bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Development of a Corrosion-Resistant Coiled Tubing Product
Authors: Martin J. R. , Van Arnam W. D. 
Published: December 2007

Abstract
This paper will review distinctive corrosive wellbore environments that can be detrimental to the performance of (High Strength Low Alloy) carbon steel coiled tubing which is typically used for workover/intervention and completion applications. The paper will demonstrate how these corrosive environments form the technical push and potential market pull for the development of coiled tubing suitable for specific corrosive applications. The product development of a corrosion resistant coiled tubing will be reviewed, indicating initial design input, verification data depicting corrosion tests, mechanical properties; inclusive of strength, hardness, full body low cycle fatigue and surface property attributes. The product range depicting diametrical and wall thickness ranges will be reviewed.
The paper will include manufacturing issues such as forming, welding and inspection techniques. The paper will conclude with a review of the strings manufactured to date with application case histories.
The Low Cycle Fatigue and Plastic Strain Response of Coiled Tubing in a Sour Environment With and Without Corrosion Inhibitor Protection
Authors: Luft H. B. 
Published: December 2007

Abstract
The post-yield material performance of 70 and 80 ksi yield strength carbon steel and high-strength corrosion resistant alloy (CRA) coiled tubing (CT) has been investigated experimentally to evaluate its response to a sour environment following plastic bending straining induced during coiled tubing operations. Although this investigation was specifically targeted for under-balanced drilling of sour wells, the results obtained can also be interpreted with respect to CT work-over operations. The four different types of laboratory testing performed were low cycle corrosion fatigue (LCCF), NACE proof ring tests, double cantilever beam tests (DCB) and slow strain rate tests (SSRT). Full-body CT specimens were used for the SSRT and LCCF testing procedures and only SSRT test results are presented for a specific CRA material. The test environments consisted of aqueous H2S, H2S/CO2, varying pH and the standard solution specified by NACE for determining the relative propensity for HIC and SSC. Tests were also performed using the NACE solution treated with an H2S corrosion inhibitor.
This paper presents the key findings from the carbon steel CT testing, the preliminary data for the experimental CRA CT and the basis on which these materials were evaluated for under-balanced drilling applications. Both 70 ksi and 80 ksi carbon steel grades were found to be fit-for-purpose for sour wells in accordance with certain qualifications discussed. A preference for the lower strength, 70 ksi CT has been identified when CRA materials are not being considered. For carbon steel, the low cycle fatigue (LCF) life in a non-inhibited sour environment was reduced to between 15% to 20% of the life in air depending upon the pH level. With the application of an H2S corrosion inhibitor, the LCF can be increased significantly to about 2/3 of the life obtained in air. The results of this research are currently being implemented for a revised issue of Industry Recommended Practises for Critical Sour Under-balanced Drilling-Drill String (IRP 6.3).
Coiled Tubing Abrasion – An Experimental Study of Field Failures
Authors: Larsen Henrik Aslak , Reichert Bruce A. 
Published: December 2007

Abstract
Abrasion between the Coiled Tubing and the well completion has been a significant failure cause over the last three years. In excess of twenty-eight of these specific failures have been observed, cataloged and investigated. These failures resulted in a series of experimental studies using a modified form of the ASTM G75 abrasion test. This test is performed with a test fixture that repeatedly slides test blocks over stationary test laps with a controlled normal force and in the presence of an intermediary fluid. In the tests reported in this investigation the blocks were made from 90 ksi yield Coiled Tubing material, the laps were made from 13Cr and L-80 tubing material, four different fluids and two different normal forces were used. The results are presented as a normalized wear rate to clearly demonstrate the high-risk conditions for abrasion. The risk associated with these failures is very high as catastrophic failures have been observed at pressures significantly below pre-job test pressures.
Well bore fluid is the most critical parameter for abrasion. Abrasion failures have occurred in both liquid and gas environments, while the gas environment severely worsens the problem. The abrasion in dry wells is almost 250 times worse than in liquid filled wells.
Based upon the experimental results, a methodology is proposed to determine the relative risk of incurring abrasion damage during Coiled Tubing operations. The methodology looks at Coiled Tubing and well parameters and results in an overall risk assessment. A table of critical running feet is given based on the overall risk assessment and minimum Coiled Tubing wall thickness. When the critical running footage is reached measures such as pressure tests or wall thickness inspection should be taken
Repair of an Openhole Gravel Pack Using Coiled Tubing
Authors: Ovesen Monica , Riise Mai , Tanem Siv Arna , Nesvik Kjell Tore 
Published: December 2007

Abstract
This case study provides an overview of the Coiled Tubing (CT) operation performed for Statoil on the Heidrun field in 2002. The operation covered cleaning of a downhole sand control screen utilizing the Roto-Jet Technology, followed by installation of new sand screens inside the existing screens and performing a circulating gravel pack with coiled tubing.
The reason for this well operation was to repair a sudden and massive sand control breakdown. It was anticipated that this resulted from plugging of the gravel pack screens and/or a gravel pack packer failure. The well was producing 1500 Sm3/day with a water cut of 30 % prior to detecting the sand production. The objective of this intervention was to stop the sand production by installing 3-1/2" screens inside the damaged 5-1/2" screens, and perform a circulating gravel pack between the old and new screens.
The operation was conducted using a compensated CT tower allowing handling and running of jointed tubulars. A total of 6 runs with 2-3/8" coiled tubing was performed to clean out sand, remove fines/kill pill behind the existing screens, drift the well prior to installing a gravel pack packer, run new screens and perform the gravel pack operation, install a straddle across the gravel pack port and acidize. To be able to deploy screens into the well, it was temporarily killed with a specially designed kill pill.
After the CT operation, additional acid stimulation has been performed to remove remaining kill pill and increase the PI. The well is now producing 700 Sm3/day. The CT operation was performed in 21.2 days, while the platform was drilling simultaneously.
Record Depth Coiled-Tubing Sand Cleanout and Gauge Retrieval
Authors: Schuurman Rene M. , Ellzey Tim , Powell John W. , Reichert Bruce 
Published: December 2007

Abstract
Drilling deeper wells with high angles are becoming the norm in the Gulf of Mexico. As time passes these wells require some type of intervention. Coiled tubing intervention being an economic option creates new challenges by pushing existing coiled tubing technology to its limits. Deeper holes increases string weights requiring stronger coiled tubing pipe, injector heads and surface equipment. Friction must also be addressed with improved fluid designs for reducing circulating pressures without compromising good solids transport capabilities or temperature stability.
Success of these deep interventions greatly depends upon proper equipment; job design, planning and execution of the plan to improve the original objectives achieved.
Evaluation of the objectives, well details, location concerns, and logistics are keys to designing the right coiled tubing string, selecting proper (BHA) bottom hole assemblies, fluids and procedures in these deep wells.
This paper describes the design, planning and execution of a record-depth job with 1½" coiled tubing in a 25,200 ft deep high-pressure gas well in the Gulf of Mexico. The objective of the job was to clean sand from the well, retrieve down-hole pressure and temperature gauges, and prepare the well for the re-completion with the rig.
Several steps were taken to ensure a successful job: A 28,700 ft 110,000 psi minimum yield strength coiled tubing string was designed and manufactured. A special hydraulically optimized fluid with high solids carrying and suspension capacity and relative low circulating pressures was designed and tested. In depth pre job planning was conducted. All these factors played key roles in success of the job.
New Life for Old Wells – A Case Study of the Effects of Re-Stimulating Gas Wells Using Fracturing Through Coiled Tubing and Snubbing Techniques
Authors: Gutor Chad , Al-Saleem Ali , Rieger Bruce , Lemp Stephen 
Published: December 2007

Abstract
The use of a coiled tubing conduit for the hydraulic fracturing of shallow gas wells in southern Alberta, Canada has increased each year since its beginnings in 1997. The coiled tubing fracturing (CTF) technique has been utilized for both new and old wells as a means of fracture-stimulating multiple reservoir intervals.
This paper will detail a re-stimulation project completed during the summer and fall of 2002, in which the CTF and snubbing-conveyed fracturing (SF) processes were utilized to re-fracture a group of shallow gas wells that were originally completed in the 1970s. The objective is to examine the possible ways of enhancing production of older shallow gas wells by fracture stimulation utilizing tubing-conveyed processes.
Specifically, the paper will outline ways to consider and select wells that are candidates for re-entries, in addition to the essential work and evaluation that has to be done both prior to and following the re-entry, re-perforation, and stimulation techniques. This study will also provide a relative comparison between conventional fracturing techniques used previously and the CTF and SF processes used most recently. Also included are pre- and post-stimulation production data that give a clear indication of how effective the fracturing through tubing process is when used to re-stimulate these older wells.
Is Acid Placement Through Coiled Tubing Better than Bullheading?
Authors: Mitchell Wayne P. , Stemberger Dario , Martin A. N. 
Published: December 2007

Abstract
It has long been postulated that placing acid into a well through coiled tubing provides for better stimulation treatments than those achieved by simply bullheading. Common sense suggests that having the stimulation fluid enter the well via a dedicated conduit, adjacent to all points along the length of a treatment interval, will produce more uniform stimulation of that interval. However, the opposing argument is that, irrespective of the delivery method, all fluid follows the path of least resistance and will, therefore, flow into the areas of highest permeability, the ones generally least in need of stimulation. Diversion techniques, employed to improve treatment distribution, can often be applied to regular bullhead treatments as easily or even more easily than they can with coiled tubing. This is not necessarily so when pumping stimulation fluids through SSD’s or through the ESP itself.
Controlled tests to compare bullheaded and coiled tubing delivered treatments are difficult, as no two wells are identical. This paper evaluates 19 wells to provide statistical evidence of which delivery system does generally provide for the best end results. The paper suggests what the underlying reasons for the spread of results might be and suggests criteria as to when coil is, and is not, the best probable choice. It also discusses innovative methods to improve treatment distribution in wells, thereby maximizing stimulation efficiency.
Gravel Pack Cleaning: A New Solution
Authors: Brunskill Doug 
Published: December 2007

Abstract
A large number of fields worldwide have sand production problems and a common solution is a gravel pack (GP) completion. Over time this GP can become plugged with production fines as well as solids that may precipitate out of the produced fluids. As the GP plugs, it creates a larger restriction to flow and the production rate will decline. At some point the operator will decide the production rates are no longer acceptable and intervention is required. As a result, the GP completion will either be pulled from the well or be cleaned in-situ.
Previous in-situ cleaning processes involved treatment fluids bull headed into the well or placed by coiled tubing, to dissolve GP plugging damage.
This paper describes a new method for cleaning a GP in-situ. The process involves a rotating jetting head to create specific pressure pulsations combined with angled nozzles to create a "circulation current" within the GP. These circulation currents are localised and result in a temporary increase in GP permeability ensuring that treatment fluid will invade the GP only in the area immediately adjacent to the tool. This new process is significantly more efficient at unplugging the GP than previous methods and treatment fluids can more effectively reach areas of the completion such as the perforation tunnels and drill-in fluid filter cake damage. This process also includes managing the jet impact pressure to ensure that fragmentation damage of the GP proppant does not occur.
The paper will report results of laboratory tests using existing wash methods compared with the new technique and demonstrate the differences in; treatment fluid placement efficiency, fines removal efficiency and damage caused to the GP proppant.
Cleaning Wire-Wrapped Screen Liners: Large Scale Field Study Shows Coiled Tubing Jetting to be the most Effective Technique
Authors: Wijaya Zein , Portman Lance , Hardianto Hardianto 
Published: December 2007

Abstract
This paper describes a large-scale field study that demonstrates the relative merits of four different approaches to a single problem. That single problem is the clogging of wire wrap screens in gravel packed producing oil wells resulting in poor well performance. The four methods evaluated are: -Jetting with acid using coiled tubingBullheading foam diverted acidBullheading acid diverted with benzoic acid flakesSqueezing acid between opposing cup packers
A total of 168 well treatments are evaluated within this paper. The large number of wells permits meaningful comparitive data; the statistical spread of the data has also been evaluated.
The data clearly shows that by far the most effective way of placing acid across a wire wrap screen is to jet with coiled tubing. This method provides for better well response, smaller acid volumes, faster jobs and a better than average cost per foot figure.
A payback analysis has also been conducted.
An Innovative High Strength Drill Pipe Mechanical Cutting Solution Using Coiled Tubing
Authors: van Steveninck Erik , Manson Jim 
Published: December 2007

Abstract
This paper will examine an unusual intervention case history for a major UK North Sea operator, where a specialised coiled tubing (CT) conveyed mechanical cutter system was used to allow the recovery of stuck drill pipe.
Previous to the CT being mobilised to the offshore installation, a number of conventional drill pipe recovery techniques had been tried. However, all proved unsuccessful in freeing the stuck DP.
The decision was made to mobilise CT, dictated by both the need to free the High Strength S-135 DP and to confirm the degree of ID access for future intervention options. Ultimately a series of three mechanical cuts were made within the drill string. All cuts were at depths greater than 14,000 feet with 11.8 PPG OBM in the well. The particular challenges presented during this operation and the steps taken to provide a successful outcome will be explored.
Flow Patterns and Minimum Suspension Velocity for Efficient Cuttings Transport in Horizontal and Deviated Wells in Coiled-Tubing Drilling
Authors: Kelessidis V. C. , Mpandelis G. E. 
Published: December 2007

Abstract
Coiled Tubing Drilling, grown significantly in recent years, is normally associated with high angle to horizontal and extended reach wells. It is, however, in these applications that hole problems become more troublesome because of inefficient cuttings removal. Among the many parameters affecting efficient cuttings transport in Coiled Tubing Drilling are pump rates, well dimensions, fluid properties, solids sizes, solids loading and hole inclination. Several attempts have been made to determine the optimum operating range of these parameters but complete and satisfactory models have yet to be developed.
The purpose of this paper is to provide a critical review of the state of the art on efficient cuttings transport during Coiled Tubing Drilling, present the critical parameters involved, establish their range according to what is observed in practice and propose a different approach for predicting the minimum suspension velocity. Finally the laboratory system that has already been set up is presented. Its primary purpose is to allow the gathering of good quality data, missing from the literature, which could enhance our understanding of the flow of solid – liquid mixtures in annuli.
Improved Reliability of Coiled Tubing Equipment by Utilisation of an Assurance Management System
Authors: Cowan M. J. , Smith I. , Angell P. 
Published: December 2007

Abstract
Reliability and the minimization of equipment downtime is an aspect of coiled tubing operations that is desirable, but all too often planned performance is below expectations.
The web enabled system presented in this paper allows operations engineers to review individual verification and inspection processes, monitor individual equipment compliance and decide on levels of verification activity based on historical reporting and defined operating hazards.
The starting point of the process is the development of the criticality matrix by the specifying engineer. The matrix is reviewed to determine the criticality ranking from a safety and business perspective. Once all critical elements have been defined and the level of assurance required is agreed with the client the assurance engineer prepares clear performance standards for each item of equipment and a crew competency assurance matrix.
The equipment and personnel are then inspected to the level established in the performance standards. This can involve full dynamic testing of the equipment, review of certification and maintenance records, personnel competence and work experience.
Using defined inspection criteria, the critical elements are assessed. Deviations from the criteria are actioned and a subsequent report raised and ranked according to impact.
Data generated by BP projects show a significant long term improvement trend of increased equipment reliability contributing to a major boost in client confidence in coiled tubing conveyed operations. This has been positively attributed as a result of the adoption of a reliability assurance management system.
Economics of Nigerian Marginal Oil Fields
Authors: Ayodele Oluropo Rufus , Frimpong Samuel 
Published: December 2007

Abstract
In this paper, a new contractual agreement is proposed for the development of marginal oil fields in the Nigerian prolific hydrocarbon sedimentary basins. The proposed agreement is a modification of the existing agreements taking into consideration the special nature of marginal oil fields. Detailed economic analyses were carried out to assess the feasibility of the agreement. The economic analyses involved cash flow modeling, project profitability analysis, project sensitivity analysis and risk modeling using available and generally accepted economic, financial and technical data about the Nigeria operating environment. The final results from this study show that investing in the development of Nigerian marginal oil fields is a worthwhile option. The results show that the proposed agreement leads to favorable return on investment for all the parties involved. Project sensitivity analysis shows that if the combined cost of seismic survey and signature bonus is increased by more than 10%, the project becomes uneconomic. Also, if the price of oil falls below US$18.07, the project would have to be re-evaluated because the discounted pay back period (DPBP) would exceed the expected project life. Furthermore, risk analysis shows that as the NPV (net present value) increases, the risk level associated with such NPV also increases. Options available for financing marginal oil fields development are also presented.
Integrating Deterministic and Probabilistic Reserves
Authors: Gair Robert 
Published: December 2007

Summary
Probabilistic reserves evaluation offers the opportunity to describe a reserves volume in terms of the specific statistical certainty associated with that volume, as opposed to relying on the definitions associated with deterministic reserve classifications. Where a reserves entity has volumes identified for two or more certainty levels, knowledge of the reserves distribution may be used to interpolate reserve volumes at other certainty levels. This interpolation forms the basis of statistical reserves aggregation. Assignment of confidence levels to the deterministic categories of Proved or Probable supports both deterministic and probabilistic reporting.
This paper examines the mechanisms which control the shape of the reserves distribution curve; demonstrates the applicability of normal distribution curves to reserves distributions; and outlines a procedure for statistical reserves aggregation which may coexist with deterministic aggregation.
Consistent Performance: Reducing the impacts of price uncertainty through portfolio management practices
Authors: Allan Paul D. 
Published: December 2007

Abstract
Most companies recognize the importance of delivering consistent performance results, yet the ability to fulfill this objective is sometimes undermined by product price uncertainties. Many companies effectively manage the impacts of price uncertainty through the use of financial hedging instruments, while others have avoided hedging due to lack of knowledge, lack of company infrastructure, or political pressures. This paper addresses the reduction of uncertainty that may be obtained through portfolio management practices as contrasted to that achieved through financial engineering or hedging. A case study and computer simulation will be used to describe a portfolio management methodology for reducing the impacts of pricing uncertainty on performance results. The results will then be compared to strategies ignoring the variability of price, as well as strategies employing the use of typical hedging instruments.
The ability to reduce pricing risks through portfolio management is dependent upon project diversity (scale, timing, capital and fiscal structure) as well as the stated objectives of the organization. The results from the case study indicate that given an adequate cross section of opportunities, significant reductions in performance variability due to product pricing may be achieved through portfolio optimization. These uncertainty reductions may then be further enhanced through price hedging, as necessary to bring the overall level of uncertainty within a range acceptable to company decision makers or the market.
This case study and the resulting comparisons will demonstrate the way in which risk reduction through portfolio management may be used in conjunction with financial hedging to dramatically improve a company's ability to deliver consistent results.