bluuebunny/crossref_metadata_2025_split huggingface dataset:
Twenty Years of Successful Coiled Tubing Re-Entry Drilling With E-Line BHA Systems - Improving Efficiency and Economics in Maturing Fields Worldwide
Authors: Krueger Stefan , Pridat Lars 
Published: February 2016

Abstract
More than 20 years ago, the first e-line coiled tubing drilling (CTD) systems were introduced. Since then, the technology has evolved and proven to be an efficient, economic means of enabling additional production from aging oil and gas fields. These systems are now established as a standard, viable solution for re-entry drilling in a variety of maturing fields and applications. Corresponding technologies and procedures were developed, and continuously improved.
Utilizing project data from more than 20 years of operational experience, this paper describes the progression from the first e-line CTD bottom hole assembly (BHA) applications in Europe through to today's continuous operations in several areas worldwide. It presents the technology changes and procedural adjustments that were necessary to address new challenges related to extending the economic life and improving the production of mature fields by economically accessing stranded reserves, and includes: Wellbore design changes from single re-entry to multilateral wells, along with the envelope extension from pure geometric wellbore placement according to plan, to real-time reservoir navigation utilizing geo and bio-steering services.Introduction of special applications such as precise kick-off from vertical, dual casing exits and extended reach drilling (ERD) with CT technology.Progression from overbalanced drilling operations to full underbalanced (UB) applications, with nitrogen injection through the CT string and the requirement to manage production while drilling.Equipment development to enable safe pressure deployment of the drilling BHA, enabling a move from conventional tower set-ups to dedicated highly mobile coiled tubing rigs.
Continual improvements of technology and steady implementation of new developments in many aspects of CTD technology were the result of innovative re-entry projects executed worldwide. To achieve the necessary efficiency and economic goals, improvements and new technology developments occurred in the downhole BHA technology, casing exit equipment, surface equipment, rig and other associated systems. Simultaneously, processes and procedures were also optimized with new ones introduced to adapt for changing environments and observed challenges.
Based on worldwide CTD experience, the trend of technology developments and continuous improvement will continue. The goal is to further drive project efficiencies and economics, enabling the life of maturing fields to be extended, deferring abandonment and improving ultimate recovery.
CT Fatigue Modeling Update
Authors: Newman Ken , Kelleher Patrick 
Published: February 2016

Abstract
SPE paper 163884 in 2013 entitled "Development of a New CT Life Tracking Process" envisaged a new CT fatigue modeling and tracking process. A new process has been implemented, with several significant changes from the original vision. This paper documents the process and system that has been implemented and is now being used by a significant portion of the CT industry.
A Novel Method to Control Tool Transport in Well Intervention and Pumpdown Operations in Oil and Gas Services
Authors: Viassolo Daniel , Coles Randy , Hill Jim , Seshadri Muralidhar 
Published: February 2016

Abstract
Shale play assets are exploited using horizontal wells in which measuring and controlling top-of-tool forces are necessary for positioning tools. Methods currently applied to deal with these forces are inefficient.
In traditional vertical wells, tool transportation relies on gravity force and simply unspools the wireline cable until the tool reaches target location. In horizontal wells, gravity is not enough to overcome friction; therefore, pumping fluid downhole or using a tractor is required to transport tools. Dynamic control of the transport rate is necessary because of the wide variation in friction forces along the tool path (attributed to well geometry), proppant settling between stage stimulations, changes or defects in casing, etc. Transport rate controls must help ensure the correct transportation force is applied. For pumping operations, this force should not be so low the tool stalls downhole, but not so high it results in a pump off and requires tool fishing with associated nonproductive time (NPT). For tractor jobs, it is important to get the tools to the target as quickly as possible without risking damage to the cable or stalling the tractor motion. Too little tension on the cable can cause drum crush in which tension loading differences between the run-in and pull-out tensions result in conductor damage; too much spooling off tension causes the tractor to stall. For wells with challenging geometries, dynamic adjustment of transport rate based on sensed cable tension and wireline speed has proven to be difficult. The tight coordination required to the wireline operator responsible for cable speed control adds to the challenge, and high risk of parting the cable or pump off of tools has been reported in these scenarios.
The authors developed a successful approach based on automation (feedback controls), which coordinates independent systems (wireline, pumping, or tractor) to improve the horizontal tool transport process. Field testing of this automated scheme is ongoing and has demonstrated its potential for improved run times, reduced risk, and cost savings for operators. This paper provides:
Description of the tool transport operation and architecture: sensors (including a key downhole tension sensor) and actuators (pumps), visualization, modeling, algorithm implementation, and tuning. Field testing results: comparing runs in real wells vs. simulation results for the same wells, listing benefits and lessons learned based on the authors experiences with one operator.
Automation of the tool transport operation by linking downhole sensors to surface controls is novel in the industry. The paper describes in detail the proposed architecture and provides compelling field test results.
Deepwater Riserless Operations with Coiled Tubing in the Gulf of Mexico: An Innovative, Safe, and Efficient Plug-and-Abandonment Technique
Authors: Ottolina Renny , Torres Carlos , Rudnik Alexander 
Published: February 2016

Abstract
The future of exploration and production (E&P) operations in the Gulf of Mexico (GoM) is focused on deep water, that is, &gt;5,000 ft [1,524 m] water depth. As the industry pushes the envelope to reach deeper reservoirs, subsea wells have become an important part of the offshore production. Although subsea completions may offer significant economic and environmental advantages over seafloor-founded structures, they require floating drilling or well intervention vessels to enable wellbore access should a workover operation be required to maintain production at an economic level or even to plug and abandon (P&A) the wells once they become uneconomical to produce. Interventions and P&A operations are very costly and may involve multiple services. The P&A of subsea wells represents no financial upside to the operators, other than the possible recycling of the subsea trees. Consequently, reducing costs and avoiding future environmental liability are the prerequisites for successful subsea decommissioning.
Riserless subsea P&A operations are often completed by setting the plugs with drillpipe after the production tubing is removed with the rig. As part of the operational improvement process, a coiled tubing (CT) service company evaluated the option of performing this task using the riserless CT technique from a multiservice vessel (MSV) after the zonal and casing isolation packer had been successfully set and tested. This technique would allow the operator to save time to complete these operations, thus reducing the cost.
Between 2010 and mid-2015, the CT service company has successfully completed 18 riserless subsea interventions at well depths ranging from 4,900 ft to 21,000 ft [1,494 m to 6,400 m] and water depths from 4,600 ft to 7,000 ft [1,402 m to 2,133 m]. Riserless wellbore access with CT has proved to be an efficient P&A method that has helped reduce operating time by up to 40% as compared to riserless workover rig-based operations.
Detailed engineering and planning as well as continuous improvements have allowed implementing the CT riserless technique in accordance with the Bureau of Safety and Environmental Enforcement regulations.
Agitating Explosives in Extended Reach Wells: A Good Idea?
Authors: Daly Kerry G. , Kollé Jack J. 
Published: February 2016

Abstract
The total length of horizontal wells increasingly exceeds the normal running limits of coiled tubing (CT), therefore the industry has invented and adopted the use of water hammers to emplace the coiled tubing and its related equipment into the farthest reaches of the lateral (toe). This equipment can include hydraulic jets, mills and motors for cleaning debris out of the well, and tubing conveyed perforating (TCP) systems (guns with firing heads) for establishing the first initial flow path into the well for fracturing and production. From a safety perspective, the use of perforating systems, which contain several types of discreet explosive components designed to fire based on impact (some more sensitive than others), may conflict with the use of water hammers, which axially impact the lowest components of the bottom hole assembly.
Sometimes the industry requires this combination in extended reach wells, especially before formation breakdown where no flow path exists for pumping down wireline perforating guns, and when primary completion equipment (sliding sleeves) fails. Modeling tools may allow users to configure tool strings with coiled tubing, water hammers, and perforating guns however this does not take into account the compatibility aspects regarding whether this is safe to do so. To truly determine the compatibility beyond simple conjecture, testing is required and has been completed.
Laboratory testing of an industry-leading water hammer run above a typical coiled tubing and TCP assembly (toe gun) was carried out to determine the effect of accelerations (G's) and long-term related vibrations (~100,000 cycles) on safety-critical TCP system equipment and simulated explosives. A field trial using live explosives was successfully completed, confirming the test results.
A novel approach, part of which is patented (Henke, 2010) is also described in which TCP equipment is configured with a fluid bypass to allow deployment on coiled tubing above a water hammer, hydraulic jets or mills and motors. This approach improves operator efficiency by allowing the clean-out and TCP system equipment to be run in a single trip. Laboratory testing measuring accelerations (G's) and long-term related vibrations (~100,000 cycles) again proved that there is no detrimental effect on safety-critical TCP equipment to include the shear pin in the firing head and liners in the perforating charges. Field testing of this system is pending.
Multiple Tubing Cuts in One Run Improve Operational Efficiency
Authors: MacLeod Anthony 
Published: February 2016

Abstract

Objective/Scope
In this paper, the author presents a case story from the Middle East in which multiple tubing cuts were performed using a new, non-explosive, electric line (e-line) conveyed tool on the same run in the hole. As this was an outstanding achievement, never accomplished before in the region, the paper discusses the planning, the operation, the achievements and the lessons learned.

Methods, Procedures, Process
A common practice for workover operations is to remove the existing completion and replace it with a new completion, either the same or sometimes with improved components. One of the steps required to pull the completion in this case is a run to cut the production tubing in one or more places prior to pulling the completion from the wellbore. A common practice is the use of an e-line cutting tool. Conventionally the best practice for this e-line tubing cut operation is to keep the pipe/casing in tension while performing the required cuts. This practice prevents "pinching" of the cutting blades and ensures higher chance of a successful cut for the operation.

Results, Observations, Conclusions
An operator in the Middle East has experienced success in performing multiple tubing cuts in a single run on an offshore well using an e-line deployed electric over hydraulic cutting tool with tubing in compression.

Novel/Additive Information
Moreover the paper reviews test results from a new style of machining arms and discusses how this technology is enabling an operator to perform rigless cuts to eliminate the cost of rig time to be more efficient, safe and cost effective.
Optimization of Coiled Tubing (CT) Performance with the Use of Rapid Tapered Section
Authors: Lee J. , Yeung J. , Williams C. , Graham-Wright T. , Elliott K. 
Published: February 2016

Abstract
The focus of this work is to optimize coiled tubing string design for greater horizontal reach in unconventional wells using a more rapidly tapered section than historically available. The string design will encompass a single outer diameter with a tapered wall thickness, resulting in a tapered inner diameter.
Comparison of string properties will include modeling a traditional straight wall (mono-wall) string design compared to a traditional continuous taper (longer tapered sections) and two rapidly tapered sections. The tapering helps limit the weight of the final string, making ground transportation within North America more feasible using common reel sizes.
Outcomes of the modeling comparing the four string designs will be presented using commercially available software for tubing forces analysis, fatigue modeling and fluid dynamics. This modeling will be used to create a database of theoretical results for typical field applications and parameters with the aim of comparing results to actual field data, when available. At the time this manuscript was authored, production of a string with the preferred design is expected to be possible near the end of 2015.
By utilizing a tapered design, improved low-cycle fatigue life can be achieved in tapered designs compared to straight wall designs of the minimum wall thickness of the tapered design. The tapered design generally has more desirable mechanical limits compared to the straight wall designs while experiencing limited reduction in friction pressure (due to the tapered inner diameter).
Advancements in Fatigue Testing and Analysis
Authors: Reichert B. , Nguyen T. , Rolovic R. , Newman K. 
Published: February 2016

Abstract
Coiled tubing is now routinely used in operations at stress and strain levels that are significantly greater than prior experience. These operating conditions have identified limitations in both the fatigue models and their underlying fatigue test data. A new experimental fatigue test program was undertaken to extend the strain and stress range used in testing. The test plan was formulated in terms of three non-dimensional variables based on the five physical variables. Data binning the three indenedant variables allowed the development of a full factorial test plan. By using the coefficient of determination as a measure of goodness of fit it was possible to test different hypotheses, including eliminating one of the three three non-dimensional variables. This fact greatly simplified the analysis and understanding of the data, and offers the possibility of significantly reducing the number of fatigue tests required to develop accurate models. The dependence of fatigue life, diametrical growth, and fracture length on the remaining two non-dimentional variables, strain and normalized hoop stress, are shown graphically. The lessons learned in this program are used to make recommendations for future fatigue test programs.
Improved CT Well Cleanout and Milling Procedures Utilizing Only Non-Viscous Cleanout Fluids
Authors: Cano Valeriano , Cardona Walther Garcia , Murphy Christopher , de Araujo Marcio 
Published: February 2016

Abstract
The use of coiled tubing service in the shale market has been of great importance in the process of preparing O&G wells for production, mainly in the post-fracturing isolation plug milling and solids cleanout. The challenges that the coiled tubing (CT) industry has been facing are substantial and range from CT pipe manufacturing and related technical matter to logistic and operational conditions. The CT industry has worked relentlessly to remain competitive both in efficiency and economic terms in comparison with new competitive completion techniques.
Well cleanouts are by far the most common operation performed with coiled tubing on a worldwide basis and also one of the most complex operations due to the large amount of operational variables involved. The shale market experiences the very same scenario, and cleanout-milling activity is far from flawless. Substantial amounts of solids, mainly the heavier ones, remain in the wellbore after the cleanout operation is completed.
Some of the traditional and deeply rooted techniques utilized in well cleaning nowadays have their origins in drilling and work-over operations in vertical wells. Some new important techniques presented in this paper, primarily addressing operations in horizontal shale wells, helped to improve overall efficiency during cleaning-milling operations.
These new techniques involved advanced cleanout procedures coupled with the utilization of non- viscous fluids throughout the operation. Use of viscous fluids was completely eliminated from the operations and even for contingency plans in critical scenarios, such as high-drag or near-stuck conditions. When most of the wellbore clean out parameters were optimized, hole-cleaning performance was significantly better when eliminating viscous pills and controlling the chemical dosage.
This paper also describes the importance of proper plug milling/well cleanout and how this was attained. As milling and cleanout procedures have a direct influence on each other's performance, it is imperative first to optimize each one to maximize overall performance.
Likewise, other operational aspects are discussed here such as the importance of RIH/POOH speeds, bottom-hole assemblies (BHA), the effect of proper formation balance on the overall results and also the advantages of using non-viscous fluids from logistic, economic and environmental viewpoints.
Novel Abrasive Perforating with Acid Soluble Material and Subsequent Hydrajet Assisted Stimulation Provides Outstanding Results in Carbonate Gas Well
Authors: Chacon Alejandro , Fadul Jose Camilo , Noguera Jose 
Published: February 2016

Abstract
Abrasive perforating with coiled tubing (CT) has been an industry available technique for several decades now and has proven to be a valuable alternative to conventional perforating with electric line (e-line). The application is even more valuable whenever a high rate or fracture stimulation treatment is to follow because of the significant reduction in tortuosity and pumping friction losses across perforations. One of the primary drawbacks of this type of perforations is that it is a much lengthier process compared to conventional perforating, and it requires large amounts of fluids and additional CT runs in the well to complete. These drawbacks discourage the wide use of the technique for more conventional applications.
This paper discusses a novel approach to abrasive perforating with the first ever use of an acid soluble abrasive material ending with a hydrajet assisted nitrified stimulation. The primary advantage of this abrasive material is that there is no need for additional cleanout runs and changeover of tools, thus significantly reducing operational time and fluid volume. Just as well, the benefits of combining the enhanced connectivity to the reservoir and the hydrajet assisted stimulation were reflected in outstanding gas production results, which exceeded all expectations. And, finally, as an added benefit, given the nature of the focused stimulation, this type of treatment in specific cases can replace plug-and-perf (P&P) or multistage fracturing completions, thus eliminating operational risks and added completion costs.
Successful Core Drilling Project Using Coiled Tubing From a Riserless Light Well Intervention Vessel in a Norwegian Fjord.
Authors: Rojas Susana , Taggart Michael , Buset Per 
Published: February 2016

Abstract
This paper details the planning, design and execution of a successful project involving the core drilling of three wellbores using coiled tubing directional drilling along the future "RogFast" tunnel route on the Norwegian coast. The project obteined core samples to verify rock quality prior to the commencement of tunnel drilling.
The project required several new technologies and techniques to enable the collection of the core samples.
The combined use of surface and subsea coiled tubing injectors operated from a vessel in combination had not been attempted and therefore was an area of concern, which was addressed during the operation design phase.
Project planning included the theoretical analysis of the fatigue effects on the coiled tubing between the surface and the subsea injectors, requiring the development of a secondary injector control panel and several modifications to the vessel systems.
The project resulted in a successful drilling and coring operation without incident or environmental spill following many months of planning, job design and use of a highly skilled team during the operation.
Optimization of Single Trip Milling Using 2-Inch Coiled Tubing
Authors: Snyder Elizabeth , Noland Justin 
Published: February 2016

Abstract
Conventionally, the same best practices from coiled tubing cleanout interventions in vertical wells have been applied to horizontal wells; pumping a high volume of viscous gel sweeps and performing a number of wiper trips in an effort to remove debris from the wellbore. Very often this practice leaves a significant amount of solids behind as a result of inadequate fluid rheology, increasing not only the risks of the operation but the overall completion cost of the well, while falling short from accomplishing the main objective of the Coiled Tubing (CT) intervention.
With the added pressure of reduced oil prices, operators are looking for ways to increase efficiency and reduce cost. Larger diameter CT has recently been used to perform millouts due to its improved set-down force and increased annular velocities for cleanout purposes. Service companies and operators have reduced the amount of wiper trips when using larger diameter coil to save time and money. Milling efficiency using 2 inch CT can be drastically improved by maintaining proper fluid rheology throughout the operation. By doing so, 2 inch CT has been used to successfully perform single trip millouts reducing operational time by 40%.
This paper will provide an analysis of the theoretical process and time comparison of multiple verse single trip millouts using 2 inch CT. The fluid rheology required to adequately clean out horizontal wells relies on the effective utilization of chemicals and correct fluid control throughout a given operation.