Estimating the thickness of shallow salt from seismic refractions

Geophysics ◽  
1987 ◽  
Vol 52 (12) ◽  
pp. 1708-1714 ◽  
Author(s):  
Joseph O. Ebeniro ◽  
Yosio Nakamura ◽  
Dale S. Sawyer
Keyword(s):  
Gulf Of Mexico ◽  
High Velocity ◽  
Seismic Reflection ◽  
Sedimentary Basins ◽  
Quaternary Sediments ◽  
Lower Velocity ◽  
Northern Gulf Of Mexico ◽  
Major Impediment

The presence of shallow, tectonized salt is a major impediment to exploration efforts in many sedimentary basins, including the northern Gulf of Mexico. The salt there forms a shallow tongue of high‐velocity material emplaced between lower‐velocity Tertiary and Quaternary sediments. Using conventional seismic reflection techniques, explorationists often have difficulty identifying the base of the salt tongue. Only in a very few instances (e.g., Buffler, 1983; Buffler et al., 1978; Watkins et al., 1978) have they been able to identify the base of the shallow salt. Interfaces below the salt are even more rarely observed.

scholarly journals SALT WELDING DURING CANOPY ADVANCE AND SHORTENING IN THE GREEN CANYON AREA, NORTHERN GULF OF MEXICO

2021 ◽  
Author(s):  
Christopher Jackson ◽  
Sian Evans ◽  
Turki Alshammasi
Keyword(s):  
Gulf Of Mexico ◽  
Seismic Reflection ◽  
Analytical Models ◽  
3D Seismic ◽  
Borehole Data ◽  
Seismic Reflection Data ◽  
Northern Gulf Of Mexico ◽  
Reflection Data ◽  
Tectonic System ◽  
Migration Pathways

Welds form due to the tectonically-induced thinning and/or dissolution of salt, with their composition and completeness thought to at least partly reflect their structural position within the salt-tectonic system. Despite their importance as seals or migration pathways for accumulations of hydrocarbons and CO2, we have relatively few examples of drilled subsurface welds; such examples would allow us to improve our understanding of the processes and products of welding, and to test analytical models of the underlying mechanics. In this study we integrate 3D seismic reflection and borehole data from the Green Canyon Area of the northern Gulf of Mexico, USA to characterize the geophysical and geological expression of a tertiary weld, as well as its broader salt-tectonic context. These data show although it appears complete on seismic reflection data, the weld contains 124 ft (c. 38 m) of pure halite. This thickness is consistent with the predictions of analytical models, and with observations from other natural examples of subsurface welds. Our observations also support a model whereby compositional fractionation of salt occurs as the salt-tectonic system evolves; in this model, less mobile and/or denser units are typically stranded within the deeper, autochthonous level, trapped in primary welds, or stranded near the basal root of diapirs, whereas less viscous and/or less dense units form the cores of these diapirs and, potentially, genetically related allochthonous sheets and canopies. We also show that shearing of the weld during downslope translation of the overlying minibasin did not lead to complete welding.

INTEGRATED CHARACTERIZATION AND FAILURE MECHANISM FOR A MID PLEISTOCENE MTC DOMINANT INTERVAL IN THE MARS URSA BASIN, NORTHERN GULF OF MEXICO, USA

2020 ◽  
pp. 1-64
Author(s):  
Mario Andres Gutierrez ◽  
John W. Snedden
Keyword(s):  
Gulf Of Mexico ◽  
Sedimentary Basins ◽  
Extraction Methods ◽  
Sediment Supply ◽  
Hydrocarbon Exploration ◽  
Seismic Survey ◽  
Data Set ◽  
Northern Gulf Of Mexico ◽  
Kinematic Indicators ◽  
Lithological Composition

The economic and operational risks associated with Mass Transport Complexes (MTCs) in deepwater hydrocarbon exploration act as a principal motivation to investigate their depositional elements utilizing industry data. There is a lack of extensive seismic and well data coverage that limits the understanding of the processes associated with the evolution of MTCs within deepwater sedimentary basins. This study leverages a unique integrated dataset to evaluate the depositional character and potential failure mechanisms of seven identified MTCs preserved in a synkinematic mid-Pleistocene MTC-dominant interval that spans the hydrocarbon bearing Mars Ursa Basin in the Northern Gulf of Mexico. Through seismic interpretation and attribute extraction methods using a 3D PDSM seismic survey, we describe kinematic indicators and preserved morphodomains geometries of the identified MTCs. The MTC-dominant interval covers an area of 631 km2, a volume of 392 km3, and a maximum thickness of 549 m in minibasin centers. The interval is penetrated by fifteen boreholes that provide stratigraphic and lithologic calibration of the morphometric analyses. The lithological composition of the MTC-rich interval is claystone/mudstone-dominant with a few interbedded, thin sandstones. The identified kinematic indicators and geometric extent of the identified MTCs are a function of both local salt tectonics extrabasinal controls. The stratigraphic framework presented in this study constrains the timing of failures to a period of high sediment deposition related to a major increase of glacial input into the Quaternary Mississippi Fan. This study offers borehole calibrated MTC morphometrics preserved in a MTC-dominant interval whose failure is triggered by local salt inflation, but ultimately is a consequence of loading following increased sediment supply into the basin. The results from this robust data set build upon past integrated seismic-well studies that strive to improve the understanding of MTC processes and their implications in hydrocarbon exploration across salt sedimentary basins.

Effects of hypoxia on habitat quality of pelagic planktivorous fishes in the northern Gulf of Mexico

2014 ◽  
Vol 505 ◽  
pp. 209-226 ◽  
Author(s):  
H Zhang ◽  
DM Mason ◽  
CA Stow ◽  
AT Adamack ◽  
SB Brandt ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Habitat Quality ◽  
Northern Gulf Of Mexico
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