Generation of synthetic sonic logs (Seislogs) from seismic data can provide lithologic, porosity, and fluid-content identifications in a variety of

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geologic settings. Case studies illustrate the type of information that can be extracted from seismic data on carbonate rocks, including North Sea chalk, fractured limestones in Venezuela, and porosity development in regional limestones of western Canada. In the North Sea, 2 adjacent structures that appear similar on conventional seismic sections display porosity development and fluid content changes within the chalk reservoir on the Seislog section. In a South American example, the Seislog display demonstrates the ability of seismic data to locate vertical fracture zones. In western Canada, secondary porosity development within Devonian carbonates was identified on Seislog displays, which led to the extension of a gas field. Examples from southeast Asia display a variety of depositio al environments in Miocene sediments. Shallow-marine and shoreline sands can be identified in a Malaysian example. An example from the Natuna Sea displays a lower delta-plain setting, with regional shale markers and thick clastic packages. An upper delta-plain example (Gulf of Thailand) displays more faulting, expansion of clastic packages, and discontinuous channel sands.

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