bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating Downhole Vibration via Machine Learning Techniques Using Only Surface Drilling Parameters
Authors: Okoli Prince , Cruz Vega Juan , Shor Roman 
Published: April 2019

Abstract
Drillstring vibration can be divided into three types: axial, lateral and torsional. All three can cause significant wear and tear in drilling equipment, which leads to increased failures, non-productive time, and poor drilling performance. It also causes wasted mechanical energy and wellbore instabilities. Access to real-time, high-frequency downhole vibration data while drilling remains prohibitively expensive; however, it may be estimated via machine learning (ML) techniques using only surface drilling parameters. The task of predicting the severity of downhole vibration using surface parameters was approached as a supervised classification ML problem. Five basic, traditional techniques were investigated: the nearest neighbour, logistic regression, naïve Bayes, discriminant analysis, and decision trees.
Drilling data was obtained from multiple bottom hole assemblies (BHAs) from several wells in North America. The learning tasks were separated into inter-BHA runs (where the learner is trained on data from one BHA and tested with data from a different BHA) and intra-BHA runs (where the learner is trained and tested with data from the same BHA). Severity of vibration was assessed primarily through the time-weighted average of root mean square amplitude and then classed into severity levels. Performance of the classification results was assessed using the predictive accuracy and weighted macro-average of precision obtained using cross validation and presented as confusion matrices for specific iterations of the cross validation. The classification ML for the intra-BHA runs produced overall predictive accuracies that averaged between 50% and 85%. Of particular concern is the misprediction of certain vibration levels as either lower or higher levels, even when overall predictive accuracy is high.
The results show that these simple ML techniques can achieve considerable accuracy in the prediction of vibration levels for intra-BHA runs. For inter-BHA runs, predictive performance was reduced. This demonstration of the viability of ML in predicting bottom hole vibration motivates the application of more advance ML techniques, including deep learning estimators, and it signals the potential benefits that can be reaped.
The Impact of Re-Injecting Flowback Fluids on Formation Damage. Case Study: Marcellus Shale
Authors: Zhang Lifu , Tice Michael , Hascakir Berna 
Published: April 2019

Abstract
Reuse of flowback water in hydraulic fracturing is usually used by industry to reduce consumption, transportation and disposal cost of water. But because of complex interactions between injected water and reservoir rocks, induced fractures may be blocked by impurities carried by flowback and mineral precipitation by water-rock interactions, which causes formation damage. Therefore, knowledge of flowback water-rock interactions is important to understand the changes within the formation and effects on hydraulic fracturing performance.
This study focuses on investigating flowback water-rock interactions during hydraulic fracturing in Marcellus Shale Formation. Simple deionized water-rock interactions and complicated flowback water-rock interactions were studied under static and dynamic conditions. In static experiments, crushed reservoir rock samples were exposed to water for three weeks at room condition. In the dynamic experiment, continuous water flow interacted with rock samples through the core-flooding experimental system for three hours at reservoir condition. Before and after experiments, rock samples were characterized to determine the change on the rock surfaces. Water samples were analyzed to estimate the particle precipitation tendency and potential to modify flow pathway.
Surface elemental concentrations, mineralogy and SEM images of rock samples were characterized. Ion contents, particle size, TDS and Zeta potential in the water samples were analyzed. In both static and dynamic experiments, compared with deionized water-rock interaction, rock samples after being exposed to flowback water show change in the elemental compositions, more fine particles attachment and new minerals detected on rock surface due to effect of flowback water. In produced water, Na, Sr and Cl are extremely high after flowback water-rock interactions because of flowback water contamination. Water parameter analysis indicates after flowback water-rock interactions, suspensions in produced water have highest precipitation tendency because of extremely highest TDS, largest particle size and lowest absolute Zeta potential relative to all water samples. Therefore, according to rock and water characterization, if flowback water without any treatment would be reused in the field hydraulic fracturing operation, created flow pathways and pores are more likely to be blocked and formation damage will be caused.
This study provides information on comparison between deionized water-rock interaction and flowback water interaction. The information enhances the understanding of basic water-rock interaction mechanisms and evaluates formation damage caused by reuse of flowback water.
A Novel Edge-Based Green Element Method for Simulating Fluid Flow in Unconventional Reservoirs with Discrete Fractures
Authors: Wu Yonghui , Cheng Linsong , Fang Sidong , Killough John E. , Huang Shijun , Jia Pin 
Published: April 2019

Abstract
The boundary element method (BEM) is widely used in modeling fluid flow in fractured reservoirs. However, the computation is extremely expensive when real heterogeneity and large numbers of fractures are modeled. This paper presents a novel edge-based Green element method (eGEM) for this problem, and two significant modifications are made to the classical GEM. An edge-based discretization scheme is proposed to improve the GEM's accuracy. The eGEM technique is further enriched for simulating discrete fractures.
The mathematical model is transformed into the Laplace domain, which makes it convenient to incorporate multi-porosity models because the boundary integral equation form is the same. The matrix is meshed using Cartesian grids, and discrete fractures are handled flexibly by embedding into the matrix grids. In eGEM, the matrix-matrix flow is coupled at the common edge, so the unknown flux could be eliminated by using the edge-based scheme. In each matrix block, the matrix-fracture flow is modeled by treating the fracture elements as sources or sinks like BEM. The finite difference method is used to handle the fracture-fracture flow.
In this paper, we tested the numerical accuracy and computational efficiency of eGEM based on several cases. First the technique was shown to have higher accuracy than the classical corner-based GEM for transient problems in the petroleum industry. This shows the advantage of the edge-based discretization approach in handling the unknown flux of each solution point. The eGEM's ability to handle discrete fractures was validated with the several models for transient flow problems. Comparing to the commercial numerical simulator in handling flow in orthogonal fractures, the eGEM is shown to be less grid-sensitive and maintain relative high precision even with coarse grids near the discrete fractures. A detailed grid sensitivity analysis on grids was performed. It is recommended that fracture grids be refined to capture the early time flow behavior in pressure transient analysis. On the other hand, relatively coarse grids meet the accuracy requirements for production performance simulation. This is the first time to present an efficient edge-based discretization scheme for GEM to enhance accuracy in handling unknown flux while at the same time utilizing eGEM to enrich simulation of discrete fracture networks. This method serves as a new efficient approach for reservoir simulation and numerical well testing. Because of eGEM's high precision with coarse grids, the technique can be readily used in larger field applications.
Characterization of Oil and Water Sound Speeds and Densities for Ultrasonic Water Cut Meters
Authors: Castrup Suzanne , Webb Charlie , Lazaruk Corey 
Published: April 2019

Abstract
This paper presents produced water and heavy oil density and speed of sound (SOS) data for an extended range of temperatures and pressures. The data were obtained from laboratory measurements of samples collected from selected heavy oil wells and and from tests conducted at a specially designed flow loop. The paper also presents recommended methods for establishing oil and water density and SOS reference values required for ultrasonic water cut measurement.
The laboratory tests were designed to evaluate short-term measurement repeatability, equipment reproducibility and long-term stability of oil and water samples at 101.3 kPa (14.7 psia) pressure and temperatures ranging from 20 to 70 °C (68 to 158 °F). Additional tests were conducted at a flow loop constructed by Chevron to evaluate two-phase and three-phase metering equipment over a range of temperatures, pressures, flow rates, water cuts and gas volume fractions. Water only and oil only flow loop density and SOS tests were conducted under steady-state conditions with pressures ranging from 377 to 653 kPa (54.7 to 94.7 psia) and temperatures ranging from 60 to 122 °C (140 to 250 °F).
This is the first time that laboratory and flow loop data have been used to conduct an in-depth assessment of published tables and empirical equations for oil and water SOS and density. As a result, this effort has produced improved methods for creating reference density and SOS values for oil and water over an extended range of temperatures and pressures, an important breakthrough in the effort to utilize ultrasonic SOS methods to measure water cut.
Comprehensive Overview of US Environmental Regulations; Implementation and Impact on the Industry
Authors: Shipman Janine , Liu Fuchen , Wilcox Andra , Haut Richard , Yuan Bo , Liu Anqi 
Published: April 2019

Abstract
The following will illustrate how laws and public concerns can serve as a framework for oil and gas exploration, drilling, and production. It will outline several case histories and how different laws and motivations intersect and shape the industry.
This is a comprehensive analysis of laws governing a particular region's actions and examined on a federal, state and, in some cases, local level. Other factors, including public image and community feedback are evaluated, too. Three case histories are explored. These are presented via a timeline of events leading up to an implementation, reevaluation, and/or development of legislation and/or legal decision. Other legislation is assessed on how an Act (e.g. Clean Air, Clean Water) is initiated apart from the oil and gas realm and then eventually adopted to address certain public concerns.
In most cases, regulations were already set in place and oil and gas entities had to interpret accordingly and work within determined protocols. In some cases, incidents occurred that, in turn, created new legislation and/or set expectations that had implications for how the industry would execute future projects. Incidents include a case of negligence and how the specific company responded as well as other operators located in the immediate vicinity. The regulations and/or best management practices that were created because of the incident will also be discussed. Other cases illustrate the cultural norms surrounding a particular set of legislation. An operator may be familiar with one area yet when branching out to other locations, conclude that the new area is not financially feasible for them due to the different technology and documentation required. Bigger and/or local operators have made these ventures profitable.
A comprehensive report on regulations and how operators execute them will also be provided. Impacts and effects on the oil and gas entities as well as the social and natural communities are assessed, illustrating the important connection between the residential/individual communities and the business entities via the government bodies to hear both sides and appropriately represent the cases at hand.
SAGD Performance Variability – Analysis of Actual Production Data for 28 Athabasca Oil Sands Well Pairs
Authors: Doan Quang T. , Farouq Ali S. M. , Tan Thomas B. 
Published: April 2019

Abstract
Since the proof-of-concept field testing at AOSTRA's Underground Test Facility (UTF) in late 1980's, the SAGD (Steam-Assisted Gravity Drainage) process has been applied for many bitumen recovery projects in Alberta. According to public-domain data, these projects have shown a wide range of recovery performance - ranging from very good to very poor - on basis of actual Oil Rate & Volume, Steam-Oil Ratio (SOR) versus expected and/or nameplate design. SAGD recovery performance in these projects is mainly affected by geological deposits, reservoir quality and operational experience. Numerical modeling has been an important tool in SAGD commercialization development, including being used for production forecasting, evaluation of process operations and enhancements.
This paper first reviews and analyzes actual field production and injection data for 28 Athabasca Oil Sands Deposit SAGD well pairs (WPs). These WPs are from 4 different pads, in close proximity to one another, producing from reservoir of different qualities from Jackfish 1 SAGD project; they have more than 1700 days of history (from first steam to end of July 2013). It is seen that reservoir quality has a considerable (bigger than commonly believed) impact on recovery performance, particularly in terms of thermal efficiency (as measured by SOR) and steam chamber dynamics. Discussion is provided in view of observed field performance vis-à-vis current/common industry practice of field production forecasting and project development planning.
Another important finding from the production data analysis is revealed in the reported gas production behavior, including cumulative volume and trend. It is seen that in many of these 28 WPs, there was considerable ‘extra’ gas (commonly attributed to aquathermolysis) production - up to 20% of total gas produced at the end of approximately 6 years of steam injection. The analysis helps providing some answers to oft-asked questions from field operators about too much production of (sour) gas; it should also help future studies model more closely SAGD gas production, in addition to liquids production.
Based on the analysis of field production data, a numerical model was built and calibrated against production data from 2 of the poorer-performing WPs among the 28 studied. Agreement between simulated and actual Cumulative Oil and SOR was within 10%, after 6 years of operations, on a first-iteration basis. The model was also successful in modeling the gas production behavior.
Active Cooling Method for Downhole Systems in High Temperature Environment
Authors: Gao Wenkai , Liu Ke , Su Yinao , Sheng Limin , Cao Chong , Dou Xiurong , Zhang Lei 
Published: April 2019

Abstract
With the further exploration of oil and gas, we have to search for new resources which buried in deep strata, and most of the deep and ultra-deep wells are categorized in high-pressure/high-temperature (HPHT) wells. The problem of high temperature and the challenge to the existing downhole equipments are becoming increasingly prominent, where the drilling depth is severely restricted. Most of the HPHT or ultra-HPHT wells with reservoir temperature about 175~220°C would be drilled with near-bit measurement and constructed. In such a temperature environment, the conventional measurement while drilling tools with common electronics will experience very high failure rates at these conditions.
There are two ways to deal with the downhole electronics system in HPHT wells. One technique is called the passive cooling, which aims to improve the anti-temperature performance of the components and add thermal insulation materials to the circuit module. In this way, the cost of the instruments would be greatly increased, and the capacity for anti temperature could not be improved indefinitely, especially in HPHT or ultra-HPHT environment for lone period. The other solution is called the active cooling, which commit to the construction of a downhole refrigeration system. The cooling system power by bettery or downhole generator ensures clectronics cabin always under suitable temperature.
According to a large number of research work by scholars worldwide, there are 2 main kinds of downhole active cooling techniques suitable for while-drilling environment. One is thermoelectric based regeneratiove cooling system, and the other technique is based on regenerative cryogenic refrigeration cycle. The thermodynamic cycle and working fluid are key concerns for the refrigeration. While reverse-Brayton cycle contains adiabatic compression, isobaric heat transfer, adiabatic expansion and isobaric heat transfer, so thermoacoustic coolers, stirling cryocoolers, and pulse tube refrigerators can all be suitable solution.
The study from this work demonstrates the active cooling method for downhole systems using in high-temperature environment, and provides a baseline framework for design methods. The preliminary laboratory test and application showed the feasibility of the method.
Imbibition Oil Recovery from the Montney Core Plugs: The Interplay of Wettability, Osmotic Potential and Microemulsion Effects
Authors: Yuan Lin , Dehghanpour Hassan , Ceccanese Ann 
Published: April 2019

Abstract
This paper presents a series of rock-fluid experiments to investigate 1) wettability of several core plugs from the Montney Formation and its correlations with other petrophysical properties such as pore-throat-radius size distribution, and 2) effects of wettability, salinity and microemulsion (ME) additive on imbibition oil recovery. First, we evaluate wettability by conducting spontaneous imbibition experiments using reservoir oil and brine (with salinity of 141,000 ppm) on six twin core plugs from the Montney Formation. In addition, we investigate the correlations between wettability and other petrophysical properties obtained from MICP data and tight-rock analyses. Second, we inject oil into brine-saturated core plugs to arrive at residual water saturation. Third, we perform soaking experiments on oil-saturated core plugs using fresh water, reservoir brine and ME system, and measure the volume of produced oil with respect to time.
We observe faster and higher oil imbibition into the core plugs compared with brine imbibition, suggesting the strong affinity of the samples to oil. The normalized imbibed volume of oil (Io) is positively correlated to the volume fraction of small pores, represented by the tail part of MICP pore-throat-radius size distribution profiles. This suggests that the tight parts of the pore network are preferentially oil-wet and host reservoir oil under in-situ conditions. The results of soaking experiments show that imbibition oil recovery is positively correlated to the water-wet porosity measured by spontaneous brine imbibition into the dry core plugs. Imbibition of fresh water results in around 3% (of initial oil volume in place) higher oil recovery compared with that of brine imbibition, possibly due to osmotic potential. Soaking the oil-saturated core plugs in ME solution after brine or fresh soaking results in 1-2% incremental oil recovery. Soaking the oil-saturated core plugs immediately in ME solution results in faster oil recovery compared with the case when the plugs are first soaked in water and then in ME solution.
Desalination of Oilfield Produced Water Using Electrocoagulation and Reverse Osmosis
Authors: Webb Charles 
Published: April 2019

Abstract
This paper presents the results of a successful field trial using electrocoagulation and reverse osmosis to desalinate oilfield produced water for surface discharge and beneficial reuse near Bakersfield, California. The paper discusses technology selection, pilot test configuration, test results, projected operating costs and reliability, and conclusions.
The field trial was conducted at an oilfield wastewater facility where up to 10,000 barrels per day of produced water containing 3,700 mg/L of TDS (total dissolved solids) was being treated in a series of un-lined ponding basins to remove free oil and solids, and then used to irrigate an area containing salt-tolerant grasses, shrubs, and trees. Due to concerns that local groundwater might be impacted, in 2016 the operator was given two years by regulators to substantially reduce the salt, aromatic hydrocarbon, and boron content of the water, or cease surface discharge.
After a detailed review of options, the operator elected to conduct a 60-day pilot test of a process that consisted primarily of electrocoagulation followed by reverse osmosis to desalinate the produced water and remove aromatic hydrocarbons. Boron removal would be accomplished by use of a boron-specific anion exchange resin downstream of the reverse osmosis membranes.
The pilot treatment system would be designed and installed to comply with the local Regional Water Quality Control Board specifications for surface discharge, herein collectively called the "Effluent Specifications" (Table 1).
In July 2016, the operator started the 60-day pilot test. After an initial commissioning period, the facility demonstrated the ability to safely and reliably treat the produced water to below the limits contained in the Effluent Specifications.
Scabies outbreak investigation in Addet town, West Gojjam Zone, Amhara region, Northwest Ethiopia, 2017
Authors: Alebachew Habtamu , Mulatu Kebadnew , Worku Mastewal 
Published: April 2019

Abstract
Background

Globally scabies was among the 50 most common infectious diseases, with a point prevalence 0.3%-46% and in terms of morbidity, at 1.5 million disability-adjusted life years. This study investigate and asses risk factors of scabies in Addet Medhanit Alem yekolo temarie in Yilmana Densa district Amhara, Ethiopia, 2017

Methods

Unmatched Case-control study was employed. Fifety five cases from line lists reviewed as per the WHO case definition. Cases were epidemiological linked to previously epidemiological confirmed cases and 118 controls were interviewed with structured questionnaires. Data was entered EPI info version 7 and analyzed by SPSS version 23. Adjusted Odds Ratios and with corresponding 95% confidence intervals were calculated to measure strength of association in multi-variable logistic regression

Results

The prevalence of scabies was 35%. The mean (SD) age of respondents was 16.4(2.785). Out of respondents 110 (63.6%) used river water for daily basis, 36(20.8%) changed their cloth frequently, 105(60.7%) washed their body frequently, 106(61.3%) had at least one scabies infected person in their house. The odds of scabies infection were 2.3 (AOR = 0.436, 95% CI: 0.205-0.929) times lower among frequent changing of cloth, And washing of body with soap and water were 2.17(AOR = 0.461% CI: 0.214-0.993) times lower having scabies infection. Share cloth was 3(AOR = 3.313, 95% CI: 1.536-7.149) times higher having scabies infection. Presence of scabies infected individuals in the family was 6 (AOR = 6.029, 95% CI: 2.071-14.275) times higher to develop scabies infection.

Conclusions

There prevalence of scabies infection was high, less than 15 years age group were most affected. Frequent changing of cloth, frequent use of soap for body wash, sharing of cloth and presence of scabies infected individuals in the family were factors affecting scabies infection. Personal, house hygiene should be strength and avail soap for students should be considered.