Published on 22 novembre 2019
Tubing Patch repairs damaged tubing section
On a gas producer well, a leak was detected between the 4.5in #13.5 production tubing and the 7in casing. It was located with a thermo-log at a collar at 988m (3240ft). The major concern for the customer was to repair the zone and be able to run a downhole safety valve (storm choke) with an OD of 84mm (3.31in) through the repaired zone.
The workover of the Cr13 tubing string would have been very expensive and a tubing patch was determined to be the most reliable and cost effective solution. In order to cover the collar with a reasonable sealing length, a 6m (20ft) 4.5in reinforced patch was selected. The patch was conveyed using a 1-3/4in smart Coiled Tubing with optical fiber inside. Due to unpredictable CT behavior under pressure (elongation, helical buckling), a tension-compression sub was added in the BHA, to enable real time monitoring of the forces applied on the setting tool and the patch. It was also equipped with temperature and pressure sensors. The initial positioning of the casing patch was performed with a GR-CCL log. Prior to the patch operation, the well was killed with 1.27sg CaCl2 brine.