Casing, Riser and Tubingadmin2020-08-28T15:50:32-05:00
Published Article – Casing Leaks
In the March 2001 edition of World Oil (Volume 222, Number 3, page 97), CamWest, Inc. and Seal-Tite® published a joint article entitled “Pressure-Activated Sealant Repairs Casing Leaks. Casing pressure results in sustained casing pressure and fluid loss.” This article describes Seal-Tite’s success in curing four CamWest casing leaks. The article outlines the cost savings and risk reduction of using Seal-Tite® versus a conventional workover intervention. World Oil Magazine Article
A lead patch on the casing of a gas lifted producing well was leaking. A leak path had developed from the casing patch to the outside of the casing strings, resulting in gas bubbling to the surface around the platform. Using Seal-Tite’s pressure-activated sealant atomized into gas lift gas, Seal-Tite® was able to create a differential pressure through the leak site, activate the sealant mechanism and cure the leak. By using ®, the customer was able to cure the leak without resorting to expensive and risky rig operations, saving more than $500K.
Seal-Tite’s pressure activated sealant technology was utilized to repair a leaking joint in a drilling riser choke line at approximately 4,200 ft water depth in the Gulf of Mexico. The leak rate was aggravated by loop currents exceeding 2.5 knots. The sealant was displaced to the leaking connection with seawater by circulating down the choke line and taking returns on the kill line. Once the sealant was in place the BOP crossover valve was closed and sealant was squeezed into the leaking seals. Over the next 12 hours the sealant injection pressure was steadily increased until an 8,000 psi seal was achieved. This pressure was held for 8 hours to allow the sealant to cure, during which no significant pressure bleedoff was observed. The sealant was then flushed from the system and the choke line tested to 7500 psi, allowing normal drilling operations to resume. The riser was tested to the 7,500 psi operating pressure every three days during the remaining 30 days of the drilling operation with no leaks observed.
Tubing Leaks – Algeria
In Algeria, a gas injector well had tubing leaks at depths above the safety valve. Injection pressure was 5050 psi. After bleeding off pressure from the P1 annulus, the pressure increased at a rate of 150 to 200 psi per hour through the tubing leak. During the Seal-Tite® operation, injecting gas and venting the P1 annulus established the leak path. While injecting gas, the sealant was atomized into the gas stream. A differential pressure was created from the tubing to the P1 annulus and the sealant was carried through the leak path with the injection gas. The sealant polymerized in the leak path and sealed the leak. At the conclusion of the sealant operation, the P1 annulus was shut-in and the shut-in P1 pressure stabilized to 35 psi.
Tubing Leaks – Gulf of Mexico
Pre-job testing indicated a tubing leak at 16,000 feet, and the subsequent diagnostics confirmed a connection leak. Annulus pressure increased to 6000 psi within two days after bleed off and CO2 and H2S were in the annulus gas sample. An 18-barrel polymer pill followed by a two-barrel Seal-Tite® sealant pill were injected into the annulus. The pills were displaced down the annulus with sodium bromide and the sealant was extruded through the tubing leak into the gas stream. A differential pressure was maintained across the leak until the leak was sealed. The tubing leak was sealed without interrupting production. The alternative to the Seal-Tite® sealant solution would have been to shut-in the well and conduct a $1 million tubing replacement workover.