bluuebunny/crossref_metadata_2025_split huggingface dataset:
Full-Scale Coiled Tubing Fatigue Tests With Tubing Pressures to 15,000 Psi
Authors: Headrick D. C. , Rosine R. S. 
Published: December 2007

Abstract
In recent years, the performance envelope of coiled tubing (CT) has expanded because of improvements in tubing manufacture and the prediction of low-cycle fatigue life. More accurate life predictions have been achieved with data from laboratory-scale and full-scale CT fatigue tests. To date, most testing has evaluated only tubing pressures below 10,000 psi. Fatigue models at higher pressures remain unvalidated.
This paper presents results from new, full-scale fatigue tests performed at 7,500 to 15,000 psi. CT with 90,000-psi minimum yield strength was cycled to failure at internal pressures of 7,500, 10,000, 12,500, and 15,000 psi. The measured fatigue-life values helped validate the fatigue model used for CT job design, and allowed the model™s further refinement.
Additional data are presented for full-scale fatigue tests performed with extended tubing-stroke lengths. This testing verifies the correlation between the tubing life observed in controlled, full-scale, short-stroke fatigue tests and the fatigue life observed in field applications with significantly longer stroke lengths. Measurements and analyses of tubing-diameter growth during high-pressure cycling are included.
Slimwell Concept – Innovative Coiled Tubing Completion Technology
Authors: Head Phil , Turner Dan , Cameron Gerald , Bottazzi Franco , Hanson Tim , Holst Tor-Kristian , Al-Rawahi Salim 
Published: December 2007

Abstract
This paper will present the results from a joint industry project (JIP) the object of which was to provide an effective solution to ‘slimming’ down the wellbore geometry whilst overcoming the associated drawbacks of slim annuli, such as surge and swab pressures during casing installation and circulation pressures while cementing.
The objective of the system is three fold;
First, to enable a conventional sized wellbore across the reservoir while significantly reducing the size of the upper hole and casing. Second, to enable an existing well with a 7″ casing/liner across the reservoir to be significantly deepened, maintaining the option for several casing points, and finally, The capability of an effective means of installing high integrity lateral liners.
The common approach throughout all of the well construction processes described in this paper is a series of liners, with tiebacks to previous liner tops as required.
With the current trend towards smaller riser and casing configurations, particularly in deep water operations, this innovative development now allows a broader range of options for well architects. A well with all the necessary casing points and contingencies can be accommodated within a jointed riser as small as 11″ internal diameter, whilst maintaining a hole size across the reservoir capable of significant production, well servicing and data gathering. Reeled drilling, reeled risers and the reeled well construction process made possible with this innovative development offers the real possibility of constructing low cost "Finder well" for exploration of hydrocarbons both in deep and shallow waters.
Laying Large-Diameter Coiled Tubing Offshore in the Arabian Gulf: A Case History
Authors: Sherwin Tom , Bauld Jim 
Published: December 2007

Abstract
The installation of offshore pipelines from a lay barge can be difficult, costly, and time-consuming. The barge generally proceeds along the pipe lay-path via winches that pull in on preplaced anchors positioned ahead of the barge. As the barge draws up to these anchors, the anchors must be periodically moved ahead and reset. Dynamically positioned ocean-going vessels temporarily equipped with coiled tubing (CT) equipment can help operators greatly reduce the complications associated with laying offshore flowlines. Recently, a service company specializing in coiled tubing operations worked with a major operator to lay continuous strings of 3,000 to 5,000 ft of large-diameter, coiled tubing flowlines between several offshore platforms in the Arabian Gulf. Modified CT well-service equipment was installed on a vessel equipped with dynamic positioning (DP) capabilities. A remote-operated-vehicle (ROV) and sonic transponders allowed operators to determine the location of the flowlines as they were placed on the seabed. Using this approach, operators successfully laid three lines in significantly less time and at a significantly smaller expense than would have been required by conventional barge-lay methods.
Optimizing Coiled-Tubing Training with Computer Simulation Modeling
Authors: Ross D , Kehler T. , Proctor R. , Campbell B. 
Published: December 2007

Abstract
To be a leader in coiled tubing technology today requires not only state of the art technology but also professionally trained operators and engineers. The coiled tubing service line within the petroleum industry is experiencing an exponential growth in technology. For example, the use of coiled tubing is frequently encountered in combination with other service lines such as drilling, cementing, stimulation, logging, well testing, et al. As demonstrated above, coiled tubing services are very much multi-disciplinary.
Typically, oilfield personnel have achieved their skill level from hard work and hands-on experience. However, in today's industry, hands on training cannot keep pace with the developments of coiled tubing related services. Due to the immeasurable costs associated with job failures attributed to human error or incompetence, it is essential that personnel receive the proper training to elevate them to the level of competence required.
One of the most outstanding accomplishments pertaining to coiled tubing training has been the implementation of coiled tubing simulators. A coiled tubing training simulator serves much the same purpose as a flight simulator does in the aeronautical industry. Students can run a coiled tubing unit and execute a real life well scenario while being challenged by a multitude of complications involving stripper leaks, BOP failures, tight hole, parted pipe, stuck pipe, etc. The main components of a coiled tubing simulator are the student station, graphics display, sound system, instructor facility and the main multi-tasking I/O computer. In addition to operating the main control consoles, the students are responsible for defining and graphically installing, function testing and pressure testing the proper surface equipment, coiled tubing string and BHA configurations required for the particular scenario. During a job simulation, the instructor can activate a multitude of problem situations that the student will need to respond to properly, to accomplish the pre-defined objectives. All of this training can be done in an accident free environment without the loss of well production or equipment. In one week of training a student may experience many different well control procedures that in the past may have taken years to experience.
The authors' intent of this paper will be to discuss the rapid growth of the coiled tubing industry and the demand for competent operations and engineering personnel required to implement emerging technologies. Secondly the advantages and process of implementing a competence based progression program to meet the personnel demand will be reviewed. Thereafter, the synergistic benefits derived from the utilization of a coiled tubing simulator to provide accelerated training and assess personnel competence levels will also be discussed. Lastly, an outline of a comprehensive coiled tubing training program, developed to compliment a competence based progression approach will be presented.
Sensitivity Analysis of Hole Cleaning Parameters in Directional Wells
Authors: Li J. , Walker S. 
Published: December 2007

Abstract
The major differences between conventional rotary drilling and Coiled Tubing drilling are the absence of pipe rotation and the continuous circulation of drilling fluids.
In rotary drilling the circulated fluid must be selected to support the cuttings while making a connection. In slide drilling, the circulated fluids can be continuously circulated. This capability greatly aids the use of gasified fluids in underbalanced drilling. In slide drilling, the pipe does not rotate; while in rotary drilling, the pipe rotation enhances the cuttings transport by the agitation effect due to the pipe rotation and vibration.
For a typical Coiled Tubing drilling job, the challenge is achieving the circulation rate required to keep the hole clean. Current field practice is to perform frequent wiper trips.
The economics of hole cleaning are crucial to the industry and therefore we seek answers to questions such as:
What is the change in the cuttings bed height when the fluids flow rates are altered? How long does it take to clean out an existing cuttings bed? Is there a need to remove the cuttings bed fully before resuming drilling?
In this study, 600 tests were conducted and a new computer program was developed for the prediction of cuttings transport in the multi-phase system (gas+liquid+cuttings). The sensitivity of cuttings bed height with respect to liquid/gas volume flow rate ratio, in-situ liquid velocity, ROP, inclination angle and circulation fluid properties was conducted. The hole cleaning time with both circulation mode and wiper trip is also discussed. The results from the sensitivity analysis presented in this paper indicate that: i) the fraction of the circulation liquid has a significant impact on the cuttings transport in underbalanced drilling with gasified fluids, ii) among different variables, the in-situ liquid velocity is the most important variable for cuttings transport, iii) the hole cleaning time decreases non-linearly with increasing fluid circulation rate.
Applications Engineering For Composite Coiled Tubing
Authors: McClatchie D. W. , Reynolds H. A. , Walsh T. J. , Lundberg C. 
Published: December 2007

Abstract
The addition of composites to the range of materials available for coiled tubing manufacture has raised a number of issues. An understanding of the advantages and limitations of this new material will serve to more clearly identify the niche for composite coiled tubing in oilfield service.
Current assumptions as to what diameter of coiled tubing is suitable for a particular application are no longer valid. The change in stiffness for any given coiled tubing diameter associated with a custom designable composite matrix requires careful modeling of all forces acting on the tubing during well interventions.
Hardware issues must also be addressed if a new tube material is to be integrated into the existing world wide coiled tubing fleet. Bend radius limitations related to product stiffness will have an impact on the suitability of existing reels and injector goosenecks. Field serviceable flush OD end and repair connections are necessary if composites are to approach the versatility of metal coiled tubing products.
Previous industry efforts have identified three principle applications for composite coiled tubing. Permanent wellbore installations such as velocity, production, and injection strings in harsh environments appear to be an obvious fit. Service strings for workovers also appear to be a good application due to the fatigue characteristics of composite materials. Composite tailpieces have also been proposed to take advantage of the best properties of both materials. The advantages and disadvantages of each application identified by modeling and hardware ultimately decide whether composites are more suitable than conventional coiled tubing materials.
The Reeled Monodiameter Well
Authors: Pointing M. E. , Betts M. J. , Bijleveld A. F. , Al-Rawahi S. 
Published: December 2007

Abstract
This paper examines the technologies required to develop a Reeled Monodiameter Well, a well using expandable coiled casing that maintains a single diameter of well bore throughout. However, a Reeled Monodiameter well will not be available to the industry tomorrow. Slotted expandable tubulars were introduced to the industry in the recent past and are now finding commercial applications. The concept of solid expandable tubulars for oil well applications is the next logical step of this technology. Joint Venture companies have recently been established to develop the concept of solid expandable tubulars and bring them to the market place. Consideration of the whole package reveals that there are various ways of achieving the end objective as described in this paper. There are still key technological challenges, notably in the areas of expandable casings, annular isolation techniques, over gauge hole drilling and novel hanger systems that will have to be addressed before this process becomes everyday reality. Possible solutions to these challenges are presented.
First Underbalanced Coiled-Tubing-Conveyed Perforating Operation Performed in an HP/HT Highly Deviated Well in East Venezuela
Authors: Villarroel Nelson , Almanza Edgar A. , Scott Martin , Vera Isidro , Fernandez Diego , Salazar Arquimedez , Gomez Luis 
Published: December 2007

Abstract
The technology for coiled-tubing-conveyed perforating (CTCP) under extreme conditions has been available for a number of years, but until recently, the techniques have not been used in Venezuela. This paper will describe the first experiences in which CTCP has been used in this area.
The first candidate identified for the application was a new well in East Venezuela. This well was the first high pressure, high temperature (HP/HT) highly deviated deep monobore well completed in El Furrial Field in the North Monagas area that was perforated underbalanced with this technology. Although several traditional perforating methods were initially evaluated, the decision was made to perform the operation underbalanced using rig-assisted coiled-tubing technology because of the following advantages that could be realized from use of this method:
Debris in the tunnel would be reduced, minimizing the potential for formation damage. The debris could be circulated out more easily. The use of kill fluid to control the well would not be necessary. By eliminating the cost of the kill fluid and the resulting costs of handling the returned kill fluid, well costs would be reduced.
The operation was performed in a live well with a 77-degree maximum well deviation and total depth (TD) of 17,907 feet.
Several engineering simulations were performed before the job. These simulations enabled the operator and service engineering personnel to quantify the effects of CT fatigue, lockup, stresses, forces, elongation due to weight and temperature, and buoyancy effects. Other important factors considered were safety, health, environment, quality and well control, taking into account all possible contingencies. Finally, nine (9) coiled tubing runs were performed to complete the well, a total of 1,190 ft of 3 3/8-in., 6 shots per foot (SPF) and 2 ¾-in., 6 SPF guns were run. In all of the coiled-tubing-conveyed perforating runs, the expended guns were retrieved successfully under live well conditions. To retrieve the guns without killing the well, a subsurface flapper-type safety valve, which enabled the operations to be performed under controlled conditions, was used.
Currently, the well is producing 19,621 BOPD through a 1-in. choke and 1,591 psi surface pressure.
Production and wellhead pressure expectations for this well were exceeded.
Force Transmission of Coiled Tubing in Horizontal Wells
Authors: Qiu Weiyong 
Published: December 2007

Abstract
This paper numerically predicts the force transmission of coiled tubing in horizontal wells. The overall friction factor, which is important for assessing the drilling feasibility of horizontal wells, minimizing the occurrence of lockup and other mechanical failures, can be predicted by using back calculation procedure. In the prediction of force transmission, three configurations of coiled tubing, i.e., straight, sinusoidal, and helical configurations, are taken into account.
A number of experiments were conducted by using TUDRP's (Tulsa University Drilling Research Projects) horizontal buckling facility to verify numerical predictions. The experiments involved applying a top load at one end of the pipe and measuring the bottom load at the other end simultaneously. As the applied load is increased continuously, straight, sinusoidal, and helical configurations can be observed. The predictions of force transmission match the experimental results reasonably well. This confirms the feasibility of back calculation procedure to predict the overall friction factor and the accuracy of theoretical contact force.
A New EOR Application in a Gas-Oil System
Authors: Stevenson M. D. , Skinner R. C. , Clifford P. J. 
Published: December 2007

Abstract
Gravity drainage in a gas-oil system can be an efficient natural recovery process and may give rise to high unit recovery efficiencies. However, as the Gas-Oil Contact descends during drainage, there is a large, effectively immobile, oil target remaining.
Detailed mechanistic studies have been performed where a miscible injectant (MI) hydrocarbon gas has been injected into the expanded gas region to recover additional oil and to accelerate production compared with continued gravity drainage. The studies were performed with finely gridded fully compositional models in both 2 & 3 dimensions. This work has built upon the significant EOR experience of three phase water-dominated systems and begins to explore two phase gas-dominated EOR processes.
There are a number unique features of the two-phase Gravity Drainage Miscible Injection (GDMI) EOR process including: –The importance of vapourisation for "oil" transport;–A condensation imbibition mechanism;–The MI having greater density than the carrier fluid;–Utilisation of gravity and reservoir flux as drive for the MI;–Some dilution of MI by mobile free gas;–Low MI trapping.
The results of the study indicate that GDMI is a viable recovery process that can be used to selectively target immobile oil at high gas saturations and, under certain conditions, achieve recovery efficiencies comparable to conventional EOR processes such as Water Alternating Gas (WAG).
Hydraulic Fracturing for Sand Control in Unconsolidated Heavy-Oil Reservoirs
Authors: Wedman Mark L. , Lynch Keith W. , Spearman Jim W. 
Published: December 2007

Abstract
The North Slope of Alaska has significant accumulations of low API-gravity oil in unconsolidated formations. The combination of low-productivity wells in relatively unconsolidated formations in the arctic environment presents many challenges. Consequently, both formation stimulation (for economic production rates), and sand control (for acceptable operating costs) are required. A fracturing technique for sand control (FSC) with a resin-coated proppant (RCP) for proppant-flowback control proved feasible in laboratory testing. The initial attempts at field implementation were an investment in learning that resulted in a large number of first-order failures resulting from proppant and formation flowback. With these early failures, these attempts were not commercially viable. Laboratory investigations and field tests revealed the source of the problems, and led to design changes and improvements in implementation procedures. Field results have demonstrated that the FSC completion is a viable technique within certain formations on the North Slope that can achieve the stated goals of effective stimulation, proppant-flowback control, and sand control.
Testing While Underbalanced Drilling: Horizontal Well Permeability Profiles
Authors: van Kruijsdijk Cor P. J. W. , Cox Richard J. W. 
Published: December 2007

Abstract
Underbalanced drilling has gained popularity during the last years as it is well-suited to the drilling of low-pressured reservoirs and provides a method to prevent formation damage, especially in horizontal wells. The production rate of formation fluids during drilling carries information on reservoir characteristics. In particular, the permeability profile along the well may be inferred from a combination of well pressure and total rate.
The transient well inflow can be interpreted as a complex well test. The complexity arises from the fact that the boundary conditions (i.e. the well trajectory open to flow) change with time during the test. Moreover, the transient rate is influenced by variation in underbalance (i.e. well pressure) and well penetration rate. However, the signal (transient rate) carries detailed information on the permeability profile along the well. Analysis is preceded by the elimination of the effects of the variable underbalance and drill speed using deconvolution techniques. An accurate approximation of the permeability profile can be obtained by a direct analysis (i.e. without having to resort to history matching) of the corrected well influx. Note that only the total well rate trqnsient is required rather than the full inflow profile along the open well trajectory.
In previous work we considered the analysis of the transient rate during underballanced drilling of a vertical well under a constant underbalance. Both the variable underbalance and the more complex outer boundary conditions of a horizontal well (the transient is very likely to see the cap-and base-rock boundaries during the test) distinguish the current study from the previous one.
Boosting Horizontal Well Performance In Carbonates By Selective Stimulation: Field Cases From Qatar
Authors: Sannier Yann , de Lapasse Hubert , Kirkhus Rune , Richard Claude 
Published: December 2007

Abstract
To enhance oil productivity in its Alkhalij field offshore Qatar in 1997, Elf Petroleum Qatar took the decision to complete the carbonated Mishrif reservoir through horizontal cemented perforated liners. The vertical or subvertical wells in this field produced an average of 3000bbl/day per well. The last 5 horizontal wells were put on stream at a more than of 8000bbl /day flow rate.
To achieve maximum productivity from the horizontal drains, complete entry exposure had to be established along the entire length of the horizontal section. To meet this objective the perforated sections of the drain were stimulated in two stages as follows: by opening the perforations in the toe of the horizontal section by pumping acid through coiled tubing and thenby performing the main acid job by bull heading, through the DST string, a retarded triphase acid system (emulsified acid diesel solution with nitrogen) with ball sealers as the diverting agent.
This paper documents the engineering methodology and the operational techniques employed on 5 horizontal wells to selective stimulate producing intervals of between 600m. and 1,200m. length.
Case histories are presented to illustrate procedures, treatment designs and productivity results.