96-4 An Offshore Oddesy: Thirty Years of Technology Advances in Subsalt Exploration - Mahogany First Oil to Elastic FWI

Session: Twenty-Seven Years of Advances in Understanding Salt-Sediment Interaction: A Legacy of Katherine A. Giles

Presenting Author:

A Kurt Tollestrup

Author:

Tollestrup, A Kurt¹

(1) Bureau of Economic Geology, University of Texas, Austin, Austin, TX, USA,

Abstract:

The 1993 discovery of the Mahogany Field marked a turning point in Gulf of Mexico (GOM) exploration, leading to the region’s first successful subsalt oil production in 1996. Situated in 400 feet of water and entirely beneath a salt canopy, Mahogany confirmed new geological concepts and spurred a wave of technological innovation. Once considered geologically mature, Mahogany revealed significant subsalt potential throughout GOM  including concurrent discoveries at Mica, Teak, Chimichanga, and Gemini. Subsalt exploration presented major challenges, including poor seismic imaging, depth conversion uncertainties, limited understanding of salt/sediment interactions, and unknown reservoir characteristics. Mahogany became a proving ground for emerging geophysical tools such as gravity gradiometry, area-wide 3D seismic acquisition, ocean bottom sensors, and prestack depth processing and migration methods, which significantly improved subsalt imaging and confirmed hydrocarbon accumulations in many subsalt, deepwater turbidite reservoirs. Driven by subsalt exploration needs, seismic imaging advanced from 2D to regional 3D, incorporating multi-azimuth surveys, ocean bottom nodes (OBN) and full-waveform inversion in seismic processing. These innovations enabled high-resolution imaging of complex salt geometries showing varied examples of salt/sediment interaction. Enhanced data allowed researchers to integrate seismic observations with numerical and laboratory models and geological outcrop studies. Recent next-generation OBN seismic projects, including a 2024 GOM Green Canyon survey, have resolved intricate, multi-level salt structures and improved imaging of autochthonous Louann salt. These achievements highlight the lasting impact of Mahogany’s pioneering tests and underscore the importance of continuous geophysical and geological innovation coupled with laboratory and field work in unlocking subsalt, deepwater hydrocarbon resources.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4685

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