AAPG Annual Convention and Exhibition

Datapages, Inc.Print this page

Regional View of Onshore Plays for the Gulf of Mexico Margin


Onshore exploration has entered a new era as the geologic column of each state is being re-examined for new shale plays and missed opportunities. Onshore regional Geology has historically been difficult as datasets, formation names, and previous studies are of limited extent. Drilling successes and failures in one area are challenging to extrapolate across state lines and across major structural and stratigraphic elements of Gulf Coast Geology. To address these problems, a mega-regional onshore dataset is assembled from legacy seismic data and consists of a seven reprocessed, PSDM strike lines and 26 updated dip lines from PSDM reprocessed data in 2007. The seven strike lines of approximately 8000 miles and 346 individual line segments, range from a southernmost line along the coast to the northernmost line which traverses the East Texas Salt Basin, Sabine Uplift, North Louisiana Salt Basin, Mississippi Interior Salt Basin and Wiggin's Arch to the Florida Panhandle. The individual segments were recorded from as early as the 1960's through the 1990's with a variety of sources, instrumentation, shot and receiver intervals and offsets. Composite seismic lines are created with consistent depth processing and are continuous across the onshore portion of the basin and onshore depocenters, structural axes, and canyons are seen in their regional context. Plays dependent on new horizontal wells can be tied around the basin. Chronostratigraphic relationships are interpreted to correctly identify and understand the major transgressions in the Gulf and how the subsequent sea level lowstands and faulting may help or compromise these potential plays. Interpretation highlights the onlap wedges of the Tuscaloosa Shale play and helps to identify sweet spots. Embayments and progradational fairways are especially evident on the strike lines and major canyon cutting throughout the Wilcox age is evident around the Gulf rim. The strike lines tie together existing mega-regional dip lines that span across the basin from South Texas to Alabama and from the northern limit of the onshore Gulf Basin to the abyssal plain. The dip lines in East Texas have been extended to the north to tie the new strike grid and gaps in coverage have been filled in key areas such as over the Davy Jones discovery. The interpretation is tied to well control with a series of sixty four synthetics and check shot surveys. Extensive velocity work produced a consistent velocity model.