bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Tubular Failures in Riserless Environments
Authors: Samuel Robello , Adari Rishi , Gradishar John , Willie lyoho A. 
Published: March 2011

Abstract
Riserless drilling poses numerous operational challenges that manifests itself in a number of ways, that can adversely affecting the efficiency of the drilling process. The problems include increased torque and drag, increased vibration, poor hole cleaning, tubular failures by buckling above the mud line, poor cement jobs, and associated problems during tripping operations. Drilling in deepwater and ultra-deepwater as well as extending the reach to a greater along hole depth in the riserless environment requires both improved models and comprehensive analysis, especially when the larger diameter casing pipes are run and cemented. The present calculations without proper modeling will gravely underestimate the hook load values when the casing strings are run in deepwater situations. This paper proposes a modeling approach, which uses scenarios in which the drillstring/casing strings are in open water and in openhole reservoirs under different operating conditions to arrive at appropriate hook-load values in addition to torque and drag calculations.
Both combinations of soft and stiff string models are used for the tension-force estimation as well as the wellhead-side loading calculations. The research results also present the hook-load calculations for scenarios when casing and inner string are run with drilling mud inside the inner string, sea water in the outer string, and pad mud in the hole below the mud line. The study concludes that various parameters influence the results, such as wellhead offset from the rig center, wellbore inclination, curvature, wellbore torsion, angle of entry into the wellhead besides the complexity from wind, wave forces, and ocean currents. This paper documents the comparison between the predicted mathematical simulation results with the actual well data from different wells to explain the rigor of implementation.
Case Histories of Recent Field Results for Advancement in Milling of Cemented Tubulars
Authors: Haq Mohammed A. , Fisher Jerry , Bailey Tom 
Published: March 2011

Abstract
Milling success is dependent upon the level of technology, mill design and overall efficiency of the operation. Any milling job requires that the mill be the most appropriate for the given set of circumstances and that the operating parameters used provide maximum efficiency to minimize time and costs. There are many different kinds of milling jobs which may arise and in each case a particular milling tool is the most appropriate to get the desired results. However, in some cases the tools available do not necessarily fit the job requirements and a lengthy and costly job can ensue.
One such set of circumstances is a tubular cemented inside casing with cement both inside the tubular and in the annulus, this is particularly difficult because the tubing is likely to be eccentric to the casing. This condition leads to a phenomenon known as coring which results in premature cessation of progress requiring that the mill be replaced. In recognition of this situation a project was commenced to develop an improved milling system which would provide substantially greater Rate of Penetration (ROP) and overall mill life. This lead to the development of the 2-pod mill for cemented tubulars and refined milling procedures which double the ROP and increase the overall mill life by a factor of 4 when compared to standard mills.
In this paper, the problems associated with milling cemented tubulars are reviewed; and the development and laboratory testing of the new mill design is described. The paper goes on to present several field results case studies which confirm the improvements noted during laboratory testing.
A Comparison of Collision Avoidance Calculations
Authors: Okewunmi Shola , Brooks Andrew 
Published: March 2011

Abstract
This paper will describe procedures commonly used in the industry for avoiding unwanted wellbore collisions. Unwanted collisions may occur if the actual position of a wellbore differs from its presumed position. Such differences may arise from errors in positioning the wellhead, errors in directional survey measurements, or incorrect assumptions regarding the survey errors or the trajectory between survey stations.
Normal practice is to assign an error model to each survey. The presumed position of the well then consists of a wellpath centerline and an associated envelope of uncertainty which is derived from the error model. Collision avoidance practices may be based on specifying minimum clearance between the centerlines or between the envelopes of uncertainty, or they may be based on estimates of collision probability.
Exercises have been conducted to compare uncertainty envelopes and estimates of collision probability, calculated by different service companies using different software packages. The exercises showed substantial variation among the results obtained, given the same input data. These results highlight the need for detailed specification of the problem, oversight of the process by suitably qualified personnel, and for clear annotation of all results to indicate the methods employed and assumptions made.
In spite of the complicated error models which are now available, it must be remembered that the values and error distributions assigned to several critical input parameters are little more than educated guesses. Under these circumstances, there are limits to how far it is worth proceeding with refining the details of error modeling, and the use of ample safety factors should be encouraged.
Documentation of Risk and Cost-reducing Potential by Utilizing an Automatic Supervision and Decision Support System During Drilling a Challenging HPHT Well
Authors: Rommetveit Rolv , Ødegård Sve Inge , Nordstrand Christine , Bjørkevoll Knut S. , Fjeldheim Mikkel 
Published: March 2011

Abstract
A very challenging HPHT well has been drilled while running an advanced decision support and ECD Management System including early diagnosis of upcoming problems and real time simulations using state-of-the art mathematical models. The System has been running in parallel with the operation, and used all available real time drilling data (surface and downhole) in combination with real time modelling to monitor and optimize the drilling process. This information was also used to visualize the wellbore in 3D in real time. Automatic forward-looking of ECD was also part of the active system. It was implemented in Total E&P Norge TASC (Total Activities Support and Collaboration) Center in Norway. The System was piloted by Total, and was therefore not integrated in Total's work and decision process.
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 modelIncreased probability for instabilities in the tight window. This was mitigated in the System by RT stability modeling during drillingUncertainties in pore pressure predictions. This was mitigated in the System by updating predictions during drilling.
Experiences from use of the System clearly show: -The forward-looking capability gave early warning of a near-future kick situation. And the diagnosis functionality gave first an early warning of an upcoming kick and then a firm diagnosis.-A loss situation was warned against and eventually diagnosed by the System.-Potentially at least 10 rig days, large amounts of drilling mud and a squeeze cement job could have been avoided by fully utilizing the System.-The drilling risks could have been reduced and safety increased through reducing the impact of the kick/loss situations and possibly even avoiding them.
Case History: Lessons Learned From Retrieval of Coiled Tubing Stuck by Massive Hydrate Plug When Well Testing in an Ultra-Deep Water Gas Well in Mexico
Authors: Arrieta Victor Vallejo , Torralba Aciel Olivares , Hernandez Pablo Crespo , García Eduardo Rafael , Maia Claudio Tigre , Guajardo Michael 
Published: March 2011

Abstract
A well testing operation was performed to confirm productivity potential in an ultra-deepwater area where a 5660-ft exploratory well had been drilled. This was a gas well, drilled from a semi-submersible drilling rig. As well testing from submersible rigs is a critical and sensitive operation; all planning had been carefully reviewed by the operator to ensure a safe, environmentally friendly operation.
The formation of hydrate plugs during ultra deepwater well testing is a critical concern, since water can be trapped and form a solid crystalline structure around gas when there are low temperatures near the mud line. This hydrate formation is a common occurrence in deepwater drilling operations, particularly while using water-based mud. Thermo-dynamic inhibition may not be effective in these cases, as several limitations in achieving the required injection rate exist.
Oilwell testing operations in deep and ultra-deep water have become common practice around the world, and vast experience with these types of operations has been acquired; experience with gas wells, however, has not been as comprehensive, and only a few gas wells have been tested under the conditions presented in this type of scenario. Because of the low number of gas wells tested in these deepwater conditions, best practice information is limited.
The intention of this paper is to present a case history and the lessons learned during a well testing operation in which water production in the gas-well was greater than anticipated during the clean-up period. A massive hydrate plug was formed while coiled tubing was being pulled out of hole, and the coiled tubing became stuck. The steps taken to free the coiled tubing will be discussed, and the discussion will include: Conditions that must be present to form hydratesHow the problem in this case was resolvedHow to help prevent hydrate formationBest practices for well testing in deep-water gas wells to maintain safety and economic viability.
This case history discusses a gas well being drilled with a semi-submersible drilling rig in ultra deep water, offshore Mexico.
FMECA and Commissioning - Guidelines to Effectively Deliver Technology and Systems for Successful Drilling Automation
Authors: de Wardt John , Moore Tom , McKenzie Andy 
Published: March 2011

Abstract
Failure Mode Effects and Criticality Analysis (FMECA) is a very powerful tool used in high risk businesses to deliver reliability. This is a known methodology applied in aerospace, nuclear and Dynamic Positioning (DP) systems that can be translated to drilling and completion operations.
Commissioning is the transition process between construction and operation that is widely used in process plants – from onshore chemicals to offshore production installations. It is a known methodology to ensure start up and operation meet specifications.
The drilling business has applied these tools to a very limited extent. When FMECA is used it is typically applied to a single component (i.e. drawworks) not the entire rig or system. Commissioning also tends to be done at the major component level rather than as an integrated facility. As the integration of systems in the drilling process grows these tools become very pertinent to reducing risk especially as wells become more complex and costly. They are the foundation of reliability for Automated Drilling Systems. Without applying tools that can deliver reliability in a manner that is cost effective a lot of value will be lost through unnecessary downtime and failures.
Participants at the SPE Emerging Technologies Workshop May 2009 and the SPE Drilling Automation Workshop April 2010 observed that they had limited knowledge of FMECA; however, after familiarization they concluded that this is a powerful tool that must be used to establish reliability of technologies and systems. The latter workshop concluded that the industry must focus on the application of FMECA and create standards for commissioning.
This paper has been created through a team of experts compiling their knowledge and guidance to provide a knowledge base for the industry to utilize for the benefit of increased reliability and reduced risk.
These two tools, properly and efficiently applied will bring immense value to the industry in terms of reliability. Specifically their application to the control and automation of the drilling process will provide the basis for successful growth of this technology application. Without correct application of these tools, growth of technologies and automated systems in drilling will be inhibited by unacceptable levels of reliability.
Predicting Salt Leaching During Drilling and Cementing Operations
Authors: Folsta M. G. , Martins A. L. , Lomba R. F. , Cardoso W. F. , Simão C. A. , Sidi I. A. , Dannenhauer C. E. 
Published: March 2011

Abstract
Drilling and completion operations in salt zones have been gaining importance in Brazil due to the discovery of large reserves of oil and gas reservoirs in the Pre-Salt zone. Thus, the pursuit of excellence in such operations, reduction of uncertainties, risks and costs are requiring considerable development of new operational practices and technologies.
The well salt surface in contact with non-saturated fluid results in leaching process. In drilling operations the continuous leaching of a given salt formation results in a "V" caliper profile. The drilling of different salts (e.g. halite, tachyhydrite and carnalite) can result in localized enlargements compromising well stability and subsequent operations. In cementing operations the thickening time and cement tensile strength are dependent on salt concentration being critical to control its maximum values at the end of the displacement.
This work details a salt solubilization study to be used both for drilling and cementing operations in salt zones. The software developed aims to estimate the amount of salt incorporated by the drilling fluid or the cement slurry during the fluids flow in contact with the salt formation. The software is based on the solution of the mass conservation equation for a component (salt) in the fluid that flows through the annular region of the well. The partial differential equations obtained in the transient 2D model were numerically solved by using the finite volume method. The formulation takes into account the mass transfer from the well salt wall and also from the drilled cuttings. Radial and axial diffusion and advection terms are considered.
Typical results obtained by the software are the diameter profile along the well and the profile of salt incorporated into the fluid. The methodology is a powerful design tool for defining initial salt concentration, flow rates and rheological properties of drilling fluids and cement slurries
Acquiring Formation Pressure Measurements in Challenging Borehole Conditions
Authors: Piber M , Ash S. C. , Hemsing J. , Kuchinski R. S. 
Published: March 2011

Abstract
Horizontal and multilateral wells are being drilled as a cost-effective approach to increasing production and adding reservoir value. The data acquisition strategy makes extensive use of formation pressure measurements that are critical to the understanding of the economic potential of a reservoir. Conventional formation testing techniques have proven inadequate for determining producibility and formation pressures in horizontal and highly deviated wells due to high costs and extreme operational risks. In this paper, a low-risk solution is described for obtaining early history formation pressures in these challenging borehole conditions using a very small sized formation tester combined with robust new operational planning, practices, and techniques.
The Compact Repeat Formation Tester (MFT), of diameter approximately 2.4 inches, was deployed in memory mode and conveyed to test depth. Extensive operational planning and pre-job modelling was completed to allow for optimum data acquisition while minimizing total operation time. Well conditions prohibited the formation tester from providing real-time surface communication, the formation tester was programmed to accommodate as wide of range of test scenarios as possible.
All tool data were stored in onboard memory for retrieval after the formation tester returned to surface. Twenty two pressure stations were attempted in two wells to a depth of 2250m under borehole conditions where information is usually not attainable. The data obtained from the stations was of good quality and the pressure results were subsequently confirmed by production.
Several examples are presented to demonstrate this new technique was successful in obtaining pressure data of highest quality and confidence allowing reservoir insights that would otherwise have been unavailable. The ability to take pressures at multiple stations throughout the reservoirs has produced a detailed understanding of critical economic information. Additionally further developments allow very near time transmission of drawdown pressures back to surface to allow for instant analysis.
Application of a New Method for Predicting Down Hole Loading of Tubulars During Expansion
Authors: Evans Merle E. , Setterberg John R. 
Published: March 2011

Abstract
This paper describes the loads experienced by solid expandable tubulars during down hole expansion. These loads are compared to the loads experienced by tubulars when expanded using current laboratory techniques. The paper demonstrates that the current practices for expanding test samples do not necessarily represent all of the loads that can be experienced in situ. The loads that are excluded in making expanded thread connection test samples may have significant impact on the performance of the threaded connections. Newly developed testing methods and equipment that have been used to replicate the actual down hole loads that are generated when casing is expanded will be described, and data generated from the testing of samples made with the new equipment presented.
Extended Reach Drilling - Offshore California. Extending Capabilities and Improving Performance
Authors: Armstrong Neil R. , Evans Andrew M. 
Published: March 2011

Abstract
El Capitan is the latest extended reach drilling (ERD) well to be drilled from the Heritage Platform into the Sacate Field, offshore California. The application of learnings from previous wells enabled El Capitan to be drilled to a total depth of 37,165 ft measured depth (MD) / 6,938 ft true vertical depth (TVD) with 33,682 ft of horizontal displacement (HD). The most challenging phases of the well will be described in this paper, concentrating on the main engineering focus areas during planning and execution.
El Capitan holds the record for the longest well drilled in North America and is the third longest directional well drilled worldwide by MD (seeFig. 1). El Capitan also holds the record for the deepest (MD) 12-1/4-in. hole section and the deepest (MD) set 9-5/8-in. liner. Application of the company's recently modified Fast Drill Process (FDP) emphasizing the redesign of borehole related performance limiters enabled a 250% improvement in drilling performance from offsets in the 12-1/4-in. and 8-1/2-in. hole sections (Dupriest et al., 2010). Casing floatation techniques used on previous wells in the field were refined to enable a 27,267 ft long 9-5/8-in. liner to be successfully run to the 12-1/4-in. hole section total depth (TD). The well objectives were achieved with no safety or environmental incidents, 92 days ahead of plan, significantly under budget and with only 15% non-productive time (NPT).
The Continuous Measurement and Recording of Drilling Fluid Density and Viscosity
Authors: Miller A. , Minton R. C. , Colquhoun R. , Ketchion M. 
Published: March 2011

Abstract:
The density and viscosity of the circulating drilling fluid are currently monitored at intervals of 15 to 30 minutes. These intermittent manual measurements are time consuming, entail a continuous presence in the shale-shaker house, are open to user error and are seldom widely communicated. Yet these measurements can offer an indication of developing drilling fluid or bore-hole problems that, if caught early, could minimise developing hole problems or limit operational delays.
This paper presents the field results of the use of a novel instrumentation package that continuously monitors these properties, exports the data to the logging data-base, permits trend analysis and the wider promulgation of the information, mitigating the limitations of the current approach.
The design of the package is such that there is no longer a requirement for manual sampling. This frees up the Derrickman / Shaker-hand for more productive tasks and minimises exposure to the noise and fumes of the shaker-house. Also, the simple, rugged, build means that it can be operated and maintained without the need for dedicated service engineers. Additionally, monitoring is still possible should the shaker house become unbearably hot, the hydrocarbon gas levels are too high or even if noxious gases are present in the enclosure.
The data is collected at 10 second intervals. This vastly increased granularity of the data set permits the identification of short duration ‘spikes’ possibly indicative of incipient Barytes sag, fluid channelling, fluid interfaces, etc. It also means that trends can be identified earlier and remedial steps taken to pre-empt developing problems.
Data will be presented from an HP/HT drilling operation in the UK sector of the North Sea. These measurements will be compared with manual readings, as a measure of their veracity, and weight and viscosity signatures / trends will be identified and correlated with known events.
MicroRNA-200b Regulates Vascular Endothelial Growth Factor–Mediated Alterations in Diabetic Retinopathy
Authors: McArthur Kara , Feng Biao , Wu Yuexiu , Chen Shali , Chakrabarti Subrata 
Published: March 2011

OBJECTIVE
Diabetic retinopathy (DR) is a leading cause of blindness. Increased vascular endothelial growth factor (VEGF), promoting angiogenesis and increased permeability, is a key mechanistic abnormality in DR. We investigated microRNA (miRNA) alterations in DR with specific focus on miR-200b, and its downstream target, VEGF.

RESEARCH DESIGN AND METHODS
miRNA expression profiling microarray was used to examine the retinas of streptozotocin-induced diabetic rats. Expressions of specific miRNAs were verified with PCR in the rat retina and in glucose-exposed endothelial cells. A target search, based on sequence complementarities, identified specific targets. We analyzed mRNA levels and protein expression in endothelial cells from large vessels and retinal capillaries and in the rat retina, with or without injection of miR-200b mimic or antagomir. Localization of miR-200b and its functional analysis in the rat and human retinas were performed.

RESULTS
Alteration of several miRNAs, including downregulation of miR-200b, were observed in the retina in diabetes. Such downregulation was validated in the retina of diabetic rats and in endothelial cells incubated in glucose. In parallel, VEGF (target of miR-200b) mRNA and protein were elevated. In the retina, miR-200b was localized in neuronal, glial, and vascular elements. Transfection of endothelial cells and intravitreal injection of miR-200b mimic prevented diabetes-induced increased VEGF mRNA and protein. Also prevented were glucose-induced increased permeability and angiogenesis. Furthermore, transfection of miR-200b antagonists (antagomir) led to increased VEGF production. Similar alterations were seen in the human retina.

CONCLUSIONS
These studies show a novel mechanism involving miR-200b in DR. Identification of such mechanisms may lead to the development of novel miRNA-based therapy.