Engineering, Procurement, and Construction Challenges of Oil and Gas Artificial Islands in the Arabian Gulf, Part 2: Settlement Prediction of Shallow Foundations

Abstract

Abstract The Abu Dhabi oil and gas industry, represented by ADNOC companies, is currently developing an array of artificial islands across its Exclusive Economic Zone in the Arabian Gulf for applications ranging from new field development and upgrade or expansion of storage and offloading facilities, to the creation of accommodation villages for offshore personnel. With favorable water depths and environmental conditions, land reclamation is often a more economical option than the construction of fixed steel jacket platforms. ADMA-OPCO is currently engaged in applying land reclamation technology to projects such as the Satah Al-Raaz Boot (SARB) field development and the Das Island Development (DID). SARB is a 105-mbd development comprising 86 wells on two artificial islands. While cost and schedule optimization will be realized with the selection of the land reclamation and artificial island option for these mega projects, geotechnical and marine engineers are facing project-specific challenges such as the development of performance criteria for the fill material used in the construction of the islands and assessment of the ground improvement works. The fill material consists of natural soil (biogenic carbonate sand) dredged from the local environment with varying fines content and mechanical characteristics. Once deposited, the sand is compacted to achieve target performance. The major geotechnical issues related to the performance of fill material are its deformability under the working loads of the drilling facilities, which are generally founded on shallow footings, and its resistance and deformability during seismic loading. A method for the computation of short term settlements of shallow foundations under static loadings is proposed. The method, which has been implemented on a worksheet to provide a simple computational tool, is based on the use of the equivalent linear elasticity and is verified by means of model plate load testing of the fill material conducted in the centrifuge laboratory and zone load tests conducted on the SARB islands.