bluuebunny/crossref_metadata_2025 huggingface dataset:
Co-Sleeping and Bed Sharing in Australian Maternity Units: An Electronic Survey of Midwifery Clinicians’ Knowledge, Practice, and Education
Authors: Drever-Smith Cassia , Bogossian Fiona , New Karen
Published: March 2015

BACKGROUND: There is little published research regarding co-sleeping and bed sharing in maternity units. As primary carers of mothers and infants, midwives’ knowledge and practice may influence co-sleeping and bed sharing.

AIM: To assess clinical midwives’ knowledge and practice surrounding co-sleeping and bed sharing in maternity units in the initial postpartum period.

METHODS: A nationwide electronic survey assessed clinical knowledge and self-reported clinical practice and personal experiences of co-sleeping and bed sharing.

FINDINGS: Eighty-six registered midwives from 48 hospitals responded to the survey. The majority responded with best practice to hypothetical scenarios. Mother–infant co-sleeping/bed sharing in maternity units was observed by 64% of midwives. All midwives reported providing some education to parents and most (80%) had received education on co-sleeping/bed sharing.

CONCLUSION: Co-sleeping and bed sharing are relatively common in postnatal maternity units. Clinical practice documents should be consistent with the UNICEF guidelines, and midwives should be supported to implement best practice.
An Atlas of Mars Sedimentary Rocks as seen by HIRISE
Authors: Beyer Ross A. , Stack Kathryn M. , Griffes Jennifer L. , Milliken Ralph E. , Herkenhoff Ken E. , Byrne Shane , Holt John W. , Grotzinger John P.
Published: March 2015

Images of distant and unknown places have long stimulated the imaginations of both explorers and scientists. The atlas of photographs collected during the Hayden (1872) expedition to the Yellowstone region was essential to its successful advocacy and selection in 1872 as America’s first national park. Photographer William Henry Jackson of the Hayden expedition captured the public’s imagination and support, returning home with a treasure of images that confirmed the existence of western landmarks previously regarded as glorified myths: the Grand Tetons, Old Faithful, and strange pools of boiling hot mud. Fifty years later, photographer Ansel Adams began his long legacy of providing the public with compilations of iconic images of natural wonders that many only see in prints.

Photography in space has provided its own bounty. Who can forget the first image of Earthrise taken by astronaut William Anders in 1968 from Apollo 8; the solemnity of the first photos of the surface of the Moon from the Apollo 11 astronauts; and the startling discovery of the tallest mountain in the solar system (Olympus Mons) on the surface of Mars in images sent from Mariner 9? The images from Mariner 9 also allowed for a game-changing discovery. Earlier, based on very limited Mariner 4 data that covered less than 10% of the planet’s surface, Chapman et al. (1968) speculated that “If substantial aqueous erosion features—such as river valleys— were produced during earlier epochs of Mars, we should not expect any trace of them to be visible
Source-to-Sink
Authors: Kocurek Gary , Ewing Ryan C.
Published: March 2015

Eolian dune fields on Earth and Mars evolve as complex systems within a set of boundary conditions. A source-to-sink comparison indicates that although differences exist in sediment production and transport, the systems largely converge at the dune-flow and pattern-development levels, but again differ in modes of accumulation and preservation. On Earth, where winds frequently exceed threshold speeds, dune fields are sourced primarily through deflation of subaqueous deposits as these sediments become available for transport. Limited weathering, widespread permafrost, and the low-density atmosphere on Mars imply that sediment production, sediment availability, and sand-transporting winds are all episodic. Possible sediment sources include relict sediments from the wetter Noachian; slow physical weathering in a cold, water-limited environment; and episodic sediment production associated with climatic cycles, outflow events, and impacts. Similarities in dune morphology, secondary airflow patterns over the dunes, and pattern evolution through dune interactions imply that dune stratification and bounding surfaces on Mars are comparable to those on Earth, an observation supported by outcrops of the Burns formation. The accumulation of eolian deposits occurs on Earth through the dynamics of dry, wet, and stabilizing eolian systems. Dry-system accumulation by flow deceleration into topographic basins has occurred throughout Martian history, whereas wet-system accumulation with a rising capillary fringe is restricted to Noachian times. The greatest difference in accumulation occurs with stabilizing systems, as manifested by the north polar Planum Boreum cavi unit, where accumulation has occurred through stabilization by permafrost development. Preservation of eolian accumulations on Earth typically occurs by sediment burial within subsiding basins or a relative rise of the water table or sea level. Preservation on Mars, measured as the generation of a stratigraphic record and not time, has an Earth analog with infill of impact-created and other basins, but differs with the cavi unit, where preservation is by burial beneath layered ice with a climatic driver.
Application of Lean Principles to Accelerate Project Development
Authors: Tønnessen Roger , Byrnes Richard , Franco Miguel , Romaine Keith
Published: March 2015

Oil and gas project development in the North Sea is known for large discoveries, requiring the need for highly complex, capital intensive infrastructure, which can take decades to complete. Recognizing that such discoveries were becoming less common, a faster and less capital intensive approach was needed to develop smaller fields. The idea was to target fields close to existing infrastructure that could tie back to current installations and only require a seabed template. Historically, these types of projects would take the company over five years to complete. A dedicated team was established to plan these smaller projects, appropriately called “Fast Track” projects, and was challenged with cutting development time in half.

The Fast Track team used lean principles to analyze project lead times and target improvement opportunities. Lean is a methodology made famous in automotive manufacturing, which seeks to eliminate time wasting activities and reduce overall lead time (De Wardt 1994). The primary lean technique employed by the team was value stream mapping. First, the team mapped out the entire project development process, from discovery to production, and identified all the key steps in the process. Second, the team estimated the time it takes to perform each major step in the process and calculated the total lead time for project development. Finally, the team quantified all the sources of delays and developed opportunities for improvement. These opportunities were then ranked based on the potential time and cost savings. With the prioritized opportunities, an improvement road map was developed to steer the team in the right direction.

The improvement road map contained a four-pronged approach to cut project development times in half: StandardizationCollaborationStreamlined processesChange management

Standardization involved developing standard subsea templates, well designs, and completions equipment to cut the time to develop solutions. Collaboration involved integrating the operator and the service company and making use of teams in different time zones to accelerate well design and planning. Streamlined processes focused on combining decision gates in capital projects and working the well construction process in parallel to the project development process to reduce planning time. Finally, change management involved establishing a continuous improvement process, a system to implement ideas and engrain them into the organization, and a common set of key performance indicators to align different stakeholders and drive execution results.

Implementation of these improvement opportunities led to a reduction of over two years in the time needed to complete the development projects: from 5.3 years to an average of three years.
'Engineering' Design of Lost Circulation Materials (LCMs) is More than Adding a Word
Authors: Savari Sharath , Kulkarni Sandeep D. , Whitfill Donald L. , Jamison Dale E.
Published: March 2015

Curing lost circulation, one of the greatest contributors to drilling non-productive time (NPT), predominately has been addressed by applying particulate lost circulation materials (LCMs) into drilling fluids. Selection of LCM combinations has largely been based on experience and driven by the availability of inexpensive materials on location. With respect to lost circulation control, little time has been invested into engineering the LCM design and the subsequent effect on rheology and suspension properties of the drilling fluid. Also, little to no information is published regarding methods or guidelines for designing LCMs for lost circulation applications.

Continuing the effort for better lost circulation treatment design, a holistic engineered approach to designing LCMs for mitigating lost circulation is discussed. Depending on the type of flow path (e.g., formation pores and natural or induced fractures), engineering methods and models are presented for the selection of LCM combinations with an appropriate particle-size distribution (PSD) capable of efficient fracture plugging. Models to estimate the effects of LCM addition on drilling fluid rheology and equivalent circulating densities (ECDs) are presented. For some applications, it is critical to have the LCMs suspended properly in the drilling fluid. A unique LCM suspension model is presented that estimates the optimum drilling fluid rheology required for proper suspension. This model is capable of accommodating any changes in drilling fluid density as well as LCM density, size, or concentration.

This holistic engineered approach, when considered during the initial drilling fluid planning phase, can be a valuable engineering tool for engineers when preparing a plan for preventing or curing lost circulation. The effort to bring engineering to LCM design should result in large savings in terms of NPT, which directly translates to reduced cost and more efficient use of available drilling rigs. This paper also presents some guidelines for designing and testing LCMs for lost circulation applications.
Advanced FEA Modeling Delivers Solution for Designing a Dual Hole Opening BHA for a Single Directional Run
Authors: Najmi Nik Fahusnaza , Soh Azrin , Nair Divya G. , Zaim Muhammad Afiq , James Biju , Subroto Bramanta , Omar Taufik
Published: March 2015

Drilling the 8½” x 10-5/8″ x 12¼” S-shaped wellbore through soft unconsolidated formation and highly compartmentalized reservoir offshore East Malaysia is exceptionally challenging. Previously, the operator has drilled a similar hole opening section in this marginal field with two separate runs. The directional requirements combined with low WOB took the operator three days to drill and open the 640m section. For the new drilling campaign, the reservoir objectives were to drill deeper and to appraise the well, with an option to complete and produce the gas reservoirs if there are any discoveries. The operator requested the hole be drilled with hole enlargement while drilling (HEWD) tools in a single run, with real-time logging tools. This technique would eliminate the requirement for extra 8½” pilot hole thus significantly reduce rig-days.

Designing a robust and durable BHA for the 1370m long directional run demands intricate planning. To ensure the three cutting structures would synchronize and work in harmony, a pre-job FEA-based modeling system was used to investigate the dynamic drilling behavior of the BHA. The results of simulations from the initial BHA predicted very high vibrations which could potentially result in tool damage. A BHA optimization analysis was then conducted to enhance the BHA design to eliminate vibration issues. The simulation results of the optimized BHA design exhibited measurable reduction in vibration levels.

The operator implemented the recommended BHA and a total of 1371m was successfully drilled and opened in one run, in just four days. All directional requirements were met and a good set of survey and log data was transmitted up the well without issues. Compared with the traditional two run approach, the single run yielded a 25% time savings to the operator. No vibrations were recorded and the BHA was pulled at section TD with no significant wear on the three cutting structures. There were no issues running casing, which implies good borehole quality.
Extending Bit Life Through Bearing Innovations
Authors: Schroder J. , AlDarwaish A. , Richards J.W. , Pasquale M. Di , Mohamed M. , Yorty Jesse
Published: March 2015

This paper describes how recent tapered bearing innovations in rock bits have significantly increased the life of the roller-cone bit, including advanced systems analysis and an endurance record set with a recent onshore exploration run in the Middle East. This record run beat the field average by over 70% in bit revolutions and 58% in footage. One of the primary constraints with roller-cone rock bits has always been bearing life. Traditional journal bearings and cylindrical roller bearings with ball-lock cone retention result in inherent play in the system, reducing bearing and seal life. As a result, this reduces overall bit life and directly affects drilling cost through increased trips and additional drill bits needed to complete a section. Recent innovations have been made to effectively package application-specific tapered bearing technology into roller-cone assemblies. This system provides a preloaded bearing package, eliminating the damaging axial and radial play found in rock bits today. In addition, the system stabilizes the sealing interface between the head and cone, promoting extended seal life. Analytical modeling was utilized to define and simulate many different loading conditions that could be experienced downhole including reaming, up-drill, directional drilling, and high weight. Through the use of proprietary bearing analysis software, optimal bearings were developed to perform effectively across the broad range of potential loading conditions. The result is an innovative, new bearing assembly, specifically developed for rock bits, that enables significant increases in the service life of bits using roller-cones. This paper will describe real-life advantages of this technology and how it is being implemented into the drilling industry.
Managed Pressure Cementing Enables Offshore Operator to Reach TD in Narrow Margin Ultra-HP/HT Well in Malaysia
Authors: Tan Brendon , Gillies James , Noh Aizat , Mohamed Khairul Anwar , Wahid Farid , Bordessoulles Willy , Jain Pankaj
Published: March 2015

This paper discusses the experiences and good practices established from successfully executing two managed pressure cementing (MPC) jobs within an ultra high-pressure/high-temperature (HP/HT) well in offshore Malaysia.

The risks associated with cementing in sections with narrow margins between pore pressure and fracture gradient can often limit the length of each cased section, hence limiting the final total depth (TD) of the well. A new cementing technique using managed pressure drilling (MPD) equipment and processes allows the wellbore to be displaced with a hydrostatically underbalanced mud after the casing string has landed and then cemented with a hydrostatically underbalanced spacer and cement slurry.

This technique was used to successfully cement an 11 3/4-in. intermediate liner and a 9 7/8-in. production liner, which, in turn, enabled the operator to reach the target depth. The 11 3/4-in. liner was cemented successfully without losses or gains, despite only a 0.2-lbm/gal window (15.6 to 15.8 lbm/gal), with bottomhole static temperature (BHST) of 133°C. This job was executed with a 15.0-lbm/gal mud, a 15.0-lbm/gal spacer, a 15.0-lbm/gal cement slurry, and up to 400 psi surface backpressure (SBP). The 9 7/8-in. liner was also cemented successfully without losses or gains with a 0.9-lbm/gal window (17.4 to 18.3 lbm/gal) with BHST of 163°C. This job was executed with a 17.0-lbm/gal mud, a 17.0-lbm/gal spacer, a 17.0-lbm/gal cement slurry, and up to 600 psi SBP. A cement bond log (CBL) was run for the 9 7/8-in. production liner and the results showed good bonding across the entire openhole section, including the critical target zones. The prejob engineering and execution involved extensive hydraulic modeling, closely coordinated with the MPD service provider, and comprehensive risk analysis and mitigation plans.
A Model for Well Reliability Analysis throughout the Life of a Well Using Barrier Engineering and Performance
Authors: Das Bibek , Samuel Robello
Published: March 2015

Maintaining well integrity and preventing loss of containment throughout the life of a well is of prime importance. This is achieved through effective and efficient operations of primary and secondary barriers. Barrier resistance and performance can change over the life of a well because of loads induced by different operations and changing well conditions. Well reliability is a key performance indicator of barrier effectiveness.

The conventional reliability calculation defines total system reliability as the probability of barrier success, or 1- the probability of barrier failure (i.e., probability that all barriers to uncontrolled flow along a particular path will fail simultaneously). However, this definition does not account for the changes in the barriers' effectiveness with time. Although such changes are accounted for during engineering calculations (i.e., design loads), conventional reliability calculations do not reflect the engineering assumptions and calculations in barrier design. Also, the reliability calculations do not account for different operations and the stresses they impose on the barriers that can speed the time-to-failure of the barrier.

In this paper, the integrity of casing as a secondary barrier is studied. To overcome the limitations mentioned, a unique well reliability model is proposed. The reliability in this model depends on individual elements, such as casing design and ratings, as well as the conditions found in the well at the time of running and cementing the casing, drilling subsequent hole sections, and during production operations. The proposed reliability model incorporates casing design calculations, any reduction in strength foreseen, and induced loads attributed to drilling operations (casing wear). A simulation program was developed using simulation software The time-to-failure for casing under the generated stress levels was computed using an accelerated test model developed using an engineering simulation software. The results show what happens when equivalent stress or von Mises stress are applied as failure criterion and acceleration factors are applied to the accelerated test model. The three failure modes considered were collapse, burst, and failure under tensile load.

Further, the Weibull distribution function is used to fit various shapes of reliability curves. A comparison of probability distribution curves of the casing capacity and the loads generated are presented in the results. A “stress modification factor” is introduced in the set of reliability equations to incorporate change in barrier performance attributed to changing conditions. Das and Samuel (2014) introduced the concept of reliability-informed drilling and a model for estimating dynamic reliability. This paper goes further in using the dynamic reliability concept and shows changing well reliability as a function of its changing barrier effectiveness, estimated over the entire life of the well.
Case Study: Tapping into Corporate Domain Expertise Using a Standard Realtime Data Solution
Authors: Regan Matt , Kucs Richard
Published: March 2015

This paper describes how a major European independent Operator, with a wide range of operating assets spread across the world, each with its own set of unique drilling and logistical challenges, has made the strategic decision to implement a realtime data management architecture supporting their entire global organisation by partnering with a vendor-neutral data management specialist to deliver a bespoke enterprise-wide solution.

The Operator mandated that at all stages the solution needed to be a common framework fit for purpose from Norway to New Zealand, from pastoral fields to desert war zones.

The paper will cover all aspects of the project through conceptualisation and functional needs assessment, technical qualification, infrastructure at rigsites and offices, data hosting and quality assurance, use of industry standards, change management and workflow design, benchmarking and key performance indicators (KPIs), and finally deployment and integration into daily operation.

Historically, the Operator had been reliant on realtime decision-making in local offices being made almost autonomously, with secondary input from the Operator's head office referenced secondarily, occasionally, and often after the event. The absence of a standard realtime data exchange solution was recognised as an impediment to efficient, collaborative use of the substantial drilling domain expertise distributed throughout the organisation.

Having invested in a corporate realtime drilling data infrastructure, the Operator now derives full value of their global knowledge base being made immediately available to any operation at any time, irrespective of location. Truly collaborative, timely, informed operational decision-making now drives performance improvement, risk and cost reduction, and optimised well delivery.
A Case Study of Flexible/Expandable and Self-Healing Cement for Ensuring Zonal Isolation in a Shallow, Hydraulically Fractured Gas Well, Onshore Thailand
Authors: Bermea J.A. Vargas , Taoutaou S. , Olutimehin K. , Vinaipanit M. , Ashraf S. , Segret G. , Asawakowitkorn J. , Kongpat N.
Published: March 2015

Cementing design and execution is key to achieving zonal isolation for safe and economic well production. The critical goal of long-term well integrity is a fundamental element of any well construction strategy especially when the well will be subject to cyclic loads and changing downhole stresses e.g from stimulations operations. Exploration and appraisal wells pose an additional challenge because many formation-specific parameters relating to the field may not be fully understood.

This case describes the use of self-healing cement and flexible and expandable cement to optimize isolation and ultimately, well delivery on a critical exploration well project for a National Oil Company. Globally, self-healing cements have been increasing used in the last decade and this was the first application for this operator onshore Thailand. The self-healing cement system was used as a secondary barrier in the well in the case of cracks or deformation within the primary cement matrix. The combination would serve as a more robust solution to mitigate the impact of stresses generated during different well lifecycle phases. The design principle of self-healing cement is the ability to swell upon contact with hydrocarbons to restore well integrity.

Upon installation in the well, cement evaluation logs and the physical indications showed that zonal isolation had been completely achieved for the entire production interval. In addition, no sustained casing pressure was experienced after the hydraulic fracturing operations were performed. Health, Safety & Environment (HSE) concerns were addressed ensuring no hydrocarbon gas leak to surface and no contamination of underground water zones.
Faster ROP in Hard Chalk: Proving a New Hypothesis for Drilling Dynamics
Authors: Akutsu Eirik , Rødsjø Mads , Gjertsen John , Andersen Mats , Reimers Nils , Granhøy-Lieng Morten , Strøm Ellen , Horvei Kjell Arvid
Published: March 2015

A well documented path to improving overall efficiency in project execution is through an integrated team approach which involves both the operator and the service suppliers. This paper describes what can be achieved when such a team adopts a fearless approach to new technology, and dares to think outside existing conventions. To be more specific, the paper covers the engineering, planning, and execution of a HTHP exploration program in the central North Sea by a Norwegian operator.

Large areas of the North Sea contain the Cretaceous period of sediments which comprise of a massive hard layer of chalk that historically has posed a major drilling risk and expense to operators in the area. To mitigate expected problems an integrated team was gathered to thoroughly analyze drilling records and lessons learned from previous offset wells and re-engineer the drilling process with the aim of minimizing cost and uncertainty when drilling the most challenging chalk interval.

The paper presents the hypothesis that formed the basis for the team effort, and the measures implemented based on said hypothesis. This includes an unconventional bit selection and the use of modern vibration measurement technology and mitigation techniques, as well as a key electro-mechanical modification of the advanced logging and directional suite completed by the lead service provider. The discussion and reasoning behind each step is included and the method was repeated in several wells with the same results, verifying the validity of the findings and making the paper a valuable input for drilling hard chalk.

The nominal result from applying the new methodology was a doubling of the rate of penetration (ROP) in the harder layers, and the entire section of problematic strata was drilled in one single bit run. Drilling time was reduced by 12 days when compared to average figures from recent offset wells representing an estimated cost saving of 15 - 20% on the overall well budget. The method and savings presented are primarily of interest to stakeholders in the central North Sea, but can also be applicable to other areas with hard chalk and stringers with similar characteristics.
All-Attitude Gyro While Drilling Technology Provides Accurate Surveys in High Angle East/West Directional Wellbores Delivering Reduced Costs and Increasing the Length of the Producing Zone
Authors: Beattie Keith , Shoup Rob , Weston John , Burke Peter
Published: March 2015

The accurate placement of directionally controlled wellbores is essential in order to maximize oil production while avoiding collisions with existing wells. Error models provide estimates of the positional uncertainty that can be expected when using a specific survey tool. For example, a Measurement While Drilling (MWD) tool will have a different ellipsoid of uncertainty when compared to a Gyro While Drilling (GWD) or a continuous gyro tool. Whichever survey tool is chosen, the uncertainty in the calculated wellbore position is dependent on the trajectory and latitude of the planned wellbore. Many drilling projects have been designed assuming specific survey instruments and favorable drilling directions. However, these assumptions are often not fulfilled due to existing wellbores, environmental safety concerns, land management issues, drilling costs and survey tools available. Different azimuthal corrections and methods of surveying have been deployed to increase confidence in the wellbore placement when drilling wells in east or west directions at high inclinations. MWD surveys with magnetic interference corrections and rate-gyro surveying on wireline are two examples of these methods. Previous GWD technology was limited to 70 degrees of inclination and was not an option for high angle and horizontal wells. With the development of an all-attitude GWD tool, it is now possible to provide accurate gyroscopic surveys at all inclinations and all directions during the drilling process in real time.

This paper describes a case study in which the all-attitude GWD tool was utilized to achieve tighter control of well trajectories drilled predominantly in an easterly direction in close proximity to a number of existing wellbores. This approach allowed a significant reduction in costs since it became possible to drill all the wells from an existing pad and so avoid land management and environmental concerns initially associated with the project. Further, the accuracy of an all-attitude GWD tool allowed the operator to drill safely through an additional 1,000 feet of geological pay zone, a result that could not have been achieved safely using MWD surveys alone.
Using Model-Based Systems Engineering for Rig-Level Safety Automation
Authors: Hetherington David
Published: March 2015

“Is the automation making us safer?” This question is coming up with increasing frequency as the industry looks to increasingly levels of automation to solve a host of different technical and business challenges that we are facing. Previous papers have looked into such questions as the appropriate level of automation, mode confusion, and envelope protection approaches. This paper looks at a more basic problem: Are we able to precisely articulate what it is we want the automation to do and rigorously trace these requirements down to their granular point of implementation?

The author is currently working as the consultant to a shipyard that is producing a high-specification jackup rig for operation in the North Sea. This rig contains ten major software systems made by several different suppliers and their subcontractors and divisions. Making sure these major rig systems work properly together in critical situations has traditionally been quite difficult. Detailed requirements are scattered throughout thousands of pages of dozens of different specifications. Accurate manual tracking of these requirements is extremely difficult. This paper reports on the application of Model-Based Systems Engineering techniques common in the aerospace and automotive industries to tighten up the accuracy, traceability, and accountability for the rig-level safety automation design.
Changing the Game from Steel to Aluminum Drill Pipe: Results from Full String Aluminum Alloy Drill Pipe Deployment to Enhance Extended Reach Drilling Performance
Authors: Legarth B.. , Lehner J.. , Okibe H.. , Koinkar V.. , Mammod Z..
Published: March 2015

An ERD well was drilled with a full string of aluminum drill pipe. Significant reductions in tension, derrick loading and torque and drag were achieved (compared to offset wells drilled with steel drill pipe); an improvement in overall drilling performance was observed (as per the operator's KPIs) and the rig crew handled the aluminum pipe safely and effectively while achieving faster tripping times and reduced connection times.

Aluminum Alloy Drill Pipe (ADP) has typically been used as part of a combination steel/aluminum string to reduce drilling loads in vertical and horizontal wells. To further improve performance and expand the Extended Reach Drilling (ERD) operating envelope, a trial was conducted to run a full drill string consisting of high strength-to-weight ADP to drill a shallow ERD well (with a step out ratio of 2:1), offshore Brunei. The trial also evaluated the overall performance of the ADP including the handling, rig interfaces and new high torque steel tool joints for subsequent deployment in a big bore ERD well. This trial was the second phase of a comprehensive assessment of the potential for ADP to enhance extended reach drilling performance through reduction of tensile and torsional loads and rig/derrick loading. Phase one of the ADP assessment evaluated use of a mixed string (22% ADP of drill string length) with steel drill pipe (SDP), in a 7500m-long, three-dimensional ERD well drilled offshore Brunei in May of 2012.

The phase two well represented the first time that a full string of ADP was used in all hole sections of an ERD well. The trial was designed to quantify the torque & drag reduction potential of the full ADP drill string and to capture operational learnings to optimize future ADP applications.
New Routes to Achieving Well Integrity in Challenging Well Scenarios
Authors: McNicol Jim , Bakken Sverre , Haavardstein Stein
Published: March 2015

In a recent North Sea well, an overburden section with weak zones, faults and a shallow set 13-3/8 in. casing shoe represented a significant challenge to achieving annular integrity during well construction.

The solution was to employ a new flexible, inner-string stage-cementing system and use unconventional circulation paths to achieve two important objectives for the operation. Firstly to build a cement foundation around, and 650 feet above, the 10 in. casing shoe. Secondly to lift cement to just below the 13-3/8 in. casing shoe to isolate weak zones with precise cement placement. Two selective-opening cementing valves were run in the 10 in. casing string above a tag-in shoe, with the upper valve to be opened on the trip in by an inner-string assembly and the lower valve left closed.

A small first stage cement job was performed with an inner-string through a tag-in shoe to take cement up the annulus to cover and isolate any potential weak zones or small faults yet stop short of the lower cementing valve. The lower cementing valve was then shifted open by the inner-string assembly and a second stage cement job circulated through the lower cementing valve up the annulus and into the upper cementing valve, 5, 000 feet higher up, where returns were taken back into the casing. Both cementing valves were shifted closed and permanently locked by the inner-string assembly on the way out; the valves are rated V0, gas-tight to API 11 D1, ISO 14310 and ISO 14998. The entire cementing operation was carried out by an inner-string assembly on a single trip leaving an unrestricted full bore behind.

The paper will discuss in detail the technical challenges of the operation, how they were overcome and the opportunities arising from using gas-tight selective-opening cementing valves.
Field Testing and Applications of a Smart Flow Diverter
Authors: Spreckelmeyer Niko , Regener Thorsten , Clemmensen Carl C. , Eidem Morten , Grindhaug Gaute
Published: March 2015

In liner drilling operations, the annular velocity of the drilling fluid drops significantly when it transits from the narrow cross section of the openhole-liner annulus into the increased annular volume between the casing and the drillpipe. The reduced annular velocity above the liner can cause critical hole cleaning problems that can jeopardize the entire drilling operation and, therefore, must be managed. To effectively mitigate this problem, a major operator and service company jointly developed and tested a smart flow diverter that can be positioned in the drillstring directly above the liner running tool.

The flow diverter (FLD) is designed as a standalone tool that can be placed anywhere in the drillstring and is independent of the measurement-while-drilling (MWD) service-supplier. It can be used in different applications, e.g. under-reaming operations and liners without tieback, where enhanced, continuous hole cleaning is required. The fluid bypass of the flow diverter is simply activated either by drillstring rotation and flow or by a flow pattern signal if string rotation is not possible. These surface manipulations are recognized and interpreted by the flow diverter sensors and electronics. The concept enables an unlimited amount of activations and both activation principles can be incorporated into standard connection procedures, thereby eliminating nonproductive time (NPT).

The FLD went through extensive testing and was run in steerable drilling liner and in other applications. The paper presents the features and activation principle of the technology, its benefits and field experience in combination with steerable drilling liner (SDL) technology and how the utilization of the technology in an underreamer application resulted in an optimized bottomhole assembly (BHA) design preventing previously experienced formation washouts.
Downhole Automation Using Spline, Catenary, and Clothoid Curves Based On Minimum Wellpath Energy
Authors: Yi Ping , Samuel Robello
Published: March 2015

To design a correction wellpath with minimum energy to return a deviated path to the planned well trajectory, an experimental downhole drilling automation is set up and applied. The criterion used to select the best curve between the deviated point and target point is the minimum well profile energy model. This criterion considers curvature and torsion together, which supplies an advanced qualification of wellbore quality. In the consideration of reducing wellbore fiction, unconventional curves are coupled in the wellpath design. Catenary, spline, and clothoid curves supply curvature bridging in transition zones as they make the wellpath smooth. Several survey points are set to check the coordinates for bit moving. The balanced average method, minimum curvature method, and natural curve method are used to build the well trajectory. Finally, this research compares the results of nine optimization models by using different unconventional curves and calculation trajectory methods.
Use of Real-Time Downhole Data Helps Mitigate Operational Risks in Challenging Deepwater Bypass Operation
Authors: Chouquette Peter , Seiler Nancy
Published: March 2015

As technology advances so does the ability to drill deeper and more complex 3D wells. The costs associated with these wells have also increased significantly. In an effort to minimize non-productive time (NPT), one key learning is that utilizing surface parameters alone for decision making is unreliable. To perform many operations, access to real-time downhole parameters can be the difference between a successful or failed operation.

Historically, pre-drill modeling and surface parameters were used for decision making during operations; current technology now allows access to real-time downhole parameters to improve the quality of the information. Understanding real-time downhole parameters can lead to more informed decision making, minimize operational risk, increase operational efficiency and eliminate unnecessary capital expenditures.

This paper describes recent activity in a deepwater subsalt development well involving a very difficult bypass in the 10 3/4 inch × 9 7/8 inch production casing in which a wellbore intervention method that records and makes use of real-time downhole parameters is utilized.

This paper will discuss different stages of the bypass operation where real-time downhole parameters; such as, torque, weight, RPM and bending moment were utilized in making real-time operational decisions. During an operation where the real-time downhole parameters were disregarded an unsuccessful operation resulted.

The stages of the bypass operation to be discussed include:

Drilling:

Fishing operation with a box tap assembly. Fishing operation with a fixed lug retrieval tool (aka Churchhill Key). Clean-out run where the tortuosity/geometry of the hole was analyzed, resulting in the modification of the whipstock BHA and the orientation and setting of the whipstock. Milling a window in the 10-3/4” x 9-7/8” production casing.

Completion:

Compression testing in the 10-3/4” x 9-7/8” x 7-3/4” production casing with water-based mud and ZnBr fluid to optimize completion BHA's.

As drilling, completion and wellbore intervention operations continue to present technical and economic challenges for deepwater operators, using real-time downhole parameters in combination with surface parameters will improve operational results. This paper will demonstrate the use of a drilling mechanics Smart Intervention system and service that helped improve the overall success of a bypass operation.
New Automated MPD System Provides a Step Change in Performance with a Streamline Equipment Footprint
Authors: Couturier Y. , Dow B. , Hardt J. , Leonard T. , Milligan B. , Thow P.
Published: March 2015

Manual choke control has been the staple of many Managed Pressure Drilling (MPD) operations. To be successful manual choke control requires close communication and cooperation with between the driller and the choke operator. Responding to contingency scenarios, such as rig pump failure, is highly dependent upon the situational awareness of the choke operator and the speed at which they can respond. The consistency and repeatability of manual methods is therefore only as good as the choke operator's skill, experience and how well the choke operator and driller work together.

Automated choke control increases the consistency and repeatability of control, as well as the ability to respond to contingency scenarios with little or no operator intervention. However, automation tends to increase the complexity of the equipment needed and changes the competencies required from personnel. Achieving a fit for purpose degree of automation that balances the delivery required to successfully drill the well without adding any more complexity than is absolutely necessary is therefore a challenge.

This paper describes a new automated MPD system that was developed with the goal of providing increased performance while minimizing any additional complexity. The new system had to be capable of providing pressure trapping, to be able to manage multi-step pressure/flow pump ramp schedules, and yet had to have a similar physical footprint to and work with existing equipment. The technology was evaluated in terms of ability to control, setup time, ease of use, and ability to perform the scope of work required.

The system represents a step change in performance compared to manual MPD and yet maintains a streamline equipment footprint.
Analysis of the Impact of Wellbore Tortuosity on Well Construction Using Scaled Tortuosity Index and High-Resolution Continuous Surveys
Authors: Lowdon Ross , Brands Sjoerd , Alexander Gregg
Published: March 2015

The increasing complexity of wells currently being drilled has led to considerable innovation in the oil and gas industry. The advent of rotary steerable systems has improved average rate of penetration (ROP), borehole quality, and, therefore, well construction times. In addition, the improvement in well placement technologies, such as deep resistivity measurements, has enables greater geological certainty in well placement. However, there is a trend towards increased trajectory complexity due to geosteering, which has led to the possibility of higher unplanned tortuosity. This will have an impact on the well construction as problems related to torque-and-drag can be expected to increase. These problems include increased casing and completion running times and possibly other types of problems, such as reduced wireline or logging-while-drilling (LWD) log quality and cementing problems. The improvement in continuous surveying techniques, which provide high-resolution surveys while drilling, enables a greater insight into the true trajectory of a wellbore and provides a more realistic input trajectory for torque-and-drag modeling.

A study comparing wells with different drive mechanisms highlighted the difference between standard 30-m (90-ft) surveys and high-resolution surveys built from standard and continuous survey measurements in the context of torque-and-drag modeling. An analysis was conducted of the wellbore tortuosity described by high-frequency continuous survey using finite-element drillstring modeling. Identifying the impact of various drive mechanisms provided insight into the level of tortuosity that may be expected on typical horizontal geosteered wells, buildup sections, and tangent sections. Findings from this study were combined with those from previous papers published on tortuosity to deliver results based on multiple wells. Recommendations stemming from this work include torque-and-drag requirements and improvements to drilling practices that will enable an improved ability to drill for completion.
The Macondo Inflow Test Decision: Implications for Well Control and Non-technical Skills Training
Authors: Thorogood John L
Published: March 2015

Information in published reports is used for this paper to review the events leading up to the Macondo loss of well control. Avoiding as far as possible the trap of hindsight, it offers an alternative interpretation based on ambiguities inherent in the data to suggest how the resulting decision could have appeared logical given the series of cues with which the crew was presented. The implications of these findings on initiatives currently underway in the industry relating to enhanced well control and crew training are considered.

A brief background is provided to some of the key psychological concepts related to the incident, including risk aversion as well as other biases that can influence teams in a similar situation. How hindsight bias can affect subsequent interpretations of the event is also discussed. By describing a scenario in which data are open to misinterpretation, it becomes evident how an incorrect conclusion can be reached with the ensuing decision leading to an unexpected outcome. Comparisons are made with accounts of other well control incidents available in the public domain as a cross-check on whether similar influences could have played a part elsewhere.

Analysis of Macondo and other similar incidents highlights the general rule that when there is ambiguous information and the potential for multiple interpretations, a natural tendency is to choose the least threatening scenario. Once an explanation is accepted, decision makers tend to hold onto it and discount information that undermines it until the situation evolves to a point where the evidence to the contrary cannot be ignored.

It is concluded that unless crews and supervisors are trained to be vigilant for potential ambiguities as part of their day to day activity, i.e. instilling a sense of chronic unease, it is unlikely that they will be capable of recognising, and pre-empting, an unusual but rare situation when it happens. Furthermore, future incident investigations should go beyond technical or managerial explanations of incidents to include an in-depth consideration of the human factors aspects as, at present, causes of incidents are simply put down to “human error” without sufficiently enquiring what might have triggered the error in the first place.