Modeling Procedure and Related Statements
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normal-incidence, ray-theory program. Neidell and Poggiagliolmi (1977) summarized the general principles and use of ray-theory models. Several seismic models were also generated by a wave-equation solution, but these models did not differ significantly from the models produced by the ray-theory program.
Each seismic model begins with a restored stratiraphic section through the stratigraphic-trap field of interest. All the stratigraphic sections in the text were constructed by the authors from available borehole logs, core data, and lithology logs. Where a section is modified from a previously published section, it is referenced accordingly. A few borehole logs from each field are presented in the text to acquaint the reader with the evidence on which the geologic interpretation was based. To validate the entire stratigraphic section, the reader can assemble all of the referenced log data and reconstruct the section.
From the geologic cross sections and their associated borehole logs we extracted the following modeling parameters for each major stratigraphic interval: (1) velocity (ft/sec), (2) density (g/cu cm), (3) thickness (ft), and (4) geometry. Our models commonly consist of 5 to 10 well and dry hole locations, 10 to 20 interfaces, and over 100 velocity and density values. Most velocity and density values were obtained from hand- blocked acoustic and density logs. The remainder of the values were calculated from porosity measurements or log crossplots (Schlumberger Ltd., 1972). We assumed that the acoustic- and density-log values for the reservoir units adequately account for the hydrocarbon.