A current profiling system on the super-drillship Jack Ryan, offshore Angola. Woods Hole Group built, installed, and maintained the system on the ship and collected data with it for BP and Shell. The system consists of a downwardlooking Teledyne RDI 38 kHz ADCP and an upward-looking 300 kHz ADCP.
There is a worldwide race on to locate and inventory reserves of oil onshore and offshore for strategic purposes. The major oil producers, including ExxonMobil, BP, Chevron and Shell are making substantial finds on offshore tracts. New subsea technologies have made this possible, by enabling easier, cheaper, and more precise extraction of oil from deep beneath the ocean. Chevron, like the other major oil companies, is pushing outward into ultra deep water for drilling, and to date it has reportedly set a record for reaching the deepest depths in the Gulf of Mexico, reaching 34,000 ft. beneath the sea surface at the Knotty Head Prospect in 2005. Chevron is doing what others are, locating oil reserves for production at a later date. When the time and the calculus is right, it will be ready to produce. In mid-2006 Chevron completed a record setting production test on the Jack #2 Well located at Walker Ridge Block 758 in the Gulf of Mexico. The test well was completed in more than 7,000 ft. of water and more than 21,000 ft. under the sea floor. This broke Chevron's own record in 2004 when the Tahiti well was deemed to be the deepest (20,000 ft. under the seafloor). The significance of the successful Jack well test is that it demonstrated Chevron is technologically capable of locating and potentially producing oil from such depths (7,000 ft. water and 21,000 ft. through sub bottom material). Now it will spend the next year and a half modeling scenarios for the construction of production facilities, to
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optimize development of the Jack field. One of the technologies that is revolutionizing offshore oil operations is the Global Positioning System (GPS). GPS enables operators to know the exact position of every piece of surface equipment at all times, to within a tolerance of a few inches. That information is fed into complex computer models that assist in all aspects of offshore operations. Navigation and positioning of the drill ships and everything below rely on GPS. Acoustic navigation technologies now extend the reach of GPS to provide precise navigation and control of equipment underwater. For example, acoustic pingers are placed on almost every piece of equipment that is deployed overboard, and arrays of bottom-mounted transponders are deployed at drilling and production sites. They "talk" to topside receivers which are constantly updating their position. This is extremely important when looking for oil pockets thousands of feet below the seabed to be able to return to that exact spot if it is deemed drillable. Current measurements become increasingly important in deep water operations due to the large drag forces that can affect a drill string or riser that is hanging 5,00010,000 ft. below an exploratory drill ship. According to Bruce Magnell of Woods Hole Group, the most active currents are typically in the top 1,000 ft., but the effect of these currents in the top 1,000 ft. can wreak havoc on the mating of the bottom of a 10,000 ft. riser to the wellhead
April 2007
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