This lecture will describe rational mechanism‐based design approaches for foundations and anchors for supporting rigs and floating facilities in the frontiers of offshore oil and gas development, with more complex soil conditions at the seabed.
In shallow waters, oil and gas exploration and production mostly rely on the stability of jack‐up rigs. The revealed soil failure mechanisms dictated to develop new design approaches for accurate prediction of spudcan penetration depth and the likelihood and severity of punch‐through in stratified seabed sediments (including calcareous soils). Mitigation measures for spudcan punch‐through and spudcan‐footprint interaction issues will ensure safe installation and operation of jack‐up rigs in the problematic seabed.
In the Gulf of Mexico, West Africa, offshore Brazil and more recently off Australia, developments have proceeded into water depths in excess of 1000 m. These deep water developments usually consist of moored floating facilities, which are tethered to the seabed via an anchoring system. For suction caissons, a new design approach was proposed removing uncertainties in regards to the soil failure mechanisms mobilised inside the long caissons with stiffeners. A particular challenge is the installation of full caisson length avoiding potential plug upheaval in layered soils. The most recent generation of anchoring systems, which is identified as the most promising and cost‐effective option for future oil and gas developments, is dynamically penetrating anchors or torpedo anchors. The relevant challenge is to ensure the installation of torpedo anchors up to the required depth in calcareous soils.
For stratified sediments, using real time continuous profiles from in‐situ piezocone and ball penetrometer tests in identifying soil layers and direct penetrometer to foundation/anchor design approaches are believed to be very useful.
Shazzad Hossain is an Associate Professor at the Centre for Offshore Foundation Systems at the University of Western Australia. He is an Australian Research Council (ARC) Postdoctoral Fellow. His research encompasses many aspects of offshore geotechnics and soil behaviour, from the initial characterisation of the seabed, to novel mechanism‐based analysis tools to quantify the response of foundations and anchors for design. His research blends physical modelling, using the UWA centrifuge facilities, with numerical analysis and field observations, and provides solutions in terms of design tools and mitigation measures for associated problems.
￼He has a particular interest in quasi‐static and dynamic large deformation problems involving changing geometry and soil failure mechanisms, such as spudcan penetration and extraction, suction caisson installation and torpedo anchor installation and pullout. He is also active in industry practice, as a consultant for local, national and international companies.
Associate Professor Shazzad has co‐authored 2 invited conference keynote and journal paper (for a special issue) on large deformation finite element analysis and spudcan foundations. His > 55 career publications have won 4 prizes including the 2005 British Geotechnical Association (BGA) Prize; the Institution of Civil Engineers (ICE), UK, David Hislop Award for 2010; the American Society of Civil Engineers (ASCE) Best Civil Engineering Paper Award for 2012 (“In recognition of the outstanding contribution to the advancement of Civil engineering for offshore structures”).
He was awarded the D.H. Trollope Medal for 2010 by the Australian Geomechanics Society (AGS). He was also the recipient of a ‘2007 Offshore Mechanics Scholarship for Outstanding Students’ awarded by the Int. Society of Offshore and Polar Engineers (ISOPE) and the ‘Institute Gold Medal’ awarded by the Prime Minister of the People’s Republic of Bangladesh.
He is a Core Member of ISO OGP TC67/SC7/WG7/P4 and contributing in developing guidelines for jack‐up rigs.
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