This study focused on investigating various existing types of offshore jacket substructures along with a proposed twisted-tripod jacket type (modified jacket (MJ)-structures). The architectures of the three-leg structure, as well as the patented twisted jacket structure motivated the design of the proposed MJ-structures. The dimensions of the structures were designed iteratively using static st...

development of a numerical model which describes launching of offshore jackets from barge is presented in this paper. in this model, in addition to capabilities of commercial softwares, water entry forces on jacket members and an implicit newmark solution technique are included. the results are in general agreement with other numerical software’s available (sacs). fluid forces acting on jacket ...

when a jack-up installed at a clay location and then leaves; it can create several meter deep footprints. in case of soft clay, the spudcan may have actually penetrated much deeper than the observed footprints. when the penetrated spudcan is pulled out, much of the soft remolded clay will flow around it and go back into the hole. this event, leaving a deep region of disturbed soil. the disturbe...

Regarding the previous earthquake damages in offshore structures, as vital structures in the oil and gas industries, it is important that their seismic design will be performed with very high reliability. Accepting the Nonlinear Time History Analyses (NLTHA) as the most reliable seismic analysis method, in this paper an offshore platform of jacket type with the height of 304 feet and with a dec...

1.1 Offshore Structures: Offshore structures used for oil and gas extraction have the common function of providing a safe, dry working environment for the equipment and persons those operates the platform. Jacket supported drilling equipment as a guide for the piled foundations. The substructure referred to as the jacket is a three dimensional space frame made from large tubular steel members. ...

The sensitivity of the seismic response parameters to the uncertain modeling variables of pile-founded fixed steel jacket platforms are investigated using the Tornado diagram and the first-order second-moment techniques. The effects of both aleatory and epistemic uncertainty on seismic response parameters have been investigated for an existing offshore platform. The sources of uncertainty consi...

Effect of earthquake directional uncertainty on the seismic response jacket-type offshore platform

The oil and gas industry has moved towards Load and Resistance Factor Design through API RP2A LRFD and the recently published international standard, ISO-19902, for design of fixed steel offshore structures. The ISO 19902 is intended to provide a harmonized design practice that offers a balanced structural fitness for the purpose, economy and safety. As part of an ongoing work, the reliability ...

Decommissioning offshore platforms present unique safety and health challenges to the oil gas industry. In Malaysian waters, there are over 300 fixed jacket platforms, most of them exceeded design service life 25 30 years. One key that determine method removal aged is subsea cutting techniques. As underwater a challenging expensive task, it very much essential develop cost-effective techniques ...