Casing structural integrity and failure modes in a range of well types: a review.

This paper focus on factors attributing to casing failure, their failure mechanism and the resulting failure mode. The casing is a critical component in a well and the main mechanical structural barrier element that provide conduits and avenue for oil and gas production over the well lifecycle and beyond. The casings are normally subjected to material degradation, varying local loads, induced stresses during stimulation, natural fractures, slip and shear during their installation and operation leading to different kinds of casing failure modes. The review paper also covers recent developments in casing integrity assessment techniques and their respective limitations. The taxonomy of the major causes and cases of casing failure in different well types is covered. In addition, an overview of casing trend utilisation and failure mix by grades is provided. The trend of casing utilisation in different wells examined show deep-water and shale gas horizontal wells employing higher tensile grades (P110 & Q125) due to their characteristics. Additionally, this review presents casing failure mixed by grades, with P110 recording the highest failure cases owing to its stiffness, high application in injection wells, shale gas, deep-water and high temperature and high temperature (HPHT) wells with high failure probability. A summary of existing tools used for the assessment of well integrity issues and their respective limitations is provided and conclusions drawn

Aeronautical Engineering: A special bibliography, supplement 60

This bibliography lists 284 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Empirical analysis of localized casing wear with variations in contact pressure and drilling conditions

Im Wettkampf die Grenzen der Kohlenwasserstoff- und Geothermie Förderung sowie Speicherung stetig zu übertreffen und optimieren, wurden horizontale Bohrungen, tiefe Ablenkungsbohrungen und Bohrungen mit großem Neigungswinkel (ERD Bohrungen) zum heutigen Standard. Bei der Planung solcher Projekte sowie Ablenkungen, wirken sich Vorgänge wie Räumen (reaming), Bohren (drilling), Rotation off-bottom und das Ein- und Ausfahren der Bohrgestänge enorm auf die Futterrohr Beschaffenheit aus. Durch das Aufeinandertreffen und dem herrschenden Kontakt zwischen dem Bohrstrang und der Innenwand des Futterrohrs, tritt eine stärkere Abnutzung des Materials auf seitens des Futterrohrs, besonders an den Verbindungsstellen des Bohrstrangs, auf. Dies führt entweder zu einem ungleichmäßigen kreisförmigen Schwund der Futterrohr-Stärke, oder bei längerem kontinuierlichem Kontakt gegen die Innenwand des Futterrohrs, zu einer punktuellen tiefen Verschleißrille. Ein dynamischer Futterrohr-Verschleiß ist aufgrund der Vielzahl von Variablen, ein komplexes, zu simulierendes Phänomen, da die Variablen das nicht-lineare Verschleißverhalten beeinflussen. Die Verschleißintensität wird durch individuelle Kombinationen von Betriebsbelastungen (verändernde Kraft-Flächen-Verteilungen) beeinflusst. Metallurgische Eigenschaften (Werkstoffhärte und Streckgrenze) und vorherrschende tribologische Mechanismen (Oberflächenrauheit, Reibungsfaktoren und Verschleißart) kommen zum Tragen. Damit Verschleißsimulationsgleichungen möglichst genau sind, müssen die erforderlichen Reibungs- und Verschleißfaktoren experimentell durch umfangreiche Versuche bestimmt werden. Um diese Anforderung zu erfüllen, besteht der erste Schritt dieser Forschung darin, vorhandene mathematische Modelle und konventionelle Bohrlochplanungssoftwares zu analysieren. Daraus folgt die Bestimmung von Parametern, die für ein umfassendes Verschleißtestverfahren in Bezug auf variable Seitenkraft, Bohrstrangdrehzahl, axiale Bewegung und Fluidtyp, notwendig sind. Der zweite Schritt und somit der Fokus dieser Studie ist die Planung, Konstruktion und Anwendung eines vollwertigen Verschleißmodels zur Reproduktion von Reibungs- und Verschleißfaktoren unter Feldbedingungen. Die entwickelte Verschleißanlage ermöglicht Abrieb verschiedener Futterrohr-Materialien unter diversen Betriebslasten und verschieden Arten von Schmiermitteln zu simulieren. Unter Anwendung nahezu gleicher Betriebslasten, wurden die Verschleißprozesse für Stahl-, Glasfaser- und Kohlefaser-Futterrohrs untereinander verglichen. Der Umfang der Testreihe beinhaltete bislang 14 Tests unter Anwendung eines Schlammbasierenden Schmiermittels oder Wasser. Vergleiche zwischen den erbrachten Ergebnissen, in Bezug auf Reibungs- und Verschleißfaktoren, zeigen eine starke Ähnlichkeit und stehen somit im Einklang mit früheren experimentellen Studien. Nachdem der höchste Verschleißfaktor binnen kurzer Testdauer erreicht wurde, ist zu beobachten, dass dieser nach einer Verringerung des Druckkontaktes drastisch und stetig sinkt. Dieses Phänomen ist bei allen getesteten Materialien unter bestimmten Betriebslasten und Bohrszenarien zu verzeichnen und kann als einen genaueren Richtwert für Feld Ereignisse genutzt werden. Des Weiteren können mithilfe der gemessenen Werte des Reibungsfaktors, die Spanne der Belastungsdruckgrenze (Contact Pressure Threshold) an den Futterrohren genauer bestimmt werden. Eine Verschleißvolumengleichung, basierend auf den experimentellen Ergebnissen, wird als Teil der Testergebnisse präsentiert. Anhand der ermittelten Werte sowie Trends der Versuchsergebnisse, können Vorhersagen, bezüglich des Verschleißes, getroffen werden. Indem weiterer Stahlsorten, Durchmesser und neue Futterrohr-Materialien in den experimentellen Umfang einbezogen werden, kann die Anlage unter praxisnahen Bedingungen Verschleißverhalten darstellen. Hersteller für Futterrohre und Verbindungen profitieren von diesen Simulationen, um genauere Werte bei ihrer Herstellungsweise integrieren zu können. Durch die Anlage simulierten Feld Bedingungen, können die Werte der Belastungsdruckgrenzen (Contact Pressure Threshold) und Verschleißfaktoren erlangt werden. Diese Werte werden benötigt, um eine empirische Daten Gliederung zu erstellen, welche daraufhin in eine Software integriert werden. Dies vermag den Futterrohr-Verschleiß im Voraus abzuwägen und zu reduzieren, aber ermöglicht gleichzeitig die Flexibilität bei Betriebslasten beizubehalten.In the race to push the limits of hydrocarbon and geothermal production (and storage), deep inclined, horizontal, and ERD wells have become the drilling norm. In building such well trajectories, processes such as drilling, reaming, rotation off-bottom and tripping always affect casing wall thickness due to its interaction with the drillstring (particularly at the tool joints) under high contact forces. This results in either an uneven circumferential thickness reduction or, in case of long continuous contact of a tense drillstring pressed against the casing inner wall, a localized deep wear-groove. Localized dynamic casing wear is a complex phenomenon to simulate due to the number of control variables influencing the non-linear wear behavior. Wear intensity is influenced by individual combinations of service loads (changing force-area distributions), metallurgical properties (material hardness and yield strength) and prevailing tribological mechanisms (surface roughness, friction factors and wear type). For wear simulation models to be accurate, the required friction- and wear factors must be experimentally determined by full-scale tests. To fulfill this requisite, the first step of this research is to analyze existing mathematical models and conventional well planning software to establish parameters for a full-scale wear test method in terms of variable side force, drillstring RPM, axial reciprocation, and fluid type. The design, construction, and application of a full-scale wear frame to reproduce friction- and wear factors under field conditions is the second step, and the core focus of this study. The wear frame is designed to incorporate different casing materials under a range of operational loads and lubrication conditions, and wear scenarios under similar service loads have been compared for steel, fibered glass and fibered carbon casings. A total of 14 wear tests have been carried out in the study time-frame for the casing materials under water and mud lubrication conditions. A comparison of test results shows good consistency and agreement with previous experimental studies in terms of friction and wear factors. After the initial peak values, the wear factor is observed to decline drastically to a steady-drop range upon contact pressure reduction. For all tested materials, this steady range of values can provide a good estimate of field wear volume over time under particular service loads and drilling scenarios. Also, the measured steady values of friction factors help determine close ranges on contact pressure threshold for the casings. A proposed wear volume equation based on the experimental results is presented as a part of test results. It has been observed from the detected trends in the test results that repeated wear tests can make casing wear predictable. With the inclusion of more steel grades, diameters and new casing materials into the experimental scope, the wear frame can be used to develop a comprehensive record of wear performance under different field scenarios for casing and tool joint manufacturing industry. Attribution of wear factors and contact pressure thresholds to specific field conditions via a wear test database, and its integration into a software solution, can fill gaps to help reduce casing wear while retaining flexibility on operational loads

Alternative applications of wired drill pipe in drilling and well operations

Master's thesis in Petroleum EngineeringOil and gas companies target to carry out drilling and other well operations in a safe and cost-effective manner with focus on the long-term integrity of the wells. Well operations become more challenging in environments such as depleted formations, extended reach horizontal well and deep-waters. In the recent years, the industry developed new technologies and methods to manage and enhance the efficiency of drilling operations in these environments. However, there are still challenges faced by the industry. For this, the industry developed a wiredpipe (WDP) technology to improve the data quality, quantity as well as speed of transfer. As a result, WDP technology improved the drilling activity significantly. The recently approved plan for development and operation (PDO) has granted Snorre field expansion project (SEP) to Equinor ASA. The field being depleted has planned equal number of injection and production wells, which could have both the pore pressure and formation stress altered. In general, one may expect operational challenges in the field. A total of eight field case studies were conducted on the application of WDP technologies. Based on the lessons learnt, problems associated with the conventional method and the corresponding possible WDP solutions to be utilized in SEP or future field development activities are proposed. Results from the field case study shows that the valued contributions of wiredpipe are faster drilling rate, time-efficient rig operations, risk reduction, enhanced well placement/quality and reduction in mud losses. Results from the possible alterative WDP solution for SEP are with regards to tripping, cementing, wellbore cleanout, perforation, completion and side-tracking operations. The author believes that integrating the solutions will enhance SEP operations, reduce non-productive time and therefore will be cost-effective.submittedVersio

Life Cycle Well Integrity and Reliability

Master's thesis for Petroleum engineeringThis thesis presents a method for reliability based casing design. The method is inspired by the model described by Das et al. (2015) - A model for Well Reliability Analysis throughout the Life of a Well Using Barrier Engineering and Performance (1). The purpose of this model is to show how reliability based casing design, based on statistical data, can be performed in practice. Monte Carlo simulation conducted in MATLAB is the basis of the approach. Statistical data of load and strength simulate a casing burst scenario for a life cycle period of 20 years. Degradation factors associated with casing wear and corrosion are accounted for. Based on the result from this simulation, the underlying life time distribution was identified using Nelson-estimator. Maximum Likelihood estimation was used to calculate parameters for the identified life time distribution. The results from the simulated data showed that the underlying lifetime distribution could be represented by a Weibull distribution. From this distribution, failure rate, failure function and survival function was found. The presented approach show how it is possible to quantify the reliability of a given design. Some of the identified challenges in using a reliability based design approach in practice, is related to the lack of qualitative statistical input data of load, and proper estimation of degradation factors related to the casing strength. To get an overview of the most important aspect of well design an introduction to the regulations, well integrity and load cases are given. The different design approaches used in well design is also explained and compared to get a full overview of how reliability based design differs from other design approaches

HORIZONTAL FLOW LOOP DESIGN FOR THE STUDY OF DRILL STRING ROTATION EFFECTS ON CUTTINGS TRANSPORT

Exploration and Production companies are continually focusing more time, energy and resources into Extended Reach Drilling in order to maximize reservoir production while minimizing both environmental impact and development costs. These long laterals (2:1 Measured Depth: True Vertical Depth) are often more difficult to drill and can be severely impacted by inadequate drilling practices. Cuttings transport efficiency is a critical parameter of Extended Reach Drilling operations, and poor wellbore cleaning can lead to excessive torque, drag, and several other serious downhole problems. Although many studies have been performed that identify the importance of drill string rotation on cuttings movement, there is still much to be learned about the correlation between rotation and hole cleaning. This increase in transport cuttings efficiency is more pronounced in larger diameter holes, where often sudden increases in transport efficiency occur when drill string rotation nears both 120 and 180 RPM. This document presents a design of a flow loop capable of emulating downhole flow conditions and high RPM drill string rotation in a large diameter wellbore, which would allow for the study and better understanding of this phenomenon. This design will also be the first that allows drill string interchangeability and adjustment of drill string centerline within the casing, further increasing research capabilities. A comprehensive computational fluid dynamics (CFD) model has also been designed. This model will be used alongside the flow loop and will be refined and validated by future flow loop experiments. This flow loop and CFD model can be used to develop working correlations and provide real world predictive models. A strong comprehension of these step changes in cuttings removal rates could allow for the development of new technology or drilling practices that could replicate this effect, increasing transport efficiency dramatically. With the ever-increasing importance of successful Extended Reach Campaigns, companies are relying heavily on technological and operational breakthroughs to push the envelope of Extended Reach

Feasibility Study on the Reduction of Hydrostatic Pressure in a Deep-Water Riser Using a Gas-Lift Method.

Recent successful exploration efforts in deep waters have heightened interest in developing oil and gas reservoirs on the continental slope. Leases have been obtained in water depths up to 10,000 ft with a requirement that they be drilled within the next decade. Use of current techniques to drill these leases will require extremely large floating drilling units and large diameter marine riser systems. This study presents the results of a feasibility study on the use of an automated gas-lift system for a marine riser that will maintain the hydrostatic pressure in the subsea well-head equal to that of the sea water at the sea floor. Hydrostatic control of abnormal formation pressure could still be maintained by a weighted mud system that is not gas-cut below the sea floor. Such a dual density mud system could reduce drilling costs by reducing the number of casing strings required to drill the well and so reducing the time required to drill a deep-water well. The system would have the advantages of riserless drilling without giving up the well control advantages of a closed, weighted mud system. A steady-state numerical model was developed that can be used to determine the gas injection requirements needed to achieve a desired dual density configuration. The numerical model was verified through tests conducted in a 6,000 foot research well. Once verified, the model was used to define the gas requirements and practical limits of a marine gas-lift system based on estimated additional costs of gas compression and nitrogen membrane filters. The practical limits are presented in terms of maximum mud density, water depth, and riser diameter combinations. The dissertation also discusses the operational changes that would be required for various drilling procedures such as making a connection, running casing, kick detection, and well control operations

Characterization of annulus well cement quality to estimate the leakage potential in cement well barriers

Cement is nowadays the most used material that is placed inside of wells as a barrier element to ensure zonal isolation and avoid migration of fluids between the reservoir and surface. Sometimes the well integrity can be compromised due to the presence of imperfections called leakage paths. Some of those paths can be the result of defects during the well construction or can be the consequence of mechanical, chemical and physical processes during the well life that induce alteration and degradation in the barriers. Annular cement barriers are the object of study of this thesis. Full-size test sections have been constructed to investigate barrier quality and their correlation with single phase gas and water leakage rates. A durability study of oil well cement 30+ years old is also presented analyzing the variation of mechanical, petrophysical and compositional properties in connection with the overall cell permeability behavior. Finally, the research conducted to construct a facility for the testing of logging technologies of annular well barriers is presented. Results show that migration paths correlate well with the logging interpretation and fit well with the variations of hydraulic properties measured on the cells

Development of a mobile technology system to measure shoulder range of motion

In patients with shoulder movement impairment, assessing and monitoring shoulder range of motion is important for determining the severity of impairments due to disease or injury and evaluating the effects of interventions. Current clinical methods of goniometry and visual estimation require an experienced user and suffer from low inter-rater reliability. More sophisticated techniques such as optical or electromagnetic motion capture exist but are expensive and restricted to a specialised laboratory environment.;Inertial measurement units (IMU), such as those within smartphones and smartwatches, show promise as tools bridge the gap between laboratory and clinical techniques and accurately measure shoulder range of motion during both clinic assessments and in daily life.;This study aims to develop an Android mobile application for both a smartphone and a smartwatch to assess shoulder range of motion. Initial performance characterisation of the inertial sensing capabilities of both a smartwatch and smartphone running the application was conducted against an industrial inclinometer, free-swinging pendulum and custom-built servo-powered gimbal.;An initial validation study comparing the smartwatch application with a universal goniometer for shoulder ROM assessment was conducted with twenty healthy participants. An impaired condition was simulated by applying kinesiology tape across the participants shoulder girdle. Agreement, intra and inter-day reliability were assessed in both the healthy and impaired states.;Both the phone and watch performed with acceptable accuracy and repeatability during static (within ±1.1°) and dynamic conditions where it was strongly correlated to the pendulum and gimbal data (ICC > 0.9). Both devices could perform accurately within optimal responsiveness range of angular velocities compliant with humerus movement during activities of daily living (frequency response of 377°/s and 358°/s for the phone and watch respectively).;The concurrent agreement between the watch and the goniometer was high in both healthy and impaired states (ICC > 0.8) and between measurement days (ICC > 0.8). The mean absolute difference between the watch and the goniometer were within the accepted minimal clinically important difference for shoulder movement (5.11° to 10.58°).;The results show promise for the use of the developed Android application to be used as a goniometry tool for assessment of shoulder ROM. However, the limits of agreement across all the tests fell out with the acceptable margin and further investigation is required to determine validity. Evaluation of validity in clinical impairment patients is also required to assess the feasibility of the use of the application in clinical practice.In patients with shoulder movement impairment, assessing and monitoring shoulder range of motion is important for determining the severity of impairments due to disease or injury and evaluating the effects of interventions. Current clinical methods of goniometry and visual estimation require an experienced user and suffer from low inter-rater reliability. More sophisticated techniques such as optical or electromagnetic motion capture exist but are expensive and restricted to a specialised laboratory environment.;Inertial measurement units (IMU), such as those within smartphones and smartwatches, show promise as tools bridge the gap between laboratory and clinical techniques and accurately measure shoulder range of motion during both clinic assessments and in daily life.;This study aims to develop an Android mobile application for both a smartphone and a smartwatch to assess shoulder range of motion. Initial performance characterisation of the inertial sensing capabilities of both a smartwatch and smartphone running the application was conducted against an industrial inclinometer, free-swinging pendulum and custom-built servo-powered gimbal.;An initial validation study comparing the smartwatch application with a universal goniometer for shoulder ROM assessment was conducted with twenty healthy participants. An impaired condition was simulated by applying kinesiology tape across the participants shoulder girdle. Agreement, intra and inter-day reliability were assessed in both the healthy and impaired states.;Both the phone and watch performed with acceptable accuracy and repeatability during static (within ±1.1°) and dynamic conditions where it was strongly correlated to the pendulum and gimbal data (ICC > 0.9). Both devices could perform accurately within optimal responsiveness range of angular velocities compliant with humerus movement during activities of daily living (frequency response of 377°/s and 358°/s for the phone and watch respectively).;The concurrent agreement between the watch and the goniometer was high in both healthy and impaired states (ICC > 0.8) and between measurement days (ICC > 0.8). The mean absolute difference between the watch and the goniometer were within the accepted minimal clinically important difference for shoulder movement (5.11° to 10.58°).;The results show promise for the use of the developed Android application to be used as a goniometry tool for assessment of shoulder ROM. However, the limits of agreement across all the tests fell out with the acceptable margin and further investigation is required to determine validity. Evaluation of validity in clinical impairment patients is also required to assess the feasibility of the use of the application in clinical practice