Abstract

In May 2015, Liza-1 encountered more than 90 m (295 ft) of high-quality oil-bearing Upper Cretaceous deepwater sandstones. Immediately, the >1 billion barrel Liza field began on its path from discovery to development.

Following the Liza-1 discovery, ExxonMobil and the Stabroek Block co-venturers, Hess Guyana Exploration Limited and CNOOC Petroleum Guyana Limited, undertook a blockwide 3D seismic survey, the largest performed by ExxonMobil at that time, to better delineate the resource potential. Subsequent appraisal drilling built confidence in the performance and connectivity of the reservoir while providing calibration data to inform the development. The initial appraisal well was the "inverted-Y" Liza-2 drilled in early 2016, which comprised an original hole and a sidetrack. A comprehensive evaluation program was implemented with conventional coring of both the original hole and the sidetrack to provide reservoir calibration critical to field development. Furthermore, a production well test was performed on the Liza-2 sidetrack to build confidence in dynamic performance and connectivity assumptions. The Liza-3 appraisal was then drilled down dip of the Liza-1 and −2 to confirm static connectivity across the field.

A scenario modeling and simulation approach was implemented at Liza to capture the full range of plausible realizations that could represent the field. The scenarios were measured against the incoming data (Liza-2 and Liza-3) when acquired, and scenarios with greater alignment to the data continued to be pursued while others were moved to a much lower probability of occurrence. This multi-scenario approach was utilized to develop an integrated reservoir model that allowed for depletion plan optimization across a range of subsurface scenarios within flow assurance constraints, ultimately supporting the final investment decision (FID) for the Liza Phase 1 project in 2017, just 25 months after the Liza-1 discovery.

Following FID, advanced, proprietary Full Wavefield Inversion seismic reprocessing and high resolution 4D baseline seismic acquisition and processing have been utilized to enable continued optimization. The path from discovery to development culminated in December 2019 with the commencement of production from Liza Phase 1 less than 5 years after the first deepwater oil discovery in Guyana.

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