bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Cuttings Transport and Annular Pack-Off Using Local Fluid Velocities with the Effects of Drillstring Rotation and Eccentricity
Authors: Erge Oney , van Oort Eric 
Published: February 2020

Abstract
One of the primary functions of the drilling fluid is to transport cuttings from the bit to the surface. This transport is mainly a function of fluid properties (rheology and density), pump rate, wellbore trajectory and geometry, drillstring rotation and eccentricity. Because these interrelated parameters all have a significant effect on cuttings transport, it is important that hole cleaning modeling is comprehensive and inclusive to yield useful, reliable results. Inaccurate models that either do not consider significant effects or oversimplify them can lead to inadequate hole cleaning advice, resulting in non-productive and invisible lost time.
A novel cuttings transport model that includes relevant effects such as pipe rotation, eccentricity and the annular blockage is presented. Local velocity profiles are calculated for a given fluid and compared against the local critical velocity for cuttings transport. Then, the location and the magnitude of annulus blockage are numerically assessed. After an annulus becomes partially blocked with cuttings deposited in a cuttings bed, continuity and momentum equations are solved for the blocked annulus to estimate the new local velocities. The annulus is divided into small sections and the pressure profile is calculated with the progression of time. By doing so, a realistic representation of a wellbore's pressure and velocity profiles is obtained.
The results from this study are in very good agreement with large-scale flow loop experiments and field observations, e.g. showing that axial flow alone is not enough for effective hole cleaning in high deviation and horizontal wells. The simulations show that in such wells the cuttings tend to deposit even at elevated axial flow rates without pipe rotation in a fully eccentric annulus, due to a significantly reduced flow rate where the drillstring is close to the borehole or previous casing string. The results also provided a way to predict "pack-off" events, when the string can become stuck, the equivalent circulating density can spike, and lost circulation can occur. The non-uniform settling of the cuttings along the wellbore will cause non-uniform distribution of pressure losses, with local pressure spikes when cuttings blockage becomes substantial. A pack-off sensitivity analysis is presented in this work. The overall aim of this work is to provide more comprehensive cuttings transport modeling for the industry to conduct safe and improved hole cleaning operations.
Will the 2020's be Known as the 20K Decade? The 20K Subsea BOP is Here
Authors: Cowan Robert "Bob" , Ellens Jonathan , Hunter Wesley , Kulkarni Ajay , Scherm Kevin 
Published: February 2020

Abstract
The subsea blowout preventer (BOP) is one of the primary technologies that has enabled the oil and gas industry to discover and develop deeper and more complex wells offshore. Since the invention of the first ram-type BOP in the 1920s, ever-developing BOP technology has expanded the boundaries of a safe drilling environment. New learnings derived from historical usage and advances in material science have been applied as we continue to push the envelope further. The 1980s saw a leap in offshore technology as 15,000psi (15K) BOPs hit the market. For nearly 40 years, 15K has been the limit. In the early 2010s, discoveries in the Gulf of Mexico (GoM) were being made that suggested a need for 20,000psi (20K) subsea BOPs. A handful of companies have spent the rest of the decade pursuing a cost-effective and technically-capable 20K subsea BOP solution, while regulatory bodies have debated the safe implementation of this step-change. The year 2020 will mark the point in time a fully qualified 20K subsea BOP becomes available to the industry. As a result, the 2020s may very well become known as the decade 20K assets became feasible, opening up a whole new set of opportunities for oil companies around the world.
The leap from 15K to 20K was far more challenging than the leap from 10K to 15K that the industry made in 1980s. Nearly everything had to change. Not just the technology, but even the way companies work together. This paper explains the challenge of the 20K leap, provides a summary of the design and testing that has gone into developing the industry's first fully qualified subsea 20K subsea BOP, and discusses how 20K has changed the way operators, contractors, and original equipment manufacturers (OEMs) work together.
Connection Fatigue Modeling with Large IDs: How Large of an ID Can Support a SRG?
Authors: Pettit Grant , Lee Kang 
Published: February 2020

Abstract
Drilling specialty tools and accessories are often machined with large Inside Diameters (IDs) so that the necessary electronic packages can fit within the component. As the ID of the component increases, the wall thickness of the pin connection is reduced. It has been established that the machining of a Stress Relief Groove (SRG) on the pin connection with a standard-sized ID will greatly improve the fatigue performance of that connection. However, no such consensus has been reached regarding the machining of SRGs on the pin connections of these special-purpose tools with large IDs.
The common concern is that the wall thickness of the pin connection has been reduced so much by the large ID that the machining of a SRG would drastically deteriorate the performance of the connection. This paper addresses that concern by providing in-depth analysis of various API connection sizes tested over a broad range of IDs. Finite Element Analysis (FEA) was used to quantify the difference in fatigue life between connections with stress relief features versus without stress relief features. Additionally, calculations were performed to understand the reduction in the capacity of the connection that results due to machining stress relief features.
This paper gives the comparative fatigue life for each of the connections modeled where the API recommended Make-Up Torque (MUT) is adjusted to compensate for the increasing ID of the connection. In every case, the benefits of machining SRGs on large ID connections are significant. Allowing larger IDs in connections where SRGs are required will bring the technical benefit of allowing larger electronics packages to fit within the bore and increased hydraulic performance, among other benefits. Additionally, the drawbacks to SRGs are considered and quantified whenever possible. Possible solutions to these drawbacks are proposed as a way to lessen their effects so the full benefit of cutting the SRGs can be realized.
In total, by looking at the potential gain in fatigue life against the trade off in lost capacity, this paper provides operators with the ability to determine the suitability of stress relief features on their components with large IDs. For those connections where a SRG is required, this paper provides guidance as to the connection's performance at various large IDs.
Prescriptive Data Analytics to Optimize Casing Exits
Authors: Popp Timothy , Shirangi Mehrdad G , Nipen Ole Petter , Berggreen Anders 
Published: February 2020

Abstract
Whipstock casing exits are a milling operation that enable operators to sidetrack from a primary wellbore. This paper describes a prescriptive data analytics workflow that was developed and applied to optimize casing exit applications. This workflow involves three major steps:
Pre-processing data to cleanse, transform, and aggregate data from past casing exit jobs Building accurate machine learning models to predict milling performance Optimizing a weighted objective function into recommend best-case operational parameters.
In collaboration with a North Sea operator, a downhole measurement-while-drilling (MWD) system was used in multiple wells during casing exit jobs to collect a rich data set of downhole measurements. Through a stringent data processing and modeling methodology, prescriptive models were developed and tested in an offset well in the North Sea. Success of the offset casing exit job resulted in greater than a 30-percent reduction in vibration, a 14-percent increase in rate-of-penetration (ROP), and a 23-percent reduction in average mill time.
Theoretical Vs. Actual Mud Motor Performance in Unconventional Formations and Strategies to Extend Motor Life
Authors: El-sayed Ibrahim , Hopkins Zachary , Dupriest Fred , Noynaert Samuel F. 
Published: February 2020

Abstract
The continued growth in unconventional drilling has resulted in downhole motors being pushed to drill more complex geometries faster, often higher downhole temperatures. This has resulted in increased rates of failure for downhole motors. The most common method to postpone motor failure has been to select a larger motor. This option ignores the root causes of motor failure and is shown to actually not improve failure rates. Impetus for this work centered on an operator who was experiencing high rates of motor failure, however in the process of investigating the failures, important findings were made that apply to any BHA with a motor.
Damage occurs in all motors in the data set, regardless of whether or not they are considered "failed." This points to a potential, unrecognized industry-wide issue wherein motor performance may be degrading over a run and is not recognized by operations teams. The result is a version of "hidden NPT" which is limiting drilling performance in wells drilled with downhole motors. Calculating the RPM factors on the operator's wells using actual motor speeds measured by downhole sensors show that motor degradation is a significant problem, resulting in a reduction of up to 40% in bit RPM.
In order to measure performance, motor properties are used to convert the traditional surface MSE measurement into a more representative downhole MSE. Further refinement of this metric was tested as downhole MSE is calculated using a simple factor and a more exact but complicated multi-dimensional correlation. Drilling data is used to show that the simplicity of the simple factor more than offsets minor loses in MSE accuracy. As noted, the real time RPM factors are also computed using downhole data showing the stark differences between the actual factors and the originally reported factors. The difference is used to determine the degree of motor damage while drilling.
A suite of downhole sensors was placed above and below the motor to monitor the rate of motor damage. Differential pressure was also analyzed in the frequency domain spectrum to demonstrate the damaging effect of bottom hole assembly (BHA) whirl during rotating.
The use of depth of cut control (DOCC) is analyzed as a method to improve motor efficiency and decrease damage. Two identical wells and BHA's are compared, one with and one without DOCC. The uses of the first derivative of differential pressure is suggested as a method to better quantify and visualize the effects of DOCC. Ultimately, the research presented provides quantitative insights into the operation of a motor, and shows that motor performance is not as expected based specification sheet values.
Experimental Study on Injection Pressure Response and Fracture Geometry during Temporary Plugging and Diverting Fracturing
Authors: Wang Bo , Zhou Fujian , Yang Chen , Wang Daobing , Yang Kai , Liang Tianbo 
Published: February 2020

Summary
Temporary plugging and diverting fracturing (TPDF) has become one of the fastest-growing techniques to maximize the stimulated reservoir volume (SRV). During the field operation of TPDF, diverters are injected to redirect the hydraulic fractures into the under-stimulated region of the reservoir, and, thus, to obtain better coverage of the created fracture network. In this study, the commonly used true tri-axial hydraulic fracturing system is modified to investigate the influences of various factors on the injection pressure response and resultant fracture geometry during diversion treatments. The experimental results show the feasibility of creating multiple fractures through TPDF, and more importantly give the following findings: (1) a complex diverted fracture network tends to be created at a small differential stress (2.5 MPa in this case), while diverted fractures tend to grow parallel to the initial fractures at a high differential stress (7.5 MPa in this case); (2) with the same concentration in the fracturing fluid, 40-mesh powder-shaped diverters can plug the created fractures and increase the net pressure more rapidly than 6-mm fiber-shaped diverters; (3) an excess of diverters can lead to a strong injection pressure response, and, thus, enhance the difficulty of creating multiple fractures; (4) when diverters are injected with the fracturing fluid, no obvious breakdown pressure or propagation pressure is shown during the fracture propagation.
Improving Safety and Health In the Exploration and Production Process --- A Long-Term Perspective
Authors: Clark Patricia 
Published: February 2020

Abstract
Good morning. It is an honor and a privilege to be one of the keynote speakers at this very important conference on health, safety and the environment in oil and gas exploration and production. This is a vital industry throughout the world, and protecting the safety and health of those who work in it, as well as the environment surrounding oil and gas well operations must be a major concern of everyone.
Today I will attempt to explain to you what the United States Government is doing to help further the goals of this conference, particularly in occupational safety and health because that is my field of expertise.
I am the Director of Compliance Programs for the U.S. Department of Labor's Occupational Safety and Health Administration. My Agency, OSHA, has the responsibility for regulating safety and health in the workplaces and worksites of the United States.
Poor mental health of livestock farmers in Africa: a mixed methods case study from Ghana
Authors: Nuvey Francis Sena , Kreppel Katharina , Nortey Priscilla Awo , Addo-Lartey Adolphina , Sarfo Bismark , Fokou Gilbert , Ameme Donne Kofi , Kenu Ernest , Sackey Samuel , Addo Kennedy Kwasi , Afari Edwin , Chibanda Dixon , Bonfoh Bassirou 
Published: February 2020

Abstract

Background
Agriculture represents the mainstay of African economies and livestock products are essential to the human population’s nutritional needs. However, in many developing countries, including Ghana, livestock production fails to meet demand due to population growth and negative effects of climate change. One of the challenges to production is livestock loss affecting farmers. However, despite stressful events experienced, livestock farmers’ mental health is poorly documented. This study aims to identify the root causes of livestock losses and their influence on pastoralists’ mental health.
Methods
We conducted a mixed methods study in two districts in the Northern and Southern Belts of Ghana. Using the Depression Anxiety and Stress Scale–21 and guided interviews, we collected quantitative and qualitative data from 287 livestock farmers and 24 key-informants respectively. Mental health scores were categorized using standard guidelines. We evaluated the factors that explained variations in mental wellbeing using general linear models (α=0.05).
Results
About 85% (240/287) of the livestock farmers lost cattle within one year. Of these, 91% lost cattle to animal diseases, 50% to theft and 27% to pasture shortages. Qualitative findings reveal that due to poor access to veterinary services, farmers treat livestock diseases themselves with drugs from unregulated sources and often sell diseased cows for meat to recover losses. Findings showed that 60% of livestock farmers had poor mental health. Of those, 72% were depressed, 66% anxious and 59% stressed. Mental wellbeing was negatively associated with the number of adverse events experienced, proportion of livestock lost to most of the major loss factors, emotional attachment to livestock and self-reported physical illnesses in farmers, but positively associated with increasing herd size [F(8,278)=14.18,p<0.001,R2=0.29].
Conclusions
Livestock diseases are the leading cause of losses to livestock farmers, whose mental wellbeing is negatively affected by these losses. Although an adaptive strategy by farmers to compensate for poor veterinary services, the arbitrary use of veterinary drugs and sale of diseased cattle pose health risks to the public. Further research to evaluate the performance of veterinary services in Ghana, mental health problems and risk to human health due to potential high-risk meat entering the food chain, is needed.
Unmet health care needs of elderly residing on urban areas of Sunsari District, Nepal. A Cross Sectional Study
Authors: Poudel Mukesh , Ojha Asmita , Yadav Deepak Kumar , Sah Ram Bilakshan , Chakravartty Avaniendra , Ghimire Anup 
Published: February 2020

Abstract
Background: The global aging population is in increasing trend. Morbidity increases with age and enhances the burden of health problems that result in new challenges to meet additional demands. There can be various types of issues such as health problems, health care utilization, physical and social care which should be carefully assessed and addressed. This study aimed to assess the unmet health care needs among elderly. Methods: A Community based, House to House, Cross-sectional study was conducted in urban areas of the sunsari district using face to face interviews. The sample size of 530 elderly was selected by a systematic proportionate random sampling technique. Results: This study unfurled the prevalence of unmet need for consultation for Nearsightedness 52.3%, Farsightedness 53.7%%, Hearing 79.7%, Dental 79.4%, Hypertension 6.7%, Diabetes 3.9%, CVD 5.3 % among those with these specific health needs and of at least one Unmet Health care need to be 64.9% among the studied participants. At least one unmet health need was significantly associated with higher odds among elderly age more than 70, of dalit and janajati ethnicity, illiterate, poor, those with difficulty leaving home, the distance of health facility > 30 mins, and those with depressive symptoms. Conclusion: The study highlighted the higher prevalence and associated factors related to unmet health care needs among the elderly which should be addressed to promote healthy ageing. There is an urgent need to promote geriatric health services and make it available at the primary health care level the first level of contact with a national health system.
Matrix Metalloproteinase 9 for Evaluating Invasiveness and Recurrence in Pituitary Adenoma Patients: A Meta-analysis
Authors: sun bowen , Dai Congxin , Liu Xiaohai , Wang Renzhi , Kang Jun 
Published: February 2020

Abstract
Background: In recent years, matrix metalloproteinase 9 (MMP-9) has been consideredto be an indicator of the aggressiveness and recurrence of pituitary adenomas, especially in China. However, some results have led to many conflicts. Therefore, it is necessary to perform a meta-analysis to obtain a clear correlation between MMP-9 and invasiveness and recurrence. Methods: Eligible studies obtained through multiple searches were included, and the odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were estimated. Funnel plots were used to evaluate publication bias. In the current meta-analysis, 23 articles with a total of 1,213 patients were included, including three studies conducted in Europe and China. Results: High MMP-9 expression and invasiveness of pituitary adenomas (n = 22, OR = 4.75, 95% CI = 3.53-6.39, p<0.05) and tumour recurrence (n = 3, OR = 4.38, 95% CI = 1.76-10.94, p = 0.002) were closely related. In addition, the expression of MMP-9 in patients with functional and non-functional pituitary adenomas was also significantly different (n = 3, OR = 2.07, 95% CI = 1.03-4.16, p = 0.041). Conclusion: MMP-9 is closely related to the invasiveness, functional status and recurrence of pituitary adenoma and should be used as a routine diagnostic index for surgical treatment of pituitary adenoma.
Evaluation of the Crosta method for the retrieval of water quality parameters from remote sensing data in the Pearl River estuary
Authors: Gao Feng , Wang Yunpeng , Zhang Yuanzhi 
Published: February 2020

Abstract
In recent decades, many algorithms have been developed for the retrieval of water quality parameters using remotely sensed data. However, these algorithms are specific to a certain geographical area and cannot be applied to other areas. In this study, feature-orientated principal component (PC) selection, based on the Crosta method and using Landsat Thematic Mapper (TM) for the retrieval of water quality parameters (i.e., total suspended sediment concentration (TSM) and chlorophyll a (Chla)), was carried out. The results show that feature-orientated PC TSM, based on the Crosta method, obtained a good agreement with the MERIS-based TSM product for eight Landsat TM images. However, the Chla information, selected using the feature-orientated PC, has a poor agreement with the MERIS-based Chla product. The accuracy of the atmospheric correction method and MERIS product may be the main factors influencing the accuracy of the TSM and Chla information identified by the Landsat TM images using the Crosta method. The findings of this study would be helpful in the retrieval of spatial distribution information on TSM from the long-term historical Landsat image archive, without using coincident ground measurements.
This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).
Partial integration of ADM1 into CFD: understanding the impact of diffusion on anaerobic digestion mixing
Authors: Tobo Yohannis Mitiku , Rehman Usman , Bartacek Jan , Nopens Ingmar 
Published: February 2020

Abstract
Sufficient mixing is crucial for the proper performance of anaerobic digestion (AD), creating a homogeneous distribution of soluble substrates, biomass, pH, and temperature. The opaqueness of the sludge and mode of operation make it challenging to study AD mixing experimentally. Therefore, hydrodynamics modelling employing computational fluid dynamics (CFD) is often used to investigate this mixing. However, CFD models mostly do not include biochemical reactions and, hence, ignore the effect of diffusion-induced transport on AD heterogeneity. The novelty of this work is the partial integration of Anaerobic Digestion Model no. 1 (ADM1) into the CFD model. The aim is to better understand the effect of advection–diffusion transport on the homogenization of soluble substrates and biomass. Furthermore, AD homogeneity analysis in terms of concentration distribution is proposed rather than the traditional velocity distributions. The computed results indicate that including diffusion-induced transport affects the homogeneity of AD.