Using 3-D seismic inversion data as a tool for predicting porosity in the Wilburton gas field, Arkoma Basin, southeastern Oklahoma
Understanding and identifying changes in rock properties over an area is critical in characterizing a reservoir. In order to identify porosity changes, a 3-D seismic inversion volume was inverted for acoustic impedance in the Red Oak and Brazil Sandstones in the Wilburton gas field located in the Arkoma Basin, southeastern Oklahoma. The tops and bases of these two sandstones were identified to be analyzed based on acoustic impedance and porosity. Establishing a relationship between acoustic impedance and porosity allows porosity to be predicted away from the wellbore using the seismic acoustic impedance data. Interpretation of the seismic inversion data suggests that a) there is a linear correlation between acoustic impedance and porosity in the sandstone portions of the Red Oak and Brazil Sandstones; b) seismic thickness cannot be used to predict actual thickness of these sandstone units due to variations in velocity; and c) prediction of porosity using seismic inversion data inverted for acoustic impedance in sandstone containing interbeds of shale is not reliable, and the method should be limited to homogeneous sandstone.