This work consisted of a multi-disciplinary data integration and reservoir characterization of an unconventional limestone and shale reservoir in the US midcontinent region (north-central Oklahoma). The reservoir is the Mississippi Limestone which overlays the organic-rich Woodford Shale. The seismic data set is a 180 sq mi high density, full azimuth, multi-component survey. Processing was carefully performed in order to quantify compressional and converted wave anisotropy. Then a reservoir characterization study was conducted that integrated rock and fracture properties with a full suite of calibration data from multiple wells, including vertical and lateral FMI logs, mudlogs, Sonic Scanners, chemical tracer in the laterals, completion results and microseismic data.

This paper describes the results from a portion of this data set, specifically surrounding a vertical saltwater disposal well (George 1–23 SWD) and two laterals (George 23–1H and 23–2H). Along these laterals rock properties change due to an increase in shale in the toe half of the lateral, which in turn causes an increase in ductility. There is also a reduction of fracture density in the toe half of the lateral (as indicted by the lateral FMI), which might be related to the increase in shale. These rock property variations cause an observable change in the characteristics and distribution of microseismic event clusters, with the heel having a larger proportion of small magnitude events.

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