Coiled tubing (CT) has been used in Alaska for over 20 years as a low-cost alternative to a workover rig to complete a variety of well interventions in Arctic conditions in an effort to increase oil production. The majority of these operations are performed on wells that have a maximum anticipated surface pressure (MASP) that does not exceed 5,000 psi and are considered low-pressure wells. The working pressure of the lowest-rated component in the well control stack, including the operator's wellhead, is typically 5,000 psi. Therefore, CT interventions in Alaska on wells where the MASP exceeds 5,000 psi must be well planned far in advance of the job date to ensure that a thorough review of the equipment requirements, job design, and other aspects of the job are completed so that the operation can be executed safely.

Given current Alaska Oil & Gas Conservation Commission (AOGCC) regulations, an operator decided to re-enter five wells in the remote Point Thomson field area that contain hydrocarbons such as diesel or “arctic pack” (gelled diesel) in the wellbore to remove the hydrocarbon fluids and plug and abandon (P&A) the wells. There were several key challenges associated with this operation; these included the well's high MASP (7,900 psi), low ambient temperatures (-50°F), performing CT milling operations in large casing (9 5/8 in.), and cement placement through CT in zones with very low bottomhole temperature (29°F). The low-temperature cement system used was designed so that volumes of cement in excess of 200 bbl could be placed in the well through CT. In addition, a pressure and fluid management system for controlling pressure and removing solids and gas from the working fluids was used to manage high well pressures and reduce fluid costs. CT operations were completed safely. The application of CT to meet the requirements of these unique well abandonments allowed the operator to complete the P&A of all five wells.