A Geological, Geotechnical, Geohazard and Geotechnical Design Ground Engineering Zoning for Offshore Abu Dhabi, UAE

Abstract

Abstract Abu Dhabi's oil and gas reserves cover a large part of country's offshore region. With the vision of continuous optimisation of its operating costs, and minimising risks through world-class innovations, ADNOC Offshore identified a significant potential of integrating its wealth of ground investigations accumulated over 50 years into a comprehensive 3D Geological, Geotechnical and Geohazard model to develop innovative probabilistic geotechnical design risk-based solutions for its offshore assets leading to significant commercial benefits industry wide. ADNOC Offshore initiated the project in collaboration with Arup and the British Geological Survey to compile and interpret the available ground investigation information into a three-dimensional geospatial database and develop the 4G Ground Engineering Model. The 4G refers to Geology model, Geohazards (submarine, seismic and tsunami hazards) and Geotechnical data and Geotechnical design components. The various components of this model were compiled into a GIS platform with an intuitive user interface. This 3D ground modelling approach was achieved by combining BGS's 3D geological modelling capability, and the application of advanced methods for probabilistic treatment of uncertainty of geotechnical parameters by Arup. The state-of-the-art 3D geological modelling, which is consistent with the onshore geology but entirely new for the offshore region, provides the basis for consistent and robust geotechnical and geohazard zonation. The geotechnical design parameters and geotechnical basis for design of shallow and deep foundations for offshore structures was achieved through interrogation of the 4G Ground Engineering Model. The model makes all geotechnical information available to decision makers, providing one source of geotechnical truth for four offshore oil and gas field areas operated by ADNOC Offshore. Extensive, multi-billion-dollar development plans are underway and planned for future decades. The 4G Ground Engineering Model provides an efficient and robust tool to provide all ground-related information to decision makers for the siting, planning and geotechnical for new facilities, the regular risk assessment updating for existing facilities and for the planning of new ground investigations to fill knowledge gaps that have been identified and may require updating in the future. Uncertainties in interpreting ground conditions over such large areas have been analysed and evaluated and are fully appreciated by ADNOC Offshore. The 4G Ground Engineering Model is seen as a robust and transparent tool for managing these uncertainties as part of a wider risk management strategy. The 4G Ground Engineering Model provides multiple benefits to ADNOC Offshore including efficiency and cost savings. The primary focus for ADNOC Offshore has been continuous enhancement of health, safety and environmental performance as part of their risk management strategy. Offshore ground investigations are costly and require operation of equipment under strict health, safety and environmental requirements. The 4G Ground Engineering Model allows these works to be optimised at the planning stage, realising cost savings, and reducing health, safety and environmental risks. This 4G Ground Model has establish a platform for integration and implementation of multi-layered and multi-focal GIS database. New information and requirements can be easily integrated into this model as well as the way of modelling implemented for new geographical areas.