bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimisation of Thermal Insulation of Subsea Flowlines for Hydrates Prevention
Authors: Abegunde Mobolaji , Adeyemi Adekola
Published: August 2020

In the development of an oil field, the assurance that produced hydrocarbon will flow is a critical determinant for the development of an oil and gas field even when other disciplines such as subsea design, reservoir engineering, artificial lift equipment, pipeline engineering have done a thorough analysis. Hydrate formation is one of the challenges of flow assurance in an oil and gas pipeline especially those installed in deepwater oil fields. Insulation of subsea pipelines is paramount to the prevention of hydrate formation. This work investigates the best material that is suitable for the thermal insulation of subsea flowlines using the ANSYS software package, and then provide the best composite arrangement of insulation materials for better heat optimisation. Four insulation materials were considered; Aerogel, Mineral Wool, Paraffin Wax and Grooved Mineral. A pipe-in-pipe (PiP) flowline model filled with fuel oil, at an inlet temperature of 60°C, was simulated on ANSYS by varying the configuration of the respective insulation material sheath; the heat transfer method in the PiP is by convection from the outer pipe to the ocean ambience at a temperature of 4°C. Results obtained from the simulation established that Aerogel is best for insulation among those considered, this is because of its low thermal conductivity and high specific heat capacity; in contrast, Grooved Mineral simulation result presented a poor performance. To ensure maximum heat conservation through optimum insulation, a composite configuration of insulation materials was proposed.
Assessment of Health, Safety and Environment Impact of Flavonoid-Derived Demulsifiers
Authors: Airiagbonaye Florence , Achugasim Ozioma , Akaranta Onyewuchi
Published: August 2020

This paper aims at quantifying the Health, Safety and Environment (HSE) impact of some flavonoid-derived demulsifiers using Chemical Scoring Index (CSI). The CSI is based on the three-hazard categories defined by United Nations' Globally Harmonized System for Classification and Labeling of Chemicals (GHS) for defining greener chemicals. Chemical components of each flavonoid-derived product were quantified by scoring the level of hazard posed by the component in relation to its percentage composition in the product.-a carcinogen in a 10% component of a product will be scored higher than in a 1% composition. Additionally, a carcinogen is weighted higher than an ‘irritant’. As such, products with low CSI within same usage group are considered to have lower intrinsic hazard and therefore used in selecting best HSE green chemicals. Eight (8) products were quantified; five (5) modified flavonoids and three (3) commercial demulsifiers. ‘Modified Flavonoids-A’ was considered best HSE chemical with a CSI of 420, while ‘Commercial demulsifier-B’ was the least HSE chemical with CSI of ‘1980’. It is recommended that rather than focus on only the performance and cost of a chemical product, it is essential to consider the Health, Safety and Environment impact in the selection of oilfield chemical products. This model will assist HSE professionals in quick assessment of safer chemicals alongside their performance.
Flow Barrier Detection and Characterisation using Capacitance-Resistance Model: Case Study of a Far East Oil Field
Authors: Ogali Oscar I. , Orodu Oyinkepreye D.
Published: August 2020

The Capacitance-Resistance Model (CRM) is a semi-analytical modelling approach utilizing non-linear multivariate regression. Using historical production and injection rates, as well as historical bottomhole pressure data if available, CRM quantifies the connectivity and degree of fluid storage between injectors and producers in a reservoir. The CRM has been applied to waterflood management and performance prediction, improved reservoir characterisation, waterflood optimisation and, production optimisation. In this study, the CRM was used in fault characterisation and flow barrier detection. Historical production and injection data from an oilfield from the "Far East" were then used to calibrate the CRM. Thereafter, the resulting CRM parameters were combined with geological data and wells data to characterise two major faults in the reservoir, as well as detect other flow barriers within the reservoir. Based on the results, several sections of one fault have varying degrees of communication. There were also smaller flow barriers within the reservoir section considered around this fault, that negatively impacted the performance of some injectors. The second fault was mostly sealing, with few leakages along the extent of the fault. Capacitance-Resistance Modelling can be used to corroborate the results of Interference Testing, Tracer Test and 4D Seismic in detecting and characterising faults, and as a cost-effective reservoir management tool.
Flared Gas Monetization in Nigeria-Status, Challenges & Opportunities
Authors: Anioke Oluchi , Obuh Matilda , Muhammed Amin , Iyalla Ere
Published: August 2020

The need to eliminate gas flaring & ultimately monetize flared gas in Nigeria is of utmost economic, social and environmental importance. This is because studies indicate that, across the Niger Delta, there are over 178 flare locations from which an estimated 800mmscf of gas is being flared daily. A Nigerian government initiative, The Nigerian Gas Flare Commercialization Programme (NGFCP), is working to achieve a near to total gas flare-out target by the end of 2020. This is planned to be attained via an initial phase programme strategy of mobilizing private sector capital towards gas flare capture projects. The next phase of the program's strategy is to develop a world class investment approach, optimize supply through domestic market utilization and create strong partnerships with the world's most innovative energy countries. The untapped potential and prospects of monetizing flared gas can contribute significantly to the country's economy as it can be utilized domestically through various technologies such as the mini gas to power (GTP), mini gas-to-liquid (GTL), and as compressed natural gas (CNG). A concise study was undertaken, carrying out an in-depth analysis of challenges and issues pertaining to the contracts and market outlets for products of these proposed gas flare-out projects. The study also explored supply chain improvement opportunities and the most effective technologies that could be deployed to take the flared gas to market at the least risk. Based on the studies carried out, the paper seeks to propose best case scenarios for the efficient and effective monetization of Nigeria's flared gas within socio-economic, political and infrastructural contexts of the country.
Implications of Petroleum Industry Fiscal Bill 2018 on Heavy Oil Field Economics
Authors: Nwosi-Anele Adaobi Stephenie , Illedare Omowunmi , Adeogun Oyebimpe
Published: August 2020

Recent increase in energy demand has made necessary the exploitation of Nigerian heavy oil fields neglected in the 1990s. These heavy oil fields were neglected due to low oil price and lack of technology to aid their recovery. Stakeholders in the heavy oil sector have been divided over what fiscal framework applies for the exploitation of Nigerian's heavy oil. The Nigerian Oil Industry has a well-developed fiscal framework for light and medium oil exploitation and the Proposed Petroleum Industry Fiscal Bill (PIFB) 2018. This work studies the economics of an onshore heavy oilfield under the PIFB 2018, to examine the implications of heavy oil exploitation using the PIFB 2018 as a fiscal policy. Field production profiles showing exponential, harmonic and hyperbolic field decline patterns were developed to represent 25.38% recovery factor for a heavy oil field of 196MMSTB OIIP. Deterministic models were built featuring the fiscal instruments of the PIFB 2018, heavy oil price, capital expenditure, operating expenditure and economic metrics. The stochastic model featured the impact of heavy oil price, capital expenditure, price escalation rate, discount rate, and peak production on the contractor's and host government takes for the PIFB 2018. Our stochastic results show that the output variables are most sensitive to heavy oil price, discount rate and capital expenditure. The petroleum industry fiscal bill 2018 is found to be an efficient fiscal policy for the host government and contractor, giving take statistics of 49% and 51% respectively. Varying oil price and discount rate did not make the investment unprofitable but reduced the investment ranking. Exponential decline behavior proved most profitable, while hyperbolic decline proves least profitable. Adjustments of two fiscal instruments of the PIFB was made to enable contractors produce heavy oil using unconventional recovery method and remain in business during periods of low heavy oil price.
Rejuvenating an Aging Asset through a Comprehensive Reservoir Simulation Study
Authors: Yusuf Nurudeen Oluwatosin , Tuitjer Eric , Silpngarmlers Lynn
Published: August 2020

With a peak production of ∼30,000 bopd, "Field_M" was one of the most prolific fields in Niger-delta. However, over a forty-year period, production has declined to less than 3% of the peak value. In order to unlock new potentials in this asset, a multi-disciplinary team embarked on an asset re-assessment using reservoir simulation studies while focusing on the top reservoirs in the field with the highest expected incremental recovery. The first group of studies were done on a genetically related stack of four (out of available eleven) reservoirs: two depleted reservoirs and two virgin reservoirs, using a single comprehensive structural and stratigraphic framework.

For virgin reservoirs, probabilistic simulation studies were conducted with decoupled static and dynamic parameters. The most dominant parameters were identified and used to guide selection of P10/P50/P90 models. Sensitivities studies were conducted under different recovery mechanisms and different development scenarios using both idle wellbores and new wells. Erstwhile economically challenged opportunities due to small in-place volumes were improved by consolidating these opportunities. Integration of new opportunities were facilitated using the comprehensive model which allowed the testing of wellbores across all reservoirs simultaneously1.

For depleted reservoirs deterministic history matches were done using available pressure and production. History match helped to characterize connectivity between faults and across multiple lobes in these reservoirs2, an important factor in planning infill drilling. Post history match sensitivities provided reactivation opportunities and infill developments under secondary recovery mechanism.

The study outcomes will drive implementation of waterflood in these reservoirs in addition to non-rig intervention and infill drilling. The study identified a total of nine opportunities: two reactivations, two new injection strings and five new producing strings with an incremental recovery of 26 MMBO.
Effect of Polymer Additives on the Rheology and Fluid Loss of Water Based Muds
Authors: Adeyemi Gbadegesin , Fadairo Adesina , Ogunkunle Temitope , Oladepo Adebowale , Oredeko Olugbenga , Vitoria Ojei , Tomomewo Olusegun , ICHI Eberechi
Published: August 2020

In drilling operations, the effects of filter cake properties and filtration control on drilling fluid cannot be undermined in the process of wellbore construction and stability in order to obtain a successful drilling activity. This paper used experimental approach to investigate the effect of filter cake on fluid loss and formation damage using the formulated environmentally friendly water base polymers. Four mud samples were formulated separately, the first four mud sample were prepared with Acrylamide monomer (AAM) while the other four mud sample were done with Carboxylmethyl cellulose (CMC) by-polymer. The polymers varied for each sample from 5g-20g while other composition remain constant. High pressure high temperature fluid loss test was conducted on the formulated mud sample.

The results obtained with Acrylamide monomer (AAM) looks more interesting, giving a reduced fluid loss of about 8. lcm3 and a reduced filter cake thickness of about 0.042cm3 this means formation damage reduction with Acrylamide monomer (AAM) based mud. The Carboxylmethyl cellulose (CMC) fluid was found to be pseudo-plastic with shear thinning behavior, the fluid experienced a drastic decrease in plastic viscosity of 11 cp and yield point of about 351b/ 100fta, Acrylamide monomer (AAM) showed the higher shear rate and shear stress than Carboxylmethyl cellulose (CMC), it also acted as a better viscosifier. This can be attributed to the OH branches on the glucose rings, because of the negative charge it carries. The Acrylamide monomer (AAM) gave a relatively lower fluid loss with an increase in the polymer concentration and also gave lower filtration values at increased temperature and pressure conditions. Results shows that AAM reduces fluid loss better than CMC
Production Tubing Integrity Evaluation for Complex Workover Well Operations in Niger Delta
Authors: Anyanwu Chinedu , Agbo Ejimofor , Olusola Bukola
Published: August 2020

To successfully carry out a workover on a well that was completed more than 20 years ago as a dual string completion with a dual packer and two Permanent Packers is complicated. The presence of a slickline fish of unknown dimensions in hole further complicated the nature of the workover thus making it susceptible to failure during the retrieval of the tubings. A Tubing Integrity Evaluation Methodology (TIEM) was used to properly assess potential failure points and craft out execution strategy to mitigate them. The TIEM adopted in this paper involved carrying out a detailed tubing stress analysis on the completion tubings where axial loads exerted on the tubing; weight, buoyancy, point loads on crossovers, piston loads, ballooning; as well as triaxial stress effect of axial, radial and tangential stresses were all estimated. The yield strength and yield stress completion tubing were de-rated by 30 percent as a precautionary measure due to the age of the completion tubings. The maximum overpulls the tubings could sustain without failing by parting, axially or yielding triaxially were calculated. These overpull forces was compared with the force required to unseat the dual packer as well as snap out from seal assemblies of the permanent packers to decide whether the tubing was to be cut prior to pulling or not during the tubing retrieval operation. Several fishing scenarios of slickline and drill pipe fishing were analysed based on the location of the slickline fish. Based on the results of the detailed tubing stress analysis, the maximum overpull the short string and long string sections could sustain were 58,000 lbs and 23,000 lbs respectively while the maximum force required to unseat the dual packer was 50,000 lbs. Thus, it was decided to pull the short string within the overpull limit while the long string was to be cut above the packer prior to unseating the packer. The Tubing evaluation helped to properly assess potential failure points and craft out execution strategy to mitigate or avoid potential problems associated with the workover operations with unknown dimensions of fish in the wellbore.
Economics of Marginal Field Crude Oil Evacuation in Nigeria
Authors: Onwuka Emmanuel I. , Pedro-Egbe Umamejale , Enemokwu Kelvin I.
Published: August 2020

Crude evacuation to the export terminals takes more than 45% of the operating expenditure of some marginal field operators (MFOs) in Nigeria. Many studies on marginal field investment focus more on composite operating cost analysis, hence overlooking its components. Crude evacuation is a major challenge for MFOs because economics of their operations may not support wholistic value chain investment of which crude transportation is a part. Oil pipeline evacuation is the primary onshore crude transportation model available to MFOs. The next option is the virtual pipelines with high risk potentials. Therefore, the market for pipeline crude evacuation becomes a monopoly cemented on several agreements with stringent terms and conditions. One recurrent feature in most of these agreements is the charge on the reserved production capacity (RPC). This cost takes more than 70% of the ullage value in a typical marginal field budget. Are there ways to navigate past this monopoly? This paper seeks to explore economics of various crude evacuation options available in the marginal field terrain onshore and develop integrated evacuation models to highlight the effect of the idiosyncratic monopoly to profitability. The approach x-rays the various crude handling, transportation, terminaling and sales agreements available to MFOs. Hydrocarbon accounting model is incorporated for both pipeline and virtual pipeline evacuations. Iteration of tariff charges and injection split optimization are done on the integrated model. Forecasts are carried out in the face of changing oil prices, oil injection profiles and crude agreements terms and conditions over a period to ascertain the effect on the MFO's bottom-line. The model may be used for policy formulations, sector regulations and the marginal field investment analysis.
Digital Transformation of the Standing and Katz Compressibility Factor Chart for Natural Gases
Authors: Chukuigwe Ndubuisi , Ikiensikimama Sunday , Okafor Ikechukwu
Published: August 2020

The ability to query data from a standard source at any given time, for engineering decision is of great importance to the industry. Hence the need for efficient, accurate, user-friendly digital solutions to the analog, error-prone and tedious charts used in the oil and gas industry. The Standing and Katz compressibility factor chart of natural gases is one of those charts needing digital transformation for seamless user experience. The result of the methodology applied in this paper is a modern desktop software called "Z-Digit". The Z-Digit software was compared to two existing techniques (Hall and Yaborough implicit correlation, and Beggs and Brills explicit correlation), for obtaining the value of the compressibility factor using the Standing and Katz chart as a benchmark. It was observed that the Z-Digit software provided values with very low percentage errors at data points for which the Hall-Yarborough implicit correlation diverges (tends to infinity). The software also produced satisfactory values of Z-factor at pseudo reduced isotherms for which the Beggs and Brill explicit correlations gave very large percentage errors. It also visualizes the full range of the Standing and Katz chart, shows points where values are read from, eliminates the constraint of reading several Z-factor values with the same set of pseudo reduced pressure and temperature data, eliminates the problem of divergence or inaccuracy incurred when using complex empirical correlations, and saves historical values of read compressibility factors together with their pseudo reduced pressure and temperature to avoid repetition.
Integrated Underreamer Technology with Real-Time Communication Helped Eliminate Rathole in Exploratory Operation Offshore Nigeria
Authors: Ozioko Raphael , Osita Humphrey , Ohia Udochukwu , Okafor Emeka
Published: August 2020

This paper describes the successful deployment of integrated underreamer technology with real-time communication through mud-pulse telemetry system, to drill and eliminate rathole in 17 1/2-in × 20-in successfully in one run and helped set casing as close as possible to the depth of suspected pressure ramp on an exploratory well offshore Nigeria. This technology uses the same communication system (actuator bypass) as Measurement While Drilling tools (MWD),Logging While Drilling tools (LWD) and Rotary Steerable System (RSS).

Integrated underreamers broadly used in the drilling operations support optimized casing and completion programs and helps reduce operational risks such as wellbore instability. The ball drop and hydraulically activated reamer technologies available today comes with limitations and HSE risks. The distinctive functionalities of the integrated underreamer technology described here, such as unlimited and fast activation and deactivation via downlinking and real time downhole feedback,reduce uncertainties and operational costs in the complex and challenging deep offshore drilling operations.

The real-time communication through mud-pulse telemetry system enabled the placement of integrated underreamer 6 meters from the bit thereby reducing rathole length to approximately 9 meters compared to 80 meters for conventional underreamer application. The integrated underreamer is compatible with existing RSS and provide unlimited activation cycles. The integrated underreamer offers flexibility in placement in the bottom hole assembly (BHA) and it can be used as a near bit reamer, or as main reamer or as both.In this case,the integrated near bit underreamer eliminated the need for a dedicated rathole removal run.It also offered a feedback confirmation of the cutter blades activation status and provided hole opening log thereby reducing the operational uncertainties for the under reaming, saving rig time up to 16 hours for shoulder test.

The underreamer was successfully deployed to drill and ream the challenging 14 ¾’’ × 17 ½’’ and ream 17 ½’’ × 20’’ section offshore Nigeria. Both sections were drilled and reamed to section Total Depth (TD) in one run with all directional requirements and Measurement While Drilling (MWD)/Logging While Drilling (LWD) met,saving client approximately 4 days of rig spread cost. The reamer appeared to provide an in-gauge borehole allowing for successful running and cementing of liners without any issues, demonstrating superior borehole quality.The new Technology proved to be a reliable and flexible hole enlargement while drilling solution that help to improve drilling performance, reduce operational risks and save cost.
The Chemical Modification of Calophyllum Inophyllum Plant Oil for Potential Base Oil in Drilling Mud Operation
Authors: Onuh Charles , Adewale Dosunmu , Paul Anawe , Oluwatosin Rotimi
Published: August 2020

Research on the use of plant oil or ester oil in drilling mud operation is on the increase. The is due to the less toxic and low cost advantage over the commercial synthetic base oil. Despite the attractive physicochemical properties of vegetable oil samples, it deteriorates and becomes unstable under downhole temperature and aging conditions when used directly in mud formulation. Hence, plant oil needs improvement in order to be compared to the conventional base oil. Calophyllum inophyllum oil was extracted and reacted with methano in the presence of catalyst to form biodiesel. The physicochemical properties of the commercial synthetic base oil, extracted Calophyllum inophyllum oil, and biodiesel Calophyllum inophyllum oil were measured and compared to the EN14214 and the ASTM D6751 standards. The commercial synthetic oil, Calophyllum inophyllum oil, and biodiesel Calophyllum inophyllum oil had a flash point of 101 ± 0.1, 164 ± 0.1, and 146 ± 0.1 °C respectively; density of 108, 172, and 152 (kgm3) respectively; viscosity index of 192, 163, and 282 respectively; acid value of 0.953, 24.24, and 1.0 respectively, and oil yield of NA, 71, and 62 respectively. The result showed that the biodiesel can also serve as alternative to commercial synthetic base oil due to their comparable property to the commercial base oil. The biodiesel Calophullum inophyllum oil is a potential base oil for drilling mud formulation.
Solving Formation Evaluation Challenges Using a Combination of Open and Cased Hole Logging Technology
Authors: Olowoyeye Oluwasola Ibidapo , Anyanwu Chinedu , Adebari Adeola , Ipinyemi Oloruntoba , Kalistratov Andrei , Smith Henry
Published: August 2020

A combination of open and cased hole logging technique was used to carryout formation evaluation in a high angle well traversing laterally displaced reservoir complexes. This method was adopted to minimize wellbore exposure and avoid risks attending logging the high angle open hole. Hence, with limited open hole data, Quad (cased hole neutron technology with dual physics), noise and production logs were used to determine reservoir properties.

The formation evaluation objectives were achieved using a combination of MLWD, mudlog and Quad neutron logs. After cementing the final hole section at 62deg, cement evaluation and Quad neutron logs were used to firm up perforation. Noise and Production logs were also acquired to assess perforations and estimate reservoir pressures and injectivity indices.

Porosity, hydrocarbon saturation, clay volume and relative bulk density of the reservoir complexes were estimated from a set of logs obtained from the cased hole neutron technology which combines neutron-gamma and neutron-neutron physics. Fluid type and contacts were also independently determined and oil saturation across a 30ft reservoir interval with anomalous LWD-Resistivity response was resolved from these logs. Integration of cement evaluation logs with the Quad logs was useful in identifying channeling across one reservoir complex of interest. This helped to optimize initial perforation and completion designs. Two independent estimates of reservoir pressures were obtained from analysing Noise and Production logs. Perforation performance and productivity indices were determined from injectivity test analysis. This data acquisition strategy demonstrates innovative implementation of low risk and cost-effective resolution of data acquisition challenges in complicated situations are feasible.

This paper is meant to demonstrate that improvements in cased hole technology has cost-effectively made derivation of quality petrophysical data achievable, in the absence of sufficient open hole data. It is also worth considering as an alternative to open hole data acquisition in complicated situations to mitigate associated risks.
Assessment of Gas Miscibility Modeling in Black-Oil and Compositional Models in a Deepwater Brown-Field Under Gas Injection
Authors: Huang Hong , Odusote Olufemi A. , Alboudwarej Hussein
Published: August 2020

In fields under gas injection, appropriately modeling and understanding gas miscibility is critical to developing accurate production forecasts and managing the field development. The field under consideration in this paper is a deep-water brownfield with crestal gas re-injection and peripheral water injection to maintain reservoir pressure. Over the past 10 years of oil production from the field, associated production gas has been largely re-injected into the reservoirs and has led to significant increases in the reservoir gas saturation. Initial fluid studies performed indicated that the injected gas is miscible above a given minimum miscibility pressure (MMP). However, as the pressure is depleted in the field, this may be challenged.

Modeling of the gas miscibility in the field is done using a modified black oil dynamic simulation model that includes Todd-Longstaff miscibility formulation. However, this method may not fully capture the change in fluid behavior as the pressure depletes and cumulative gas injection into the reservoir is increased.

This study focuses on the gas phase behavior and gas miscible displacement process through a full-field compositional simulation model to evaluate the performance of the black oil model as well as to gain additional insight into the fluid behavior in this field. This study also compares the long-term production prediction between the two models where the gas production and gas injection rates are high and reservoir pressures decline near to minimum miscibility pressure. The comparison results in a similar oil recovery in the two models. The results also indicate that the black oil model with Todd-Longstaff option can effectively simulate the gas miscible process, but the compositional model is essential to gain a more in-depth understanding of the gas miscible process and displacement over time.
Kill Line Base Fluid Lost Circulation Management Methodology
Authors: Bajomo Victor Mobolaji , Elendu Chidi , Lawal Olumide , Aremu Olakunle Olufemi , Samuel Oluwafemi Michael , Ezeora Ebere , Bello Kayode
Published: August 2020

The loss of drilling and completion fluids during well operations are not uncommon occurrences; the major challenge is the loss rate and duration of these events. Studies and experiences have shown that several factors contribute to loss events and are broadly classified into human and natural factors, and in most cases a combination of both. Agbami well operation is not an exception; while drilling well CZ46, an oil producer well in the Agbami field, severe losses in the magnitude of 350 bph was encountered. This happened while drilling the 12-1/4" hole section in the top part of the KMY reservoir. The solution to this loss circulation event is based on the a relatively simple well control principle; manage the reduction of the bottom hole pressure (BHP) to stop or drastically reduce losses without taking influx. Previous works provided a comprehensive description of the Agbami field and its reservoirs1,2. In line with conventional drilling engineering practices3,4,5,6 the choice of the mud weight was informed by pore pressure prognosis which was not accurately predicted in the case of this well. The losses were initially slowed down by intermittently pumping sized calcium carbonate and some other LCM pills; however, it soon became obvious that the pills will not cure the losses for wellbore drilling to continue. This event was happening at a time when the Deepwater Horizon/Macondo incident7 was still very fresh in the minds of most drilling folks especially those working in deepwater operations. The major pre-occupation for the drilling operations personnel on this well when the loss event happened was not to lose the primary means of well control which is the drilling mud hydrostatic pressure.

The three main challenges that this loss rate posed were: how to reduce the loss rate in order not to run out of mud at surface; what lighter mud weight to displace the hole with; and how to carry out the displacement to a lighter mud weight. All the challenges must be resolved without taking influx or negatively impacting wellbore stability. The systematic method of displacement developed by the rig-site drilling operations personnel presented here was successfully implemented and has evolved to be called "Kill Line Base Fluid Displacement Method". The method can be adapted for use in severe loss circulation event in the deepwater environment and its success can be credited to treating the situation like a response to a well control event, although it is more of trying to avert one.
Environmental factors and spatiotemporal distribution of Japanese encephalitis after vaccination campaign in Guizhou Province, China (2004–2016)
Authors: Zhao Suye , Li Yidan , Fu Shihong , Liu Ming , Li Fan , Liu Chunting , Yu Jing , Rui Liping , Wang Dingming , Wang Huanyu , Tian Huaiyu
Published: August 2020

Background Although a vaccination campaign has been conducted since 2004, Japanese encephalitis (JE) is still a public health problem in Guizhou, one of the provinces with the highest incidence of JE in China. The aim of this study was to understand the spatiotemporal distribution of JE and its relationship with environmental factors in Guizhou Province in the post-vaccination era, 2004–2016. Methods We collected data on human JE cases in Guizhou Province from 2004 to 2016 from the national infectious disease reporting system. A Poisson regression model was used to analyze the relationship between JE occurrence and environmental factors amongst counties. Results Our results showed that the incidence and mortality of JE decreased after the initiation of vaccination. JE cases were mainly concentrated in preschool and school-age children and the number of cases in children over age 15 years was significantly decreased compared with the previous 10 years; the seasonality of JE before and after the use of vaccines was unchanged. JE incidence was positively associated with cultivated land and negatively associated with gross domestic product (GDP) per capita, vegetation coverage, and developed land. In areas with cultivated land coverage <25%, vegetation coverage >55%, and urban area coverage >25%, the JE risk was lower. The highest JE incidence was among mid-level GDP per capita areas and in moderately urbanized areas. Conclusions This study assessed the relationship between incidence of JE and environmental factors in Guizhou Province. Our results highlight that the highest risk of JE transmission in the post-vaccination era is in mid-level developed areas.
A simple model established by blood markers predicting overall survival after radical resection of type II and III Adenocarcinomas of the Esophagogastric Junction
Authors: Zhang Li-xiang , Wei Zhi-jian , Xu A-Man
Published: August 2020

Background. The prognostic prediction after radical resection of Adenocarcinomas of the esophagogastric junction (AEG) has not been well established. We aimed to establish a prognostic model for AEG(type II and III) based on routine markers. Methods. 355 patients who underwent curative AEG at the first affiliated Hospital of Anhui Medical University from January 2010 to January 2011 were included in this study. Univariate and multivariate analysis were used to screen for risk factors. The construction of the nomogram was based on Cox proportional hazard regression models. The new score models was analyzed by C index and Calibration curves. Results. Multivariate analysis showed that TNM stage, NLR and BMI were independent prognostic factors. The new score system had a higher C-index, and the Calibration curves of the nomogram were reliable. Conclusions. Based on the serum markers and other clinical indicators, we developed a precise model to predict the prognosis of patients with AEG(type II and III). This score system can provide effective help for surgeons and patients.
Factors facilitating trained NIMART nurses’ adherence to treatment guidelines: A vital matter in the management of TB/HIV treatment in South Africa
Authors: MAKHADO LUFUNO , Davhana-Maselesele Mashudu , Lebese Rachel Tsakani , Maputle Sonto Maria
Published: August 2020

Background: Globally, the burden of tuberculosis or human immunodeficiency virus (TB/HIV) is at 24% and this alarming rate compelled the World Health Organization (WHO) to declare the African region as a critical workforce shortage area. To facilitate adherence to treatment guidelines, WHO recommended a strategy of task shifting for countries with high health workforce shortages. The strategy aimed at the redistribution of health care tasks to available workers. The study aimed to determine the factors facilitating nurse-initiated management of antiretroviral therapy (NIMART) trained nurses’ adherence to TB/HIV treatment guidelines. Methods: The study employed an exploratory-descriptive design. The study was conducted in Ugu and Ngaka Modiri Molema Districts of KwaZulu-Natal (KZN) and North West (NW) Provinces of South Africa. The population comprised of 24 participants who were purposively selected. The in-depth focus group discussions were conducted and ATLAS T.I. was used for data analysis following the basic steps of notice-collect-think (NCT) analysis. Trustworthiness and adherence to ethics were ensured.Results: The singular theme of factors facilitating NIMART trained nurses’ adherence to treatment guidelines which included positive attitudinal needs and positive behavioural change emerged from raw data. Conclusion: Continuous training, support supervision, and improved relationships with colleagues need to be enhanced to enable NIMART trained nurses to adhere to treatment guidelines.
Efficacy and safety of the long-acting C5 inhibitor ravulizumab in patients with atypical hemolytic uremic syndrome triggered by pregnancy: a subgroup analysis
Authors: Gäckler Anja , Schönermarck Ulf , Dobronravov Vladimir , Manna Gaetano La , Denker Andrew , Liu Peng , Vinogradova Maria , Yoon Sung-Soo , Praga Manuel
Published: August 2020

Background: Atypical hemolytic uremic syndrome (aHUS) triggered by pregnancy is a rare disease caused by dysregulation of the alternative complement pathway that occurs in approximately 1 in 25,000 pregnancies. The 311 phase 3 trial (NCT02949128) showed that ravulizumab, a long-acting C5 inhibitor obtained through selective modifications to eculizumab, is efficacious in inhibiting complement-mediated thrombotic microangiopathy (TMA) in patients with aHUS. In this analysis, we report outcomes in a subgroup of patients from the 311 study who developed TMA postpartum. Methods: This was a phase 3, multicenter trial evaluating efficacy and safety of ravulizumab in adults (≥18 years of age) with aHUS naïve to complement inhibitor treatment. The primary endpoint was complete TMA response (simultaneous platelet count normalization [≥150 x 109/L], lactate dehydrogenase normalization [≤246 U/L] and 25% improvement in serum creatinine) through the 183-day initial evaluation period. Additional efficacy endpoints included time to complete TMA response, hematologic normalization, and dialysis requirement status. Results: Eight patients presenting with TMA postpartum (median age of 37.7 [range; 22.1–45.2] years) were diagnosed with aHUS and received ≥1 dose of ravulizumab. Five patients (63%) were on dialysis at baseline. Complete TMA response was achieved in 7/8 patients (87.5%) in a median time of 31.5 days. Hematologic normalization was observed in all patients. All patients on dialysis at baseline discontinued dialysis within 21 days after treatment with ravulizumab. All patients showed continued improvements in the estimated glomerular filtration rate from baseline to Day 183. Three possible treatment-related adverse events were observed in 2 patients (arthralgia and nasopharyngitis [both non-severe]; urinary tract infection). No deaths or meningococcal infections occurred.Conclusions: Treatment with ravulizumab provided immediate and complete C5 inhibition, resulting in rapid clinical and laboratory improvements and complete TMA response through 183 days in patients with aHUS triggered by pregnancy. The safety profile observed in this subset of patients analysed is consistent with the 311 study investigating ravulizumab in patients with aHUS naïve to complement treatment. Clinical trial identifier: NCT02949128
Transplanted Hair Follicle Stem Cells Migrate to the Penumbra and Express Neural Markers in a Rat Model of Cerebral Ischaemia/Reperfusion
Authors: Zhang Xuemei , Tang Hao , Mao Senlin , Li Bing , Zhou Yinglian , Yue Hui , Wang Duo , Wang Yifei , Fu Jin
Published: August 2020

Background: Ischaemic stroke has become the main cause of death and severe neurological disorders, for which effective restorative treatments are currently limited. While stem cell transplantation offers therapeutic potential through neural regeneration, this approach is associated with challenges of limited applicable sources. Hair follicle stem cells (HFSCs) are multipotential cells that can differentiate into ectodermal and mesodermal lineages and proliferate for long periods. The therapeutic potentials of HFSCs have not been investigated in ischaemic stroke models and, therefore, in this study, we aimed to determine whether they could survive and migrate to ischaemic areas after stroke attack. Methods : A rat model of middle cerebral artery ischaemia/reperfusion was established and intravenously administered HFSCs. The potential of HFSCs to migrate and differentiate into neuron-like cells as well as their ability to reduce the infarct size was evaluated. Rat brain tissue samples were collected 2 weeks after cell transplantation and analysed via TTC staining, immunofluorescence, and immunohistochemistry methods. The data were statistically analysed and presented as the means ± standard deviations. Results : Intravenously administrated rat HFSCs were able to migrate to the penumbra where they expressed neuron-specific markers, reduced the infarct volume, and promoted neurological recovery. Conclusion : HFSC transplantation has therapeutic potential for ischaemic stroke, and is, therefore, worthy of further investigation toward possible clinical development for treating stroke patients.
Usefulness of Surgical Lung Biopsies after Cryobiopsies when Pathological Results Are Inconclusive or show a Pattern Suggestive of a Nonspecific Interstitial Pneumonia
Authors: Bondue Benjamin , Leduc Dimitri , Froidure Antoine , Pieters Thierry , Taton Olivier , Heinen Vincent , Alexander Patrick , Hoton Delphine , Dome Florence , Remmelink Myriam
Published: August 2020

BACKGROUND Although increasing data supports the use of transbronchial lung cryobiopsies (TBLCs) for the diagnosis of diffuse parenchymal lung diseases (DPLDs), its role as an alternative to surgical lung biopsy (SLB) is still under debate. The aim of this study was to assess the benefit of additional SLBs performed in selected patients after TBLCs. METHOD We conducted a multicentric Belgian prospective trial in which SLBs were performed after TBLCs when the pathological diagnosis was uncertain or if a nonspecific interstitial pneumonia (NSIP) pattern was observed hypothesizing that SLB could provide additional information and that a co-existent UIP pattern could be missed. RESULTS 81 patients with TBLCs performed for a DPLD were included in the study between April 2015 and December 2019. A specific histological diagnosis was obtained in 52 patients (64%) whereas no pathological diagnosis following TBLCs was obtained in 13 patients (16%) and a pattern suggestive of a NSIP was observed in 16 patients (20%). 14 out of these 29 patients had SLBs after TBLCs. SLBs showed a UIP pattern in 11 (79%), a pattern suggestive of a hypersensitivity pneumonitis in two (14%) and a NSIP pattern in one patient (7%). Among the 16 patients with pathological NSIP following TBLCs, six underwent a SLBs showing a UIP in five and confirming a NSIP in one patient only. A retrospective pathological analysis of patients having both procedures showed a lower diagnostic confidence and agreement among pathologists for TBLCs compared to SLBs. Major factors underlying the added value of SLBs were the bigger size of the sample as well as the subpleural localization of the biopsies. CONCLUSIONS TBLCs are useful in the setting of DPLDs with a good diagnostic yield. However, our study suggests that SLB provides critical additional information in case TBLCs are inconclusive or show a pattern suggestive of a NSIP, questioning the accuracy of TBLC to adequately identify this histological pattern.
Restless abdomen: a spectrum or a phenotype variant of restless legs syndrome?
Authors: Wang Xi-Xi , Zhu Xiao-Ying , Wang Zan , Dong Jian-Wei , Ondo William G. , Wu Yun-Cheng
Published: August 2020

Background: With the growing awareness of restless legs syndrome (RLS), sensory disorders similar to RLS but initially confined to the arms, abdomen, and perineum have been reported. One of them is restless abdomen, which refers to a restless sensation in abdomen. Our study is designed to evaluate the clinical phenotype of restless abdomen and investigate its relationship with RLS.Methods: We enrolled 10 patients with restless abdomen according to RLS diagnostic criteria, excluding the requiring of leg involvement. Laboratory examinations were performed to exclude mimics and notable comorbidities.Results: All 10 patients had RLS like symptoms in the abdomen and otherwise satisfied all other RLS diagnostic criteria, and responded to dopaminergic therapy.Conclusions: Neurologists and gastroenterologists should be aware that RLS-related restlessness can occur in extra-leg anatomy in the absence of episodes of worsening or augmentation of restlessness.
Effects of Er:YAG laser pre-treatment on dentin structure and bonding strength of primary teeth: An in vitro study
Authors: WANG Jun hui , YANG Kuan , ZHANG Bai ze , ZHOU Zhi fei , WANG Zi rui , GE Xin , WANG Lu lu , CHEN Yu jiang , WANG Xiao jing
Published: August 2020

Background: To investigate the effects of Er:YAG laser pre-treatment on the dentin structure and shear bond strength of primary teeth. Methods: Dentin specimens were prepared using freshly extracted intact primary molars and divided randomly into four groups based on the surface treatment applied. The control and etchant groups received no treatment and conventional acid etching treatment, respectively, while the energy and frequency groups received laser surface treatment with variable energy and frequency parameters. The morphology was observed using scanning electron microscopy. The surface-treated dentin slices were bonded to resin tablets, followed by thermocycle treatment. The shear strengths were determined with a universal testing machine and de-bonded surfaces were observed with a stereomicroscope. Results: SEM observation showed that the surface morphology of the dentin slices changed after etching as well as after Er:YAG laser pre-treatment with different energy and frequency values. The dentin tubules opened within a specific energy (50-200 mJ) and frequency (5-20 Hz) range. Beyond this range, the intertubular dentin showed cracks and structural disintegration. Shear strength tests showed no significant change after acid etching. The shear strength increased significantly (P<0.05) after Er:YAG laser pre-treatment compared with that of the control group. The shear strength increased within the same energy (50-200 mJ) and frequency (5-20 Hz) range as the tubule opening, but not significantly (P>0.05). The most common mode of interface failure was adhesive (interface) failure, followed by mixed and resin cohesive failure. Conclusions: Er:YAG laser pre-treatment may improve the bonding strength between the dentin and the resin in primary teeth.
Does tooth extraction and perioperative medication affect PT-INR of patients taking warfarin?
Authors: Iwata Eiji , Tachibana Akira , Kusumoto Junya , Takata Naoki , Hasegawa Takumi , Akashi Masaya
Published: August 2020

Background: Various antibiotics and analgesics have been reported to interact with　warfarin. Reports that investigate the effects of medication taken for just a few days during tooth extraction on the prothrombin time-international normalized ratio (PT-INR) are rare. Methods: A total of 110 patients receiving long-term stable warfarin therapy underwent tooth extraction without interruption of warfarin treatment. INR values were measured one month before the tooth extraction, the day of the extraction, and one week after the extraction. We investigated the changes of INR values between the day of extraction and one week after the extraction, as well as the various risk factors for increases in INR values.Results: Before and after tooth extraction, the number of patients taking cefcapene pivoxil, amoxicillin, and azithromycin was 57, 36, and 8, respectively. Nine patients were administered ampicillin before tooth extraction and received amoxicillin after their tooth extraction. One week after tooth extraction, the INR values increased beyond the therapeutic range in 3 out of 110 patients (2.7%). The INR values before tooth extraction in these three patients were close to 3.0. The INR value increased by more than twice as much in 1 of 110 patients (0.9%).Conclusion: When a tooth extraction is performed in patients taking warfarin, certain factors could increase the INR, such as interaction between warfarin and antibiotics or analgesics, post-extraction inflammation or infection, and eating disorders due to post-extraction pain. However, our results suggest that it has little effect on the INR values one week after extraction.