Posted on 23.11.2010 - 12:00 EST in ROV NEWS by Rons_ROV_Links
Pro-ROV Services of San Diego, California was contracted by Exxon/Mobil Pipeline to conduct video inspections on two risers of the GA-A244. The platform is located 130 kilometers (80 miles) off the coast of Galveston, Texas in the Gulf of Mexico. Situated in 110 meters (360 feet) of water and acting as a pumping platform for five other drilling platforms in the area.
Exxon/Mobile had been using a large global oilfield provider of engineered services and products to conduct their inspections using a large ROV, vessel and crew. The Exxon/Mobil engineer who contacted Pro-ROV Services was concerned about the size of the ROVs that Pro-ROV Services was planning on using and how they would handle the typical 1-3 knot currents in the area. As the goal of Exxon/Mobil was to see if the job could be done as well as or better than using a larger work class ROV, thereby saving costs and perhaps get a closer all around look of the risers, clamps, braces, flanges, etc.
An initial inspection was done prior to actual ROV inspection to familiarize Pro-ROV Services with the platform layout, sea conditions and specific job requirements. This initial inspection utilized a drop camera that has two cameras on board and stabilizing fins to help deal with local currents. After descending to 92 meters (300 feet) it was determined that the ROV inspection could be accomplished off the lower deck of the platform itself versus having to perform the inspection on-board a vessel with crew, as previous inspections had been conducted.
Actual inspections were done using two SeaBotix LBV ROVs, a LBV300-6 and a LBV200-4. When going offshore Pro-ROV Services always recommends having a backup ROV available in the event of unforeseen circumstances that may cause delay in completion of the job. The inspections were completed in two days, one day of inspections from inside the platform structure itself with the second day outside the structure, both off decks on the platform.
Due to the multiple and different directions of currents at different water depths, a finned clump weight system was used to help navigate the interior crisscrossed lateral bracing supporting the legs of the platform. Not only were substantial cost savings recognized by the client but previous inspections were only capable of an outside view of each riser due to the size of the ROV and their inability to go inside the platform structure. The smaller SeaBotix ROVs used by Pro-ROV Services were able to offer a 360 degree inspection of each riser along with up close inspections of each clamp saddle, knee brace and condition of bolts, in addition to overall marine growth on each of the risers.