wells intersecting the deep low permeability "D" reservoir, the risk of multiple fractures and influence of tortuosity have been diminished through corrective techniques and unique solutions applied for each fracturing stage.
A Self-Adaptive Artificial Neural Network Technique to Estimate Static Young's Modulus Based on Well Logs
Authors: Mahmoud Ahmed Abdulhamid , Elkatatny Salaheldin , Ali Abdulwahab , Moussa Tamer
Published: March 2022

Static Young's modulus (Estatic) is an essential parameter needed to develop the earth geomechanical model, Young's modulus (E) considerably varies with the change in the lithology. Recently, artificial intelligence (AI) techniques were used to estimate Estatic for carbonate formation. In this study, artificial neural network (ANN) was used to estimate Estatic for sandstone formation.

In this study, the ANN design parameters were optimized using the self-adaptive differential evolution (SaDE) optimization algorithm. The ANN model was trained to predict Estatic from conventional well log data such as bulk density, compressional time, and shear time. 409 data points from Well-A were used to train the ANN model which was then tested using 183 unseen data from the same well and validated on 11 data points from a different well (Well-B).

The developed SaDE-ANN model estimated Estatic for the training data set with a very low average absolute percentage error (AAPE) of 0.46%, very high correlation coefficient (R) of 0.999 and coefficient of determination (R2) of 0.9978. And the Estatic values of testing data set were estimated with AAPE, R, and R2 of 1.46%, 0.998, and 0.9951, respectively. These results confirmed the high accuracy of the developed Estatic model.
The Dynamic Performance Evaluation of the New Generation of Outflow Control Devices Autonomously Controlling the Conformance of Injection Fluids
Authors: Moradi Mojtaba , Todman Steven
Published: March 2022

Several techniques have been applied to improve fluid conformance of injection wells to increase water flooding performance and eventually field oil recovery. Normal outflow control devices (OCDs) are effective solutions for this problem in reservoirs with static properties, however, they fail in reservoirs with complex/dynamic properties including growing fractures. There, the continuously increasing contrast in the injectivity of a section with the fractures compared to the rest of the well causes diverting a great portion of the injected fluid into the thief zone thus creating short-circuit to the nearby producer wells.

A new autonomous outflow control device (AOCD) has been developed recently to choke the injection fluid into the propagating fractures crossing the well autonomously after reaching a designed flowrate thus maintaining a balanced/prescribed injection distribution. This work focuses on modelling design workflow to find the optimum completion design and demonstrates its added value through an extensive dynamic reservoir simulation study. Like other OCDs, this device should be installed in several zones in the injection well. The device is a bi-stable flow control device with two operating conditions, one, devices operate as normal passive OCDs initially, and two, if the injected flowrate flowing through the valve exceeds a designed limit, the device will automatically shut off. This allows the denied fluid to that specific zone to be distributed among the neighbouring zones. This performance enables the operators to minimise the impacts of thief zones on the injected fluid conformance and to react to a dynamic change in reservoirs properties specifically the growth of fractures. This also reduces the injection cost and improving the reliability of the injection well systems.

A sector reservoir-model coupled with a Geomechanics model via commercial reservoir simulation software was established to study the impacts of temperature and flowrate of injection fluids on the performance of injection wells completed with various completions. The simulation study showed less imposed pressure and much more efficient fluid conformance and fracture growth was delivered with the new device compared to various other completions. The results showed how the new device may change the sequence of thermal fractures initiation and the extends of their growth. This autonomously reactive control on the injection fluid conformance resulted in an increased sweep and ultimate oil recovery (up to 20%) while reducing the total volume of injected fluid (by 30%), so significantly increased field NPV. This study illustrates how efficiently the new injection valve chokes/restricts water into dynamic thief zones in a reservoir. This new device is autonomous and reacts to the rate of fluid passing through and eliminates the cost of alternative techniques including running PLT and following intervention actions.
Polymer Stability at Harsh Temperature and Salinity Conditions
Authors: Skauge Tormod , Ormehaug Per Arne , Alsumaiti Ali , Masalmeh Shehadeh , Skauge Arne
Published: March 2022

Polymer flooding has a large potential for unlocking EOR reserves in carbonate reservoirs in the Middle East. ADNOC has developed an EOR roadmap to realize some of these reserves. A milestone on this roadmap is to identify and verify polymers that have good performance at high temperature and high salinity conditions.

The reservoir conditions include temperatures in the range of 100 – 130 ºC and formation brines of more than 200 000 ppm TDS with high concentrations of divalent ions in carbonate rock. These conditions have been beyond the limitations of synthetic polymers and most biopolymers. Here we report thermal stability measurements performed at anaerobic conditions for a number of synthetic polymers at high temperature, high salinity (HTHS) conditions. A custom thermal stability chamber and flooding rig was designed and produced where storage and measurements were performed without contact with oxygen or iron.

A series of synthetic polymers with different ratios of the monomers amide, acrylate, ATBS and NVP were tested for temperature stability for up to 2 years at 120 ºC. Shear viscosity was measured frequently from the start while the time between tests was increased after trends in viscosity versus temperature was established. The viscosity was determined by measuring the differential pressure over a long coiled tubing. Three different brines ranging from ~200 to ~180 000 mg/L TDS were used as solvents. The results show that polymers with a low degree of ATBS and/or NVP have poor stability at the combined conditions of high temperature and high salinity and degrade within a short time. Polymers with a high degree of ATBS showed good stability at HTHS conditions. For these polymers high salinity improved stability, probably by stabilizing polymer conformation.

In this paper, we report thermal stability at HTHS conditions for a number of polymers using a custom designed thermal stability chamber and flooding rig for storage and viscosity measurement. The design gives significant improvement over other methods where samples are either removed and exposed to air during measurement or opened to inert atmosphere during measurement. Polymers stable at HTHS conditions were identified, expanding the boundaries for polymer EOR applications to carbonate reservoirs with temperatures up to 120 ºC and high salinity formation water.
Post-Frac Clean Up and Testing Optimization
Authors: Al Shidhani Ruqia , Al Shueili Ahmed , Shehab Ragab , Masood Nabeel
Published: March 2022

The Oil and Gas industry currently faces the dual challenge of meeting the global energy demand with minimal carbon footprint. The Barik formation is a tight to low-end conventional reservoir in Khazzan/Ghazeer Field (Block 61) in the central of the Sultanate of Oman. The field requires hydraulic fracturing to economically produce the wells, in which chemicals and proppant are pumped into the formation. Each well requires a period of clean up after pumping the frac and before connecting it to the facility in order to get rid of all the undesirable material from entering the processing facility. During this clean up and testing period, all produced gas and condensate are flared in the atmosphere.

This paper presents an optimization project which was implemented in Khazzan and Ghazeer fields in Block 61 to optimize the post frac clean up and testing period in order to reduce hydrocarbon flaring and CO2 emissions as well as reducing the testing cost, without compromising the overall well clean up and testing objectives.

The optimization project was originally started in 2015 where the clean-up and testing period was reduced gradually by optimizing the well bean up schedule (choke management and duration for each choke).
Addressing Challenges for Consistent Improvement of Cement Bonds in South Oman Fields
Authors: Meza Gluber , Satti Samiullah , Al-Sabti Hashem
Published: March 2022

Short liner cementing is very common in Oman southern oil fields. Among the challenges one can find no mechanical separation between the fluids, cement and pre-flush volumes are relatively small leading or increasing the chances of contamination and requiring remedial cementing jobs with uncertain success.

As a result, poor cement bond log across the liner section were observed in more than 80% of all the cementing jobs.

An engineering approach was proposed for this scenario. First increase rheologies of the fluids using physics instead of chemistry to diminish the fluid contamination inside of the casing and create a better sweeping effect outside of the casing. Selecting the adequate solid size ratios of the weighting agent to reduce the possible loss circulation problems generated by higher friction pressure. Increasing the generation and ultimate compressive strength of the cement system and finally providing expansion properties to the set cement.

This paper presents the field CBL/USIT logs results and a case study showing the application and effectiveness of the technique proposed comparing with the previous approach in different wells.
Addressing the Challenges of Hydraulic Fracturing Vertical Wells in Differential Depleted Tight Gas Accumulations in Oman
Authors: Al Bahri Khalfan , Chaves Juan , Al Hinai Adnan Saif , Al Sulaimani Ahmed Abdullah , Nunez Alvaro Javier
Published: March 2022

Hydraulic fracturing has been a key technology enabler for the development of tight gas formations in Oman. This tight gas accumulation has been developed with the supported of vertical wells, fractured at different depth covering up to 10 different hydrocarbons units. The intrinsic geomechanical, petrophysical and lithological heterogeneities of this tight units impact not only the fracture conductivity distribution but the drainage efficiency of the fractured zones, this is observed as mobility variations across this unit impact their contributions once all become commingle, with the areas of higher mobility dominating the total gas well production. It was anticipated that depletion of the higher mobility units will impact and change the contribution dynamics of the commingle production. However, this is only one dimension of the challenges to be considered as part of the hydraulic fracture strategy during the field development.

This paper will be focus key operational challenges and the fundamental formation characterization requirements to assess in-situ stress dynamic variations during the life of the field; incorporating formation pressure points as integral part of the drilling program and in-situ stress measurements supported by wellbore stability evaluation and mini-fracture operations. It will be presented how variations on pressure and stress profiles, as the field developed, will impact the perforation and fracture strategies as well as pressure operating envelop to assure well integrity.

It will be described the logging requirements as well as the lab characterization needed to determine key elastic properties to assess the hydraulic requirements for fracturing individual units or combination of them. It will be discussed how increase of pressure confinement potentially affects the in-situ elastic properties as depletion is experienced on specific gas units, inducing alterations on stress profiles that impact fracture propagation and final conductivity distribution. The use of radioactive tracers in combination with production logging were implemented to assess containment and fracture prediction, providing this an essential tool to determine fracture propagation behavior, deployment strategy and final conductivity distribution. Key operations covering plug milling, post fracture clean out and well lifting will be also discussed.

Finally, it will presented key observation that can be implemented as part of methodologies used for fracture deployment on differential depletion formation, this leading to optimum field development while maximize investment.
Cheaper and More Effective Stimulation of Horizontal Polymer Injectors in South Sultanate of Oman
Authors: Harrasi Ameera , Urdaneta Gerardo , Al-Jumah Ali , Nasif Mohammed , Qassabi Hajir
Published: March 2022

The multidisciplinary Authors summarize the lessons learned from stimulating a long horizontal Polymer Injection well with a Hoisting Unit; the main objective was to reduce the associated cost as compared to a Coiled Conventional Tubing (CCT) Unit, but achieving the same or even improved results. The details procedures for conducting this type of job is summarized in this paper.

The well was completed with a smart completion, creating four distinguished zones, Earlier, bullheading approach was carried out, but later on when the smart completion failed, it was necessary to stimulate with a CCT to cover all the different zones in the long well section. This has caused a sharp increase in the price of the job. Hence, a trial has been carried out utilizing a Hoist, with improved acid recipe that is cheaper and better in performance as compared to earlier. The detailed procedure for conducting this type of job is summarized in this paper

The tables show the injectivity test result in three stages, in the Hoist and the CCT approach the result shows a good improvement after main treatment and a success of the trial with Hoist as compared to CCT. This has proven to be economically viable and unlocked huge cost savings for all future stimulation jobs. A 50% reduction in the total cost is observed. This work has concluded a successful methodology in the utilization of a hoist in performing multi-stage stimulation in long horizontal wells. Very encouraging results have been observed and the suggested method is highly recommended, further trials will continue to be done with other wells

The authors believe the learnings from these trials are of great benefit and will add to the state of knowledge of the industry relating to stimulating long horizontal wells
Full-Scale Implementation of Conformance Control by Nanospheres in Large Sandstone Oil Field
Authors: Andrianov Alexey , Hou Jason , Li Erxiao , Liu Echo , Yang Lisheng
Published: March 2022

The polymeric nanospheres (NS) is the conformance control agent significantly improving oil recovery through redistribution of water flows deep in reservoir. The operator took a decision to pilot nanospheres technology in their large sandstone Changqing oil field in China after the experimental program has been conducted proved its potential. The nanospheres pilot has been executed in the oil field, resulting in substantial oil recovery improvement and water-cut reversal. Full-field implementation began.

Extensive experimental study was conducted to analyze the effect of nanospheres on oil displacement in the Changqing field. The focus of the program was on the impact of reservoir heterogeneity and effect of nanospheres on oil displacement at different permeability contrast. Coreflood experiments were conducted with dual-core set-up, where sand cores were mimicking permeability contrast of the target reservoir. The program resulted in selecting optimum injection concentration and volumes for the pilot. Nanospheres solution has been injected in the oil field, and dedicated surveillance program was executed.

Water flooding is effective in heterogeneous reservoirs when the average permeability contrast is below 20. When the contrast is higher e.g. as in target reservoir with permeability ranging from 7 to 2900 mD, water flooding is less efficient, especially in low-permeability zones. Nanospheres can mitigate the negative impact of high permeability contrast by diverting flow into previously unswept reservoir layers. This improves oil recovery, chiefly from low-permeability areas. Coreflood experiments proved the feasibility – incremental oil recovery was observed at 34%. Optimum pilot injection strategy has been designed.

The effectiveness of nanospheres with high permeability variation has been demonstrated in the field tests. The field results have confirmed the positive impact of nanospheres on water flooding. In one of the tests, an average oil production rate increased from 5.1 to 10.8 t/d while water-cut was reduced from 94% to 83%. Analysis confirmed that nanospheres provided efficient conformance control deep in reservoir and did not result in loss of injectivity. Chemical utilization factor achieved is more than 100 tons of oil produced per ton of chemicals injected. Treatment costs per pattern were significantly lower compared to other IOR/EOR techniques. The operator has decided to implement nanospheres for conformance control in all field.

Dedicated experimental program to select and, more important, optimize conformance control in heterogeneous reservoirs will be presented. Further, the paper will describe the field trial conducted. Both experimental and field data demonstrate the relationship between the oil displacement efficiency and injection conditions for different permeability contrasts. Results of field implementation will be presented. The technology effectiveness has been confirmed and full-field implementation has started.
Field Tests with a Multi Chamber Flotation Technology: Advanced Water Treatment in EOR Polymer Operation
Authors: Grillneder Roland , Marx Markus , Jamek Karl , Rodriguez Wiston
Published: March 2022

Cost-effective treatment of produced water is crucial for the implementation of EOR technologies. A multi-chamber flotation unit was tested under real-field conditions for a polymer flood of the Matzen field, Austria. The operating conditions, performance, and potential for cost-effective separation were successfully assessed with HPAM polymers for a concentration up to 800 ppm.

In order to evaluate the performance of the flotation technology, a comprehensive test matrix for a widespread operating envelope was defined. Characteristics of the feed water were varied by selecting specific production wells from the Torton reservoir. Consequently, a wide range of retention times, oil-in-water contents, oil droplet size distributions, and EOR polymer concentrations were tested. The unit was operated with and without the application of a water clarifier. Performance was evaluated by measuring inlet and outlet water quality parameters via laboratory analyses and an in-line monitoring device. The impact of EOR polymer on the treatment efficiency clearly indicated a turning-point of treatment efficiency dependent on polymer concentration. Produced water conditions of polymer flooding operations are considered harsh due to the impact on oil droplet coalescing behavior and impacted viscosity. The influence of oil droplet size and shearing of polymer versus the impact of retention time on effectiveness was assessed. On-site core-flood tests were performed to evaluate the injection behavior of treated water with different HPAM polymer concentrations and in combination with and without a water clarifier.
Geochemical Investigation of Water Composition Effect on Formation Damage and Related Oil Recovery in Carbonates
Authors: Khurshid Ilyas , Al-Shalabi Emad W. , Alameri Waleed
Published: March 2022

Several benefits of low salinity/engineered water injection (LSWI/EWI) have been reported in the literature including its ability to increase oil recovery at low cost and with least environmental impact. However, the related reservoir-engineering problems to these techniques such as formation damage and fluid mobility control are still uncertain and have not been thoroughly investigated. This study investigates the effect of water composition on formation damage and the related oil recovery from a geochemical prospective.

The study presents coupling of the IPhreeqc geochemical engine with Matlab to simultaneously solve the oil-water multiphase flow and the related geochemical reactions. Using this coupling technique, the geochemical capabilities of Phreeqc were successfully incorporated in a multiphase flow simulator. The latter enabled modeling of reactive transport and formation damage in subsurface multiphase reservoir. The results showed that the temperature, sulfate concentration, and dilution of injection water have a pronounced effect on formation dissolution and precipitation during LSWI/EWI. Also, anhydrite scale is the main controlling solid specie for formation damage. In addition, high temperature water injection should be avoided in carbonate reservoirs due to the likelihood of anhydrite precipitation and formation damage. This precipitation occurs because of the low-solubility of anhydrite at high temperature. Moreover, water dilution could decrease the scale formation while sulfate spiking might increase scale precipitation. Hence, sulfate concentration should be optimized as a wettability alteration agent to enhance oil recovery while avoid formation damage. Furthermore, as a sequence of anhydrite precipitation by sulfate spiking, oil production is expected to decrease by around 23% in the selected case study. The dissolution and precipitation mechanisms during LSWI are very case-dependent and subject of pore distribution, crude oil/brine/rock compositions, and thermodynamic conditions. Hence, the findings of this study cannot be generalized.
The Effects of Kaolinite Fine Particles in Sandstone Reservoir on Omani Medium Oil Recovery by Low-Salinity Water Flooding
Authors: Al Hadabi Ibrahim , Sasaki Kyuro , Sugai Yuichi , Kano Nobuhiko
Published: March 2022

The effect of kaolinite fine particles migration and wettability alteration during low salinity water-flooding (LSW-flooding) has been investigated for Omani sandstone reservoirs. Water flooding by re-injecting the reservoir brine is currently operated in the subjected Omani oil fields, and LSW is one of the operations to improve the oil production. However, relatively large amount of precipitated oil sludge was observed in the production and surface facilities along with the produced crude oil. In present experimental study, Omani intermediate oil (API gravity of 30°) and oil sludge were sampled from a skimming tank in the production facility. The physical and chemical characteristics of the clay particles were analyzed by a laser particle size distribution analyzer, SEM, XRD, and SQX after separated from oil. Furthermore, water-flooding tests by brine and LSW were carried out using Berea sandstone cores saturated by three different conditions of the Omani oil and kaolinite fine particles to simulate clay particles in the reservoir conditions. The kaolinite-particles slurry of 0.4μm in average size were used for the tests. The first core was saturated with oil only, the second one was filled up with kaolinite fine particles slurry then saturated with the oil, and the third one was saturated with the mixture of kaolinite-particles slurry and the oil. The results of LSW flooding after brine flooding showed that 30 % increase of oil recovery was obtained in the cases including kaolinite fine particles compared to that of oil only. In addition, the wettability of the cores contained kaolinite fine particles showed stronger water-wettability than the core without kaolinite. Zeta potential was measured to investigate the surface charge of kaolinite-particles in brine and water. The kaolinite fine particles were negatively charged as -15 mV in the brine, while it was -50 mV in the LSW used for the LSW flooding test. This difference has explained that the increase of oil recovery ratio in the water-flooding test was induced by kaolinite fine particles in the cores. The ions were traced in the effluents in LSW flooding, and it was found that the concentration of Ca2+ and Mg2+ reduced sharply from their initial concentration of 722 and 788 ppm to 34 and 26 ppm respectively with pH increasing from 6.8 to below 9.0.Those results indicate clearly that the kaolinite fine particles have a function to reduce the Sor and shift the wettability to water-wet that attributed to the interactions between oil, water and kaolinite-particles in the process of LSW flooding.
Non-Ionic Surfactant Formulation with Ultra-Low Interfacial Tension at High-Temperature and High-Salinity Conditions
Authors: Chen Shaohua , Han Ming , AlSofi Abdulkareem , Fuseni Alhasan
Published: March 2022

Non-ionic alkyl polyglucoside (APG) surfactants have been considered as eco-friendly, nontoxic and biodegradable surfactants. In this study, the physicochemical properties of two APG surfactants under high-temperature and high-salinity conditions were evaluated. The effectiveness of the surfactants as imbibition agents on improving oil production in carbonate reservoirs was investigated. A formulation with ultra-low interfacial tension (IFT) was introduced and the mechanisms resulting in such low IFT were probed and discussed.

Two APG surfactants were studied. Compatibility was evaluated by the transparency in brine solutions after aging. IFT was measured with the formulations of surfactant/additives. The morphology of network formed by surfactant/additives was observed via scanning electron microscope (SEM). The static adsorption of the APGs onto carbonate powder was determined by total organic carbon (TOC) analyzer. The contact angle of oil droplet on surface of carbonate core was measured in surfactant solution. The oil production via spontaneous imbibition of water in carbonate core was obtained using Amott cell. An imbibition simulation model was validated by the experimental results using UTCHEM simulator.

Both surfactants APG-1 and APG-2 exhibited excellent compatibility with the simulated high salinity water at reservoir temperature. They also demonstrated low static adsorption on carbonate reservoir. The surfactant containing larger hydrophobic carbons (APG-1) showed more incremental oil production potential than the other one bearing shorter hydrophobic chain (APG-2). At a concentration of 0.2 wt%, APG-1 yielded a low IFT in the order of 10-2 mN/m and an ultra-low IFT in the order of 10-3 mN/m was obtained upon addition of a small amount of additives. SEM pictures indicated that APG-1 and the additives synergistically generated a more compact structure via interaction between hydrophobic moieties of the chemicals compared to the aggregated structure formed by APG-1 alone. Such an effect could eventually lead to a decrease in IFT between oil and water. APG-1 slightly altered the wettability of carbonate core surface toward water-wet. The experimental results of spontaneous imbibition tests showed an oil production of 28% and 21% by APG-1 and APG-2, respectively. After parameter tuning, the yielded curves from numerical simulation by UTCHEM simulator perfectly matched the experimental data.

A new APG-based formulation was designed with an ultra-low IFT resulting in a much more compact amphiphilic structure along the oil-water interface. This study shows a great potential of APG surfactants and the relevant derivative formulations in improving oil production application for high-temperature and high-salinity carbonate reservoirs.
Experience on Application of Non-Metallic Materials for Offshore Facilities
Authors: Montalto Salvatore , Cavassi Paolo , Ponteggia Luca , Romano Michele
Published: March 2022

The scope of this paper is to share technical knowledge and experience gained on the use of non-metallic materials in off-shore environments. The proposed applications lead to the highest benefit level in terms of maintenance interventions as well as to weaknesses jeopardizing the productivity.

In particular, we evaluated the use of:Glass-reinforced composite material in offshore platform boat landing and stairs, instead of galvanized grating;Glass-reinforced epoxy pipe for offshore firefighting network;Plastic reinforcement sleeve on the protection of tube bundle heat exchanger welding.

Analysis was carried out on obtained results. The approach took into consideration the technical results after long period of installation in a boat landing and firefighting network offshore with averse environmental conditions, while for the plastic sleeve it was a proactive action against failure and the relevant study of consequences in case of removal. Present paper is not an innovative implementation but it is born from the daily offshore plant observation with the particular aim to improve the asset integrity trying to guarantee the best performance, reducing maintenance and restoration cost.

Positive and negative results on the above applications will be mentioned to permit as final conclusion a proper material selection and design accuracy for future application.
Evaluating Interwell Connectivity in Waterflooding Reservoirs with Graph-Based Cooperation-Mission Neural Networks
Authors: Zeng Xingjie , Zhang Weishan , Chen Tao , Jacobsen Hans-Arno , Zhou Jiehan , Chen Bingyang
Published: March 2022

Interwell connectivity plays a key role in waterflooding for guiding water injection. The existing works focus on the response relationship between one injection well and one production well. No research has explored the structural information of waterflooding on a well pattern. To address this challenge, this paper proposes cooperation-mission neural networks for interwell connectivity with graph information. Specifically, we propose some assumptions based on the petroleum domain to represent the well pattern with an adjacent matrix of the graph. Then we propose two targets from the view of injection well groups and production well groups. Accordingly, we propose cooperation-mission neural networks from these two aspects to evaluate the interwell connectivity in the well pattern. We test our model from two perspectives: the accuracy of estimation with tracer and the graduality of interwell connectivity. The results demonstrate that our model makes a good performance and achieves the connectivity analysis accuracy rate of 91.4%. Moreover, this study demonstrates that it is practical to evaluate the interwell connectivity with graph.
Natural Disaster Events and Social Media: An Orderly Mechanism for Online Rescue of Multiple Subjects
Authors: Deng Guobin , Zhang Qing
Published: March 2022

Giving full play to the various roles of social media in the emergency rescue of natural disasters is an effective way to improve the existing disaster relief mechanism and improve the efficiency of rescue. "Online Disaster Relief" is supported by modern information technologies, and various entities are used to coordinate the orderly behavior of various rescue resources through online methods to improve rescue efficiency. From the perspective of field theory, this research analyzes the operating mechanism of the online disaster relief work with the 7/20 torrential rain in Henan as a case. Research has found that social media platforms rely on their powerful technical support and information interaction functions to construct a specific field space, promote resource coordination and exchange among subjects, and reconstruct habitual behaviors. At the same time, a behavioral coordination mechanism with consistent goals, a standardized and orderly information interaction mechanism, a rational and powerful social mobilization mechanism, and a self-management mechanism for multiple subjects have been formed in the field, which promote the orderly progress of online disaster relief work, thereby improving the rescue efficiency.
Effects of crocin supplementation on lipid profile and oxidative stress in patients with type 2 diabetes: a randomized clinical trial
Authors: Dastkhosh Ali , Behrouz Vahideh , Sohrab Golbon , Sedaghat Meghdad
Published: March 2022

Background: Type 2 diabetes mellitus (T2DM) is a major problem around the world. Dietary phytochemicals have been recommended to modify the risk factors and slow down the disease progression. Available data indicated the beneficial effects of crocin, a carotenoid compound, on T2DM; however, no clinical trial study has not been done in this regard. So, the goal of this study was to see the effects of crocin supplementation on lipid profile and oxidative stress in patients with T2DM.Methods: In this 12-week clinical trial using a parallel-group design, 50 patients with T2DM were randomly assigned to either 30 mg crocin or placebo using categorized blocks based on age and sex. Anthropometric measurements, dietary intake, physical activity, lipid profile, and oxidative stress were assessed at the beginning and end of the intervention. Results: Compared with the placebo group, crocin reduced plasma levels of triglyceride (TG) (P= 0.007) and Total Oxidant Status (TOS) (P= 0.012). Crocin resulted in substantial improvements in plasma levels of TG, TOS, Total Antioxidant Capacity (TAC), and Oxidative Stress Index (OSI), according to the within-group analyses.Conclusions: Crocin intake may help people with T2DM to improve their TG and TOS levels. More research is needed to confirm these results.Trial registration: IRCT20170408033308N2 (first registration: 13/ 08/ 2019).
Growth, gut dimension, immune change and impact of Aeromonas hydrophila in Nile Tilapia (Oreochromis niloticus) fed Onion (Allium cepa. L) fortified diets.
Authors: Ajani Kolawole , Orisasona Olugbenga , Jenyo-Oni Adetola , Omitoyin Bamidele Oluwarotimi , Kane Aboubacar , Adekanmbi Abimbola Olumide , Kareem Kazeem Oladeji , Osho Elijah Friday
Published: March 2022

This study investigated effects of powdery Onions (Allium cepa) on the growth, gut area, innate immune reaction of Oreochromis niloticus and ability to resist Aeromonas hydrophila challenge. Six 35% crude protein diets were prepared adding fresh onions at 0.0% (OP0), 0.5% (OP1), 1.0% (OP2), 1.5% (OP3), 2.0% (OP4) and 2.5% (OP5) levels. Diets were allotted to triplicate groups of fish (1.79±0.14g) twice daily to apparent satiation for 12 weeks. Fish in each treatments were then challenged with Aeromonas hydrophila and followed for 2 weeks. After 84 days of feeding, growth was not significantly (P>0.05) varied by onion powder. Percentage survival rates was higher in fish fed onion supplements with a regression equation (Y = 75.655 – 10.423X – 1.399X2). Total heterotrophic count (THC) increased with higher inclusion of onion. . Red blood cells were higher in fish fed onion based diets in comparison to OP0 with values ranged from 1.68 x106/µL in OP0 to 2.83 x106/µL in OP1. Alkaline phosphate was higher in fish fed onion supplements. Villi height and width showed no significant variation across treatments. Relative survival was highest in fish fed onion powder supplements when challenged with Aeromonas hydrophila. This study showed onion powder improved survival of Oreochromis niloticus, but did not affect growth and nutrient utilization.
A multi-detector comparison to determine convergence of measured relative output factors for small field dosimetryAuthor InformationDo Duc Chi1, Tran Ngoc Toan2 and Robin Hill3,4,5
Authors: Duc Chi Do , Ngoc Toan Tran , Hill Robin
Published: March 2022

Purpose Good clinical practice in small field dosimetry relies on using multiple detectors for the determination of relative output factors (ROFs). The TRS-483 Code of Practice (CoP) provides recommended output correction factors, k, for a range of detectors and beam energies as used in small field dosimetry. In this work, the convergence of the ROFs for 6MV x-ray beams with and without flattening-filters were investigated under a different combinations of beam collimation and published detector correction factors. Method Three IBA detectors SFD, PFD and CC04 were used to measure ROFs on a TrueBeam STx linear accelerator with small fields collimated by the high definition MLC which has 2.5 mm and 5.0 mm wide leaves. Two configurations were used for the collimators being 1) fixed-jaws at 10 × 10 cm2 and 2) with a 2 mm offset from the MLC edge, in line with the recommended geometry from IROC-H as part of their auditing program and published dataset. The k factors for the three detectors were taken from the TRS483 CoP and other published works. Results The standard deviation in measured ROFs between detectors under 6MV-WFF beam are 1.4% and 1.9% while these under 6MV-FFF beam are 2.3% and 2.4% in MLC field with fixed-jaw and with 2 mm jaws-offset, respectively. The relative difference in averaged ROFs of three reference detectors from corresponding IROC-H dataset are 2.0% and 3.1% under 6MV-WFF beam while they are 2.4% and 3.2% under 6MV-FFF beam at the smallest available field size 2 × 2 cm2. For smaller field sizes, the uncertainty in averaged ROFs of three reference detectors from corresponding results of from 2 mm jaws-offset setting by Akino and Dufreneix showed the largest difference are 6.6% and 6.2% under 6MV-WFF beam while they are 3.4% and 3.6% under 6MVWFF beam at smallest field size 0.5 × 0.5 cm2. Conclusion The corresponding datasets provided by TRS-483 and IROC-H are generic and may not statistically large enough with 6MV-FFF and also MLC field with 2 mm jaws-offset setting, so that clinical users should use at least three different types of small field detector in measurements. The IROC-H dataset is not available for field size smaller than 2 × 2 cm2 so that user should carefully check with other publications with the same setting.
The Further Understanding of Burdens and Needed Support for Caregivers of Mental Illness in China: A Perceptive of Mental Health Workers in Chongqing
Authors: Nkundimana Balthazar , Li Kuang , Xiaoming Xu , Yi Zhou
Published: March 2022

Background
Caregivers of mental illness play crucial roles in taking care of people diagnosed with mental illness especially those who are rehabilitated in the community. The further understanding of burden and needs of caregivers should be emphasized. This study aimed to further investigate perception on burdens and needs of caregivers in China as perceived by mental health workers.
Methods
A total of 80 mental health workers were involved in our study. An electronic data collection questionnaire with open ended question was given to mental health workers in different hospitals. Questions were designed to explore mental health workers’ perceptive on burdens, needed support for improvements.
Results
Immersed themes indicated that caregivers of mental illness are suffering from sorts of burdens. They emphasized that they would require more supports.
Conclusions
Caregivers of mental illness suffer from sorts of burdens and they lack knowledge and enough supports. political will in support of them should be improved.
Nanomicelles co-loaded with doxorubicin and salvianolic acid A for breast cancer chemotherapy
Authors: Li Zhiyong , Liu Jiali , Sun Zheng , Li Yanli , Yu Bin , Zhao Feng , Wang Hongbo , Xu Hui
Published: March 2022

Background: Multi-drug delivery system based on polymer carrier is emerging for alleviating dose-limiting toxicities of first-line cytotoxic anticancer drugs such as doxorubicin (DOX) for breast cancer chemotherapy. By co-loading the premium natural antioxidant salvianolic acid A (SAA) through colloidal self-assembly of amphiphilic copolymer, we herein developed CPMSD, a complex polymeric micellar system to overcome cardiotoxicity associated with DOX.Results: Optimal formulation was obtained by DOE study and CPMSD micelles were well constructed by using mPEG-PCL for entrapment at a drug-carrier mass ratio of 1:5 and DOX-SAA mass ratio of 1:4. Molecular dynamics simulation revealed the ratiometrical co-encapsulation of SAA into the hydrophobic cavity but DOX to ball-shaped surface of micelles due to hydrophilicity. Characterization study manifested favorable biopharmaceutical properties such as small and uniform particle size, fairly high drug loading capacity, as well as good colloidal stability and controlled drug release. CPMSD maintained anticancer efficacy of DOX and the action mechanism, which did not be affected by co-administering SAA. More to the point, it was of great benefit to systemic safety and cardio-protective effect against oxidative stress injuries associated with DOX in tumor-bearing mice.Conclusions: All the findings substantiated that CPMSD would be a promising multifunctional nanosystem of DOX for breast cancer chemotherapy.
Perceptions and Stress of Conscience in Relation to Burnout Among Nursing Staff in Older People Care Settings: A Quantitative Study
Authors: Nazari Shima , Norberg Astrid , Strandberg Gunilla , Åhlin Johan , Ericson-Lidman Eva , Mazaheri Monir
Published: March 2022

Background
Considering cultural influences, it is important to study the perceptions and stress of conscience in different contexts. This study aimed to investigate the association between perceptions of conscience, stress of conscience, and burnout among nursing staff working in older people care settings in Tehran.
Methods
This was a descriptive, cross-sectional study. A total of 161 participants completed the Perceptions of Conscience Questionnaire, Stress of Conscience Questionnaire, and Oldenburg Burnout Inventory.
Results
Nursing staff mainly perceived their conscience as an authority, asset, and warning signal. Furthermore, the influence of workload on family life was the most common source of stress. Dealing with incompatible demands, the impact of workload on family life, witnessing insulated patients, inability to meet one’s standards in providing care, and perception of conscience as a burden were strongly associated with burnout.
Conclusions
Perceiving conscience as a warning signal or authority may serve as a buffer against burnout among nursing staff. This study highlights the need for further exploration of perceptions of conscience in different cultural and social backgrounds.
Influence of Device Performance and Agent Advice on User Trust and Behaviour in a Care-taking Scenario
Authors: Zukerman Ingrid , Partovi Andisheh , Hohwy Jakob
Published: March 2022

We present insights obtained from two user studies performed in the context of a web-based game set in a care-taking scenario — a retirement village, where elderly residents live in smart homes equipped with monitoring systems. These systems should raise alerts when adverse events happen, but they do not function perfectly (they may issue false alerts or miss true events). Players, who “work” in the village, perform a primary task whereby they must ensure the welfare of the residents by attending to adverse events in a timely manner, and a secondary routine task that demands their attention. In the first user study, we investigate the relationship between the performance of different monitoring systems, in terms of error type, and user behaviour and trust in these systems. In the second study, we examine the effect of the advice offered by an advisor agent on users’ behaviour. Our contributions are (1) the game itself, which supports experimentation with various trust-related factors, and a version of the game augmented with an advisor agent; (2) a methodology for calibrating the parameters of the game; (3) insights regarding the relationship between device accuracy and user behaviour and trust in automation; (4) findings about the training effect of an advisor agent; and (5) insights from predictive models about factors that influence trust and behaviour.
Multi-Hazard Risk to Global Port Infrastructure and Resulting Trade and Logistics Losses
Authors: Verschuur Jasper , Koks Elco , Li Sihan , Hall Jim
Published: March 2022

Despite their economic importance, the risk that ports face from multiple natural hazards has not yet been monetised on a global scale. Here, we perform an asset-level risk analysis of global port infrastructure from multiple hazards, quantifying the risk to physical asset damages and logistics services (i.e. port-specific risk) and risk to maritime trade flows (i.e. trade risk). We find that the vast majority of ports (~ 86%) are exposed to more than three hazards. Globally, port-specific risk totals 7.5 USD bn per year, dominated by tropical cyclone impacts (~ 32%). In addition, 63.1 USD bn of trade is at-risk every year, with trade risk as a fraction of total trade being particularly high in Small Island Developing States. Our result underline that port resilience is determined by various critical factors (e.g. engineering standards, operational thresholds, recovery duration) that vary widely across ports, requiring tailored solutions to improve port resilience.