HDC-XREAM - CASE HISTORY

Production Tree De-Scaling Operation – Avoiding Snubbing

An HPHT well in Louisiana was known to contain varying degrees of barium sulphate scale impairment prior to a re-perforating operation attempt in 2003. The guns were force flowed back up the well during the perforating operation and became lodged in the tree, and wedged tightly into severe barium scale material.

The scale within the tree prevented the closure of the operating valves which would have allowed the isolation of the upper tree and the removal of the guns. Due to the high pressure of the well, the Operator mobilized a contractor to the site with the intention of freezing the well and performing a snubbing operation to remove the wellhead and access the guns. During this mobilization period, scale samples were sent for analysis and dissolver screening by a third party lab. The laboratory notified the Operator that Terra Expro's HDC XREAM product rapidly dissolved the scale.

Terra Expro designed a de-scaling operation based on tree pre-heating and HDC XREAM dissolver injection to remove the scales, which were holding the guns in place.

With the tree temperature brought up to > 175 º F using a heat blanket system, HDC XREAM was injected through a needle valve and working wing valve inlet. The dissolver was pumped through these access ports under pressure using a 30,000 psi hydraulic pump (Injection pressure 11,000 psi) and allowed to soak for 24 hours. The valves were function tested and found to be loosened but not free. More HDC XREAM was pumped and left over night. After the second function tests – 36 hours after the initial treatment, the Master Valve, Wing Valves and Lower Safety Valves were all found to be completely free and functioning.

Result: The guns were allowed to drop out of the tree and retained on a lower closed safety valve. The tree operated normally to allow slick-line rig up and retrieval of the guns. Consequently the Operator saved $450,000 on a snubbing operation and tree rebuilding.. and are understandably very pleased with the Operation.