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Offshore Drilling and Completion
Published in Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani, Offshore Operations and Engineering, 2019
Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani
Jackup rigs are the most widely used drilling rigs in offshore drilling operations. A jackup rig is a barge fitted with long support legs that can be raised or lowered. The jackup is maneuvered (self-propelled or towed) into location with its legs up and the hull floating on the water. Upon arrival at the desired location, the legs are jacked down onto the seafloor. Subsequently, “preloading” takes place, where the weight of the barge and additional ballast water are used to drive the legs securely into the sea bottom such that they do not further penetrate during operations. After preloading, the jacking system is used to raise the entire barge above water to a predetermined height or “air gap”, so that wave, tidal, and current loading acts only on the relatively slender legs and not on the barge hull [2].
Offshore energy
Published in David R. Green, Jeffrey L. Payne, Marine and Coastal Resource Management, 2017
In exploration aeromagnetic and gravimetric surveys are conducted from the air. The marine influence is greatest with seismic exploration, carried out using specialist survey vessels. For test drilling a primary requirement is mobility of the drilling rigs, which can be readily moved from one test well to the next. In relatively shallow waters, less than 100 m deep, jack-up rigs are commonly used: the deck can float, and the supporting legs can be raised when the rig is moved and lowered to the seabed when drilling. For the deeper parts of the continental shelf and upper parts of the continental slope just beyond 200 m depth, exploration is largely carried out using semi-submersible rigs which are self-propelled and can be maintained in position using systems of anchors supplemented by thrusters. In the deeper waters down to the seaward limits of the continental slope at depths of several thousand metres, dynamically positioned drill ships are employed.
Offshore site investigation
Published in White David, Cassidy Mark, Offshore Geotechnical Engineering, 2017
Jack-up rigs have their own drilling equipment, designed for well drilling, and this may be used for geotechnical investigation. A better approach, however, is to mobilise conventional onshore (geotechnical) drilling equipment, either positioned on the drill floor itself or cantilevered over the edge (Figure 3.25).
Experimental and numerical studies on the adjacent pile response to bucket spudcan penetration and extraction
Published in Ships and Offshore Structures, 2023
Chengfeng Li, Qunan WU, Run Liu, Pengcheng Ma, Haiyang Zhang
Jack-up rigs are widely used in offshore oil and gas developments and are typically supported by conventional inverted cone spudcan foundations. Recently, the bucket spudcan has been increasingly considered a more desirable foundation that can improve the jack-up rigs’ performance.