Complex Coiled Tubing Fishing Operation of Slickline Tools with No Kill Fluid in the Well in Danish North Sea

Abstract

As part of offshore workover operations in the Danish North Sea to safeguard the future of producing oil wells, older completions are being changed to new 5 in Glass Reinforced Epoxy (GRE) lined completions using workover rigs. During one of the several phases of this operation in one of these wells, slickline (SL) was being used to remove scale using a bailer when the Bottom Hole Assembly (BHA) got stuck and lost in the well. The wire was pulled to 70% of its breaking strength of 2150 lb with no indication of the SL jar firing. The fish left in the wellbore was a 37 ft long tool consisting of a roller stem, spang jar, and a 3 in pump bailer assembly. The top fishing point was a 1.75 in fish neck rope socket, with the top of the fish at 7219 ft. This horizontal oil producer was first drilled and completed in 2001 using a jack-up rig over a platform. The job objective for Coiled Tubing (CT) was to return the well to the original workover plan by safely fishing the lost BHA while considering the following conditions: The fishing tool combined with the fish would be too long for the available lubricator length.The hydrostatic pressure of the existing well fluid would be insufficient to overcome the reservoir pressure.A pressure-tested barrier is present between the casing and tubing annulus.The deep-set plug installed in the tubing at ~7350 ft has been pressure and inflow tested to 2900 psi.