bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wellbore Positions Obtained While Drilling by the Most Advanced Magnetic Surveying Methods May Be Less Accurate than Predicted
Authors: Ekseth Roger , Weston John 
Published: February 2010

Abstract
Various methods, often referred to as in-field referencing (IFR) techniques, are used to enhance the performance of traditional magnetic measurement while drilling (MWD) well-bore surveys. Simulation and field data studies of effects commonly not accounted for, like the fact that the geomagnetic field varies with depth, indicates an unrealistically high level of confidence in the IFR techniques, especially when run in conjunction with multi station corrections (MSC). The SPE wellbore position technical section (WPTS) is currently recommending the use of the standard MWD error model weighting functions, which do not reflect a horizontal east-west singularity associated with combined IFR-MSC surveys. The WPTS is further recommending the use of geographically dependent IFR azimuth uncertainty figures, which average globally to 0.22º (1σ). The WPTS average is supposed to account for all errors that corrupt an IFR survey, not only those affected by the IFR correction itself which, according to WPTS, have an average of only 0.18º (1σ). The WPTS figures do not account for the additional uncertainty generated by geomagnetic depth variation. Simulations show a global uncertainty of 0.38º (1σ) from this error source alone. Geomagnetic depth corrections are possible, but not commonly applied, and are far from error free; residual errors after correction exceeding 30% appear to be common. The study described here indicates an underestimation of the real wellbore position (IFR based) uncertainty of 50% or more, a fact that represents a potential safety hazard to both human life and equipment of which the industry needs to be made aware.
Managing Circulation Losses in a Harsh Drilling Environment: Conventional Solution vs. CHCD Through a Risk Assessment
Authors: Masi S. , Molaschi C. , Zausa F. , Michelez J. 
Published: February 2010

Abstract
Conventional drilling techniques used in harsh drilling environments are sometimes impractical or uneconomical. This was experienced while drilling through the reservoir section being investigated. This section is characterized by high pressure and formation fluids estimated to contain 18-20% of H2S and 4-6% of CO2. The presence of extensive karst/fractures along with severe circulation losses prevents successful drilling using the conventional circulation technique. For this scenario, the Pressurized Mud Cap Closed Hole Circulation Drilling (CHCD) technique was applied, and proved to be the most effective method to drill through the Lower Carboniferous Carbonate.
In conventional drilling through such loss circulation zones, the typical method is to isolate the thief formation (LCM's pills, gunks and cement plugs) in order to maintain an overbalanced condition. These methods have their disadvantages: uncertain results, time and cost increase, damages on well productivity. Furthermore, it may be a long, ineffective process due to multiple leak-off zones or massively fractured zones.
Where unsustainable losses occur and conventional circulation is no longer possible, the "CHCD" technique may be used to allow the continuation of drilling. This technique is not under balanced drilling. The annulus is closed and no returns are circulated to the surface.
The CHCD is not a simple or an inexpensive system. It is used only when other systems for controlling losses have proven to be ineffective. Large quantities of water and mud are required as well as additional equipment and specialized personnel. An accurate evaluation of several factors has to be performed. Drilling hazard is the major issue as the primary barrier to well influx is jeopardised, but also rig time, material availability and consumption have to be considered.
The aforementioned uncertainties can be addressed through risk evaluations by comparing two drilling scenarios of a typical development well where one uses CHCD technology and the other uses conventional drilling techniques.
This paper will discuss the operational details of conducting CHCD as well as the risk management approach which involves the identification, evaluation and mapping of all risks involved in each scenario (qualitative risk assessment). A probabilistic model is therefore developed in order to combine all the risks identified and to address their consequences within operational time (quantitative assessment).
The Automated Drilling Pilot on Statfjord C
Authors: Larsen H. F. , Alfsen T. E. , Kvalsund R. , Iversen F. P. , Welmer M. , Hult Ø. , Ekrene S. 
Published: February 2010

Abstract
In the Automated Drilling Pilot three newly developed technologies aiming to improve the quality of the drilling operation, have been submitted to an extensive offshore field test in the North Sea. The technologies involved were: (1) Software for drilling control automation based on real time process modeling, (2) system for drillpipe tracking based on RFID technology and (3) sensors for continuous measurements of drilling fluid parameters. During this field test the listed technologies were not only tested simultaneously, but also set up to exchange data in real time, forming one integrated drilling automation system.
In this paper the relevant functionalities of the technologies tested in the pilot are described. The paper also outlines the preparations for the pilot, including work performed on risk mitigation, onshore testing and training of personnel. In addition, the actual field performance of the technologies have been measured and evaluated regarding their influence on a number of important operational areas such as HSE, operational efficiency, work tasks/responsibilities and demands on surrounding technology. Lastly the capability of these technologies for exchanging data in real-time to form a closely integrated automation system has been demonstrated and evaluated.
Based on the experiences from the Automated Drilling Pilot, several crucial technology enablers have been identified for the technologies involved, the most important being related to personnel training/experience building, drilling data quality/availability and offshore expert support.
Elimination of Errors in Cement Displacement Volumes and Plug Bump-Plug Indicator System
Authors: Gradishar John , Groesbeck Brad Michael 
Published: February 2010

Abstract
This paper describes the development and deployment of a new method of determining the physical location of a top cementing plug in a subsea casing string. Typically, the position of the top plug is approximated based on the calculated volume of the string, which can often vary significantly from actual casing volume, especially in long, heavy subsea casing intervals.
Such discrepancies can create major problems during primary cementing operations, including failure to bump the top plug or potential overdisplacement of cement. The former tends to increase subsequent drillout times; the latter may result in contaminated cement in the shoe track.
After review of the problems, the operator in the region concluded that utilizing the described technology, the Plug Indicator System (PIS), was warranted. The PIS was expected to facilitate more effective primary cementing operations by mitigating these risks, thereby reducing nonproductive time (NPT) and associated costs and avoiding expensive remedial operations.
This paper reviews and helps familiarize the reader with the problems associated with subsea casing primary cementing operations. A case history of the PIS and its successful conclusion is presented.
Behavior and Shape of Gas Kicks in Well Bores
Authors: Spoerker H. F. , Tuschl T. 
Published: February 2010

Abstract
Conventional assumptions of how a gas kick develops in the wellbore mostly refer to one "dry gas bubble" over a wellbore length equivalent to the total influx volume and – while fulfilling all requirements for volumetric/hydraulic well control calculations – are clearly unrealistic. However, modeling the system of gas entering the annulus out of a porous medium and with drilling mud moving in most cases under turbulent flow conditions is highly complex and computer-power intensive.
The paper describes the driving mechanisms of gas entering into the wellbore, the methodology used for simulating and visualizing the percolation of gas after the well has been shut in and the influence that gas distribution/movement has on the chemical buffering of sour gas influxes in high-pH drilling fluids. It is part of a multi-year research project aimed at understanding the well bore / gas influx system in more detail and allowing a better definition of the behaviour of high-strength steel drill pipe in potentially sour environments. As the buffer reaction between the sour gas influx and the (generally) caustic drilling mud is heavily influenced by the initial distribution of the gas into the mud, the generation of bubbles (i.e. active surfaces) and the kinetic energy transferred to the system during the mixing process, the results of this study form the basis for subsequent high-definition simulators.
Well Integrity Monitoring & Analysis Using Distributed Acoustic Fiber Optic Sensors
Authors: Hull John , Gosselin Lance , Borzel Kevin 
Published: February 2010

Abstract
Evaluating well integrity (i.e. flow of fluids or gas) from behind casing can be challenging using existing single mode analog sensors; they offer limited representation and data acquisition can be time consuming. Further, traditional processing algorithms such as Fourier Transforms are not responsive to non-stationary, nonlinear events such as random, low volume leak signatures. Recent advancements in both fiber optic Distributed Acoustic Sensors (DAS), and processing algorithms stand to significantly simplify downhole low rate leak detection. This paper will explain the capabilities and limitations of this monitoring approach.
Distributed Acoustic Sensors; Proven in demanding applications such as submarine sonar systems, optical fiber can be packaged in such a way that makes it extremely sensitive to acoustic disturbances along its entire length. Using the fiber itself as a sensor has several advantages, some of which include; extreme sensitivity, design simplicity, and the ability to obtain 1000’s of simultaneous measurements with little or no loss of fidelity. Datasets were obtained from both a specifically designed 200 ft vertical controlled test well simulator and actual problematic gas wells in Canada.
Processing Algorithms: Using DSP techniques and real time methods, the engineer can tune the system to a specific leak signature which eliminates unwanted events and highlight useful acoustic components pertaining specifically to the leak. Once the data is obtained the high fidelity acoustic data undergoes various filtering and error detection processing. Algorithms were tested in Matlab and converted to executable code once verified.
The integrated well monitoring and analysis system offers a more comprehensive, detailed solution. When compared to traditional technologies, future remedial strategies were often strategically more accurate using the fiber based systems, especially when low leak rates were involved. It is anticipated that engineers will be able to locate problematic leaks with higher confidence and save money by reducing the number of failed interventions; similarly, the need for experienced highly trained log analysts will be reduced. Applications for this information may include: low rate leak detection through casing, pipe integrity failures, zonal isolation issues, long term well monitoring, carbon storage and sequestration, evaluating intervention effectiveness, and locating multiple source leaks along a wellbore.
Liner Drilling Technology as a Mitigation to Hole Instability and Loss Intervals: A Case Study in the Gulf of Mexico
Authors: Rosenberg S. , Gala Deepak M. , Xu Wei 
Published: February 2010

Abstract
The combination of liner drilling with a casing while drilling (CWD) bit to successfully drill and cement a 7-in. liner in place through a severe loss zone in the Gulf of Mexico, offshore Texas, USA, will be presented in this paper. Previous attempts to drill this problem formation were unable to reach the objective depth because of lost-circulation and hole stability issues. This paper will present equipment selection, operation, and results of liner drilling that allowed this well to be successfully drilled and cased.
Vertical Riser Handling with a Knuckle Boom Crane
Authors: Hagen Sondre , Talberg Kaare Tommy , Kristiansen Narve 
Published: February 2010

Abstract
This paper presents a new solution in terms of how to handle drilling riser vertically on a floating drilling rig by means of the well known offshore crane type, the Knuckle Boom Crane and vertical column storage. The main reason for introducing this new solution is the resulting increased free deck capacity and the overall increase in VDL capacity on a floating drilling rig.
The solution has recently been implemented as part of a deepwater upgrade on an old semi-submersible drilling rig from the mid 70’s and has been in operation for nearly 1 year.
The paper focus on the Human Machine Interface specifically developed to enable a smooth handling process, in addition to the resulting general operational and construction project related benefits from implementing the solution.
The solution has proven its benefits throughout the design and construction phase in terms of limited interference with existing deck structure, in addition to operation in terms of an available free deck space comparable with the significantly bigger new generation deepwater semi-submersibles.
Real-Time Well Tool Face Information Reduces Directional Uncertainty and Risks in Difficult Sidetracks in Gulf of Suez
Authors: Howes Thomas B. , Farouk Mohamed , Darwish Mohamed , Koroletz Wilhelm , Ismail Ahmed , Moustafa Amin , Heisig Gerald 
Published: February 2010

Abstract
To address risk and uncertainties in difficult sidetrack operations in the Gulf of Suez in Egypt, a new method was implemented to identify and control the direction of the wellbore during the whipstock exit, and close to the liner, where standard directional measurements are compromised due to magnetic interference. Bending moment sensors were placed directly above the motor and only 26 ft behind the bit. These sensors delivered two perpendicular bending moment measurements referenced to gravity high side. Transmitted to surface via mud pulse telemetry, the two signals were further processed to deliver the well tool face and - with the help of a mathematical BHA model - the dogleg severity of the well.
In one case the well tool face confirmed the orientation of the whipstock and the window milled. However, in a second case, the measurement revealed a 40 degree deviation from the original whipstock orientation. The well plan was immediately adjusted to compensate for this deviation from plan. The dogleg severity information gave improved azimuth control when steering away from the existing well in sliding mode. As a result, both sidetracks achieved their directional objectives and could be steered into the target. The directional estimates derived from the bending moment measurements were later confirmed by the first valid MWD surveys and by gyroscopic survey measurements.
The paper will start with a detailed description of the directional challenges in this application. It will then introduce the concept of the bending moment measurements and the derived directional information, well tool face and dogleg severity. After a description of the implementation and directional execution of the sidetracks, the paper will conclude with a discussion of the benefits and the potential of this new directional control method, which could result in a reduction or even complete elimination of gyro runs during similar casing exits and significant rig time savings.
Drilling a Challenging HPHT Well Utilizing an Advanced ECD Management System with Decision Support and Real Time Simulations
Authors: Rommetveit Rolv , Ødegård Sven Inge , Nordstrand Christine , Bjørkevoll Knut S. , Cerasi Pierre , Helset Hans Martin , Fjeldheim Mikkel , Håvardstein Stein T. 
Published: February 2010

AbstractA very challenging HPHT well has been drilled utilizing an advanced ECD Management System including real time simulations, early diagnosis of upcoming problems, and real time simulations using state-of-the art models. The System uses all available real time drilling data (surface and downhole) in combination with real time modeling to monitor and optimize the drilling process. This information is used to visualize the wellbore in 3D in real time. It has been implemented in Total E&P Norge TASC (Total Activities Support and Collaboration) Center in Norway. The system is composed of the following elements, some of which are unique and ground-breaking:An advanced and fast Integrated Drilling Simulator which is capable of modeling the different drilling sub-processes dynamically, with interaction between these sub-processes in real time. Automatic quality check and corrections of drilling data; making it suitable for processing by computer models Real time supervision methodology for the drilling process using time based drilling data as well as drilling models / the integrated drilling simulator. Methodology for diagnosis of the drilling state and conditions. This is obtained from comparing model predictions with measured data. Advisory technology for more optimal drilling. A Virtual Wellbore, with advanced 2D and 3D visualization of the downhole process. Data flow and computer infrastructure.Among the challenges during planning and drilling of this well have been:Very small window between pore and fracture pressure. RT ECD simulations were performed with an advanced hydraulic and thermal wellbore model. Increased probability for instabilities in the tight window. Was mitigated by RT stability modeling during drilling. Pore pressure predictions which were updated during drilling.Experiences from the drilling as well as use of the ECD Management System will be summarized and presented. The usefulness of supervision and diagnosis functionalities is illustrated.
Wellbore Stability in Fractured Rock
Authors: Ottesen Steinar 
Published: February 2010

AbstractNumerous wellbore instability problems related to drilling through potentially fractured formations have been reported. Often, these rocks are characterized by the abundance of macro and micro scale bedding planes and/or networks of natural fractures. The presence of fractures weakens the rock mechanically and produces potentially higher-permeability fluid-flow paths within the low-permeability rock matrix. Practically, it is difficult to identify fracture size and fracture density without a costly core sample. A number of wellbore stability case studies have therefore been published where the author relied on anecdotal evidence to postulate failure mechanisms involving fractured rock, and recommendations for how to mitigate the observed instability range from increasing to decreasing the wellbore pressure.This paper presents results from a geomechanical investigation of a wellbore instability incident experienced in a fractured shale formation. As part of this assessment, a preserved core was obtained from the fractured shale interval and the presence of fractures was identified both by CAT scan and visual inspection. A series of triaxial tests were conducted to characterize the mechanical properties and failure strength of this shale. This data, combined with wellbore stability modeling, suggests that the residual strength, rather than the peak failure strength, is a more representative measure of a fractured rock's in-situ strength. The Hoek and Brown (1982) failure criterion was found to be particularly suitable for modeling fractured rock.Multi-arm caliper logs from two boreholes through the same fractured shale suggests that wellbore instability is more complex in the fractured interval than in the over- and underlying intact rock. These caliper logs also clearly demonstrate that the borehole quality was significantly improved by increasing the drilling fluid density, which contradicts the conclusions drawn in a number of published wellbore stability case studies (Santarelli et al., 1992; McClellan et al., 1996; Edwards et al., 2004; Fontana et al., 2007).
Controlled Pressure Drilling (CPD) Candidate Screening Methodology, an Update
Authors: Villatoro Jaime , Boutalbi Said , Schmigel Kevin , van Galen Martijn , Lakshminarayanan Sunil 
Published: February 2010

Abstract
Controlled pressure drilling (CPD) is an emerging, multi-component drilling application that can improve drilling time and reduce previously recorded lost time on offset conventionally drilled wells—when applied appropriately. In addition, specific drilling techniques offered within CPD technology not only improve the time it takes to reach total depth (TD), but also have been proven to optimize reservoir section productivity and maximize economically recoverable reserves. CPD is composed of three main techniques: air drilling, underbalanced drilling, and managed pressure drilling. This paper provides an updated discussion of CPD techniques, the nonproductive time that it can address and screening methodology.
A methodology to properly screen CPD techniques to reduce failure/misapplication and align objectives with expectations had been lacking. This paper addresses the latest refinements in an expert system developed to better understand and screen options for CPD operations. The Internet-based selection tool provides guidance by using key indicator questions, beginning with the primary objective(s) for the given wellbore section. If the specific CPD technique is known, the user can activate the online screening tool. The online screening tool considers a range of economic and technical parameters, which are applied to algorithms and logic rules, to provide a relative ranking for each CPD candidate. This paper will also address modifications that have been made to reduce cost related sensitivity when screening air and managed pressure drilling, which previously made the screening process less consistent. Sensitivity analysis can also be performed to determine the impact of key uncertainty parameters. Additional expert-user screening and selection can be incorporated upon the completion of the online CPD candidate selection process. Lastly, the paper will also include supporting case histories.
Bending Tool Face Measurements While Drilling Delivers New Directional Information, Improved Directional Control
Authors: Heisig Gerald , Macpherson John D. , Mounzer Fadi , Linke Christian , Jenkins Mark 
Published: February 2010

Abstract
This paper introduces bending tool face, a new measurement with applications in directional drilling. The measurement is derived from two perpendicular bending moment sensors in the BHA and identifies the orientation of BHA bending with respect to gravity high side while drilling, both in rotating and sliding modes. The paper presents the underlying theory and motivation for the measurement, describes its implementation into a downhole MWD tool and shows measurement examples from field applications. Furthermore, the paper outlines the use of the data for directional calculations. The paper concludes with a discussion of applications in which the bending tool face information adds value, such as reducing uncertainty in casing exit applications and improving directional control in challenging 3-D well profiles. The discussion is supported with field results.