bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analisis Model Mental Siswa pada Materi Larutan Elektrolit dan Nonelektrolit: Studi Kasus di Pandeglang
Authors: Wilandari Dinda Novia , Ridwan Achmad , Rahmawati Yuli 
Published: February 2019

Penelitian ini bertujuan untuk menganalisis model mental siswa di salah satu SMA di Pandeglang pada materi larutan elektrolit dan nonelektrolit. Subjek penelitian adalah siswa kelas X. Metode yang digunakan dalam penelitian ini adalah etnografi yang merupakan salah satu tipe penelitian studi kasus yang terfokus memahami latar belakang partisipan. Teknik pengumpulan data berupa observasi kelas, wawancara, reflektif jurnal siswa, free words association, dan free drawing techniques. Hasil penelitian menunjukkan bahwa siswa mengkonstruksi model mental berdasarkan pemahaman dan pengalaman siswa yang dibantu dengan analogi yang dibuatnya dan dipengaruhi oleh karakteristik dan lingkungan sekitar siswa. Analogi ion bergerak bebas pada materi larutan elektrolit dan nonelektrolit yang dikonstruk siswa adalah ikan, lebah, kambing, sedangkan analogi ikatan ion yang dibuat siswa adalah sedekah, zakat, dan wakaf. Model mental siswa pada materi larutan elektrolit terbagi dalam model mental yang sesuai dengan konsep dan model mental yang tidak sesuai dengan konsep. Ketidaksesuaian model mental siswa dipengaruhi oleh pemahaman dan pengalaman siswa.
Kata Kunci: model mental, kualitatif, larutan elektrolit dan nonelektrolit
Face-to-face tandem and etandem: differences that influence the maintenance of tandem learning activities.
Authors: Wakisaka Masako 
Published: February 2019

This paper compared two qualitative multiple case studies and discussed the influence that face-toface tandem and eTandem methods had on maintaining learning activities in tandem. One study focused on faceto-face tandem learning and the other focused on eTandem via e-mail and Skype. The participants of the former were three Japanese-English tandem pairs who participated in a face-to-face tandem project on the campus of a Japanese University. The participants of the latter were three Japanese-German tandem pairs who participated in an eTandem project as part of a collaboration between a Japanese and a German university. These multiple qualitative case studies employed multiple data, including recordings of tandem sessions, learning diaries, resources used in tandem sessions, e-mail/chat logs, field notes, and post-research interviews. The result of the comparison between the two case studies revealed the following three differences affecting the maintenance of learning activities in tandem: 1) distance and physical restriction caused differences in accessibility to sessions, 2) when encountering communication breakdowns, partners in face-to-face tandem learning drew pictures and used nonverbal communication, whereas learners in eTandem tended to rely on online or electronic dictionaries, and 3) learners supported each other more actively in face-to-face tandem learning.
Pilot Bit and Reamer Matching: Real-Time Downhole Data Differentiates Hybrid Drill Bit’s Suitability with Concentric Reamer in Deepwater, Gulf of Mexico Application
Authors: Roy Chowdhury Ashabikash , Serrano Ralph , Rodrigue Wayne 
Published: February 2019

Abstract
Deepwater wells routinely use concentric reaming devices in the bottomhole assembly (BHA) to lower the equivalent circulating density (ECD). In Gulf of Mexico (GOM) applications, concentric reamers are frequently used and are positioned approximately 100 to 150 feet behind the pilot bit to address formation evaluation and other operational constraints. This distance between a drill bit and the concentric reamer poses bit–reamer synchronization challenges, especially while drilling interbedded formations, where the bit could drill a softer formation while the reamer is placed in a harder formation or vice versa. This situation causes fluctuations in the compressive load at the bit and reamer. Cutting element damage often results from overloading, leading to a premature and costly trip. In many cases, the pilot bit or reamer could be deprived of the optimal compressive load to cut the formation, resulting in lower-than-expected penetration rates. Inadequate and fluctuating compressive loads at the bit or reamer often trigger unsustainable vibrations.
Efforts to address the bit-reamer matching issue are ongoing in the industry, and managing the aggressiveness of pilot bit and reamer is frequently used as a potential solution. Although modelling programs are extensively used during the well planning process, a lack of specific guidelines continues to exist in the industry.
Hybrid bits, which combine polycrystalline diamond compact (PDC) and tungsten carbide insert (TCI) rolling cutter elements, have been widely and successfully used in GOM. These bits offer higher drilling efficiency because of their dual cutting elements and balanced aggressiveness. The results of 18⅛-in. hybrid drill bit usage with a concentric reamer provided encouraging results and offered a potential solution to the bit-reamer synchronization issue.
Using real-time downhole data, this paper evaluates and compares bit and reamer load distribution, drilling mechanics of PDC and hybrid bits, and provides valuable analytical insights on successful application of hybrid bits to address the issue of bit-reamer synchronization.
High-Frequency at-Bit Measurements Provide New Insights into Torsional Dynamics When Drilling with Steerable Mud Motors in Unconventional Horizontal Wells
Authors: Wilson J. K. , Whitacre T. , Heisig G. 
Published: February 2019

Abstract
New insights into torsional BHA dynamics have been gained from high-frequency at-bit measurements when drilling with steerable mud motors in horizontal wells. Steerable mud motors are traditionally thought to decouple the bit from "sticking" as the BHA and drillstring are subject to torsional fluctuations. However, newly gathered data shows that the bit can actually come to a complete stop while the motor is forced into backwards rotation. Motor twist-offs and back-offs while drilling can be the costly consequence of such behavior.
Using high-frequency, at-bit, measurements, dynamic and environmental characteristics of the bit were recorded in a dedicated bit sub at 200 Hz while drilling a horizontal well in the Granite Wash formation in the Texas Panhandle. The recorded variables include azimuthal-gamma, tri-axial accelerations, inclination, RPM, and temperature. Recorded data was examined, after each interval drilled, and correlated with standard MWD data (measured and recorded above the motor) as well as surface-recorded variables.
Examination of the data revealed that the bit experienced full stick-slip behavior and, instead of being decoupled from the BHA as is traditionally thought, drove the BHA into backwards rotation via the action of the mud motor's power section. It is believed that, due to the tortuosity of the wellbore and the relative hardness of the formation being drilled, the lower end of the motor periodically "caught" and hung up while rotating, such that the negative driving torque generated in the power section (during the "bit-stick" intervals) loosened the connections below the motor's power section and ultimately led to back-offs of the connections downhole.
This new high-frequency at-bit measurement tool has led to clear insights of the stick-slip behavior while drilling horizontal wells with steerable mud motors. As this new understanding contradicts traditional thinking of torsional oscillations in motor BHAs, the authors believe it is worth sharing with the industry as it can help prevent NPT related to this mechanism in the future.
Barrier Verification During Plug and Abandonment Using Spectral Noise Logging Technology, Reference Cells Yard Test
Authors: Gardner Dave , Volkov Maxim , Greiss Rita-Michel 
Published: February 2019

Abstract
With the onset of offshore decommissioning resulting in an increasing number of permanent plug and abandonment (P&A) campaigns it is critical to manage these in a safe and cost-effective way. A robust methodology is important to manage the magnitude of wells in Norway to be P&A’d including the need to comply with Norsok Standard D-010 (Norsok, 2013). Many technologies have come to the forefront to aid with safe permanent well abandonment, with different criteria to be met, principally by verifying the integrity of the casing and cement barriers across the zones that are plugged. To inspect the cement barrier interval, spectral noise logging was utilized to investigate noise generated by flow in fluid and gas phases. A practical test in a controlled environment was required to document the sensitivity of the spectral noise logging techniques ability to detect liquid and gas flow for different annular cement quality scenarios.
Full-scale barrier reference test cells were constructed to represent a range of cement defects such as gas channels, mud channels and de-bonded cement. These test cells have been utilized to evaluate the performance of well barrier verification technologies. The measurement resolution of spectral noise logs to detect flow behind casing was investigated by flowing water and gas through the different leakage paths. The flowrate range used for this experiment was between 1 and 1300 mL/min for water and between 1 and 24 L/min for gas (N2). The experiment was performed in a low noise environment to avoid ambient noise sources that might compromise the experiment. P&A regulations and recommended practices were considered when developing the test procedure.
Controlled annular leakage rates of water and gas were established using barrier reference cells representing good cement, no cement, gas channels and micro-annuli. Spectral noise logging measurements were recorded using a memory based, commercially available logging tool and the results were analyzed. The data showed the spectral noise logging tool was able to detect the noise generated by low flowrates of water and gas through different leakage paths.
The yard test results provide a basis for considering noise logging and its spectrum analysis as an alternative means or an addition to currently used cement bond logging technologies for cement barrier verification. The applicability of utilizing spectral noise logging as an additional proof of annular barrier integrity was demonstrated.
Steering Advisory System for Mud Motors
Authors: Zalluhoglu Umut , Gharib Hossam , Marck Julien , Demirer Nazli , Darbe Robert 
Published: February 2019

Abstract
The ever-increasing global demand for hydrocarbon has brought new challenges in drilling through offshore and shale reservoirs. Bringing automation to directional drilling aims to address these challenges by reducing non-productive time (NPT) while drilling more accurate and smoother boreholes. This paper discusses the architecture, testing and field validation of a steering advisory system deployed for mud motors, which automates the steering-related decisions. The predictive performance of the advisory system is tested on 20 commercial jobs across North America for different motor sizes, stabilizer configurations, and hole diameters. The resulting performance, measured in terms of positional accuracy and precision, indicates a reliable prediction relative to the surveys. Furthermore, several curve sections were drilled entirely by following the steering decisions provided by the advisory system, resulting in successful landing within tight targets.
Relocate Monitoring Tasks Ashore with Advanced Data Streaming and Data Assurance
Authors: Neri Philip , Philo Ross 
Published: February 2019

Abstract
To lower costs, simplify operations and improve HSE, offshore operators have set aggressive goals to relocate technical roles from the rig to onshore centralized facilities. This is only possible if the specialists who are remotely supervising and advising the drilling operations see the data as it is being acquired, as well as obtain enough information about the data's reliability and integrity to accurately appraise the events observed during drilling to make fully informed decisions. The amount of data being transferred to shore has dramatically increased over the past 15 years, saturating a legacy data transfer process hampered by inherent limitations in responsiveness and bandwidth utilization. In addition to this, the data models used for transfer lacked indispensable metadata to properly qualify and assure that the data being received onshore was trustworthy.
These issues were addressed with two initiatives. First re-engineer the data transfer process to minimize lag time and overheads. Legacy architectures delivered buffered data with a lag of 10 seconds or more. The transaction overhead wasted about 90% of available bandwidth. The new streaming protocol reduces lag to about one second, delivering a stream of data that updates continuously. The second initiative addressed the scant amount of metadata, resulting in time-consuming verifications. This is of particular importance to analyze anomalies, e.g. whether the measuring device is properly calibrated. The metadata specifications cover not only the source specifications and process history, but also the information on adherence to data quality rules specific to an operator.
Over a test period of months, the operator saw that the quality and speed of analysis resulted in faster and more confident decisions, avoiding costly rig interventions. The technical ability to stream larger amounts of better-qualified data to multiple recipients simultaneously is opening up new, more collaborative ways to operate offshore drilling remotely.
An Integrated Thermal and Multi-Phase Flow Model for Estimating Transient Temperature Dynamics During Drilling Operations
Authors: Fallah AmirHossein , Gu Qifan , Ma Zheren , Karimi Vajargah Ali , Chen Dongmei , Ashok Pradeepkumar , van Oort Eric , May Roland 
Published: February 2019

Abstract
There is a growing need for comprehensive multi-phase hydraulic models that can accurately model more complex well control situations associated with the use of Managed Pressure Drilling (MPD) techniques, complex well geometries, High-Pressure High-Temperature (HPHT) conditions, riser gas unloading, etc.
A new thermal model integrated with previously developed multi-phase hydraulics software is presented here to address this need. This de-coupled thermal model is added to a sophisticated multi-phase flow code to estimate the mud temperature in the drillstring and the annulus and in the formation adjacent to the well during complex well control situations. The model uses an explicit finite volume approach and solves the mixture energy equation for the wellbore fluids, assuming that all the phases are at thermal equilibrium. Heat transfer between the drillstring and the wellbore fluid, and between wellbore and formation is calculated using a thermal resistance network. Axial heat conduction in the mud and heat generation (e.g. at the bit) are accounted for. The steady-state results of the proposed thermal model are compared to the steady-state Hasan and Kabir model and commercial software. In addition, the transient, time-dependent temperature behavior during mud circulation is compared against the results of the commercial software. Results show a very good match for both steady-state and transient cases.
Kick scenarios are simulated to show the importance of accurate temperature estimation of the drillstring and annulus fluids in HPHT conditions. Using advanced numerical schemes, a comprehensive model for heat transfer and energy storage in combination with a user-friendly Graphical User Interface (GUI) makes this model a robust tool for estimating the transient temperature profile of the mud and the formation. The model allows for evaluation of crucial parameters during well control, such as the wellbore pressure and temperature profiles, increased outflow and pit gain during kicks, gas thermodynamic behavior including solubility and unloading at low pressure conditions, gas rising velocity, and even temperature-dependent formation strength. These added features provided by the model come without loss of previous modeling capabilities, such as accounting for area discontinuity in the well and drillstring, gas dissolution in mud, non-Newtonian fluid rheology, MPD techniques, and arbitrary 3-D well trajectories.
Details of the new model and the simulation approach are shared, and various applications of the new thermal modeling capability are illustrated.
Using an Advanced Digital Twin to Improve Downhole Pressure Control
Authors: Thoresen Karl Erik , Kyllingstad Åge , Hovland Svein , Hetland Anders 
Published: February 2019

Abstract
Gartner named digital twin as one of the top ten technology trends for 2019. The awareness of this trend has now also reached the E&P industry, which can be seen by an increasing number of papers being published about the subject the last two years. Even though the term is new, the technology behind has been around for many years. In this paper we will show how a digital twin araised through the development of the comprehensive model. A model that has evolved through the development of smaller simulation models, each made to solve a different problem. With only minor extension, this model represented a complete virtual rig, ready to connect and develop the managed pressure drilling (MPD) control system. Running together with the control system it was also, with some minor changes, ready to be used in a training simulator. The big step was to prepare the model for running in parallel with a real well to estimate downhole pressure and other variables where they were not measured. Various issues around this are discussed in the paper. Finally, some results from a full-scale test of an MPD system on a rig at a research and development facility in Navasota, Texas, are presented. These tests showed that after some tuning the model could assist the control system in maintaining the pressure at any given arbitrary point in the well, an important point toward making a fully integrated MPD system.
Long-term Oil Well Zonal Isolation Control Using Geopolymers: An Analysis of Shrinkage Behavior
Authors: Olvera Raul , Panchmatia Parth , Juenger Maria , Aldin Munir , van Oort Eric 
Published: February 2019

Abstract
Volume changes due to shrinkage are inherent to the hydration process of ordinary portland cement (OPC) and alkali-activated cementitious materials. Under elevated temperature and pressure conditions, as is the case in oil and gas wells, the internal stresses created by shrinkage can result in loss of zonal isolation and the need for expensive repairs.
This paper compares the early age shrinkage behavior of Class H OPC, alkali-activated Class F fly ash (referred to as geopolymer in this study), and geopolymer-hybrid (geopolymers incorporating drilling mud) slurries with up to 20% (by volume) synthetic based mud (SBM) contamination cured at 23°C and 50°C. In addition, the use of zinc and aluminum-based expansive agents to mitigate shrinkage was explored. Results from various test methods characterizing shrinkage behavior show that (a) shrinkage increases with temperature for all cases, (b) geopolymers shrink less than OPC slurries at low temperature, (c) geopolymer shrinkage exceeds that of OPC slurries at higher temperatures, (d) the addition of SBM increases the shrinkage of both OPC and geopolymer slurries, and (e) the use of suitable expansive agents has the potential to neutralize shrinkage of both OPC and geopolymer slurries. The work also shows that the current set of ASTM and API shrinkage tests need to be augmented with a test that can be conducted at elevated temperature and pressure, particularly when testing expansive agents that generate gases. A proposal for a more relevant test is included.
Myth-Busting Performance Properties of Nonmetallic Rigid Centralizers
Authors: Rodrigue Maxime , Kendziora Larry , Farley Douglas 
Published: February 2019

Abstract
Performance characteristics of nonmetallic rigid centralizers are not defined under the API 10D, Methods for Testing of Solid and Rigid Centralizers. API Technical Report 10TR5 defines recommended performance tests for rigid centralizers, but does not describe testing for coefficient of friction or wear loss. Selection criteria are often based on manufacturer's test methods, material supplier data sheets, and end-user experience using various materials and designs. While American Society for Testing and Materials (ASTM) testing methods are available to measure mass loss caused by wear and frictional coefficient, the selection of the test method that provides the most accurate data replication use in a wellbore is proposed.
Rapid advancements in the mechanical properties of composite materials have given manufacturers a multitude of material choices. However, comparative data based on standardized testing is inconsistent throughout the industry. Not only should consistent test methods for wear and coefficient of friction be established, but resistance to load-at-temperature should also be a criterion for measurement. Because of a lack of an industry standard testing protocol during product development, a standardized method was generated to best replicate the performance characteristics required for downhole conditions.
Various ASTM test methods are deployed in the qualification of rigid composite centralizers, which yield a wide array of results attributed to the inconsistencies of test apparatus and conditions of testing. Through trial and error, a best practice was established for the qualification on nonmetallic rigid centralizers that resulted in more accurate measurements of wear and frictional coefficient. However, friction factor and wear resistance are not the only attributes for durable centralizer requirements to effectively run casing to the target depth. In some instances the casing may need to be retrieved from the wellbore. Other factors such as the ability to rotate the casing string at a prescribed temperature and load rating need to be tested and fully understood. By standardizing the test method for nonmetallic centralizers, the mystery regarding their performance is more clearly understood. The proposal is for lessons learned during product development to be considered for adaptation in API 10TR5.
The rapid advancement of new types of composite materials and the ability to measure their performance properties in downhole conditions will lead to further cost-effective product innovations.