Fangjian 'Jack' Xue¹, Kim Hemsley¹

(1) Schlumberger, Houston, TX

ABSTRACT: Miocene Sequence Shelf-Slope Relationships in South Louisiana - a Seismic Facies Analysis

An integrated seismic facies study based on deep-targeted high-resolution seismic data, sequence stratigraphy, and advanced visualization techniques has revealed the complex shelf-slope relationships, depositional systems and distribution of reservoir sand bodies in a series of regional interpreted lines of the productive Miocene trend of South Louisiana.

The Miocene shelf and slope consisted of two different but interdependent depositional systems. The shelf section is sand-dominated with abundant channel features. The slope section is shale-dominated with local, thick, lowstand sand accumulations associated with basin floor fan, slope fan and progradation wedge complexes. Syndepositional salt movement and growth faulting complicate the slope systems tracts. The progradation of paleo-shelf edges and the geometry of the sand-prone lowstand facies are controlled not only by regional depositional center shifts but also local salt tectonics.

Historical production analysis demonstrates that fields with deep production from lowstand reservoir sands have greater cumulative production and higher success rates. The hydrocarbon trapping conditions are strongly influenced by the differences in shelf and slope facies relationships and structural characteristics. The deeply buried, thick, lowstand sand complexes that accumulated in Miocene intra-slope basins across South Louisiana's coastal parishes are relatively unexploited. These onshore Miocene reservoirs are analogous to the Plio-Pleistocene deep-water targets in present-day Gulf of Mexico. South Louisiana appears to offer one of the most prospective target areas for future exploration in the Gulf Coast.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado