--> ABSTRACT: Innovative Methodology Applied to 3-D Exploration in an Emerging Trend; Norphlet (Upper Jurassic) Sandstone, Monroe County, Alabama, by William R. Dean, Jozica H. Gabitzsch; #91020 (1995).
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Innovative Methodology Applied to Previous Hit3-DNext Hit Exploration in an Emerging Trend; Norphlet (Upper Jurassic) Sandstone, Monroe County, Alabama

William R. Dean, Jozica H. Gabitzsch

Exploration of the Frisco City (lower Haynesville) sand trend of Monroe County, Alabama has lead to the discovery of an updip Norphlet play. The Norphlet (upper Jurassic) sandstone was deposited in the low ravines and valleys that were incised into pre-existing metamorphic basement ridges. Recent Previous Hit3-DNext Hit seismic surveys have provided the first look at the areal distribution of these sands. There are, however, certain Previous Hit3-DNext Hit acquisition and processing pitfalls that can effect the accuracy of locating these structural and stratigraphic traps. The purpose of this presentation is to illustrate a method for refining a spatially varying Previous HitvelocityNext Hit field from sonic derived velocities for a more accurate Previous Hit3-DNext Hit Previous HitmigrationNext Hit in the North Excel Field area.

Many processors now have one-pass Previous Hit3-DNext Hit Previous HitmigrationNext Hit algorithms that can utilize spatially varying Previous HitvelocityNext Hit fields. The results are generally quite good--especially after Previous Hit3-DNext Hit DMO has been applied. in this case, however, over-Previous HitmigrationNext Hit of the Frisco City amplitude was observed. Other events in the Norphlet section below the clastic/carbonate interface were under-migrated and poorly focused. A comparison of the interval velocities extracted from the seismic data to the sonic derived velocities from well control revealed a high correlation before Previous HitmigrationNext Hit and a poor match after. A new spatially varying Previous HitvelocityNext Hit field was generated by interactively adjusting the Previous HitmigrationNext Hit velocities at 260 locations along a mapped horizon to precisely tie the sonic derived Previous HitvelocityNext Hit model. Application of the n w Previous HitvelocityNext Hit field with the appropriate Previous HitmigrationTop algorithm resulted in a product with coherent, well-defined amplitudes and an overall better focused seismic image.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995