Attenuation coefficient tomogram and Q distribution image from crosswell survey in the Northern Reef Trend of Michigan Basin

Document Type

Conference Proceeding

Publication Date

1-1-2007

Abstract

Many studies concerning seismic attenuation and the resultant Quality Factor (Q), which may be calculated from it, reveal its value in reservoir descriptions. Attenuation is an important measurement for our understanding of rock properties and has been used to quantify such characteristics as: Porosity, permeability, viscosity, saturation and rock composition. Attenuation and the resulting Quality Factor have played a key role in assisting in the targeted drilling of high porosity and naturally fractured streaks within reservoirs, intelligent completions programs, reservoir optimization, and accurate calculations of reserves. Through all stages of the exploitation of a reservoir, attenuation studies could confirm and provide additional information of the rock properties and saturation conditions. The extraction of accurate values of attenuation could be useful for enhancing the interpretation of seismic data for reservoir definition. During production stage, the attenuation attribute can be helpful for searching for hydrocarbon accumulations and discriminating lithology and fluid contents. Estimates of seismic attenuation are useful for a variety of applications such as studies of compartmentalization of reservoir, partially saturated reservoir, permeability and pore space of rocks, and fluid mobility undergoing steam flood for enhanced oil recovery, among others. We present here a study using attenuation, velocity and reflectivity from crosswell seismic to optimize imaging of a carbonate reef reservoir in the Michigan Basin. Based on the analysis of travel times and average frequencies, we estimate velocity and attenuation coefficient tomograms; combining both tomograms we calculate a Q-value distribution image for wells spaced over 2000 feet. The attenuation coefficient tomogram validates the main features observed in the velocity tomogram. Moreover, the attenuation tomogram shows a better image of the structure and relief of the pinnacle reef, contributing to an interpretation of its possible lateral and depth limits. In summary, the attenuation tomogram is independent information from the crosswell seismic data that confirms the unique low velocity, high attenuation characteristics of the reef. © 2007 Society of Exploration Geophysicists.

Publication Title

SEG Technical Program Expanded Abstracts

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