Petrophysics Calibrated Seismic Attribute Interpretation for Lithology and Fluid Classification - Offshore Peninsular Malaysia

Seismic data are a composite response to contrasts in lithology, fluid and petrophysical properties across interfaces, amongst other influences. Seismic data attributes, analyzed in isolation, are useful in interpreting structure / stratigraphy and in visualizing patterns that can be given geological meaning. But they provide no direct insight into the types of lithology and fluid that the features represent. Decomposing the seismic response into constituent lithology and fluid types requires that the attributes be calibrated to well data – specifically to the petrophysical characteristics of the formation. Petrophysics calibrated seismic attribute interpretation is a powerful method for lithology and fluid type classifications and for determining their spatial extents.

We present the application of this workflow to a clastic gas-field where the formation is characterized by intercalated fluvial deposits of varying thicknesses, distributed over a large vertical extent. The workflow was successful in classifying the formation using fluid, reservoir porosity and litho-fraction. Prominent, thick gas sands could be mapped, and sand-filled channels could be separated from shale-filled ones.