Abstract
This paper proposes an alternative design of small wellhead platforms in shallow water that require permanent manning due to operational requirements. The proposed structure is a combination of two monopods of moderate diameter (54″) connected rigidly by structural members. Multiple wells can be drilled through one of the two piles by using conductor sharing wellhead technology. The inadequate structural stability of the twin-pile platform without a jacket against environmental loads will be ensured by a few tie members connected to seabed with help of specially-designed small concrete foundations. Tie members will be bolted to the pile and the foundation. Each tie member will be lifted offshore together with the concrete foundation for quick installation and correct positioning of the foundation on the seabed. The pre-fabricated deck will be welded to the top of the pile. Numerical studies include structural design of a platform at 20m water depth for omnidirectional waves of 10.5m height as per API RP 2A working stress design method. Analytical method is provided to simulate interaction of concrete foundations with soil that can be easily implemented in structural analysis. The results indicate that the proposed structure has considerable reserve strength against failure due to extreme environmental loads and impact from medium sized boats.
