Challenges in offshore geotechnics in Southeast Asia

Abstract

The first part of this paper describes the offshore oil and gas exploration activities in Southeast Asia. Typical subsurface conditions in the Sunda Shelf in Southeast Asia are highlighted and hazards in oil and gas exploration caused by the peculiar soil profile and parameters in the region are identified. These hazards include the punch through failure of spudcan supporting mobile jack-up rigs during installation and difficulties in removing the spudcans during extraction. The second part of this paper describes the results of centrifuge model study carried out at the National University of Singapore on punch through hazards during installation of spudcans in layered soils and performance of spudcans during extraction. The study on spudcan punch through reveals that a plug consisting of the overlying stiff soils develops when a spudcan punches through the underlying soft clay layer. Owing to such failure mechanism, conventional bearing capacity theories are not applicable to predict the spudcan punch through phenomenon. The study on spudcan extraction reveals that the suction developed at the spudcan base is the major component in the breakout resistance of spudcan with long operation periods.