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 nonviscous 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.

Pampo was among the first producing fields offshore in Brazil, and it produced through a fixed platform. The maturation of the field and consequent decrease in oil production required a different completion strategy for the operator. The key reservoir, the Macaé/Quissamã, is the prime target for exploitation because it still has substantial oil in place, with good total recovery and actual recovery factors. The development of this reservoir was vital to the survival of the field. Several technical issues exist for developing this reservoir, especially during drilling, because of the high density of wells in the area. Each new well had to be carefully planned to avoid collision with existing wells and also to optimize the reservoir drainage. Several depleted wells have been evaluated to determine whether they should be abandoned and/or substituted. There were limited options for replacing these depleted wells. With collision problems at shallow depth looming as a huge risk, the number of new wells that could be drilled was low. Furthermore, the lack of rigs available for production drilling and the high slot utilization on these platforms provided additional complications. Ultimately, the development of multilateral wells was identified as the most viable solution. From the main bore, once past the critical collision zone, several legs could be drilled to increase the drainage area. Multilateral construction in this scenario is a nontrivial task. It requires the well junction to be placed at an area of high deviation, adding complexity for any intervention work. Nonetheless, the use of coiled tubing for most of the well completion operations proved to be the key enabler in this successful multilateral well development campaign. The versatility of CT technology significantly decreased the time needed for well completions and its other applications. This paper discusses the development, planning, and preparation activities involved with use of the CT in this milestone project. It summarizes the results of the development of the idea and lessons learned from the numerous runs during the completions operation, including CT-conveyed perforating; CT-conveyed logging for cement evaluation; stimulation, featuring the use of isolation tools; and several Stiffline applications. Introduction During the conception phase of this project there were many obstacles that needed careful attention:The position of the ML Junction at a near-horizontal position required the use of CT for a set of tools designed to be used with SlicklineThe changes in the project with the scaling down of the tool in order to fit Petrobras's existing 4" configuration presented a last minute challenge, with many tools being changed to allow for the access to the main bore or the later leg of this ML System. This ML System was designed to be used in a 5" Bore configuration.Given the rig's age, the crane capacity has been scaling down considerably over the years, even during the project execution, with a maximum limitation of 18 tons. Obviously this restricted the use of larger CT diameters, and even with the minimum amount of CT in the reels it was impossible to place the CT Reel on a position to execute these wells were the slots were placed in relation to the crane's maximum reach.The notion that CT was to be used as the main tool to allow wellbore access and to perform the majority of the tasks downhole posed a conceptual challenge, as in general there were not many people within the Client organization who felt CT was the way to execute these tasks.CT Perforating with high angle and large OD Perforating Guns presented a CT damage possibility due to the shock wave travel that could happen during the detonation. Field Description Pampo, located at south part of Campos Basin, is an offshore location, 80 km far from the coast and 105 m water depth was discovered in 1977.

The use of large-diameter coiled tubing (CT) pipe, 2 inches and greater, as the typical work strings in HP/HT extended reach wells has brought new challenges to the CT intervention industry. The CT strings utilized in this service are expensive and, by nature, short-lived expendables. As well reach increases, the strings become increasingly more sophisticated and costly. Identifying, predicting and controlling the factors that govern the pipe reliability is important to further extend the usable life of strings and contribute to the operational and economical success of CT service providers, CT pipe manufacturers and O&G operators. Furthermore, if any CT failure takes place, the root cause investigation is essential to the continuous improvement of the service and must be looked at in a holistic, systematic manner [1][2][6]. Hence we must understand how the combination of operational procedures, surface equipment, CT pipe manufacturing, and overall well conditions can affect pipe performance. In this proactive process, a new mechanism that can contribute to failures has been identified. This failure mode is associated with larger outside diameter (OD) CT pipe being subjected to a combination of high hoop stresses, high strain levels and run-in or retrieved from wells at high speeds. These new set of operational dynamic conditions expose the CT pipe material to higher forces, stresses and deformations not considered in the traditional conventional working envelope and in the associated performance tests and models. This new field CT pipe failure mechanism is presented in this work, its possible origins are explained in addition to laboratory test data reproducing such failures and identifying the potential set of combined operational conditions in which it can take place. An alternative CT fatigue-data generation procedure is proposed to better predict pipe performance, avoiding failures under field conditions, improve operational procedures, and enhance overall service quality.

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