Mad Dog Phase 2 – Gulf of Mexico
NGI Houston provided specialized laboratory testing and geotechnical design of BP's deep-water floating production platform, Mad Dog 2, operating in the Gulf of Mexico.
The water depth in the area is up to 1300 meters, and the floating platform was designed to be anchored to the seabed with suction piles, also known as suction anchors or caissons. The Mad Dog 2 project was dominated by two factors; the strong loop currents at the site of the platform and the massive dimensions of the platform. Cyclic capacity and behavior of the foundation soil were therefore vital.
Advanced geotechnical lab testing
NGI Houston performed advanced tests on soil samples, including specialized cyclic tests, simulating dynamic wave loading from loop currents. The cyclic laboratory tests performed for Mad Dog 2 were designed to simulate the lower natural periods resulting from a polyester mooring system. They were performed at a lower frequency than typical for cyclic soil testing. Some tests lasted nearly four days instead of the typical 3–4 hours under normal circumstances.
The test data were interpreted into geotechnical engineering parameters required for the foundation design of the suction anchors to secure the massive platform to the seabed.
Advanced geotechnical laboratory test equipment at NGI Houston, apparatus set-up from left: Cyclic Direct Simple Shear, KoCU Triaxial, and Controlled Rate of Strain (CRS) Consolidation (oedometer) equipment.
In a previous phase of the Mad Dog development in 2011-2012, NGI Houston had successfully performed an integrated geohazard study at the Mad Dog 2 prospect, including slope stability and risk analyses. Colleagues at NGI Oslo, who also did slope stability assessments for the first Mad Dog platform, did quality assurance on the projects for Mad Dog 2.
