bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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.
Smart Wired Pipe: Drilling Field Trials
Authors: Macpherson John , Roders Ingo , Schoenborn Kai , Mieting Ralf , Lopez Fernando
Published: February 2019

Drilling systems automation requires a downhole digital backbone for closed-loop control, as do many other real-time drilling, completion and production operations. The absence of a reliable, high data bandwidth, bi-directional communication method between surface and downhole is a barrier to digitalization and automation of the oil field. This paper describes the development and successful drilling field trial of a micro-repeater wired pipe – effectively "smart pipe" – that removes this barrier.

The developed system uses battery-powered micro-repeaters (a fail-safe signal booster) placed within the box of each tubular and fully encapsulated dual RF-resonant antennas to transmit data between tubulars. The current system delivers 1-Mbps backbone data rate with a maximum payload of 720 kbps, and with a very low latency of 15 μsec/km, making it ideal for control-loop applications. The system design focusses on reliability: failure of multiple components will not affect telemetry. The prototype system has been rigorously field tested during drilling in Oklahoma.

Testing occurred on a drilling rig in Beggs, Oklahoma. The first trial (2016) covered drilling operations, the second (2017) covered controlling downhole technology; both were successful. The drilling trial demonstrated fitting the system to pipe with conventional API connections, standard rig-floor pipe handling, reliable wireless transmission between surface receivers and wired pipe network, the use of multiple along-string measurements of temperature and vibration, and simulated component failure. Of particular note was the surface system: it is wireless and no modification to the drilling rig was required.

Conventional tubulars can be refit with the system, which removes a barrier to the use of wired pipe for automation and LWD/MWD measurements in lower cost onshore operations. There is a benefit for drilling operations: all pipe joints contain a micro-repeater and are addressable for "smart pipe" applications such as an electronic pipe tally, and pipe condition monitoring. Drilling operations are the first users of the system, but it serves other operations, for example tubing conveyed wireline operations. The smart wired pipe concept is truly innovative. It enables drilling systems automation and logging-while-drilling applications, such as seismic-while-drilling with along-string sensors, by providing a fully open acquisition and control platform to the industry.
Unplanned Tortuosity Index: Separating Directional Drilling Performance from Planned Well Geometry
Authors: D'Angelo John , Ashok Pradeepkumar , van Oort Eric , Shahri Mojtaba , Thetford Taylor , Nelson Brian , Behounek Michael , White Matthew
Published: February 2019

Wellbore tortuosity is an important metric of wellbore quality; however, it is not always an appropriate reflection of directional drilling performance. Drilling planned tortuous features will increase wellbore tortuosity, but this in itself says nothing about directional drilling performance. Not only is there a need for a metric of wellbore tortuosity, it isalso necessary to have a metric of "unplanned" wellbore tortuosity. The former provides information about wellbore quality, whereas the latteris reflective of directional drilling performance.

The directional drilling literature contains metrics for both wellbore and unplanned tortuosity; however, they are largely unique and difficult to relate to one another. It is desirable for the planned and unplanned tortuosity metrics to be relatable. This would allow operators to not only quantify overall wellbore tortuosity in real time, but also to understand how much of that tortuosity is unplanned and possibly avoidable. This, then, opens up avenues for directional drilling performance improvement.

In this paper, a new metric, the "Unplanned" Tortuosity Index is developed on the basis of an existing metric of wellbore tortuosity. This is done by systematically removing the effects of intended tortuous features from the wellbore tortuosity analysis, retaining only those tortuous features in the wellbore trajectory that are unplanned. The unplanned tortuosity index is then tested on two distinct sets of survey data from actual wells drilled. The results are compared between the sets and with the wellbore tortuosity metric from which the new index was derived. It is shown that thenewly developed unplanned tortuosity index canhelp operators and directional drilling companies discern their directional drilling performance, especially forwell paths with multiple, planned tortuous features.
Mitigation of Multi-Frequency Stick/Slip
Authors: Sun Zhijie , Gu Qiuying
Published: February 2019

Stick/slip-induced vibration has been recognized as a cause for bit wear, premature tool failure, and poor drilling performance, which represents a contribution of approximately 30% of drilling vibration dysfunction. Dynamic modeling of stick/slip phenomena in drillstrings shows that the vibrational waves travel back and forth along the drillstring between the bit and top drive, which typically leads to 15% fluctuation in surface torque. It is also found that stick/slip is much more likely to occur with certain drilling fluid types and in deviated holes with large dogleg severity. One method of stick/slip mitigation is through control of the top drive. In existing applications, the vibrational wave at a fundamental frequency is absorbed by tuning a proportional-integral (PI) controller.

Stick/slip-induced vibrations do not exist at a single frequency, and the simple PI controller cannot mitigate stick/slip occurrence at all vibration frequencies. Vibrations at frequencies other than the frequency chosen for mitigation can be amplified using existing tuning methods. In tests in which the method was applied, there were cases in which the vibration shifts to the second mode when the first torsional mode is mitigated. Therefore, the challenge is to target more than one vibration frequency.

A new control system has been designed to observe stick/slip frequencies and then to dampen the stick/slip across a wide frequency range, while regulating the rotational speed of the drillstring at the desired set point. All control algorithms are implemented on a standard programmable logic controller (PLC). To eliminate the need to modify the existing top variable-frequency drives (VFD), this paper also proposes several methods to seamlessly implement the proposed controller.

Existing configurations and stick/slip mitigation tests based on PI controller-gained tuning have been achieved on a test rig. Field tests demonstrating the new control method have been performed, and the results are presented and analyzed in this paper.
Automatic Control of Mud Pumps, Draw-Works and Top-Drive on a Floater
Authors: Benoît Daireaux , Erik Dvergsnes , Eric Cayeux , Ronny Bergerud , Ivar Kjøsnes
Published: February 2019

The application of safe-guards, safety triggers and automated procedures to control the mud-pumps, hoisting system and top-drive allows for safer, more consistent and more efficient drilling operations. Attempting to apply drilling automation on a floater needs to manage the impact of the unpredictable movement of the drill-string induced by heave movements.

Because of the drill-string elasticity and the continuous movement of the rig, it is challenging to estimate the bit position, the bottom hole depth or the instantaneous rate of penetration. Yet, these estimations are crucial for the evaluation of cuttings production and their transport, or dynamic open hole pressures. Furthermore, the variability of the top of string movement can change abruptly when heave compensation is turned on or off or depending on the efficiency of the heave compensation system. These facts have an impact on the look-ahead strategy to determine safe drilling parameters.

An existing drilling automation system, originally designed for fixed platforms, has been modified to meet those new requirements. For this first adaptation, only vertical drilling has been considered. Heave movements with and without compensation are constantly monitored so that sudden or slow changes in amplitudes get accounted for. Induced effects on downhole pressures are estimated via hydraulic simulations for a wide range of drilling and heave scenarios. Consequently, the design of the automation system had to be deeply modified to incorporate this additional dimension. The resulting system has been used for the drilling of three exploration wells, in eleven sections.

Offshore drilling operations are characterized by a large variability of the drilling operation conditions. On a floater, the drilling context is even more challenging as it is subject to ever changing weather conditions. Yet, by utilizing model-based drilling automation solutions it is possible to improve drilling efficiency.
Intelligent Wellbore Path Estimation Using Multiple Integrated MEMS Sensors
Authors: Liu Huan , Shor Roman , Park Simon
Published: February 2019

To improve magnetic disturbance rejection and robustness of wellbore survey measurements, an adaptive neuro network-based fuzzy inference system (ANFIS) filter for wellbore position calculation is presented. This technique significantly improves magnetic disturbance rejection and reduces sensor error influence for borehole survey measurements. The new approach for the ANFIS filter is based on two redundant sets of IMUs which are located in different positions in the BHA at a known, constant distance. The distance between these two sets of IMUs will physically fade the effect of the magnetic disturbances. Each IMU set outputs position estimation based on the splines method which is then input into an ANFIS filter. The inputs of the splines calculation are azimuth, inclination angles and measurement depth, and the outputs are moving distance in three directions (Northing, Easting and True Vertical Depth). However, the accuracy of the splines method highly depends on the accuracy of the inputs, which are difficult to obtain during the measurement while drilling process even under pure clean environments (without any magnetic disturbances). Furthermore, the distorted azimuth caused by magnetic interference affects the borehole position accuracy. In order to deal with those problems, the designed ANFIS filter has a two-level structure. First a local level position estimation (splines method or well trained local ANFIS based on the sensor accuracy) for two sensor sets is used. If the sensor measurement accuracy is low, this local ANFIS will correct the position estimation. Then the outputs of the local modules were input into ANFIS for second level filtering (global filter) to remove the error which caused by unknown magnetic disturbances. According to the judgement of the ANFIS, the IMU set with the smaller magnetic disturbance is given greater weight to reduce the interference effect on the borehole position estimation. This two-level filter is compared to the traditional splines method under different tests situations. First, we evaluate this method by comparing with GPS positioning, from this test we know that the ANFIS filter shows a good performance when the magnitude of magnetic disturbance is within the training magnitude range. Even when the magnitude of magnetic disturbance is above the training range, the ANFIS filter shows a higher robustness than the traditional splines method. Also, this method was applied to borehole data with two IMU containing accelerometers and one magnetometer measurements. In order to apply our method, we duplicated one more magnetometer measurement data under magnetic interference for assessment. The results proved its magnetic disturbance robustness in borehole position estimation. Finally, we demonstrate the full potential using a laboratory experimental setup.
Concurrent Real-Time Distributed Fiber Optic Sensing of Casing Deformation and Cement Integrity Loss
Authors: Wu Qian , Nair Sriramya , Oort Eric van , Guzik Artur , Kishida Kinzo
Published: February 2019

Subsurface geomechanical changes can cause severe damage to oil and gas well casing strings and cement barriers, which can compromise the zonal isolation of either an abandoned or active well, in the latter case jeopardizing its productive life. A novel system was developed based on laboratory experiments to simultaneously monitor casing deformation and cement integrity using fiber optic distributed temperature and strain sensing (DTSS). The proposed system consists of a hybrid-Brillouin-Rayleigh-based DTSS technique used in combination with two dedicated fiber optic cables. The first is a standard telecommunication fiber, which is used to measure strain changes due to casing deformation. The second cable, coated with a hydrocarbon-sensitive polymer, detects an additional strain caused by the presence of hydrocarbons due to a loss of zonal isolation. The combined system can also detect temperature changes caused by formation fluid invasion from a lower depth into the cement annulus. Since the two cables will be installed side-by-side on the outside of a casing string within the cement sheath, the system can also be used for monitoring the quality of a cementing job. The proposed system provides continuous, real-time and in-situ monitoring of casing deformation and cement integrity to prevent substantial impact on production, or to detect plug failure and hydrocarbon leakage for abandoned and decommissioned wells. It can thereby provide detailed information (i.e. location, type, and event severity) to plan and execute remedial operations, if necessary.
Managing Drilling Losses in the Permian Using Airborne Gravity Full Tensor Gradiometry
Authors: Sallee Adam , Dick Hans , Sudhakar Vasudhaven , Morgan Alan , Payton Scott , Paddock David
Published: February 2019

Shallow drilling losses are a significant problem in the Permian basin because of the presence of subsurface karst features. Karst weakens the soluble rock producing voids and caves systems that result in drilling losses. An operator drilling in Culberson County, Texas recently experienced total losses drilling four surface holes in a pair of neighboring pads located in bordering leases. Drilling into caves negatively affected operations by reducing the drilled footage per day, increasing fluid and cementing costs, and increasing the difficulty in performing satisfactory cementing jobs to cover the water table.

This paper will describe the issues faced drilling with losses and explain how to manage the risk of losses by improving surface well placement with airborne gravity full tensor gradiometry (FTG) to map subsurface hazards.

Airborne gravity FTG measures the directional components of the gravity field. Multiple simultaneously acquired tensor components allow identification of anomalies associated with subsurface voids. For this project, a Basler BT67 aircraft acquired data over the targeted expanse with line spacing of 328 ft. The aerial survey took place over 3 days in July 2017.

Feasibility modeling using Castile formation cave systems reveals detectability of single caves larger than 10 m diameter with FTG, however networks of smaller caves are also detectable. Polygons created from analysis of negative vertical gravity tensor (Tzz) anomalies separate the cave systems into tiered risk areas.

Initial analysis reveals risk at both pads where losses occurred. Extending the analysis to the entire survey, the drilling events in the drilled offset wells match with the risk interpreted for karst. FTG data and subsequent interpretation offer strong correlation to known shallow hazards and cave systems, making it a useful tool for risk assessment. It recommended to locate future drill pads in the identified moderate risk areas and that any new wells be located away from elevated risk areas.

This is the first application of FTG to classify drilling risk of karst features in the Permian basin. The FTG hazard map improves operational integrity of surface location selection and is a complement to surface topography and geology considerations. The FTG data and analysis also holds promise for fault mapping and for water drilling efforts.
Subsea Xmas Tree and Completion Operations on Two Different Subsea Providers with a Single Rig Using One Common IWOCS System
Authors: Thibault Blanckaert , Arthur Bottomley
Published: February 2019

Offshore Congo West Africa, one of the subsea field developments has been installed with subsea production equipment designed and manufactured by two different subsea equipment suppliers. Therefore, it is a major challenge to be able to perform subsea intervention and installation with just one drilling rig being available on this subsea development as the subsea equipment from different subsea equipment suppliers is not design compatible. The conventional approach would be to change out the topside installation and intervention equipment from one manufacturer to that of the other on the rig. As this solution is far too expensive and time consuming, a need for one universal subsea installation and intervention system became an operational requirement.

This paper explains how one operator along with two subsea production equipment suppliers were able to design, manufacture and implement one universal drilling system refered to as –IDIMS (Interface for Dual Intervention Mode System). IDIMS increases the operational response while lowering the intervention cost on this field. Indeed IDIMS allows one single rig to intervene, drill and complete with two different subsea production equipment suppliers at a lower cost and with a shorter lead-time, which is a first in the oil industry.

For operators, IDIMS XT and TH modes represent a major innovation to reduce costs and drilling times in all subsidiaries with mature submarine fields equipped with different subsea production systems and equipment.

Over three years, this innovation allowed 107 MUSD of savings on this field.

The IDIMS concept could be reproduced and developed to intervene and drill on other subsea field developments with even more than two subsea production equipment suppliers. A single rig would then be able to operate on all of the subsea wellheads, tubing hangers, subsea XT installed/to be installed in one area, significantly reducing project development costs.
Tortuosity: The Rest of the Hidden Story
Authors: Samuel Robello , Zhang Yuan
Published: February 2019

Conventional methods calculate tortuosity based on the predetermined shape of the trajectory using the minimum curvature method; however, this discontinuity vanishes after the casing is run, and thus the well path becomes smooth. A fundamental flaw to calculate drag force, hook load, stretch, and casing wear using openhole surveys inside the casing is overestimation or underestimation of these values, depending on whether the torque-and-drag model used is soft or stiff string. This paper describes a mathematical formulation that considers flexural and torsional rigidities of casing pipes to estimate the vanishing tortuosity. It also presents research findings concerning the structural shape of wellbore tortuosity when combined with the data-driven approach from measurement while drilling (MWD)/gyroscope data, and an objective approach of smoothing using a new tortuosity calculation method.
Study of Formation Bonding in the Wells of the Varg Field Based on Ultrasonic and Sonic Wireline Log Data
Authors: Noble L. , Vindheim H. , Govil A. , Obando G. , Haga J. , Shams A.
Published: February 2019

This paper is based on the analysis of the ultrasonic/sonic data of the 9 5/8-in. casing logging of the 14 wells of the Varg field within the Norwegian Continental Shelf. While writing this papper Varg field was undergoing a plug and abandonment (P&A) phase after 19 years of production. High-quality bonding is observed behind the 9 5/8-in. casing far above expected theoretical top of cement within single casing areas. This bonding is attributed to the formation influence. Formation is used as an alternative to traditional cement barriers during P&A, and its use is regulated by the legislation.

The paper aims to develop better understanding of the mechanisms responsible for formation bonding development. The percentage of observed bonding at "high" and "high and moderate-to-high" quality is calculated within each well and is related to the various factors that could influence formation bonding development. Factors such as duration of time lapsed from well completion to well logging, type of well (producer versus injector), geological formation, type of drilling mud used, duration of production periods, volumes of production, and well deviation and azimuth were looked at to determine observable trends and relationships.

The results of the study allowed us to conclude which factors are critical or influence formation bonding. Based on the observations, recommendations can be made for the selection of the first well to be logged on the planned P&A campaigns. Correct selection of the first well saves time and resources on the formation testing for the qualification of the formation as a barrier.
Rigless Solutions to Well Intervention with Bismuth and Thermite
Authors: Carragher Paul , Fulks Jeff , McWilliam Gary
Published: February 2019

Excessive water production from oil and gas wells has long been an expensive problem to operators. Effectively shutting off this unwanted water production has been costly and largely ineffective, until now. By using a bismuth-based alloy and a chemical reaction thermite heater, there is an effective, rigless approach to shutting off unwanted water production that is also cost effective.

Previous methods for shutting off unwanted water zones typically involved setting multiple bridge plugs inside the completion. Although this baffled the flow of water, it did not stop it. The challenge was to isolate not only inside the completion, but in the annular space behind the completion to fully stop all water from the zone and do this all without the use of a rig. This has been achieved by melting a bismuth- based alloy with a thermite heater that is run on electric line.
Numerical Modeling and Experimental Validation of Advanced Rotary Shouldered Threaded Connections
Authors: Song Fei , Du Michael H. , Li Ke
Published: February 2019

To mitigate the risk of twistoff during high dogleg-severity (DLS) drilling and to reduce cost of service delivery induced by frequent recuts, an advanced rotary shouldered threaded connection design with significantly enhanced fatigue life over existing API connections has recently been developed and released for field operation. Modeling and simulation techniques had been extensively used to drive the design and qualification processes. In this paper, an overview of the numerical modeling methodology and its experimental validation is presented with an emphasis on the key functional requirements of the design.

The newly developed connection design involves an optimized thread form and an advanced manufacturing process. Finite element analysis (FEA) was heavily used to optimize the design prior to physical prototyping and testing. High-fidelity modeling methods were developed, and comprehensive numerical analyses were performed to digitally evaluate the performance of the new design, including fatigue resistance, galling resistance, combined load capacity, sealability, and so on. The FEA models had very well predicted the performance of the new design, which was later validated through full-scale experimental tests. Several qualification tests, such as torsional yield limit test and tensile capacity test, were carried out completely digitally. As a result of the extensive modeling and simulation work conducted, the connection design met all requirements in one iteration.

The work presented in this paper represents a successful example of model-driven product development, which significantly reduces development time and cost. It is the first time that a high-fidelity modeling methodology, in conjunction with full-scale experimental validation, is introduced for advanced rotary shouldered threaded connections in the oil and gas industry.
Binafuxi Granules in the treatment of common cold with heat syndrome based on traditional Uighur medicine: study protocol for a multicenter randomized controlled trial
Authors: Min Jie , She Bin , Zhang Xin , Mao Bing , Chen Yan
Published: February 2019

Background

Common cold is a highly prevalent illness with significant impact on society and health care. Common cold with heat syndrome (CCHS) is one of most common type based on traditional Uighur medicine (TUM) syndrome differentiation, which is widely used in Central Asia. The study is designed to explore the efficacy, safety and optimal therapeutic dosage of Binafuxi Granules in treating CCHS.

Methods

This is a multicenter, randomized, double-blind, placebo-controlled, phase II clinical trial. A total of 240 patients will be recruited from 5 centers across China and randomly assigned to the high-dose group, low-dose group or placebo control group in a 1:1:1 ratio. All subjects will receive test drugs twice daily for 3 days. The primary outcome is the time to fever relief. Secondary outcomes include the time to fever clearance, duration of primary symptoms and each symptom, change in TUM symptom score.

Discussion

This is the first placebo-controlled randomized clinical trial for a Uighur medicine in treating common cold. It will provide robust evidence on the efficacy and safety of Binafuxi Granules in the treatment of CCHS.

Trial registration

The registration number is ChiCTR-IIR-17013379, which was assigned by the Chinese Clinical Trial Registry on 14 November 2017.
A case report of spontaneously healed isolated posterior inferior cerebellar artery dissection with headache alone
Authors: Kishi Yo
Published: February 2019

Background
Isolated posterior inferior cerebellar artery dissections can cause subarachnoid hemorrhages or infarctions. Surgical treatments for hemorrhagic stroke cases and medical treatments using antithrombotic agents for ischemic stroke cases have been done, whereas there are very few reports on non-stroke posterior inferior cerebellar artery dissections and the treatment strategy for non-stroke cases has not been established. This is the first detailed report on spontaneously healed isolated posterior inferior cerebellar artery dissection with headache alone.
Case presentation
48 years old healthy male felt severe right-side throbbing headache and came to OIKE Clinic on the fourth day after the onset. MRI studies revealed his right posterior inferior cerebellar artery dissection and showed no infarctions or hemorrhages. He was observed carefully under continuous monitoring of blood pressure and hydrated sufficiently, given analgesic anti-inflammatory agents. Two weeks later, the dissected vessel’s diameter grew up to the maximal size, though the patient’s headache was rapidly improved around that day. Surgical treatments for prevention of subarachnoid hemorrhage were considered but careful conservative therapy continued in accordance with the patient’s strong desire. Gradually the dissection finding had been improving. Four months later, MRI study showed his right posterior inferior cerebellar artery was seen almost normal in size and shape.
Conclusions
With the progress of high resolution MRI techniques, iPICAD will be detected more frequently. Further collection and assessment of iPICAD cases will lead to determine the optimal therapeutic strategy for iPICAD with headache alone.
Infant Screening System Based on Cry Analysis
Authors: Mendhakar Akshay M , N Sreedevi , K Arunraj , Shanbal Jayashree C
Published: February 2019

Acoustical investigation of infant cries has been a clinical and research focus in the recent years. Findings of several studies reveal the importance of cry as a useful window for early detection of several diseases and communication difficulties such as hearing impairment, intellectual disabilities, cerebral palsy etc. This motivates us to use a minimal interface system that can automatically classify infant cries into normal and pathological with the help of state-of-the-art machine learning strategies. In this paper, we propose a software program for screening infants based on their cries. The proposed system is able to detect & classify infant cries into normal and pathological based on the acoustic input. To build and train the system, infant cries of normal and Low Birth Weight (LBW) newborn within 7 days of birth were considered. A pain induced cry elicited using the routine intramuscular immunization was recorded using a standard Olympus LS-100 recorder which was held about 10 centimetres away from the infant’s mouth. The acoustic correlates of these cries were used to build the software tool. Artificial Neural Network was employed to improve its functionality. Therefore, we propose a screening tool for further accessibility and large-scale implementation.
Phytominerals and Phytochemical Studies of Azadiracthta indica, Leea guineensis and Parkia biglobosa Leaves
Authors: Awotedu Olamilekan Lanre , Ogunbamowo P. O. , Emmanuel I. B. , Lawal I. O.
Published: February 2019

Medicinal plants have great importance in African medicine and are also used as precursors in drug discovery. The medicinal value of plants lie in their bioactive constituents which usually allow them to fight against several diseases. Plant-based natural constituents can be derived from any part of the plant like bark, leaves, flowers, roots, fruits, seeds. The mineral and phytochemical analysis of the leaves of Azadirachta indica, Parkia biglobosa and Leea guineensis were investigated. The leaves were collected from the Herbal Garden, Forestry Research Institute of Nigeria, Jericho hills, Ibadan, Nigeria and identified at Forest Herbarium Ibadan. Oyo State. The leaves were air dried and milled to powder using a medium-sized milling machine and stored in an air-tight container until needed for analysis. Phytochemical screening/analysis and mineral analysis were determined using standard analytical methods. Phytochemicals like Alkaloids, Flavonoids, Tannins, Saponins, Anthraquinone, Cardiac glycoside were determined. while Minerals, such as Potassium, Sodium determined using flame photometer; Calcium, Phosphorus, Magnesium, Iron, Zinc, Manganese, and Copper were determined using Atomic Absorption Spectrophotometer. Results indicates that the bioactive contents of the leaves varied significantly (p<0.05) among the medicinal plants. The phytochemical analysis showed that the three medicinal plants contained alkaloid, saponins, tannins, flavonoids, polyphenols, cardiac glycoside and anthraquinone in varying quantities with the trend: A indica > P. biglobosa > L. guineensis; the macro elements showed similar trend as the phytochemicals while the micro elements followed the trend: P. biglobosa > L. guineensis > A indica. These results conceivably indicate that the three medicinal plant are good source of essential minerals and phyto-nutrients which possess strong pharmacological activities and provide scientific credence for its therapeutic usage.
The Global Higgs Picture at 27 TeV
Authors: Biekoetter Anke , Gonçalves Dorival , Plehn Tilman , Takeuchi Michihisa , Zerwas Dirk
Published: February 2019

We estimate the reach of global Higgs analyses at a 27 TeV hadron
collider in terms of Higgs couplings and in terms of a gauge-invariant
effective Lagrangian, including invisible Higgs decays and the Higgs
self-coupling. The new collider will indirectly probe new physics in the
TeV range and allow for a meaningful test of the Higgs self-coupling
also embedded in a global analysis.
Central bank impact on practicing Mudarabah financing in Islamic banks: the case of Tanzania
Authors: H. Omar Habiba , E. Yusoff Mohd
Published: February 2019

This paper investigates the challenges faced by Islamic banks in practicing Mudarabah financing under conventional regulatory regime by interviewing eleven Islamic bank managers from three selected banks. Thematic data analysis was employed to understand hindrances for Islamic banks in operating Mudarabah financing under conventional regulatory regime. Findings of the study have provided a number of major challenges that hinder Islamic banks performance in Tanzanian context. The challenges include irregularities of policies and regulations, non-supportive operational and technical structure, and missed perceptions of Mudarabah among the public. However, a new challenge of the impact of the central bank on Islamic banks was identified. It is expected that Tanzanian Islamic banking performance will enhance if the central bank introduces sharia regulations for Islamic banking, initiates the central sharia supervisory board, and harmonize country regulations with financial regulations regarding Islamic perspectives.