bluuebunny/crossref_metadata_2025 huggingface dataset:
BIMWIN SEBAGAI STRATEGI KOMUNIKASI BIMAS ISLAM KABUPATEN PONOROGO DALAM MENCEGAH PERCERAIAN
Authors: Luthfi Mohammad , Rifa’i M.
Published: February 2020

ABSTRACTThis study aims to find out BIMWIN as a communication strategy for the Islamic CommunityGuidance in Ponorogo Regency in preventing divorce. The location of this study was located inthe Islamic Guidance Office of Ponorogo Regency with the research subjects being the Head of theIslamic Guidance Section in Ponorogo Regency, the chief executive of BIMWIN, the facilitator andBIMWIN participants. The method used in this research is a qualitative descriptive approach withdata collection methods through interviews, observation and documentation. The results showedthat in an effort to prevent divorce, the Islamic Community Guidance in Ponorogo Regency carriedout Marriage Guidance activities for prospective bridal partners. The mapping of communicantsis based on the sociological and psychological aspects of the participants. The message deliverystrategy is packaged in the form of lectures and group discussions that focus on participants.The media used are LCD projectors, white boards and the Sakinah Family Foundation book. Thestrategy of selecting communicators is based on aspects of credibility and attractiveness so thatthose who are used as communicators in the implementation of BIMWIN are facilitators who havebeen certified in the field of motivators and sakinah family counselors.Keywords: BIMWIN, Communication Strategy, Divorce.
Aalenian–Lower Bajocian Foraminiferal Fauna from the Ammonitico Rosso Series of Bakonycsernye (Hungary). Part 2: Palaeoecological and Palaeobiogeographical Aspects
Authors: Zsiborás Gábor , Görög Ágnes
Published: February 2020

This paper provides the first assessment of the paleoecology and biogeography of foraminiferal assemblages from the continuous Aalenian–lower Bajocian succession from the pelagic region of the Neotethys. Foraminiferal assemblages were extracted by glacial acetic acid from the Tűzkövesárok section B of Bakonycsernye (Hungary), which is well dated by ammonites and consists of Ammonitico Rosso type limestones. Palaeoenvironmental changes were evaluated based on microfacies studies, taxonomic and palaeoecological analyses (abundance, diversity, morphogroups, and ecozones) of the 49 benthic and one planktic taxa. The grazer-dominated foraminiferal assemblages indicated normal marine salinity and well-oxygenated conditions in a pelagic swell-graben environment below the photic zone. The majority of the foraminifera likely grazed on a biofilm or mat produced by microbes and/or fungi and also may have fed on marine snow. At the Aalenian–Bajocian transition, the decrease in abundance and diversity was linked with a sea-level fall event (JBj1). In the upper Bajocian, dissolution due to deepening resulted in the gradual and selective impoverishment of the fauna. In addition, two biomes, Boreal-Atlantic and Mediterranean, were distinguished within the area of the Boreal-Atlantic-Caucasian Province, based on the review of the coeval faunas.
A Study of the Reeving Efficiency and Inertia of Drawworks
Authors: Kyllingstad Åge
Published: February 2020

The reeving efficiency is a measure of how effectively the drill line and sheaves transfer the drawworks power to the moving external load. The drill line is a steel wire rope having an inherent bending resistance. The internal bending friction is the dominating component of the single sheave efficiency, which is a function of line to sheave diameter ratio, the line tension force, the rope construction type, and the lubricator. The model used here is an empirical two parameter model validated by measurements. Experimental evidence found in the literature strongly suggests that the single sheave efficiency for typical sheaves and loads is around 99.8%. This is much higher than the 96% efficiency suggested by the American Petroleum Institute (2015) in their Recommended Practice 9B.

The paper also discusses the inertia of the drill line and sheaves and presents general models for reeving efficiency and reeving inertia valid for both single and dual drawworks. It also discusses some of the implications of both the friction losses and the inertia effects. One is that systematic errors in the deadline-based hookload can be minimized by applying simple speed and acceleration dependent corrections. Another implication is that the downwards acceleration (or upwards retardation) of the external load must be limited to avoid hazardous situations with fast-line slack.
Intelligent Pipe-Handling: A Case Study for Automation
Authors: Moralez Nathan , Ronquillo Nahum , Lisi Dario , Lynch Michael , Parker Christopher , Sutler John , Machum Matias
Published: February 2020

This paper provides a case study on the successes and challenges with retrofitting tripping automation on two deepwater rigs operating in the Gulf of Mexico. The paper details the approach taken to overcome challenges associated with implementing and adopting automation technology and presents an analysis of key performance indicators that illustrate the success of the project. The paper also presents learnings and recommendations for deploying process automation while discussing some of the remaining challenges to overcome acceptance of automation in the upstream oil and gas drilling industry including implications to human performance.
Automated BOP Testing Technologies Provide Economic Benefits Along with Personal and Process Safety Improvements
Authors: Anderson Mark W. , Hilpert Jeff , Graziano Matthew , Zimpfer Douglas , Boegershausen Sebastian , Kirker Christian
Published: February 2020

In 2013, a technology development project was started that digitized, automated and applied analytics to the blowout preventer (BOP) pressure testing process. At the time it was viewed that BOP testing was a neglected process and could benefit from a technology development project.

As a result of the deployment of automated BOP testing technologies, significant improvements have been achieved in process safety, personal safety and rig time savings. Rig time savings of up to 50% of the BOP testing time have been achieved.

Analog circular pressure chart recorders were replaced with a personal computer (PC) based digital pressure recording software. An automated valve actuation device was developed that can retrofit any API 6A style gate valve. An acoustic detection system for leaking valve identification was developed. A novel method of directly measuring a leak using a linear press pump was trialed that, after additional development work, may supersede the indirect leak measurement of the pressure decay leak testing method.

Future enhancements and development are underway to go beyond BOP testing. These are being developed to cover casing pressure tests, casing inflow tests and completions pressure tests. Also, field trials will commence shortly to apply this technology suite to completion and hydraulic fracturing domains.
Gyro Wellbore Placement Using Advanced Solid-State Sensor Technology
Authors: Ledroz Adrián , Weston John , Moisan James
Published: February 2020

This paper describes the construction of a wellbore that has been drilled using gyroscopic measurements alone to control the path of the well. Wellbores have not been drilled solely using gyroscopes since the early days of oil and gas extraction in the last century, and it is many years since a wellbore has been constructed without the use of magnetic MWD measurements. The exercise described here therefore marks a milestone in the application of downhole gyroscopic technology.

The wellbore development described has been implemented using advanced solid-state gyroscopic sensors based on a new Coriolis vibratory gyroscope (CVG). Recent studies have demonstrated how this new sensor technology has become both a viable and practical option for high accuracy wellbore placement, largely achievable since CVGs are not affected significantly by the high levels of shock and vibration that can be experienced under extreme drilling conditions. The new technology provides an attractive option for while-drilling application, not only as an alternative to conventional gyro while drilling technology but also as a potential replacement for magnetic MWD.

The results presented here illustrate the ability to use the gyroscopic measurements alone to achieve a planned wellbore trajectory. For the purpose of this case study, a post-drilling gyroscopic survey was conducted using a high accuracy gyro tool to verify the accuracy of the while drilling measurements.

The paper sets out the numerous benefits that accrue from the application of CVG technology for the drilling of all types of well. First of all, it allows close proximity well placement in top-hole sections since the gyros are immune to magnetic interference from nearby wells. It also eliminates the need to add a nudge to the wellbore trajectory, a process that normally increases the tortuosity. The need to incorporate non-magnetic drill collars in the tool string is now removed, as well as the need for magnetic models and corrections, both with consequent cost savings. The new survey tool allows measurements to be taken near the bit facilitating more precise well path control. Multiple gyro sensor packages may be run simultaneously, thus providing independent surveys for quality control purposes and greater confidence in the detection of gross error.
Step Changing Safety and Efficiency Gains by Fast Rig Moves, Automated Sequences and Data Processing
Authors: De Mul Arthur , Hooft Daniel , Ziatdinov Sergey
Published: February 2020

In the last years drilling industry is rapidly, changing from mechanized/manual rig solutions to fully automated hands-free remotely controlled drilling operations. This is mainly driven by the strive to achieve consistent high operational speeds.

The automated rig minimizes man's factor on the performance equation. However, new types of operations require new equipment with new requirements. The other main driver is to decrease total well delivery time and costs by reducing or eliminating flat time and improving drilling performance. To meet these significant industry challenges a contractor, together with a rig manufacturer set an ambitious target by introducing automation into the whole drilling process to cut total well cost on 30% for a project where the contractor intends to drill wells with total depth up to 1400 meter.

To reach the target the new rig needs to be extremely mobile, have less personnel, automated pipe and casing handling, smart mud system, automated drilling capabilities, directional drilling through remote operating centers, have next generation digital interface etc. Another great aspect of such automated rig is improved safety by removing people from dangerous areas.

Full automation depends on knowing exactly where the tubular is at each moment of the process. This required a new design for the steelwork to provide sufficient stiffness as well as the right sensor packag

The above resulted in the first onshore system in the industry that provides fully automated tripping (RIH and POOH) and automated casing running, included automated casing connections. The connection time during drilling operations has been reduced by 20-30% in comparison to manual handling.

To reduce the time between rig release and spud on the next well to hours instead days, a trailer-mounted solution is introduced with advanced BOP handling and offline testing.

Further incremental improvements will be made possible by collecting all rig and downhole data on the server and share this via the open source server (OPC-UA). The same server is controlling mud system, downhole data, cementing unit and other important systems. From here the processed data is sent to the cloud based digital eco system, and shared with the back office. Real time setpoints can be submitted back to the rig to adjust the auto driller, enabling maximum drilling speeds. The rif control system will interface with the remote data system from the contractor that enables an interconnected rig fleet that connects all the activity on a rig, end-to-end process automation and advanced QA/QC on all aspects of drilling.

The intention with the new technology is to offer a full section automated well construction service.

Such an integrated design approach, rather than adding sensors to existing steel, enables the biggest time and cost savings and is a game changer for the complete well delivery process
BHA Lateral Vibration Chatter Impedes Application of Weight to Bit
Authors: Bailey Jeffrey R , Lathi Harshit , Tenny Matthew J. , Payette Gregory S. , Wang Lei
Published: February 2020

Lateral vibration modeling of certain BHA (bottomhole assembly) designs has shown great sensitivity to the proximity of stabilizer blades. In a previous paper, the BHA chatter vibration mode was presented, including the basic theory and three field examples. In each case, lower drilling rates were associated with higher levels of BHA dynamic dysfunction as determined using a lateral vibration model. One case clearly illustrated a reduction in effective weight applied to the bit, determined using bit dull grade results. This paper will further explore the mechanisms in which BHA dynamic contact forces can act to reduce the effective weight on bit.

The contact forces that push a stabilizer blade to be constrained within a borehole include both static and dynamic components. The dynamic forces are difficult to visualize as they are generated by the BHA in motion, and a well-formulated dynamic model is required to evaluate these forces. In drilling, we simply see the effects as worn and damaged drillstring components.

A frequency-domain BHA lateral vibration model represents lateral vibration flexural waves propagating in the BHA. This model can be used to calculate dynamic side forces acting at stabilizer and LWD tool blade contacts with the borehole for reference excitation forces. These contact forces may be strong functions of rotary speed and BHA contact spacing, and they typically create a non-trivial level of residual drag that impedes getting weight to bit.

The physics of dynamic contact forces are similar in some respects to static contact forces. Superposition of the dynamic modes illustrate that, although an individual component may vanish momentarily, additional modes and phases can constructively combine such that the total force summation does not vanish. The net result is that dynamic forces can generate significant lateral forces that are similar to static contact forces.

Static effects are known to impede application of weight to bit in deviated and horizontal wells, and small ledges can prevent a stabilizer blade from moving forward. Dynamic effects from improper stabilizer placement are potent sources of lateral dysfunction that can have a similar effect. BHA dynamics have the potential to both create borehole irregularities and resist forward motion resulting from contact forces between drilling tools and the borehole.
Plume Analysis Establishes Safe Work Zone and Confirms Well-Access for Subsea Capping Equipment Installation
Authors: Godse Uday , Gill Alistair
Published: February 2020

The scope of this paper is to present the benefits of incorporating plume analysis studies into source control emergency response planning (SCERP) and preparations, prior to a blowout event. By using modeling and engineering analysis as part of the SCERP, plume studies can improve the likelihood of successful capping stack installation efforts during a blowout.

A blowout is a low probability but potentially high impact event that could occur during any well's life. Immediate action is required to bring the well back under control and minimize the consequences. Protocols for dealing with a blowout are usually outlined in an emergency response plan (ERP) developed ahead of time. In the case of subsea wells, a subset of an ERP is a source control emergency response plan (SCERP) focused on how to halt the flow of hydrocarbons from the well. As described by the International Association of Oil and Gas Producers (IOGP) planning guide published in January 2019, multiple engineering assessments are recommended in support of the SCERP, including plume studies. Generally, Computational Fluid Dynamics (CFD) or similar tools are used to carry out the plume studies. Plume studies model the subsea release, comprised of hydrocarbons (oil and/or gas) and water, and track the dispersion of the hydrocarbons from the seabed through the water column to the sea surface. The surface concentrations of hydrocarbons pose a flammable threat above the water surface and hence, are a threat to the response teams. The plume modelling also identifies whether vertical well access is compromised; an important consideration for capping stack installation. Further, interaction between the blowout flow and the capping stack during its installation can complicate and threaten a successful intervention. The subsea plume studies can also examine such interaction.

Multiple case studies from wells throughout the world, along with the plume studies performed to support the SCERP, will be presented. The state-of-the-art techniques including models to cater for turbulence effects, gas bubble and liquid droplet break-up and coalescence, gas dissolution, hydrate formation and dynamic fluid-body interactions used within the CFD analyses will be outlined.

Current CFD techniques to model plume studies demonstrating the adequacies as well as challenges will be presented. Wherever possible, how the numerical predictions compare to measured data will be highlighted.
Capturing Stick-Slip in the Lab Using Hardware-in-the-Loop
Authors: Panayirci H. Murat , Robinson Andrew , Scott David , Skoff Greg
Published: February 2020

Stick-slip is a torsional vibration mode observed in drilling systems, which are used in creating boreholes for the exploration and production of oil and natural gas. This paper presents a method to create and assess stick-slip in the laboratory environment. This is achieved by using the hardware-in-the-loop method, where a numerical drillstring model is combined with an experimental drilling machine. In this setup, the numerical model captures the axial and torsional oscillations between the surface and the drill bit, while the drilling machine acts as the hardware in the loop, capturing the actual bit-rock interaction. The proposed framework allows creating self-excited stick-slip oscillations in a controlled, repeatable and measurable manner. This enables reducing the risk, cost, and time for activities related to testing, developing, debugging or optimizing any stick-slip related tool or mitigation concept.
Identification and Mitigation of Friction- and Cutting Action-Induced Stick-Slip Vibrations with PDC Bits
Authors: Chen Shilin , Wisinger John , Dunbar Brad , Propes Chris
Published: February 2020

This paper provides some new insights into stick-slip vibration in drilling with polycrystalline diamond compact (PDC) bits. Fifty-six field runs under various drilling conditions were collected with the help of on-bit vibration sensors. Stick-slip vibration occurrence during drilling was analyzed. Two types of stick-slip vibrations were identified: cutting action-induced stick-slip and friction-induced stick-slip. Methods were developed to determine whether a stick-slip occurrence is induced by cutting action or by friction. Statistical analysis found that bit drilling efficiency is well correlated with the occurrence of cutting action-induced bit stick-slip vibration. If a PDC bit is designed so that its drilling efficiency is greater than a critical value, then the cutting action-induced bit stick-slip vibration is not expected in drilling. Increasing the aggressiveness of the cutting structure of a PDC bit within a limited critical depth of cut is found to be helpful to mitigate bit stick-slip vibration.
Automating Tubular-Running Operations to Increase Rig Efficiency
Authors: Amezaga Federico , Cummins Tracy , Hooker John
Published: February 2020

Rig efficiency is essential to success in oil and gas operations. Innovative solutions such as automation help to reduce operating costs and minimize safety hazards, which improve efficiency. Traditional tubular-running operations require extensive manual intervention with increased red-zone exposure, especially during equipment rig up and rig down. Equipment interfaces between different manufacturers are often not existing or poorly designed, which can reduce productivity. Automated processes with open interfaces in tubular-running operations would significantly improve rig efficiencies and safety.

Drilling and casing plans include multiple strings, various connection types with different torque requirements, and a variety of hydraulic power tongs. Newly developed, intelligent positioning devices with hands-free, automatic multi-couplers for power and data transfer enable fast, simple, and safe rig up and rig down of tong modules with the push of a button. With a state-of-the-art control system, equipped with an open interface to connect tong modules, it is now possible to eliminate manual intervention. Automatic module identification eliminates manual data entry, removes the human factor, and saves set-up time and therefore valuable rig time.

Automated tubular-running processes provide a wide range of benefits from an operational, safety, and financial standpoint for both drilling contractors and operators. Full rig-control-system integration, along with intelligent positioning devices, maximize advantages by reducing the personnel required to operate equipment during the construction of the well. Automation eliminates time-consuming and dangerous equipment handling on the rig floor and helps to implement a new set of operational and safety standards. Rig up and rig down time is significantly reduced by up to 90%-time compared to conventional tool-handling operations. Fully automated sequences using new generation positioning devices considerably improve well construction running times and minimize potential safety incidents.

Implementing cutting-edge technology with improved rig-control systems integration to automate tubular-running processes increases the potential to bring rig efficiencies to a higher operational level.
Simplifying Well Abandonments Using Shale as a Barrier
Authors: van Oort Eric , Juenger Maria , Aldin Munir , Thombare Akshay , McDonald Mike
Published: February 2020

Well abandonment is one of the biggest challenges in the oil and gas industry, both in terms of cost and effort as well as the technical hurdles associated with wellbore isolation for an indefinite term. A mechanism that may be exploited to simplify well abandonments is using natural shale formations for the creation of annular barriers. Currently, uncemented annuli often require casing milling and pulling before abandonment plugs can be set, which necessitates the use of a drilling rig. This is an expensive, time- and labor-intensive process, particularly offshore. However, shale creep may naturally form a barrier behind uncemented casing sections. With a qualified annular shale barrier in place, the well may only require the setting of abandonment plugs within the existing casing string(s), a task that can often be done rigless and with significantly less effort.

The work described in this paper presents the results of a rock mechanical investigation into the creep behavior of North Sea shales and their ability to form effective annular barriers. Field core from the Lark-Horda shale was used to conduct dedicated, customized experiments that simulated the behavior of shale confined under downhole effective stress, pressure and temperature conditions to fill in an annular space behind a simulated casing string. Full scale tri-axial rock mechanics equipment was used for testing cylindrical shale samples obtained from well-preserved field core in a set-up that mimicked an uncemented casing section of a well. The deformation behavior of the shale was monitored for days to weeks, and the formation of the annular barrier was characterized using dedicated strain measurements and pressure pulse decay probing of the annular space.

The large-scale lab results clearly show that the Lark-Horda shales will form competent low permeability annular barriers when left uncemented, as confirmed using pressure-pulse decay measurements. They also show that experimental conditions influence the rate of barrier formation: higher effective stress, higher temperature and beneficial manipulation of the annular fluid chemistry all have a significant effect. This then opens up the possibility of activating shale formations that do not naturally create barriers by themselves into forming them, e.g. by exposing them to low annular pressure, elevated temperature, different annular fluid chemistry, or a combination. The results are in very good agreement with field observations reported earlier by several North Sea operators.
Low-Density Invert Emulsion Drilling Fluid Enables Recovery of Oil Reserves in Extremely Depleted Reservoirs: A Case History From Valhall, Norway
Authors: Askø Arne , Alsvik Eva Teresia , Danielsen Trond Helge , Haga Marton Audun
Published: February 2020

A drilling fluid designed for drilling long horizontal wells in extremely depleted chalk reservoirs within the limitations of a narrow mud weight window, high overbalance, high solids contamination and static periods was successfully implemented when drilling a water injection well on Valhall Flank North in the southern Norwegian Continental Shelf.

In parts of the Valhall reservoir the depletion is estimated to 313 bar (4500 psi). The estimated pressure gradients in the planned trajectory were pore pressures between 0.64 sg and 0.70 sg (5.3 ppg to 5.8 ppg) and with a corresponding fracture gradient of 0.95 sg (7.9 ppg). These conditions required a drilling fluid which could be maintained at a density as low as 0.78 sg (6.5 ppg) combined with a low viscosity, strict fluid loss control, tolerance towards contamination of chalk and high stability. No conventional drilling fluid would provide a sufficiently low density to drill this section, thus an unconventional solution had to be found. The proposed solution was to add hollow glass spheres (HGS) rated to withstand pressures up to 1310 bar (19,000 psi) to reduce the density of a conventional fluid. However, previous experience using HGS as an additive in drilling fluid was limited. Therefore, the design and qualification of this drilling fluid had to be conducted both in the laboratory as well as on a larger scale yard-trial.

Laboratory testing and the yard trial verified the feasibility of mixing the HGS in a large-scale production and confirmed their ability to withstand the expected downhole pressure and mechanical strain while drilling. The 1750 m (5740 ft) 8.5" injection well on Valhall Flank North was drilled in one run, with no drilling fluid-related problems. The drilling fluid density was maintained between 0.78 sg (6.5 ppg) and 0.85 sg (7.1 ppg) while the maximum measured equivalent circulation density (ECD) increased from 0.83 sg (6.9 ppg) at start of the section, to 0.96 sg (8.0 ppg) at section TD.

Completing this well was resulted in an increase of 7.5 mmboe recoverable oil demonstrating that implementing HGS in drilling fluids provides an expanded operational envelope and access to so far inaccessible oil reserves.
Early Identification of Drilling Collision Risk Using MWD Survey Quality Data
Authors: Cosca Nicolas , Willerth Marc
Published: February 2020

By identifying changes in the error characteristics of magnetic surveys while drilling, crews can be alerted early on to a potential close approach with an offset well. This alert does not require expert analysis prior to trigger, enabling safer deployment of remote monitoring and drilling automation systems.

That magnetic interference can be used to identify offset wells has been long known, however identification of the interference pattern is not always straightforward. Safe operation in close-approach situations currently requires proactive monitoring by an expert. This new method uses a conditional expectation of survey quality parameters ("marginal sigma") trained on previously accepted surveys to identify new errors. Quality control data from several wells with known close approaches are analyzed with this technique alongside traditional survey quality assessments. Automatic flagging of high-risk surveys for review would enable proactive monitoring workflows to be replaced with "management by exception" workflows making more efficient use of expertise.

Survey quality data from several close approach scenarios were analyzed using traditional QC methods along with the marginal sigma method. Traditional QC measures are not readily adapted to automated identification of offset wells. Problematic situations include cases where:

Surveys are already failing QC for a known reason, External interference temporarily improving QC data masks the problem, The onset of interference is too small to cause an immediate QC failure.

In light of this, traditional QC parameters still require proactive monitoring by an expert individual. Using the marginal sigma estimation, even small changes in magnetic measurement patterns are identified and escalated for review. These changes are often detected with even a single outlier survey, implying that escalation would occur as quickly as with the most vigilant observer. This system would be of particular value in situations where a limited number of experts are used to oversee a high volume of work, such as remote monitoring in North America Land, or in the future, supervising autonomous drilling systems.

The proposed system changes the drilling supervision requirements for what has previously been a high-risk scenario (collision avoidance drilling). Proactive monitoring by an expert can be safely transitioned to a "management by exception" system enabling better utilization of resources.
Wellbore Integrity During Blowouts: Broaching Prevention and Control
Authors: Michael Andreas , Gupta Ipsita
Published: February 2020

During loss of well control events, fracture initiation occurring during the post-blowout capping stage following uncontrolled discharge, can lead to reservoir fluids broaching to the seafloor. A classic example is Union Oil's 1969 oil spill in Santa Barbara channel, where fracture initiation at various locations caused thousands of gallons per hour to broach in the ocean floor over a period of a month before it could be controlled (Mullineaux, 1970; Easton, 1972). The impacts on California's oil industry are still felt strongly today. Disasters as such could be prevented if the effects of the post-blowout loss of well control stages (uncontrolled discharge and capping) are incorporated into the shut-n procedures and the wellbore architecture.

Analytical models are used to simulate the loads on the wellbore in the different stages during loss of control and predict capping pressure build-up during the shut-in to indicate fracture initiation during the capping stage. Using these models, critical capping pressure and subsequently critical discharge flowrates is calculated for a well below which fracture initiation would occur. A hypothetical case study with typical deepwater Gulf of Mexico parameters is performed demonstrating the likelihood of fracture initiation during different discharge flowrates, discharge periods and shut-in methods (abrupt/"hard" or multi-stage/"soft"). Further discussion addresses reservoir depletion during the discharge stage preceding the capping, as well as the conditions necessary for upward propagation of these fractures towards the seafloor. Through these fractures fluids from the reservoir ultimately broach into the seawater.

The ability to model these fracture failures will enhance the understanding of wellbore integrity problems induced during loss of control situations and create workflows for predicting possible broaching happening during the post-blowout capping stage early on. Dimensionless plots are used to present fracture initiation for different scenarios useful for drilling and wellbore integrity engineers when making contingency plans for dealing with loss of well control situations.
A New Look at Elastic Collapse
Authors: Mitchell Robert
Published: February 2020

Elastic collapse is an important piece of the tubular collapse formulation in API TR 5C3 and ISO 10400. Elastic collapse is significant because it is independent of the strength of the tubing, e.g. K-55 and Q-125 have the same resistance to elastic collapse. Advanced collapse models, such as Klever (2006), require a thick-wall collapse result as part of their formulation.

What would the effect of a thick-wall have on elastic collapse? There really is no way to tell from the classic formulation. What is needed is a formulation that is based on an elastic solution for a thick-wall cylinder, but that can derive the classic solution for a thin-wall.

The elastic equations for a thick-walled cylinder exist, known as the Kirsch equations. This elastic solution was expanded in a series as a function of t/D. Using terms of order t/D only, the boundary conditions were set, and balance of moments yielded the classical result. This shows that the Kirsch equation is a valid starting point for a thick-wall collapse result.

A new set of physically reasonable boundary conditions was proposed for the Kirsch equation, which were then used to determine the collapse resistance for thick-wall pipe. This result also yielded the classic result in the limit as t/D is small.
Analysis of Torsional Stick-Slip Situations Observed with Downhole High-Frequency Magnetometer Data
Authors: Cayeux Eric , Ambrus Adrian , Øy Lars , Helleland Arvid , Brundtland Svein Tore , Nevøy Harald
Published: February 2020

The use of downhole rotational speed measurements made at 300Hz gives new insight into the conditions under which stick-slip torsional oscillations occur. Observations made with high-frequency magnetometers while drilling two reservoir sections have shown, that for these wellbores, using top-drive speeds below 140rpm leads to severe downhole torsional oscillations, also in off-bottom conditions. Additionally, it was observed that downlinking the rotary steerable system (RSS) initiated heavy stick-slip and that reaming downward had a negative damping effect on downhole torsional stability.

These observations have been compared and partly matched with estimations made with a transient hydro-mechanical model. Some ill-defined information had to be estimated, like the amount of flow diversion during the downlinking procedure, the coefficients of static and kinetic friction along the borehole, or the bit efficiency and aggressivity.

Downhole measurements have shown that when the drill-string is subject to strong stick-slip conditions, the downhole rotational speed changes from stationary to more than 400rpm in just a fraction of a second. It is therefore important to utilize sampling rates that are compatible with such very fast events. In practice, that means several hundred Hertz.

A challenge associated with analysis of downhole high frequency data is time synchronization and drift of clocks between the surface and downhole measurements. After time synchronization and correction, it appears that the downhole rotational movement is delayed by several tens of seconds compared to the actual top-drive speed. This leads to question whether rotating the drill-string off-bottom, typically done in order to break gelled-up mud prior to establishing circulation, has any significant the intended effects deviated wells as torque along the drill-string must be built up.

Direct observations of downhole rotational speed at high frequency help in discovering conditions that were not suspected to lead to large torsional oscillations. This new information can be used to improve drilling operational procedures and models of the drilling process, therefore enabling increased drilling efficiency.
Digital Twins for Drilling Fluids: Advances and Opportunities
Authors: Shirangi Mehrdad G , Ettehadi Reza , Aragall Roger , Furlong Edward , May Roland , Dahl Thomas , Samnejad Mahshad , Thompson Charles
Published: February 2020

In this work, we present our unique technology to develop and apply digital twins for drilling fluids and associated wellbore phenomena during drilling operations. A drilling fluid digital twin is a series of interconnected models that incorporate the learning from geological uncertainty, complexity of drilling fluids and operational parameters to support well planning and real-time operations. We transform data collected throughout the years from all aspects of drilling fluids to value-added applications and include real-world conditions such as operation at extended temperatures and pressures, consideration for sensitive zones with tight control of the equivalent circulating density (ECD), and hole cleaning in deviated wellbores. With the advances presented in this work, cuttings bed height along the wellbore can be determined more accurately, and hence the ‘fluid plan’ together with operational parameters (such as mud flow rate and rate of penetration (ROP)) can be optimized to a higher level. In addition to the cuttings bed, an accurate workflow for monitoring of downhole fluid rheological properties at the rigsite is developed. Through the use of a digital twin, accurate high-pressure high-temperature (HPHT) properties can be determined at the rigsite, which can more easily enable efficient and safe operations, as opposed to lab experiments that are often conducted remotely. We demonstrate the application of automated machine learning (autoML) to represent computational simulations and lab experiments. We also use test datasets and rotating cross-validation methods to ensure accurate and robust results. In both cases, very accurate models were obtained, and point the way for the inclusion of more aspects of the drilling operation including ROP optimization, fluid-loss control, drilling fluid properties management, and power transmission.
Simulation of Immiscible Water-Alternating-Gas Injection in a Stratified Reservoir: Performance Characterization Using a New Dimensionless Number
Authors: Nygård Jan Inge , Andersen Pål Østebø
Published: February 2020

Water alternating gas (WAG) is a well-established enhanced-oil-recovery process where gas and water are injected in alternating fashion. Good volumetric sweep is achieved as water and gas target both the oil residing in low and high portions of the reservoir, respectively. Other important features in three-phase hysteretic flow include phase trapping, which is believed to be more strongly associated with the gas phase. With these aspects in mind, a vast simulation study has been performed investigating immiscible WAG injection focusing on mechanisms such as mobility, gravity, injected volume fractions, reservoir heterogeneity, gas entrapment, and relative permeability hysteresis.

The aim of our work is to investigate the interplay between these mechanisms for a model system with sufficient complexity to be of relevance and then scale recovery performance using a new dimensionless number that incorporates the relevant model input parameters. A horizontally layered reservoir is considered where oil is displaced by water and gas alternately injected toward a producer. The model is a modified black-oil type, where hysteresis in the gas phase is modeled using the Land (1968) model for trapping and the Carlson (1981) model for relative permeability hysteresis. It is seen that gravity segregation in uniform models and increased heterogeneity in no-gravity models both lead to lower oil recovery. However, in heterogeneous models, gravity can divert flow from high-permeability layers into low-permeability layers and improve recovery. Hysteresis lowers gas mobility and hence improves gas/oil mobility ratio and reduces gravity segregation. The first effect is always positive, but the second is mainly positive in more uniform reservoirs where gravity segregation has a negative effect on recovery. In heterogeneous reservoirs, reducing gravity segregation can lead to the oil in low-permeability layers remaining unswept.

The newly derived characteristic dimensionless number is effectively a WAG mobility ratio, termed M*, expressing how well the injected-fluid mixture is able to displace oil, whether it is because of fluid mobilities, heterogeneity, or other effects. At a value of M* near unity, optimal recovery is achieved, whereas logarithmic increase of M* reduces recovery.
Prevalence and risk factors of chronic kidney disease and diabetic kidney disease in a central Chinese urban population: a cross-sectional survey
Authors: Duan Jiayu , Duan Guang-Cai , Wang Chong-Jian , Liu Dong-Wei , Qiao Ying-Jin , Pan Shao-Kang , Jiang Deng-Ke , Liu Yong , Zhao Zi-Hao , Liang Lu-Lu , Tian Fei , Liu Zhang-Suo
Published: February 2020

Background : This study was conducted to evaluate and update the current prevalence of and risk factors for chronic kidney disease (CKD) and diabetic kidney disease (DKD) in China.
Methods : From December 2017 to June 2018, a total of 5231 subjects were randomly enrolled from 3 communities in 3 districts of Zhengzhou. CKD was defined as estimated glomerular filtration rate (eGFR) < 60 mL/min.1.73m 2 or urinary albumin to creatinine ratio ≥ 30 mg/g (albuminuria). Diabetic subjects with systolic blood blood pressure > 140 mmHg, albuminuria or an eGFR less than 60 mL/min/1.73 m 2 were classified as having DKD. Participants completed a questionnaire assessing lifestyle and relevant medical history, and blood and urine specimens were taken. Serum creatinine, uric acid, total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein and urinary albumin were assessed. The age- and sex-adjusted prevalences of CKD and DKD were calculated, and risk factors associated with the presence of reduced eGFR, albuminuria, DKD, severity of albuminuria and progression of reduced renal function were analyzed by binary and ordinal logistic regression.
Results : The overall adjusted prevalence of CKD was 16.8% (15.8 – 17.8%) and that of DKD was 3.5% (3.0 – 4.0%). Decreased renal function was detected in 132 participants (2.9%, 95% confidence interval [CI]: 2.5 – 3.2%), whereas albuminuria was found in 858 participants (14.9%, 95% CI: 13.9 – 15.9%). In all participants with diabetes, the prevalence of reduced eGFR was 6.3% (95% CI = 3.9 – 8.6%) and that of albuminuria was 45.3% (95% CI = 40.4 – 50.1%). The overall prevalence of CKD in participants with diabetes was 48.0% (95% CI = 43.1 – 52.9%). The results of the binary and ordinal logistic regression indicated that the factors independently associated with a higher risk of reduced eGFR and albuminuria were older age, sex, smoking, alcohol consumption, overweight, obesity, diabetes, hypertension, dyslipidemia and hyperuricemia.
Conclusions : Our study shows the current prevalence of CKD and DKD in residents of Central China. The high prevalence suggests an urgent need to implement interventions to relieve the high burden of CKD and DKD in China.
Assessing the training needs of medical students in patient information gathering; a qualitative study
Authors: Gilligan Conor , Brubacher Sonja , Powell Martine
Published: February 2020

Background Effective communication is at the heart of good medical practice but rates of error, patient complaints, and poor clinician job satisfaction are suggestive of room for improvement in this component of medical practice and education. Methods We conducted semi-structured interviews with experienced clinicians (n = 19) and medical students (n = 20) to explore their experiences associated with teaching and learning clinical communication skills and identify targets for improvements to addressing these skills in medical curricula. Results Interviews were thematically analysed and four key themes emerged; the importance of experience, the value of role-models, the structure of a consultation, and confidence. Conclusions The findings reinforce the need for improvement in teaching and learning communication skills in medicine, with particular opportunity to target approaches to teaching foundational skills which can establish a strong grounding before moving into more complex situations, thus preparing students for the flexibility required in medical interviewing. A second area of opportunity and need is in the engagement and training of clinicians as mentors and teachers, with the findings from both groups indicating that preparation for teaching and feedback is lacking. Medical programs can improve their teaching of communication skills and could learn from other fields s to identify applicable innovative approaches.
Light Enhanced Cognitive Behavioural Therapy (CBT+) for Sleep and Fatigue: Study Protocol for a Randomized Controlled Trial during Chemotherapy for Breast Cancer
Authors: Bean Helena Rose , Stafford Lesley , Little Ruth , Diggens Justine , Ftanou Maria , Alexander Marliese , Francis Prudence A , Bei Bei , Wiley Joshua F
Published: February 2020

Background: Women with breast cancer experience a significantly higher prevalence of sleep disturbances and insomnia compared with the general population. The experience of persistent sleep disturbance places these women at a higher risk of psychological and physical morbidity and a reduced quality of life. Treatment of sleep in this population is not part of routine care, and often is managed inadequately. This randomised controlled trial will examine the combined effects of Cognitive Behavioural Therapy (CBT) and bright light therapy (BLT) on the symptoms of insomnia, fatigue, and mental health.

Method/design: Women diagnosed with breast cancer who receive intravenous chemotherapy treatment at a quaternary referral metropolitan cancer centre in Melbourne Australia will be recruited. Recruitment will occur after diagnosis and prior to completion of chemotherapy. Eligible women will be randomised to the combined CBT and BLT intervention (CBT+) or relaxation audio enhanced treatment as usual (TAU+). The CBT+ group will receive one face-to-face session on sleep strategies, one subsequent telephone call, and seven email packages containing CBT-based information and strategies. CBT+ participants will also wear Luminette® light glasses for 20 minutes each morning for the six-week duration of the intervention. Women in TAU+ will receive two relaxation audio tracks via email. Outcomes will be measured at multiple points throughout the six weeks. Primary outcomes will be symptoms of insomnia and sleep efficiency, measured using the Insomnia Severity Index and a self-reported sleep diary. Secondary outcomes include objective measures of sleep assessed using the ActiGraph wGT3X-BT; and sleep-related complaints, fatigue and mental health, all assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) measure. Data will also be collected on potential treatment moderators and mechanisms, and adherence to treatment. There will be three-month follow-up measurements of fatigue, sleep-related impairment, sleep disturbance, depression, and anxiety.

Discussion: This is the first randomised controlled trial to combine CBT and BLT for the treatment of sleep disturbances in women with breast cancer. This novel design addresses the multiple causal factors for sleep complaints in this population. Results from this trial will advance knowledge in this field and may have important clinical implications for how best to treat sleep disturbance and insomnia in this population. If effective, the largely email-based format of the intervention would allow for relatively easy translation.

Trial Registration: Australian New Zealand Clinical Trials Registry (ANZCTR), Registration number: ACTRN12618001255279. Retrospectively registered on: 25/07/2018, recruitment began: 24/07/2018.