Abstract
An operator company in Bolivia needed a solution to a corrosion and pressure integrity problem caused by the presence of CO2 gas in the production fluids, resulting in deep tubing corrosion over certain sections of completion components with measured penetrations up to 96% of tubing's wall thickness.
Based on the corrosion's profiles, the intervention objective was to install a 16% chrome corrosion-resistant velocity string inside the production string to produce the well avoiding the exposure of those highly corroded components from the tubing.
The repair intervention concept was to set a hydraulic packer over the lower completion below the most compromised section of the production string and connect the isolation packer with 2" OD 16%Cr coiled tubing pipe up to the surface, hanging the string on the wellhead.
The velocity string installation should be performed in a single run with the well in live condition, avoiding the need to kill the well during the intervention.
The well's lower completion was composed of TPC-fired guns, a combination of 2-7/8" 6.4# and 3-1/2" 9.2# N80 tubing, and a 7" 23-29# packer. The upper completion was basically an arrangement of 3-1/2" 9.2# N80 tubing with a retrievable SSSV set at 107 m, a sliding sleeve device, and a seal unit sub to connect the upper to the lower completion.
