Cementing through coiled tubing electric line (CT e-line) is not a common practice; this application is highly recommended in Coiled Tubing Drilling (CTD) applications using the existing CT e-line pipe to achieve a better time performance for sidetracking a well since using the CTD technique is mainly based on economical evaluation. Several considerations need to be taken into account while designing the job and performing the operation. The relatively high density and viscosity fluid can lead to bird nesting the cable due to high friction and excessive slack inside the pipe; it can also affect the integrity of the cable as well as the performance of the bottomhole assembly (BHA). The interface between cement and other fluids pumped through CT e-line pipe can be also affected. A review on a feasibility study of cementing through CT e-line that was performed in 2003 in Alaska highlights all the concerns, challenges, and potential issues that can be encountered during a cementing job through CT e-line, best practices, lessons learned, and way forward to implement this technique. This review is supported by two successful case histories performed in Malaysia CTD campaign applying this technique for different objectives: remedial cementing for casing and tubing sealing in a deviated well and remedial cement plug for window recovery. By implementing cementing through CT e-line, the effective job time was improved by avoiding swapping pipes in an offshore environment where the logistic, safety, and space accommodation is a huge challenge. The use of CTD as an economical sidetracking technology was reinforced by making the CT e-line pipe universally utilized in all the project steps, even for running and setting completion.

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After an operator confirmed wellbore integrity failure in a well located on a small platform, a coiled tubing (CT) catenary intervention was urgently required. However, the production facilities of the platform were not authorized to operate, which represented an impediment to receive returns from the wellbore. This paper documents the analysis and implementation of nonconventional flowback methods and the actions taken to perform the intervention using a state-of-the-art fly-by-wire CT catenary package in a setup that had never used before in this field. After a shut-in period, the subject well faced integrity issues that could end in an uncontrolled situation. To remediate this situation, milling and plug-setting runs were designed using a catenary system with a fly-by-wire CT unit set for first time completely on the vessel and leaving only the injector head on the platform. To address the flowback limitation, technical and economical assessments were performed on three options: using slope barges to receive fluids in storage tanks, setting conventional flowback equipment on board the catenary vessel, or using the gas injection pipeline available on the platform. After analyzing each alternative, the options to use slope barges and flowback equipment on the vessel were discarded after confirming that they represented an additional risk and generated higher costs for their implementation. The use of the gas injection pipeline involved the modification of many resources on land and at the offshore facilities, and a detailed plan was needed to utilize the lines in a different way from their initial design. Additionally, weather conditions played a major role during the job execution. Consequently, a special focus was placed on elaborating contingency plans to address emergencies during the operation taking into account that the method implied handling hydrocarbons at surface under uncommon situations. The coordination and collaboration in the operation enabled the operator to achieve the expected results, recovering the wellbore integrity in a cost-effective way, while also eliminating the exposure of additional vessels or sophisticated equipment on location. The paper presents the large amount of information that was amassed during the implementation of the solution, which could be used by other locations facing similar conditions where conventional production facilities cannot be used during well interventions. The document also includes contingency plans for every stage of the project, safety measurements, lessons learned, and details of the modifications done to the gas injection system and the CT equipment.

The limitations to performing rigless interventions in small platforms and safety concerns of performing multiple heavy lifts to the platform have motivated different locations worldwide to find solutions for accomplishing their objectives by utilizing proven techniques. In Brunei, after more than 8 years of continuous coiled tubing (CT) catenary operations, comprehensive and detailed processes have been strongly established and have created a guide that can be used for implementing similar operations in other locations that do not have such experience. A methodology was implemented to find the bottlenecks in each process involved during the entire cycle of a CT intervention as well as the actions taken by an operator and a service company to eliminate them. Statistical comparisons were used to contrast what was done in the past with what has been implemented in recent years. Additionally, new vessel positioning systems, improved disconnect systems, and proven safety considerations were analyzed, and a streamlined process to operation design, execution, and evaluation (DEE) cycles was developed. As a result of the process improvement documentation has been elaborated which include the flexibility and limitations of the system to cover concerns that are usually present in every stage of the intervention. Checklists and local guidelines will aid workers from other locations to implement catenary operations by using a reference document to cover HSE requirements and well integrity issues including volatile operating conditions and to obtain the information necessary to deliver technically challenging operations. This work supplements the current literature that addresses the "what" of past case histories by providing guidelines for the "how" to achieve an implementation of successful operations while complying with global HSE and environmental regulations. A priority of this work was sharing of knowledge obtained while giving space for continuous improvement related to this type of operation in the future.