SPECIAL REPORT: NEXT GENERATION CENTRALIZER SOLUTIONS
There are four main types of MODUs: •A submersible MODU usually consists of a barge that rests on the sea floor at depths of around 30 to 35 feet (9.1 to 10.7 meters) in areas with calm water. •A jackup rig sits on top of a floating barge and can extend legs down to the sea floor. Jackups can operate in depths of up to 525 feet (160 meters). •D rill ships can pilot to the drill site then use anchors and propellers to correct for drift as the rig drills for oil. They can operate in deep water conditions. •S emisubmersibles float on the surface of the ocean on top of submerged pontoons using several anchors to maintain orientation. Computers control the tension on each anchor chain to correct for drift.
All of this presents a number of engineering challenges whose complex characteristics are also reflected in the variety of drilling and production facilities available to the sector including fixed platforms, jack-up drilling rigs, floating drilling rigs, TLP (tension-leg platforms), spars and FPSOs (floating production, storage and offloading systems).
with several allowances for the offshore environment. A conduit made from lengths of steel pipe permits drilling fluids to move between the rig-at the water’s surface-and the sea floor. This conduit is called a “riser.” The riser is fitted with ball-and-slip joints that permit the long string of riser pipe to move up and down and bend slightly with the wave-induced movement of the rig.” With such levels of challenge and risk and the innate complexity of almost every solution applied in offshore drilling, accuracy and placement of drills and associated equipment become critical to the success of the operation. As a result of this there several systems designed to bring higher levels of predictability and consistency in structures where neither of those might be an inherent quality. High on that list are centralizers which help manage difficult engineering tasks in holes subject to distortion from geological pressure or, simply, wear and tear.
Challenges Offshore drilling itself presents a number of unique challenges not only from the engineering point of view but also from the degree of environmental risk and high levels of potential damage should that risk become a reality. Diamond Offshore6 explains some of the challenges; “Offshore wells are drilled in much the same way as their onshore counterparts,
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Defence Industry – Special Report on Next Centralizer Solutions