Pressure Activated Sealant to Restore Tubing Integrity – case study of well TN-x in Mahakam

Abstract

Pressure activated sealant is used to repair tubing leak and restore tubing integrity without the need to install downhole devices which yield additional restriction inside tubing and reduce tubing ID.

Leak on tubing was detected in early production phase from the continuous increase of A annulus pressure. The leak point was indicated from Production Logging Tool (PLT) at 183 m suspected from tubing thread connection, with annulus pressure buildup rate 435 psi/24 hrs.

Pressure activated sealant was selected as the means to cure the leak. Retrievable plug was set below the leak point and sealant was pumped on top of plug, followed by inhibited water. Then pressure was applied at surface to squeeze and activate the  sealant. The remaining fluid inside tubing remained liquid, allowing the plug to be retrieved.

A total of 59 L sealant mixture and 750 L of inhibited water was pumped to the well. Hesitation pressure was performed to activate the sealant, and got indication of chemical sealing at 1000 psi. The tubing was then pressure tested to 5000 psi and pressure was holding in 1 hour, indicating positive isolation has been established between tubing-annulus. From continuous annulus pressure monitoring, pressure in A annulus has been stable at ~40 psi for the last 8 months after sealant injection has been performed.

Pressure activated sealant is proven as a reliable method to cure small leak in tubing. Since the sealant will only be hardened inside the leaking point, there will be no additional restriction in the tubing, thus Internal Diameter (ID) reduction will not be a concern for future well intervention operations.

Pressure activated sealant could become one of the alternatives to cure tubing leaks, especially in the cases where tubing ID reduction is not favored.