Conductor Encapsulations: Anadarko Petroleum Corporation
Gulf of Mexico, 1995
This report covers the field encapsulation of six conductors on Anadarko Petroleum Corporation's production platforms at High Island 367 B and East Cameron 157 A in the Gulf of Mexico. The encapsulations were 20 feet long, extending from -10' to +10'. In photo 1, surface preparation of two conductors is underway. On the conductor at right, the work is being carried out underwater, as evidenced by air breaking the surface. Proper surface preparation is a vital step in the process. It helps ensure that every square inch of the encapsulation will be tightly bonded to the conductor.
The next step is to install the rigid FRP jackets around the conductors. The inside surfaces of the jackets have been lightly grit blasted to ensure bond with the epoxy encapsulation grout. In photo 2, a jacket half is being lowered into position on the center conductor. Temporary ratchet straps that hold the jackets in place until the seams are sealed, can be seen on the conductors at right and left. These straps are placed over patterns of polymer stand-offs that are adhered to the insides of the jackets. The stand-offs maintain the proper clearance between the jacket and conductor. Note one of the grout injection ports at the waterline on the jacket at right. These ports are positioned at 5 foot intervals on alternately opposite halves of the jackets.
After the FRP jacket is positioned around the conductor, the two vertical seams are sealed with marine epoxy paste and fastened with stainless steel rivets. After the seams are sealed, a special gasket is adhered into the molded upset at he bottom of the jacket. Note the extent of surface preparation on the conductor in photo 3. One of the two grout injection ports that are positioned at the bottom of each jacket can also be seen.
In photo 4, the diver can be seen monitoring the progression of grout through the translucent jacket as the grout is being pumped into the jacket from the bottom up. The grout hose is connected to the second injection port. Previously, a short lift of grout had been pumped into the lowermost port on the opposite side of the jacket and allowed to cure. This step is carried out to provide a positive bottom seal. As the aggregate filled grout is forced upward within the confines of the jacket, a scouring effect is created. This scouring effect, combined with surface preparation of both the conductor and the jacket, is the principal reason why the A-P-E Process stays tightly bonded, when other systems fail. On this conductor, a collar can be seen just below the bottom of the jacket. On two of the conductors, collars were within the length to be encapsulated and upsets to accomodate the collars were molded into the jackets at the factory.
Topside, the aggregate filled epoxy grout is batched, mixed and pumped by the plural component method. In photo 5, the air operated A-P-E grout handling unit can be seen on the deck of the service vessel. This unit separately pre-mixes aggregate with each of the epoxy reactive components. The premixed components are then moved through separate hoppers and hoses to be finally blended just before entering the FRP jacket. (The blending unit can be seen, just behind the diver, in photo 4). This allows the contractor to start and stop the pumping operation without concern for the reaction time of the epoxy grout. It also enables the equipment to be cleaned with sea-water and greatly reduces the need for solvents. After the FRP jacket is completely filled with grout, it is topped off with a fillet of marine epoxy paste. In photo 6, a completed encapsulation is seen. This particular conductor had a collar near the waterline and the jacket was molded to fit. The owner intends to complete the repair by coating the conductor from the top of the encapsulation to the deck. Note two of the grout injection ports that have been sealed with polymer plugs.
The project described in this report was completed in six days with no interruption to operations on either platform. With the exception of some surface preparation tools that were brought to a landing on the platform, all materials and equipment were confined to the deck of the service vehicle.
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