AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Seismic Attribute Mapping for Identification of Cypress Sands, Illinois Basin, Indiana, USA
(1) School of Geology and Geophysics, University of Oklahoma, Norman, OK.
(2) Exploration and Development, Spyglass Energy Group, Tulsa, OK.
Mississippian Cypress sands are the major exploration and exploitation target in the Illinois basin with the thickness of the sands varying from well to well in the same field. The present study area is from Illinois basin, Posey County, Indiana, U.S.A. The Posey County area is a mature exploration area with production established in the 1920s. More than 7000 wells have been drilled in Posey County, with the majority being drilled before 1960. If any well log data exist, they are typically in the form of old electrical logs. The renewed interest in understanding the subsurface started in mid 1990s during which time independent operators started acquiring 3D seismic data, with the present survey covering 40 Sq.km. In this paper we report on the success in delineating the Mississippian Cypress sands with the aid of modern seismic attribute technology.
We use modern 3D visualization tools of opacity and Hue-Lightness-Saturation (HLS) color modulation to co-render complementary seismic attributes along stratal slices at 2 ms intervals. Such co-rendering allows us to interactively cluster mathematically independent attributes that are coupled through the same geologic features (e.g. low impedance with lower peak frequency). We present our findings through a suite of multi-attribute displays and animations loops through the data volume to highlight the subtle lenticular sand bodies associated with structural faults/ridges characteristic of braided channels.