E-Line Intervention Enables Operator to Design, Manufacture A New Customized Bit to Mill Out Isolation Valve in Record Time and Enable Early Production from Well

Abstract A well in the Panna-Mukta-Tapti Joint Venture (PMT JV) was completed using an isolation valve as the method of isolating the reservoir whilst running the completion into the well. Mechanical failure to open the valve was not anticipated as the isolation valve had a successful history in the JV with no failures in the last 10 years. However, in this well, the isolation valve failed to open. After spending multiple days attempting to open the valve and diagnosing the cause of the failure, it was concluded that the isolation valve was mechanically stuck. Further evaluatios of solutions incorporating Coil tubing (CT) and e-line interventions concluded that standard milling operations would pose additional challenges for the well due to the design of the completion below the isolation valve. Subsequently, a unique, star shaped milling bit was designed and manufactured to enable milling of the isolation which was smaller than 2.56" SSD and landing nipple present below the isolation valve. This was required to ensure future access for interventions through the SSD and landing nipples is not compromised and milling out the coupon from the flapper isolation valve does not get stuck in the smaller ID completion profile below it. The newly designed bit enabled milling and subsequently expanding that hole to the desired OD of 2.7" which would allow for future interventions. E-line milling was selected due to limitations in control with CT for debris generated. The total time from identification of the problem to designing, manufacturing, testing the new bit, transporting it to India and executing the solution was 45 days. The operation itself was carried out within 45 hours vs 120 hours projected with CT, leading to a significant cost saving, equivalent of 3 times daily spread rate for the rig. This unique methodology also enabled early onset of production, avoiding a delay of approxmately three month. This was the first time this new mill bit was applied and the first time that this isolation valve had been milled out using E-line. Existing, standard bit designs were not sufficient to accomplish this solution nor were conventional approaches satisfactory in today's economic climate. This paper will present the significant benefits accomplished from the utilization of the robotic, electric-line (e-line) intervention to mill out a malfunctioning isolation valve versus the use of coiled tubing (CT). In addition, it will use the flexibility and control features of e-line based, intervention technology towards addressing short lead time and design modification required to meet dynamic well challenges.