bluuebunny/crossref_metadata_2025 huggingface dataset:
What Could Explain the Lower COVID-19 Burden in Africa Despite Considerable Circulation of the SARS-CoV-2 Virus?
Authors: Wamai Richard G. , Hirsch Jason L. , Van Damme Wim , Alnwick David , Bailey Robert C. , Hodgins Stephen , Alam Uzma , Anyona Mamka
Published: May 2021

COVID-19 differential spread and impacts across regions is a major focus for researchers and policy makers. Africa has attracted tremendous attention due to predictions of catastrophic impacts that have not yet materialized. Early in the pandemic, the seemingly low African case count was largely attributed to low testing and case reporting. However, there is also reason to consider that many African countries got out ahead of the virus early on. Factors explaining low spread include early government mandated lockdowns, community-wide actions, population distribution, social contacts, and ecology of human habitation. While recent data from seroprevalence studies posit more extensive circulation of the virus, continuing low COVID-19 burden may be explained by the demographic pyramid, prevalence of pre-existing conditions, trained immunity, genetics, and broader sociocultural dynamics. Though all these prongs contribute to the observed profile of COVID-19 in Africa, some provide stronger evidence than others. This review is important to expand what is known about the differential impacts of pandemics enhancing scientific understanding and gearing appropriate public health responses. Also, highlighting potential lessons the world may draw from Africa for global health on assumptions regarding deadly viral pandemics given its long experience with infectious diseases.
Therapeutic Drug Monitoring in Fungal Infections: the Dawn of Proactive Monitoring
Authors: Schoenenberger-Arnaiz Joan Antoni , Aragones-Eroles Ana , Taberner-Bonastre Pilar , Morales-Portillo Arturo
Published: May 2021

Therapeutic Drug Monitoring (TDM) is potentially a useful tool that can be employed to increase the efficacy and decrease the toxicity of antifungal drugs. The aim of this narrative review is to provide an overview of the current use of TDM in clinical practice, and to present the evidence available regarding its use in proactive clinical settings for preventing and managing treatment failure. This review also presents the existing evidence regarding the association of various clinical outcomes with specific thresholds of drug concentrations in everyday practice. Articles concerning the use of TDM of triazoles in the treatment of fungal infections were retrieved through an electronic search using PubMed. In clinical practice, TDM has an increasingly important role in the management of antifungal drugs as a consequence of the improvement in the knowledge of the pharmacokinetics and pharmacodynamics of these drugs. The currently available evidence shows a direct exposure-response relationship for triazoles, though the PK/PD profile is unpredictable. Current guidelines and treatment consensus statements recommend the proactive TDM of voriconazole, posaconazole, and itraconazole to optimize dosage regimens and improve outcomes for adult and pediatric patients.
Relevance to the Introduction of eLearning on Higher Education of Bangladesh: An Experience from the Educational Cost of COVID-19
Authors: Dey Sajib , Khan Md. Gias Uddin , Hakim Md. Mahbubul
Published: May 2021

The great lockdown of the current COVID-19 pandemic has significant consequences on the global Higher Education Studies (HES).To find the relevance of eLearning in the HES, our study calculates the economic costs of higher education during Covid-19 in Bangladesh, which includes both stu-dents’ cost and institutional cost. The study used a purposive random sample survey conducted on 105 students enrolled in higher education in different categories of institutions to identify the stu-dents’ cost during this pandemic. The institutional cost of higher education is analyzed by breaking down the budget allocated in the education sector in Bangladesh and reviewing the literature. The result indicates that the HES of Bangladesh experiences a huge economic cost due to this pandemic and the study found eLearning can reduce the economic impact of HES. In the post-COVID-19 world, higher education will never be the similar because many institutions that already had experi-ence a huge advantage from online education. The findings of the study might be helpful for the policymakers to frame effective education policies during any bizarre situation that creates huge cost in higher education sector.
Autonomous Driving Implementation in an Experimental Environment
Authors: Aliyev Namig , Guzel Mehmet Turan , Sezer Oguzhan
Published: May 2021

Autonomous systems require identifying the environment and it has a long way to go before putting it safely into practice. In autonomous driving systems, the detection of obstacles and traffic lights are of importance as well as lane tracking. In this study, an autonomous driving system is developed and tested in the experimental environment designed for this purpose. In this system, a model vehicle having a camera is used to trace the lanes and avoid obstacles to experimentally study autonomous driving behavior. Convolutional Neural Network models were trained for Lane tracking. For the vehicle to avoid obstacles, corner detection, optical flow, focus of expansion, time to collision, balance calculation, and decision mechanism were created, respectively.
How do Quorum Sensing Signals Mediate Algae–Bacteria Interactions?
Authors: Dow Lachlan
Published: May 2021

Quorum sensing (QS) describes a process by which bacteria can sense the local cell density of their own species, thus enabling them to coordinate gene expression and physiological processes on a community-wide scale. Small molecules called autoinducers or QS signals, which act as intraspecies signals, mediate quorum sensing. As our knowledge of QS has progressed, so too has our understanding of the structural diversity of QS signals, along with the diversity of bacteria conducting QS and the range of ecosystems in which QS takes place. It is now also clear that QS signals are more than just intraspecies signals. QS signals mediate interactions between species of prokaryotes, and between prokaryotes and eukaryotes. In recent years, our understanding of QS signals as mediators of algae–bacteria interactions has advanced such that we are beginning to develop a mechanistic understanding of their effects. This review will summarize the recent efforts to understand how different classes of QS signals contribute to the interactions between planktonic microalgae and bacteria in our oceans, primarily N-acyl-homoserine lactones, their degradation products tetramic acids, and 2-alkyl-4-quinolones. In particular, this review will discuss the ways in which QS signals alter microalgae growth and metabolism, namely as direct effectors of photosynthesis, regulators of the cell cycle, and as modulators of other algicidal mechanisms. Furthermore, the contribution of QS signals to nutrient acquisition is discussed, and finally how microalgae can modulate these small molecules to dampen their effects.
Ionic Liquids based on the Concept of Melting Point Lowering due to Ethoxylation
Authors: Rothe Manuel , Müller Eva , Denk Patrick , Kunz Werner
Published: May 2021

Most of the commonly used Ionic Liquids (ILs) contain bulky organic cations with suitable anions. With our COMPLET (Concept of Melting Point Lowering due to Ethoxylation), we follow a different approach. We use simple, low-toxic, cheap and commercially available anions of the type Cx(EO)yCH2COO– to liquefy presumably any simple metal ion, independently of its charge. In the simplest case, the cation can be sodium or lithium, but synthesis of Ionic Liquids is also possible with cations of higher valences such as transition or rare earth metals. Anions with longer alkyl chains are surface active and form surface active ionic liquids (SAILs), which combine properties of ionic and nonionic surfactants at room temperature. They show significant structuring even in their pure state, i.e. in the absence of water or any other added solvent.
Precise Engineering Design and Technology Integration Delivers the First Successful Shoe to Shoe Run that Enhanced Drilling Efficiency in Highly Intercalated Formations
Authors: Krikor Ara , Sanderson Martin , Merino Lizeth , Benny Praveen , Ibrahim Sameh , Al-Khayat Khaled , AlYasiri Siffien
Published: May 2021

Drilling highly intercalated formations with Polycrystalline Diamond Compact (PDC) bits has been a challenge in few Southern Iraqi Fields. The established drilling practice for the 17.5-in section has been a two-run strategy - Top section formation is mostly dolomite intercalated with anhydrite drilled with a Tungsten Carbide Insert (TCI) bit, then trip out of hole to change to a PDC bit and drill to section TD. The upper section comprises highly intercalated formations known to induce severe bit and BHA damage. The application of new Conical Diamond Elements (CDEs) backing up traditional PDC cutters on the bit blades had significantly improved bit durability in the bottom half of the section. The subsequent challenge was to apply this CDE technology onto an optimized PDC chassis and achieve a single run section thus eliminating a trip for bit change as well as improving overall Rate of Penetration (ROP) of the section.

A Bit and drill string optimization exercise was initiated by the Technology Integration Center to develop a new PDC bit design that could deliver a shoe-to-shoe section. Analysis of offset well data highlighted the need for greater cutter redundancy on the bit to survive high impact loading and optimized cutter arrangement to minimize bit induced instability while drilling through intercalations with highly fluctuating rock strengths. A finite element analysis (FEA)-based modelling system was used to evaluate the dynamic behavior of multiple bit design configurations in various rock scenarios and narrow down to the optimum design for the challenge. The optimization exercise shortlisted a PDC bit design characterized by 8 Blades, 16-mm PDC cutters and CDEs backing-up the nose and shoulder PDC cutting structure. A detailed drilling parameter road map was also generated to ensure optimum drilling parameter application for shoe-to-shoe assurance.

The new bit drilled the entire section in single run with a field record average on-bottom ROP of 20 m/hr which was a 11% improvement over the best offset performance with a two-bit strategy. In addition, a trip for bit change was eliminated. A minimum saving of 20 rig hours was realized thus reducing section time by almost one day compared to the offset wells. The bit was pulled out of hole with minor cutter damage indicative of efficient drilling dynamics and opportunities for further performance enhancement through improved parameter management, alternate drive systems and high torque drill pipes.

This paper further will discuss how the technology integration and precise engineering design can solve complicated on bottom drilling problems and address the problematic challenges of drilling highly intercalated formations. This strategy enabled a significant time and cost saving compared to drilling the section conventionally.
Overcoming Hole Instability in Highly Deviated Wells in the Kafr El Sheikh Shale, Offshore Mediterranean, Egypt
Authors: Kholaif Yasser , Elmaghraby Mahmoud , Nago Annick , Embry Jean-Michel , Basu Pramit , Perumalla Satya , El-Said Mohamed M. , ElMenshawy Ali , Baghdadi Ahmed
Published: May 2021

Drilling challenges in offshore Nile Delta have been largely documented in the literature. Operators are often confronted with drilling problems related to shale swelling, cavings, tight holes in combination with increased risks of lost circulation in some of the highly depleted formations. The Kafr El Sheikh shale in particular, has been linked to many instances of wellbore instability, due to its mineralogical composition (estimated to be mostly smectite, >70%). From offset well drilling experience, it could also be noticed that insufficient mud weight was often used to drill through the Kafr El Sheikh Shale, causing wellbore failure in shear due to lack of support of the wellbore wall. In the past, multiple mud weight designs have been implemented relying solely on pore pressure as lower bound of the mud window. With the increased use of geomechanics, it has been demonstrated that the lower bound should be taken as the maximum of the pore pressure and borehole collapse pressure, thus accounting for the effects of formation pressure, horizontal and vertical stresses, rock properties as well as wellbore trajectory. It has been proven that slight overpressure is often encountered halfway through the Kafr El Sheikh formation, which would typically result in slightly higher borehole collapse pressures. In the study fields, the operator expressed interest in drilling highly deviated wells (> 60-70 degrees). This raised concerns for increased drilling challenges, especially in the Kafr El Sheikh.

A comprehensive and systematic risk assessment, design of a fit-for-purpose solution and its implementation during drilling took place in the fields of interest. Offset well data analytics from the subject fields supported a holistic evaluation of drilling risks associated with the Kafr El Sheikh, providing good understanding of stress sensitivity on deviation, azimuth and lithology. Upon building a robust geomechanical model, calibrated against offset well drilling experience, pre-drill mud weight and drilling practices recommendations were provided to optimize the drilling program. Near real-time geomechanical monitoring was implemented which helped to manage the model uncertainties.

The implementation of a holistic risk assessment, including geomechanical recommendations and near real-time geomechanical monitoring, was effective to lead the drilling campaign successfully. As a result, three high angle wells (> 60-70 degrees) were drilled through the challenging Kafr El Sheikh formation without any hole instability. An integrated risk assessment of hole instability, managed in stages (pre-drill and during drilling), has helped to understand and simulate the behaviors of the formation. Proactive decisions have established a controlled drilling environment for successful operations.
Successful Application of Managed Pressure Drilling MPD Technology to Reach TD in a Narrow Margin HPHT Well in the North Sea – A Case History
Authors: Kamal Babar , Stoian Emil , MacFarlane Graeme
Published: May 2021

This paper reviews the recently concluded successful application of a Managed Pressure Drilling (MPD) system on a High-Pressure High-Temperature (HPHT) well with Narrow Mud Weight Window (NMWW) in the UK sector in the Central North Sea. Well-A was drilled with the Constant Bottom Hole Pressure (CBHP) version of MPD with a mud weight statically underbalanced and dynamically close to formation pore pressure.

Whilst drilling the 12-1/2" section of the well with statically under-balanced mud weight, to minimize the overbalance across the open hole, an influx was detected by the MPD system as a result of drilling into a pressure ramp. The MPD system allowed surface back pressure to be applied and the primary barrier of the well re-established, resulting in a minimal influx volume of 0.06 m3 and the ability to circulate the influx out by keeping the Stand Pipe Pressure (SPP) constant while adjusting Surface Back Pressure (SBP) through the MPD chokes in less than 4 hours with a single circulation.

After reaching the 12-1/2" section TD, only ~0.025sg (175 psi) Equivalent Mud Weight (EMW) window was available to displace the well and pull out of hole (POOH) the bottom hole assembly (BHA) therefore, 3 × LCM pills of different concentrations were pumped and squeezed into the formation with SBP to enhance the NMWW to 0.035sg EMW (245 psi) deemed necessary to kill the well and retrieve BHA. MPD allowed efficient cement squeeze operations to be performed in order to cement the fractured/weak zones which sufficiently strengthened the well bore to continue drilling. A series of Dynamic Pore Pressure and Formation Integrity Tests (DPPT and DFIT) were performed to evaluate the formation strength post remedial work and to define the updated MMW.

Despite the challenges, the MPD system enabled the delivery of a conventionally un-drillable well to target depth (TD) without any unplanned increase/decrease in mud weight or any costly contingency architecture operations, whilst decreasing the amount of NPT (Non Productive Time) and ILT (Invisible Lost Time) incurred.

This paper discusses the planning, design, and execution of MPD operations on the Infill Well-A, the results achieved, and lessons learned that recommend using the technology both as an enabler and performance enhancer.
Offshore Installation of Rigless Shuttle ESP
Authors: Obeid Ahmad Fayyad , Bespalov Eugene , Sanghavi Dharam , Almasri Ahmad , Magri Jose , Al Hammadi Majid Ismail , Al Marzooqi A. M. , Yoshimoto Kazuhito Kazumi , Yamashita Hajime , Al Zaabi Ali Yousef
Published: May 2021

Electric submersible pumps (ESPs) used as an artificial lift method have a relatively short life span despite the industry's efforts to improve reliability. The resulting economic impact realized in workover costs and production loss is substantial. This has driven efforts toward design change by introducing retrievable ESP independent of the completion string and hence extending ESP wells’ life cycle. This paper covers the company's first installation of a rigless shuttle ESP system, including a customized completion design and special deployment procedures.

A comprehensive approach was taken to deploy this technology, from procurement to installation, in a detailed process. It started with acquiring reservoir data and setting up matching specifications for the required equipment in order to issue a competitive tender. Following technical evaluation of tender submissions, the most suitable technology was selected for the field trial. The completion design was then customized to accommodate the new technology without jeopardizing well integrity. Fit-for-purpose well barriers were incorporated in the completion design because conventional barriers were not applicable. Detailed running procedures were produced from dedicated workshops and risk assessment reviews. Project execution was closely monitored and firmly controlled.

The company has accomplished the first successful offshore deployment of the shuttle ESP system in the MENA region. The system was deployed using tailored procedures for installation and comprehensive testing while ensuring compliance with well barrier requirements. Following successful deployment, the ESP performance was positively tested. Part of the project validation requirement was a rigless retrieval and redeployment the ESP system. The ESP retrieval process was challenging due to unexpected tar or asphaltene material encountered above the ESP. However, contingency retrieval procedures were promptly amended with detailed steps to overcome this challenge, which led to successful retrieval and redeployment of the ESP without NPT. This success is paving the way for a major change in the company's field development strategies by considering rigless, replaceable ESP systems instead of the conventional ESPs.

This paper sheds the light on a new advancement in completion technology that has a strong potential to prevail for ESP-lifted wells in the future. The focus of the paper is on the design and execution parts, as well as installation and post-completion operations while maintaining sufficient well barriers―the challenging aspect that appears to be slowing down the wider use of this technology as a replacement of conventional ESP completions.
Developing New Generation of Environmentally Friendly Nano Based Low Saline Water-Based Drilling Fluid
Authors: Kalhor Mohammadi Mojtaba , Taraghikhah Shervin , Karimi Rad Mohammad Saeed , Tahmasbi Nowtaraki Koroush
Published: May 2021

Developing high-performance environmentally friendly drilling fluids is always a requirement by oil and gas operators to reduce the waste management associated cost with the drilling fluid treatment and disposal. Conventional water-based drilling fluid is formulated with the brine-based polymer which consists of sodium and potassium chloride salts to improve the performance of the polymer and also providing clay inhibition in reactive clay and shale. This paper describes the development of nanotechnology-based drilling fluid to replace salt from the conventional application.

Nano Based Low Saline Water Based Mud (NBLS-WBM) was formulated and developed based on laboratory experiments. Different nano additives with different concentrations were evaluated and the optimum concentration was selected to reduce the sodium and potassium chloride salts concentration to almost zero. The rheological properties and fluid loss were measured according to the API standard before and after hot rolling. Also, HPHT fluid loss, lubricity, and shale inhibition were evaluated. All the results were compared with sodium salt-saturated and potassium-based polymer muds.

Laboratory evaluation of NBLS-WBM indicated that sodium salt concentration can be reduced considerably up to 5% W/V and potassium chloride can be eliminated by adding 1% W/W of nano additive. The rheological properties including plastic viscosity and yield point were constant and stable after hot rolling 16 hours at 250 °F. Also, Clay inhibition improved significantly up to 95% recovery comparing with conventional water-based polymer mud.

Although the application of nanotechnology to improve the performance of conventional water-based drilling fluid was studied by many researchers, it is the novelty of this research to reduce the salt concentration and remove it to develop the new generation of salt-free water-based drilling fluid with economical consideration and lower environmental impact.
A Systematic Approach to De-Risk and Improve Shale Gas Horizontal Well Drilling
Authors: Gao Xiang , Zeng Jiaxin , Xie Jiajun , Tang Liang , Li Wenzhe , Gui Feng , Ghosh Amitava , Ong See Hong , Huang Xingning , Deng Lichuan
Published: May 2021

Horizontal well drilling contribute to a dramatic increase of shale gas production in unconventional reservoirs. However, the drilling is also risky and challenging with different types of drilling problems often encountered including stuck pipes, inflows, losses and pack-offs, etc. To reduce shale-gas development costs, shale gas operators are faced with finding effective solutions to minimize drilling risks and improve drilling efficiency. A holistic workflow, which can be divided into three steps: pre-drilled modelling and assessment, real-time monitoring, and post-drilled validation, is proposed. Based on the pre-drilled geomechanical modeling, mud weights, mud formulations and casing setting depths are optimized to ensure wellbore stability during the drilling process. Real-time operations involve monitoring drilling parameters and cavings characteristics (shape and volume), and providing updated recommendations for field drilling engineers to mitigate and reduce borehole instability related problems. During the post-drilled stage, the updated geomechanical model will be used for optimizing the drilling designs of upcoming wells. With geomechanics as foundation, a systematic workflow was developed to provide integrated solutions by using multiple technologies and services to reduce serious wellbore instability caused by abnormal formation pressures, wellbore collapse and other complex drilling problems. The implementation of the systematic and holistic workflow has proven to be extremely successful in supporting the drilling of shale gas wells in China. The integrated approach, which was applied in a Changning shale gas block in Sichuan Basin for the first time in March 2019, recorded an improvement in ROP by 111.2% and a reduction in mud losses by 89.9% compared with an offset well without the risk mitigation strategy applied in the same pad. The geomechanics-based approach provides a convenient and effective means to assist field engineers in mud weight optimization, drilling risk assessments, and horizontal well drilling performance evaluation. The approach can also be extended to reduce potential drilling risks and improve wellbore stability, all of which contributes to reducing drilling costs and optimizing subsequent massive hydraulic fracturing jobs.
The Theory and the Practical Validation of the Fluid Level Position in the Annulus During Lost Circulation
Authors: Ruzhnikov Alexey , Echevarria Edgar
Published: May 2021

Carbonate formations around the world and specifically in a Middle East are prone to have total losses while drilling. And the nature of the losses often related to the highly fractured formations of the pay zone. When such fracture(s) is crossed by the wellbore the lost circulation initiated and led to a drilling without a return to a surface.

To avoid undesired well control event or wellbore instability and to maintain the constant bottom hole pressure the mud cap drilling strategy often used as a preventative measure. The mud cap can be either the continuous or based on some volume or time interval, depends on the local practices or the policy of an operator. The mud cap flow rate as well as mud cap mud weight are often based on the best practices, not supported by an engineering study.

To understand the behavior of the drilling fluid level in the annulus while drilling with total losses the drilling bottom hole assembly equipped with annular pressure while drilling tool was used. As the drilling required to use the continuous mud cap, then the specific guideline was developed on measurement of the bottom hole pressure and further conversion of it to the fluid level.

The study was performed across pay zone with one or several loss circulation zones identified. As the result it was confirmed that the used mud cap flow rate had minor to none effect on the fluid level position in the annulus and that the bottom hole pressure remained the same. It showed as well that different loss zones are behaving in a different way, what can be considered as a factor affecting their ability to be sealed.

The obtained knowledge and the information should help to understand better the loss circulation behavior as well be an important step toward development of the product which may cure the losses in high fractured carbonate formations. The results of the study can be implemented in any other project or a field.
All-Electric Intelligent Completion System: Evolution of Smart Completion
Authors: Samuel Orient Balbir , Chandrakant Ashvin Avalani , Salleh Fairus Azwardy , Jamil Ahsan , Ibrahim Zulkifli , Ivey Alan
Published: May 2021

Field D is a mature offshore field located in East Malaysia. A geologically complex field having multiple-stacked reservoirs with lateral and vertical faulted compartments & uncertainty in reservoir connectivity posed a great challenge to improve recovery from the field. Severe pressure depletion below bubble point and unconstrained production from gas cap had contributed to premature shut-ins of more than 50% of strings. As of Dec 2019, the field has produced at a RF less than 20%. Initial wells design consisted of conventional dual strings & straddle packers with sliding sleeves (SSD). Field development team was challenged for a revamp on completion design to enhance economic life of the depleting field.

In 2015, as part of Phase-1 development campaign, nine wells including four water injectors were completed initiating secondary recovery through water flood. An approach of Smart completion comprising of permanent downhole monitoring system (PDHMS) and hydraulic controlled downhole chokes or commonly known as flow control valve (FCV) was adopted in all the wells in order to optimize recovery from the field and step towards intervention-less solutions. Seeing the benefits of intelligent completion in Phase-1, Phase-2, drilled and completed in 2019 – 2020 has been equipped with new technology "All-electric Intelligent Completion System" in 4 out of 8 oil producers. The new design addresses the reservoir complexity, formation pressure and production challenges and substantial cost optimization, phasing out the load of high OPEX to CAPEX.

Installation of "All-electric Intelligent Completion System" has proven to be an efficient system compared to hydraulic smart completions system. It requires 50% to 75% less installation time per zone and downhole FCV shifting time is less than five minutes compared to several hours full cycle for hydraulic system. The new system has capability to complete up to 27 zones per well with single cable. It gave more options and flexibility in order to selectively complete more zones compared to hydraulic FCVs which requires individual control line for each zone. Future behind casing opportunities (BCO) have been addressed upfront, saving millions of future investment on rig-less intervention. In addition to that, non-associated gas (NAG) zones have been completed to initiate in-situ gaslift as and when required avoiding the dependency on aging gaslift facility.

The scope of the paper is to show case the well design evolution during Field D development and highlight on how smart completion has evolved from original dual completion to hydraulic smart and recently to electric smart system, how it has contributed to cost and production optimization during installation and production life and also support the gradual digitalization of the Field D. In the end it demonstrates the optimized completion design to enhance the overall economic life of the depleting field.
Probabilistic Estimation of Water Flood Requirement to Control Flow Behind the Casing on Offshore Platforms
Authors: Haghshenas Arash , Luengo Emilio , Bansal Yogesh , Mijares Geraldo
Published: May 2021

Recently, flood kill applications have been evaluated to cure blowouts due to gas migration from behind the casing while keeping the well integrity intact for further production. Traditionally, deterministic evaluations are used in planning these operations, ignoring the uncertainties in the characteristics of the gas sources behind the casing. This work focuses on using reservoir simulation-based workflow to evaluate the uncertainty providing probabilistic operating conditions to control the gas rates coming from behind the casing. The results of the simulations are combined to provide general guidelines for performing an effective flood kill operation. The studied parameters are divided in different categories based on their influence/impact on the effective kill. For example, the relationship between the best relief well position and reservoir permeability and anisotropy are studied, and the guidelines for the definition of the best location is identified. Based on the results of the analysis, the optimum required proximity of the wells can be determined. The analysis identifies the main factors for a successful flood kill operation. The situations where flood kill could be beneficial are identified and the success rate could be evaluated. This paper presents a methodology and guidelines for the design of an effective flood kill application. This methodology will help in positioning of the relief well and provide required control mechanisms to increase the chances of a successful operation. The methodology also provides insight on the required operating parameters, such as pump rates and total volume to be injected, for the operation to be successful. In addition, the developed workflow can be updated as more information is gathered while drilling the relief well. This will help in improving the chances of a flood-kill operation while providing tighter controls on the operational conditions.
Impact of Multi-Branched Ionic Liquid on Shale Swelling and Hydration for High Temperature Drilling Applications
Authors: Khan Rizwan Ahmed , Ahmad Hafiz Mudaser , Murtaza Mobeen , Abdulraheem Abdulazeez , Kamal Muhammad Shahzad , Mahmoud Mohamed
Published: May 2021

Shale swelling and hydration during the drilling operation have adverse effects on the stability of a wellbore. Hydrophilic interactions of shale results in swelling and disintegration of the shale formation. This paper discusses wettability changes and hydration characteristics of shale to improve the wellbore stability. The use of multibranched ionic liquid as drilling fluid for high temperature applications was investigated.

The novel multibranched ionic liquid (Trihexyltetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate, denoted as Tpb-P) water-based drilling fluid was prepared by mixing different concentrations of ionic liquid and other additives such as filtration controller, rheological modifier, and pH controller. The wettability of bentonite powder was determined using a contact angle in the presence of various concentrations of ionic liquids. Several other experimental techniques, such as linear swelling, hot rolling recovery, and bentonite swell index, were used to examine the inhibition performance of ionic liquid. The rheology and filtration properties of ionic liquid-based drilling fluid were also examined.

Various concentrations of multibranched ionic liquid were used to formulate the drilling fluids ranging from (0.1 to 0.5 wt.%), and their performances were compared with the base drilling fluid prepared without ionic liquid. The hydrophobicity of the shale surface was determined by measuring the contact angle, and results showed that drilling fluid having 0.1 wt.% concentration of ionic liquid has a maximum contact angle indicating the highly hydrophobic shale surface. The hot rolling shale recovery experiment was conducted at 150°F, and it was observed that adding ionic liquid improved the shale recovery (24.4%) compared to the base fluid recovery (12.8%). The linear swelling was evaluated over the time of 24 hours, and the least swelling of bentonite was noticed with 0.1 wt.% ionic liquid (98.1%) compared to linear swelling in deionized water (125%). The results suggested that the ionic liquid in the drilling fluid chemically interacted with the clay surface and reduced the hydrophilicity of clay, which restricts the exchange of water onto the clay surface.
A New Pdc Bit Selection Method Based on 3d Realistic Cutter Damage Simulation Aimed at Maximizing Product Life–Cycle
Authors: Pelfrene Gilles , Al Fayez Fayez Abdulrahman , Baqer Hussain Ali , Al-Jarki Jasem Ahmed , Alsarhan Meshal Hamoud , Al-Otaibi Mohammad , Al-Suraie Abdulkarim , Soletta Laurent , El-Genidy Ehab , Gamal Mohamed , Reboul Sebastien , Cuillier Bruno , Tissot Vincent , Gabas Xavier , Stab Olivier
Published: May 2021

Increasing the life of PDC bits without compromising on bit performance is crucial in drilling operations. It allows the operator to reduce non-productive time and the bit manufacturer to increase the reliability and the repairability of its products. This paper introduces a new PDC bit selection method designed to maximize the durability of the selected bit based on simulations of 3D realistic cutter damage.

During PDC bit drilling operations, any damage caused to one cutter tends to overload others and compromise the balancing and the durability of the whole cutting structure. The impact of various kinds of bit failure and cutter damage on the performance of different cutting structures is estimated. The analysis is performed with the help of a 3D bit-rock interaction model which simulates the drilling process considering both the drill bit and the hole being drilled as 3D meshed surfaces. The simulator is based on a generic computational geometry algorithm which estimates the exact volume of rock removed by each cutter while making minimal assumptions on the geometry of the cutter. Any cutter shape, including damaged ones can be simulated based on this model. Thus, realistic dull conditions can be applied to PDC cutters to analyse how the bit performs once damaged.

A series of simulation scenarios involving different failure mechanisms like abrasive wear, broken cutters, or lost cutters, have been conducted on a series of targeted 9 ¼ in. bit designs aimed to be run in an application in South East Kuwait. Bit designs have been ranked with respect to simulated performance indicators like drillability, steerability, stability, tool face control and also to their ability to withstand mild to catastrophic failure events. Based on this analysis, the top ranked bit design has been selected, manufactured and successfully run in the field. For the first time in the area, the bit achieved two sections (9 ¼ and 6 ½) in one, showing both a high durability and a good compatibility with the directional system used along the formation sequence drilled.

While the classical bit selection process is usually limited to the comparison of different bit designs in a given drilling scenario, the present paper demonstrates how this process can be further optimized by selecting the bit which also guarantees a maximum level of performance when subjected to worst case failure scenarios. This new method should benefit both the operator and the bit manufacturer as it is designed to achieve longer intervals, reduce operating costs and increase the global bit performance.
Unlocking Value From Data is Key to Successful Digital Transformation
Authors: AlSaadi Hamdan , Rashid Faisal , Bimastianto Paulinus , Khambete Shreepad , Toader Lucian , Landaeta Rivas Fernando , Couzigou Erwan , Al-Marzouqi Adel , El-Masri Hassan , Pausin Wiliem
Published: May 2021

Big data analytics is the often complex process of examining large andvaried data sets to uncover information. The aim of this paper is to describe how Real TimeOperation Center structuring drilling data in an informative and systematic manner throughdigital solution that can help organizations make informed business decisions and leverage business value to deliver wells efficiently and effectively.

Real Time Operation Center process of collecting largechunks of structured/unstructured data, segregating and analyzing it and discovering thepatterns and other useful business insights from it. The methods were based on structuringa detailed workflow, RACI, quality check list for every single process of the provision of real-timedrilling data and digitally transform into valuable information through robust auditableprocess, quality standards and sophisticated software. The paper will explain RTOC DataManagement System and how it helped the organization determining which data is relevantand can be analyzed to drive better business decisions in the future.

The big data platform, in-house built-in software, andautomated dashboards have helped the company build the links between different assets,analyzing technical gaps, creating opportunities and moving away from manual data entry(e.g. Excel) which was causing data errors, disconnection between information and wastedworker hours due to inefficiency. These solutions leverage analytics and unlock the valuefrom data to enhance operational efficiency, drive performance and maximize profitability.

As a result, the company has successfully delivered 160 wells in 2019 (6% higher than 2019 Business Plan and 10% higher than number of delivered wellsin 2018) more efficiently with 28.2 days per 10kft fornew wells (10% better than 2018), without compromising the well objectives and quality of the wells. Moreover, despite increasing complexity, the highest level ofconfidence on data analytics has permitted the company to go beyond their normaloperating envelop and set a major record for drilling the world's fifth longest well as amilestone in 2019.
Innovative Remediation Techniques for Restoring Well Integrity with Coil Tubing Patch
Authors: Yap Ho Yin , Chua Leong Hing , Rayner Fidelis Sipangkui Brian , Low Peng Yoke , Connie Bato
Published: May 2021

Well BO-X is located in offshore East Malaysia and was completed as a single string producer on 22nd July 2014. Well BO-X has maximum deviation of 57.5 deg at depth 3,150ft MDTHF. Based on the MIT logs, several leaks have been detected on the string which caused the well unable to flow. Well was flowing for 2 years before identified with multiple leaks due to severe metal loss and high penetration along more than 1,400 ft tubing interval (400 ft above the TRSCSSV and 1000ft below the TRSCSSV). Multiple attempts tried to flow well but failed due to circulation of gas through leak points at tubing. Tubing was found to be leaking at multiple points above TRSCSSV (449 ft MDTHF) with severe pitting / penetration at a single point below between ESP discharge head and TRSCSSV from 2 MIT runs. The leaks were detected at depth (1) 64 ft MDTHF, (2) 126.8 ft MDTHF and (3) 221.2 ft MDTHF. There were also several potential leaks detected along the long string above the top packer

Reservoir simulation studies and production rate both indicated that the production tubing leaks is deteriorate and few methods were considered to bring back the optimum production. Tubing pack off system technique was considered as it can deploy with slickline, retrievable and ideal use to isolate tubing leaks however there is potential that more leaks will develop along the production years. Workover as an option to replace the tubing could easily cost millions of dollar (USD)

Before surrender the well to workover team, a coiled tubing patch system was designed in a cooperative project involving operator and service company to provide an improved tubing pack off system which can straddle the tubing leaks by using coiled tubing instead of spacer pipe. This coiled tubing patch system was significantly lower cost and keep the functionality of Tubing Retrievable Surface Control Subsurface Safety Valve (TRSCSSV) by installing two straddle packer system – upper straddle packer system to cover leak points above TRSCSSV while another straddle system to cover leak points below TRSCSSV (Fig 1).
Mud-Sealing Cement System Delivers Notable Cement Bond Log Result in a Challenging Offshore Horizontal 4 ½-in Liner: A New Technology Case Study
Authors: Nzoutchoua Degaul Nana , Johnson Carl R. , Mounguele Armelle Boukoulou , Onyia Chibuzor , Rizza Giovanni , Sinibaldi Giuliano , Gravante Elpidio
Published: May 2021

A 1575m [4922-ft] offshore horizontal 4-½-in. liner cemented using a mud-sealing cement system (MSCS) resulted in an outstanding cement bond log result. The decision to use the MSCS was taken after realizing that four offset liners, previously cemented using conventional cement systems, did not yield acceptable cement bond log results despite following oil and gas cementing industry best practices, including pipe rotation. This paper documents a comparison of six offset horizontal liners, focusing on the impact of the MSCS technology.

The paper focuses on several 4-½-in. liners in the same field. The wells were drilled by a similar rig and had similar well profiles. The drilling bit, directional drilling tool, drilling fluids system, logging tool, centralizer type and pumping sequences were comparable across all wells. In addition, the logging company performing the cement bond log evaluation was not the same company performing the cementing service. After the first MSCS-cemented well, the subsequent well used a conventional cement system to isolate the 4-½-in. liner and tighten the cementing best practices. This was initiated to irrefutably confirm the impact of MSCS technology on the quality of cement bond log recorded on the earlier well.

The cement bond log recorded from the well isolated with MSCS is easily identified among the six comparison wells even though the cementing operation faced several well challenges, includinga single dart liner system implementation (for all liners), which can promote the intermixing of slurry with fluid ahead while travelling down the pipemud losses in the drilling phase, which resulted in a reduction of the displacement rate to control ECD during cement placement.

The bond log results of the other wells were qualified as poor or fair, even though significant precautions were taken to optimize zonal isolation. These efforts included batch mixing the spacer and slurry, using more than one centralizer per casing joint, and implementing pipe rotation during pre-job circulation and job execution when the torque limit allowed.

This multi-well comparison based on field results brings solid evidence of the MSCS technology interacting with the residual layer of nonaqueous fluid (NAF) when well conditions reach or exceed the practical normative limitations for mud removal. This in-situ interaction generates a viscous paste that positively impacts the bond log response and bolsters the isolation between zones of interest. The result has yielded a step forward in the provision of a dedicated barrier technology for horizontal or highly deviated sections.
Development of A Particle Swarm Optimization-Backpropagation Artificial Neural Network Model And Effects of Age And Gender On Pharmacokinetics Study of Omeprazole Enteric-Coated Tablets In Chinese Population
Authors: Xu Yichao , Chen Jinliang , Yang Dandan , Hu Yin , Jiang Bo , Ruan Zourong , Lou Honggang
Published: May 2021

Background: The effects of age and gender were explored on pharmacokinetics study of omeprazole enteric-coated tablets in Chinese population and a plasma concentration prediction model was developed. All the data (demographic characteristics and results of clinical laboratory tests) were collected from healthy Chinese subjects in pharmacokinetics study using 20 mg omeprazole enteric-coated tablets. A noncompartmental method was used to calculate pharmacokinetic parameters, and 47 subjects were divided into two groups based on the calculation of the median age. Pharmacokinetic data from the low-age and high-age groups or male and female groups were compared by Student t-test. After a total of 12 variables were reconstruct and convert into independent or irrelative variables by principal component analysis, particle swarm optimization (PSO) was used to construct a backpropagation artificial neural network (BPANN) model. Result: The model was fully validated and used to predict the plasma concentration in Chinese population. It was noticed that the Cmax, AUC0-t, AUC0-∞ and t1/2 values have significant differences when omeprazole was administered by low-age groups or high-age groups while there were slight or no significant differences of pharmacokinetic data were found between male and female subjects. The PSO-BPANN model was fully validated and there was 0.000355 for MSE, 0.000133 for the magnitude of the gradient, 50 for the number of validation checks. The correlation coefficient of training, validation, test groups were 0.949, 0.903 and 0.874.Conclusion: It is necessary to pay attention to the age and gender effects on omeprazole and PSO-BPANN model could be used to predict omeprazole concentration in Chinese subjects to minimize the associated morbidity and mortality with peptic ulcer.
A Demand Prediction Model of Repairable Components based on Grey Birth and Death Process
Authors: Gu Yingjing , Chang Ching-Ter
Published: May 2021

During the life cycle of equipment, the failure and repair rates of repairable components show uncertain characteristics. The birth and death process (BDP) based on the determined failure and repair rates may not meet the demand forecasting of spare parts. In order to resolve this problem, the grey state transition matrix is constructed by using interval grey numbers to appropriately represent the failure and repair rates of repairable components. In addition, the grey BDP model is built for the demand forecasting of spare parts. The memoryless and existence conditions of steady solution of the grey BDP are studied. To some extent, the spare parts demand law with the uncertain information of the failure and repair rates can easily be revealed. The practical case study is provided to verify the validity and practicability of the proposed model. Also, it provides a new perspective for the spare parts demand prediction problem under the condition of uncertain Markov Process. Accordingly, airlines can predict the maintenance resources demand more accurately and avoid two situations which are not allowed: (1) lower spare parts inventory will lead to the delay production; and (2) higher spare parts inventory will lead to the operating cost pressure.