bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water and Sediment Supply Requirements for Post-Wildfire Debris Flows in the Western United States
Authors: Santi Paul M. , Macaulay Blaire 
Published: March 2021

ABSTRACT
This work explores two hypotheses related to runoff-related post-wildfire debris flows: 1) their initiation is limited by rainstorm intensity rather than cumulative rainfall depths and 2) they are not sediment supply limited. The first hypothesis suggests that it is common to generate more than enough rainfall to account for the volume of water in the debris flow, but to actually produce a debris flow, the water must be delivered with sufficient intensity. This is demonstrated by data from 44 debris flows from eight burned areas in California, Colorado, and Utah. Assuming a debris flow comprises 30 percent water and 70 percent solids, these events were generated during rainstorms that produced an average of 17 times as much water as necessary to develop a debris flow. Even accounting for infiltration, the rainstorms still generated an overabundance of water. Intensity dependence is also shown by numerous cases in which the exact timing of debris flows can be pinpointed and is contemporaneous with high-intensity bursts of rainfall. The hypothesis is also supported by rainfall intensity-duration thresholds where high-volume storms without high-intensity bursts do not generate debris flows. The second hypothesis of sediment-supply independence for the initiation of debris flows is supported by a significant increase in flow volume occurring directly after wildfire, compared to flows in unburned terrain. Also, repeated flows within short time intervals are only possible with an abundance of channel sediment, dry ravel, and bank failure material that can be mobilized. Field observations confirm these sediment sources, even directly after a debris-flow.
Using High Sample Rate Lidar to Measure Debris-Flow Velocity and Surface Geometry
Authors: Rengers Francis K. , Rapstine Thomas D. , Olsen Michael , Allstadt Kate E. , Iverson Richard M. , Leshchinsky Ben , Obryk Maciej , Smith Joel B. 
Published: March 2021

ABSTRACT
Debris flows evolve in both time and space in complex ways, commonly starting as coherent failures but then quickly developing structures such as roll waves and surges. These processes are readily observed but difficult to study or quantify because of the speed at which they evolve. Many methods for studying debris flows consist of point measurements (e.g., flow height or basal stresses), which are inherently limited in spatial coverage and cannot fully characterize the spatiotemporal evolution of a flow. In this study, we use terrestrial lidar to measure debris-flow profiles at high sampling rates to examine debris-flow movement with high temporal and spatial precision and accuracy. We acquired measurements during gate-release experiments at the U.S. Geological Survey debris-flow flume, a unique experimental facility where debris flows can be artificially generated at a large scale. A lidar scanner was used to record repeat topographic profiles of the moving debris flows along the length of the flume with a narrow swath width (∼1 mm) at a rate of 60 Hz. The high-resolution lidar profiles enabled us to quantify flow front velocity of the debris flows and provided an unprecedented record of the development and evolution of the flow structure with a sub-second time resolution. The findings of this study demonstrate how to obtain quantitative measurements of debris-flow movement. In addition, the data help us to quantitatively define the development of a saltating debris-flow front and roll waves behind the debris-flow front. Such measurements may help constrain future modeling efforts.
Real Time Geosteering Integrated Services. A Key Issue in Maximizing Geothermal Exposure and Minimizing Drilling and Completion Risks. A Paris Basin Case Study
Authors: Ungemach Pierre , Antics Miklos , Di Tommaso Davide , Casali Filippo 
Published: March 2021

Abstract
Geothermal District Heating (GDH) doublets in the Central part of the Paris Basin, particularly in the Capital City suburban areas, face two major concerns:
The replacement of aging and declining, when not damaged, well infrastructures and productive/injective capacities; GDH doublets density, approaching overpopulation in some areas, which limits well replacement opportunities and clouds new development issues bearing in mind the space limitations in urban areas and the thermal breakthrough/reservoir cooling shortcomings.
The Paris suburban Cachan site was considered a relevant candidate for a first implementation of an alternative well architecture design. In March 2018, the second sub-horizontal geothermal injection well, GCAH2, was successfully tested at the Paris suburban Cachan site, thus validating this innovative sub-horizontal well (SHW) architecture, initiated on the previously drilled production well, GCAH1, recorded as a world first with 1000 m 8-1/2 in. open hole horizontal drain.
The sub-horizontal drain sections of the wells were drilled using the geosteering technique in place of the usual geometric pre-planned trajectory. Geosteering was successfully used for optimal well placement of the geothermal injection/production doublet. The real-time data was correlated to reservoir model to design and implement a reliable well trajectory and to increase reservoir exposure. Alongside LWD (logging while drilling), advanced near real-time cuttings analysis utilizing elemental and mineralogical measurements and custom software was used to improve decision making while drilling. The integration of chemo-stratigraphy, mud logging, wireline, logging while drilling and production test results improved the correlation between wells, supporting the building of a proper geological model and reservoir characterization.
Wellbore Stabilizing Technology Enhances Cementing Efforts in the North Sea
Authors: Ilnicka Agnieszka , Bottiglieri Antonio , Jaskiewicz Maja , Kulakofsky David 
Published: March 2021

Abstract
North Sea lithologies are often complex creating a difficult environment to deliver effective zonal isolation with standard cementing practices. With ever-present weak, fractured, and unconsolidated formations, the practice of fully lifting heavier cement up the annular gap between the formation and the casing or liner often times compromises the formation and the cement integrity. Wellbore Stabilizing (WBS) technology has been shown capable of providing zonal isolation under these difficult conditions.
A cementing spacer has been developed that incorporates WBS technology providing a simple way to deliver the technology in front of any cement job, without compromising the cement integrity or requiring any last-minute slurry design or redesign. By separating the placement of the WBS technology from the cement itself, the cement slurry can be designed with the sole focus being on the interval's zonal isolation requirements.
On Askepott wells in the Norwegian part of the North Sea, the Nordland weak zone is encountered after drilling out the 30-inch shoe from the Oseberg Vest H template. Cement back to the seafloor is required when cementing the 20-in casing in these 26-in. holes. Prior to the introduction of the WBS technology, pressure had been observed on the D-annulus, hinting at a lack of sufficient cement circulation. With assistance from this new WBS spacer, pressure is no longer observed in the D-annulus indicating the cement is now being circulated back inside of the conductor string. The WBS spacer has also been used successfully ahead of cement across the production interval in wells where losses were typically expected, and again full returns were observed.
Normally cement spacers are utilized to separate the drilling fluid from the cement as these two fluids are normally incompatible with each other and to help push the drilling fluid out of the well so the annulus may be completely filled with cement. If the drilling fluid is not successfully displaced from the annular space, the zonal isolation intended by the primary cement job is usually less than ideal. In addition to these standard functions in preparation for cementing operations, this specialized WBS spacer also can prevent loss of cement to the formation.
A Comparison of the Measured Properties of Annular Cement with Ultrasonic Cement Evaluation Logs
Authors: Gardner Dave , Skadsem Hans Joakim , Beltrán-Jiménez Katherine , Govil Amit , Obando Palacio Guillermo , Delabroy Laurent 
Published: March 2021

Abstract
Different measurement methods have been utilized to investigate the quality of the cement sheath inside two cemented sandwich sections including high-resolution ultrasonic cement evaluation logs, analysis of samples, mechanical loading, and fluid seepage measurements. The sections were recovered from a North Sea well during a permanent plug and abandonment operation. The measurements have been analyzed with an aim to describe in detail the spatial variations in the cement properties and relate them to the logs.
Ultrasonic cement evaluation logs were recorded to map the acoustic properties of the annular cement in the casing sections. Logging passes were recorded using different annular fluids and with different internal casing pressures to investigate the potential effect on the casing to cement bond response. The casing annulus was pressure tested using water and gas, and seepage rates were recorded whilst varying the annulus and the inner casing pressures. The sections tested were instrumented with an array of annulus pressure sensors. On one section, strain gauges were installed on the casing outer surface to record the transfer of strain through the cement sheath to the outer casing.
The eccentricity of the inner casing was up to 70% compared with the outer casing which results in a substantial variation of the cement sheath thickness. Accordingly, the pressure sensors and strain gauge arrays were positioned to capture both axial and azimuthal variations of the cement sealing properties. Cement mechanical, chemical, and acoustic bulk properties were also measured on core plugs taken from the cement sheath.
The log recordings and sensor measurements showed that the cement sheath properties vary considerably, both along the section length and from the narrow to the wide side of the annulus in the casing sandwich sections. The sealing quality of the cement sheath measured by pressure testing could be correlated with the log response. We observed a nearly linear reduction in seepage rates when increasing the inner casing pressure due to the reduction in size of the annular leakage path. Analysis of bulk properties confirm the presence of cement defects such as mud contamination and microannuli. The logs identified features related to the test cell construction that demonstrated the log spatial resolution and enabled an accurate spatial comparison to be made between the logs and cement sheath sealing properties.
A comprehensive data set has been recorded on casing in casing-cemented sandwich sections with axial and azimuthal variations in the cement sheath quality. The data analysis has improved the understanding of the cement sheath mechanical properties, the seal quality, and the response of the ultrasonic cement evaluation logs.
Fully Automated Directional Drilling is Now a Reality - An Example from the Norwegian Continental Shelf
Authors: Heredia Jorge , Marck Julien , Heller Sara , Ferreira Filipe , Lindal Anders , Kvandal Petter 
Published: March 2021

Abstract
Automated drilling has been discussed for a long time, with much of the discussion being around future ambitions – what could be or might be possible. Given the complexity of a modern drilling operation, the idea of automating all or part of it is daunting. Despite the apparent obstacles, there has recently been significant progress toward this goal, centred on the core process of drilling new boreholes.
This paper presents an automated directional-drilling process executed on a commercial well in the Norwegian sector of the North Sea in 2019, where a next-generation intelligent rotary-steerable system completed a well section in a single run with all drilling commands automatically computed, optimized, and downlinked by a drilling automation platform. The section was complex, comprising two intervals requiring steering in three dimensions, separated by a tangent section. Directional-drilling engineers onshore, who had the authority to override the system if necessary, supervised the operation remotely. No such override was required, and the automated system was able to drill the entire section while automatically sending steering decisions.
The 12¼-in. landing interval required precise positional control to enter the reservoir in the correct location and with the correct attitude. At the end of the section, with over 1500 m drilled, the final well position was 0.28 m above the target position and 3.89 m to the left, with minimal tortuosity, making it easy to land the subsequent casing string. The final build section, from 33 to 71.6° of inclination, was drilled between 100 and 150 m/hr, with a planned dogleg severity of 3°/30 m. To drill such a complex trajectory automatically would have been unthinkable only a short time ago and marks a major milestone in the development of automated drilling technology.
IMoDD: Intelligent Mapping of Downhole Dynamics
Authors: Sims Kelly Scott , Bomidi John Abhishek , Moss William Anthony , Wilson Thomas Andrew 
Published: March 2021

Abstract
With the ever-increasing pressure to drill wells efficiently at lower costs, the utilization of downhole sensors in the Bottom Hole Assembly (BHA) that reveal true downhole dynamics has become scarce. Surface sensors are notoriously inaccurate in translating readings to an accurate representation of downhole dynamics. The issue of 1 to 1 interpretation of surface to downhole dynamics is prevalent in all sensors and creates a paradigm of inefficient drilling practices and decision making. Intelligent mapping of downhole dynamics (IMoDD) is an analytical suite to address these inefficiencies and maximize the use of surface sensors, thus doing more with less. IMoDD features a new zeroing beyond the traditional workflows of zeroing the surface sensors related to weight and torque at the connection. A new method, Second-order Identifier of Maximum Stand-pipe-pressure: SIMS, is introduced. The method examines changes in stand-pipe pressure and identifies the point before bit-wellbore contact, using a set of conditions. The resulting calculations of weight and torque are verified with measured values of downhole weight and torque, for multiple stands of drilling in vertical, curve-lateral drilling. After the new zero, the deviation of torque-weight correlations is further examined to reveal the downhole weight changes confirmed also by the downhole sensor data. It is demonstrated that an intelligent mapping system that improves downhole characterizations would improve decision making to facilitate smoother energy transfer thus reducing Non-Productive Time (NPT) and increasing BHA life span.
Experimental Investigation of Induced Low Frequency Axial Vibration on Drilling Response of a PDC Bit
Authors: Trivedi Ajesh Sanjay , Mostofi Masood , Shor Roman J 
Published: March 2021

Abstract
This study investigates the impact of induced low frequency axial excitations on drilling actions of Polycrystalline Diamond Compact (PDC) bits. Variations in drilling efficiency have been documented through a series of experiments at different intensities (frequency and amplitude) of axial excitations. Prior work has identified the challenges of bit wear due to high frequency oscillations and an experimental validation is conducted to incorporate vibration related force changes into mechanical specific energy (MSE) to allow for identification while drilling. Axial vibrations were induced using a controlled linear actuator at the cutter-rock interface, in low frequency regime (up to 5 Hz) using a rotary experimental setup, based on state-of-the-art modified lathe machine. Through imposition of bit kinematics of angular velocity and rate of penetration (ROP), a PDC cutter was used to drill several cores of donnybrook sandstone, at a constant angular velocity of 100 revolutions per minute (RPM). A piezoelectric triaxial sensor measured the cutting forces: normal (weight) and shear (torque) force, at the cutter-rock interface. The results quantify variation of drilling response under several combinations of frequency, amplitude and cutting speed. It was observed that forces required to penetrate through rock were reduced with minimum effect on degree of wear on the cutter, mainly due to lower intensity of induced oscillations. This shows that once periodic axial oscillations are imposed, a lesser amount of energy is required to achieve same rate of penetration (ROP), thereby indicating improvement in cutting efficiency of the drilling process. The results from this study also provides experimental evidence for the need to incorporate vibration induced force losses into the equation of drilling efficiency for correct estimations of rock strength downhole.
Time-Series Data Augmentation Techniques for Improving Automated Drilling Dysfunction Classifiers
Authors: Yi Michael , Ramos Dawson , Ashok Pradeepkumar , Thetford Taylor , Bohlander Spencer , Noworyta Mickey , Behounek Michael 
Published: March 2021

Abstract
Detecting drilling dysfunctions from surface data is not always easy as downhole vibrations tend to get damped before they reach surface sensors. Building machine learning models to recognize patterns in the surface data requires vibration signals captured by downhole sensors for training purposes. Such datasets are not widely available and therefore a methodology to expand these datasets is highly desirable. This work explores ways to utilize data augmentation to artificially diversify and increase datasets to build better models.
Stick-slip (including full-stick), bit bounce, whirl, and bit balling are the primary dysfunctions considered in this work. Bayesian networks are used as classifiers to keep the model intuitive, and address situations where some input data is missing or unavailable. Once the dysfunction events in the downhole dataset were labeled, data augmentation techniques were used to generate synthetic data for scenarios where data was sparse.
The dataset used in the project consisted of nine wells (with 19 bit runs). Most of the bit runs had a downhole vibration sensor at the bit, while some had sensors along the string as well. Of these 19 bit runs, 15 were used for training and four were used to test the models. Various data augmentations techniques were applied, and validated manually as appropriate synthetic data. In the case of full-stick event detection, the saw tooth pattern in the surface torque signal was captured and provided as an input to the classifier. The classifiers thus trained were able to detect the dysfunctions using data from surface sensors to a high level of accuracy and with low false alarm rates.
This paper presents models to predict downhole dysfunctions from surface data alone. This paper also provides guidance on data augmentation techniques that use sparse downhole datasets to improve machine learning drilling advisory models. For identifying drilling dysfunction from surface data, the tortuosity of the well is also taken into account.
A Hybrid Test Environment for Verification of Drilling Automation Systems
Authors: Gravdal Jan Einar , Sui Dan , Nagy Attila , Saadallah Nejm , Ewald Robert 
Published: March 2021

Abstract
The transition towards drilling automation put high demands on new software for controlling or assisting during drilling. Along with the software development, adequate infrastructures for testing and verification of this software need to be in place. In other industries, such as aviation, the development of advanced simulators goes hand in hand with the technological developments and ensures a fit for purpose test environment at all time.
Since 2017, a high-fidelity online drilling simulator has been available to the public. The purpose has been to facilitate and accelerate the development and testing of real-time drilling automation systems.
The simulator can be accessed through a web Application Programming Interface (API) and run from a web client, or in a Hardware-in-the-loop (HIL) simulator from a control system environment with programmable logic controllers (PLCs) from leading industry vendors. To facilitate testing and verification of systems also on real data, recent developments have enabled a user-friendly access to openly available drilling data through the web API. Automatic functions have been developed to create model configurations from recorded data sets. This setup enables benchmarking of simulation models against recorded data and allows efficient verification of drilling automation systems.
The web enablement makes the infrastructure suitable for development projects and software verification from anywhere in the world without any installation needed. Better availability of realistic and scalable test environments for automated drilling systems is expected to speed up the qualification of new drilling technologies. This will in turn reduce costs and minimize the carbon footprint from drilling operations.
This paper describes the hybrid test environment and key learnings from the developers and user's perspective.
Improving Surface Oscillation Tools Performance Using Time-Domain Dynamics and Torque and Drag Models
Authors: Mahjoub Mohamed , Dao Ngoc-Ha , Nguyen Khac-Long , Badri Seif , Summersgill Matthew , Menand Stéphane 
Published: March 2021

Abstract
Overcoming friction in sliding mode represents a challenging task when drilling an unconventional well with a long lateral section. Among the possible ways to reduce these frictional forces is to use a surface oscillation tool (SOT). By alternating the rotation at surface between the forward and reverse directions, a part of the friction forces is transferred from the axial to tangential direction. Hence, a better transmission of the weight to the drill bit and increased rate of penetration can be achieved. To take full advantage of this tool, an accurate and fast modeling of the influence of its oscillation characteristics is necessary.
The SOT is operated at surface by changing its rotation speed and number of wraps in forward and reverse directions. If these characteristics are underestimated, the torsional oscillationsare quickly stopped by the friction moments, and the rate of penetration is not increased enough. However, if they are over estimated, the torsional oscillations can reach the bent motor, and destabilize the tool face orientation (TFO). In this paper, a full time-domain dynamics model and a simplified model coupled with a stiff-string torque and drag model are used to identity the influence length of the SOT, and hence provide an opportunity to optimize its operating parameters.
Full and simplified models are compared to each other to ensure their validity. Namely, the effect of the drillstring-wellbore contact distribution is showed to have a substantial impact on the SOT performance. Consequently, it was proved that optimal SOT characteristics Off-Bottom are generally not enough to overcome the friction when drilling. In addition, the torque and drag model is applied to a real case study of an unconventional well with surface and downhole data. It helps provide the driller with a guideline of recommendations on the SOT parameters. These results open some very interesting perspectives in terms of TFO accuracy and slide optimization.
The use of modelling in the calibration of the SOT characteristics and the development of the simplified model are both novelties introduced here. This work should lead to significant improvement to extend the length of laterals with steerable mud motor with minimum tortuosity.