Crustal Architecture and Passive-Margin Evolution of the Northern Gulf of Mexico Basin – Applications to Exploration Work-Flows

Abstract

A revolutionary 2012 seismic reflection survey, SuperCache, consisting of 17,000 km of 2D PSDM data was acquired across the US, deep-water Gulf of Mexico (GoM). The acquisition configuration of long-offset, powerful source and deep-tow of both source and receivers was designed to optimize the imaging of crustal architecture. The source was found to be at least 40% more powerful in the 3-40HZ range than prior seismic surveys in the GoM. A 15 km. single contiguous solid streamer, the first known commercial application of such an ultra-long streamer, improved velocity estimation to 15 km. As a result of these parameters, the crustal architecture of the GoM basin has been illuminated to a depth of 40 km. Based on these seismic data, the base of the post-rift, sag and syn-rift sequences, as well as the Moho have been mapped around the basin. Geodynamic basin-modeling, including basin-wide 3D gravity inversion and targeted 2D flexural backstripping, has been used to test, corroborate and quantify the kinematic and subsidence implications of the seismic interpretations, further constraining and quantifying the timing and spatial distribution of crustal thinning. The area of investigation extends from low-extension, through highly attenuated continental crust, onto oceanic crust. The ocean-to-continent transition (OCT) exhibits along-strike (∼2000 km) variations from anomalously thin, possibly magma-poor crust in the northwestern and north-central GoM, to an area of thicker ocean crust and volcanic seaward-dipping-reflectors (SDRs) to the east. The original depositional extent, thickness and timing of the Middle Jurassic salt can be related to these along-strike changes in continental breakup. This crustal architecture has significant implications for exploration work-flows. We describe results from targeted modeling of subsidence history and spatial and temporal variations in basal heat flow, with calibration to recorded temperatures in wells. This approach is shown to be applicable to constraining the bottom-up heat-flow inputs required in geochemical basin models. The effects on constraining uncertainty are likely to be most important in areas of significant continental crustal attenuation, with limited well control.

AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014