Guyana: Liza Phase 1 Rapid Development in a Deepwater Frontier

The Liza Phase 1 development project, offshore Guyana, is an unique example of what the offshore oil and gas industry is capable of when working together to deliver a common objective. ExxonMobil and the Stabroek Block co-venturers, Hess Guyana Exploration Limited and CNOOC Petroleum Guyana Limited, commenced oil production from the Liza Destiny floating production, storage, and offloading (FPSO) vessel in December of 2019, less than 5 years from the initial discovery of hydrocarbons in the Staebroek block. With the production and export of its first barrels of oil, the project completed the establishment of a nascent oil and gas industry in Guyana that is poised for tremendous growth in the coming years. The Liza Phase 1 development consists of a 120 kbd conversion FPSO (The Liza Destiny) and a network of subsea infrastructure to produce from and inject in two drill centers. It is expected to develop a resource of about 450 MBO gross estimated ultimate recovery. The water depth ranges from 1,690–1,860 m throughout the development which is located approximately 200 km offshore Guyana. This paper highlights the scope and pace of the project and discusses three specific challenges overcome: the uncertainty of the metocean conditions, extending the application of the selected riser technology, and executing in a challenging and frontier offshore location. A key to the success of the project was the unified approach between stakeholders and the commitment to act as One Team. The Liza Phase 1 project rapidly developed a newly discovered deep water resource in a frontier location while overcoming numerous challenges. By delivering Guyana's first ever oil production among industry leading cycle times, the Liza Phase 1 project has set the foundation for the future of deep water developments in Guyana.

Numerical Investigation for Vortex-Induced Vibrations of Steel-Lazy-Wave-Risers: Part I — CFD Validation Against Forced Oscillation Model Test

Vortex-Induced Vibration (VIV) is one of the main sources of fatigue damage for long slender risers. Typical VIV assessment of risers is conducted using semi-empirical software tools with the sectional hydrodynamic coefficients derived from forced-oscillation model tests on short rigid riser sections. The Steel Lazy Wave Riser (SLWR) with buoyancy sections is an attractive concept for improving fatigue performance in deep water developments, but there is limited model test data available for the hydrodynamic coefficients on SLWR’s. CFD simulation is an alternative VIV assessment tool, once it is validated for an existing model test. It can provide accurate estimates of VIV response and help to design configurations of SLWR’s without additional model tests. The present CFD simulations are performed to validate hydrodynamic coefficients of a SLWR section. The predicted drag and excitation (lift) coefficients on both bare riser and buoyancy sections are compared to the test data with respect to oscillation frequency and amplitude.

Numerical Investigation for Vortex-Induced Vibrations of Steel-Lazy-Wave-Risers: Part II — CFD Study on Long Flexible Riser

Vortex-Induced Vibration (VIV) is one of the main sources of fatigue damage for long slender risers. Typical VIV assessment of risers is conducted using semi-empirical software tools in which the sectional hydrodynamic coefficients are derived from forced oscillation model tests on short rigid risers. The Steel Lazy Wave Riser (SLWR) with buoyancy sections is an attractive concept for improving fatigue performance in deep water developments, but there is limited model test data available for the hydrodynamic coefficients on SLWR’s. In Part I of the present study (Jang & Kim, 2019), CFD simulations are successfully validated against forced-oscillation model tests. In this paper, the feasibility of using CFD simulations for VIV response of a long flexible SLWR has been studied based on the CFD modeling practice developed in Part I. The CFD simulation is coupled with a simple structural model of the riser, and the structural equations of motions are solved via modal analysis. The simulation results capture all excitation frequencies measured from the model tests.