Re-entry of subsea wells can always hide unforeseen difficulties. Contingency mobilization of coiled tubing (CT) usually gives a wide spread of solutions to overcome most of the possible events. However, when operating on a winterized semisubmersible rig in the remote fields of the Barents Sea, rig-up of CT spread can be costly and complicated. Furthermore, lighter and easily deployable wireline powered mechanical tools have proven to be effective in tackling most of the possible challenges. Possible tubing obstruction issues can be resolved via clean-out/suction, pumping, or milling methods. In this instance, all three were used with different tools to clear the obstruction from the tubing and to clean with precision inside an internal fishing profile of a well head barrier plug to allow for well access. The first challenge encountered when re-entering the tubing in Well-1 was the presence of a 151m long hydrate plug. It was easily removed by an e-line tool capable of applying 10 bar of dynamic underbalance, while maintaining a continuous flow circulation. Such an application is a novel development in the use of existing tools. After removing the hydrate plug, it was discovered that the tubing was plugged by 246m of wax deposits, which were preventing communication with the reservoir. To overcome this problem, a jetting tool was utilized to continuously pump fresh wax solvent inside the landing string. Pumping continuously fresh wax dissolvent provided a unique and effective means to mechanically and chemically remove a significant obstruction. Once the communication with the reservoir was re-established, an additional obstruction of almost 129m (resistant to the wax dissolvent) was encountered. To overcome this challenge an e-line milling tool was utilized, and the resulting debris was bullheaded down into the reservoir. Similarly, when re-entering Well-2 a challenge was encountered to pull a barrier plug due to debris deposits inside the internal fishing profile. Both e-line milling and suction tools were sequentially used to resolve the problem and prepare the plug for retrieval. The tools used were already available on the market for different applications. In this case the tools were used in an alternative way, using their features to solve issues beyond conventional expectations. The result fosters confidence to plan future re-entry without the need for mobilizing a CT spread.

To rapidly increase production from the Goliat Field without adding costly subsea equipment and infrastructure or mobilizing a high-end subsea construction vessel, an operator transformed two single-bore subsea wells into multilateral producers with independently controlled branches. A multidisciplinary team was assigned to perform a feasibility study for the introduction of multilateral wells. Work started with a reservoir geomechanics/wellbore stability review, based on which well construction/completion basis of design was made. The design and operations sequence were analyzed by a well engineering team. As a result, the main risks, uncertainties, and assumptions were clarified. Two candidate wells were identified, and then a multidisciplinary team was assigned to manage the project, finalize design, initiate procurement, and write procedures. Workshop preparation was closely monitored and reported on a weekly basis. The onshore team closely followed up and supported operational execution. The new laterals were added to the existing wells, and multilateral junctions were installed and tested. An intelligent completion was installed, and independent branch production started. In addition, the estimated reduction in generation of CO2 is estimated to be between 10 to 20 thousand metric tons per well as compared with drilling two new subsea wells and installing the associated infrastructure. The technology enables an exploration and production (E&P) company to introduce subsea reentry multilateral technology to increase production while minimizing costs. The process includes well candidate identification, planning, and execution. This practical example can be used for future reference by drilling and production-focused petroleum industry professionals to better understand the benefits and limitations of existing technologies.