bluuebunny/crossref_metadata_2025_split huggingface dataset:
Economics of Marginal Field Crude Oil Evacuation in Nigeria
Authors: Onwuka Emmanuel I. , Pedro-Egbe Umamejale , Enemokwu Kelvin I. 
Published: August 2020

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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