Optimization of perforation drilling for mitigating punch-through in multi-layered clays

• Published in: Canadian geotechnical journal Vol. 48; no. 11; pp. 1658 - 1673
• Main Authors: HOSSAIN, M. S, CASSIDY, M. J, BAKER, R, RANDOLPH, M. F
• Format: Journal Article
• Language: English
• Published: Ottawa, ON NRC Research Press 01-11-2011; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Analysis; argiles stratifiées; bearing capacity; capacité portante; centrifuge tests; Centrifuges; Clay; Clay minerals; Clays; Drilling; Drilling rigs; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Engineering geology; essais en centrifuge; Exact sciences and technology; Experimental methods; Failure analysis; fondations sur caisson de support; forage de perforation; Geotechnology; Marine; Ocean floor; Offshore; Offshore drilling; Offshore drilling rigs; Offshore engineering; Oil and gas industry; Oil well drilling rigs; Perforation; perforation drilling; prévention de la perforation; punch-through mitigation; Simulation; Soil (material); spudcan foundations; stratified clays; Asia; Southeast Asia; United States; Malaysia; ISEW, South China Sea, Sunda Shelf; marine drilling; preventive measures; models; efficiency; centrifuge methods; foundations; marine platforms; rupture; borings; ocean floors; optimization; bearing capacity; soils
• ISSN: 0008-3674; 1208-6010
• DOI: 10.1139/t11-065

“Spudcan” foundations for mobile drilling rigs continue to exhibit a high failure rate in the offshore oil and gas industry. The more frequent use of larger jack-ups in highly stratified regions, such as the Sunda Shelf in Southeast Asia, contributes to this concerning increase in “punch-through” incidents, which can lead to buckling of a leg or even toppling of the rig. An industry practice known as “perforation drilling” is sometimes used to mitigate the punch-through risk in layered clays, extracting soil from the upper strong layer before the jack-up is installed. This paper reports results from centrifuge model tests exploring the efficiency of perforation drilling. The soil conditions tested simulate offshore strength profiles that have reported punch-through failures. An experimental method for “drilling” sites in an enhanced gravity centrifuge environment was developed and the installation responses of model spudcan foundations penetrating through multi-layered clays with interbedded stiff layers were recorded. The experimental results show that the removal of soil inside the spudcan perimeter, with an area of 9% perforated, eliminated rapid leg run and severe punch-through on the two- and four-layer seabed profiles tested. This confirms the effectiveness of perforation drilling and indicates how the offshore drilling plan may be optimized.