ABSTRACT

With sparse well control along the Rose Run sandstone subcrop fairway in south-central Ohio, exploration for Rose Run sand remnants is dominated by seismic techniques. The purpose of this paper is to describe a method for acquiring high-resolution dynamite seismic data, and to discuss interpretation techniques for detecting remnants, predicting sand presence, and estimating sand thickness.

Seismic-data acquisition parameters for maximizing Rose Run remnant signatures in the 3,000- to 4,000-foot depth range of south-central Ohio include small charge arrays, 75-foot station intervals, and a 27-hertz low-cut field filter. To maximize temporal and spatial resolution in the processing sequence, wavelet processing to zero phase, and post-stack spectral whitening are most critical.

Since seismic reflections are complex composites of many formation contacts, exact identification of reflection events using synthetic seismograms is crucial to understanding remnant seismic signatures. Follow-up with two dimensional, well-log interpolation modeling gives a clearer understanding of what indicators to look for, and which attributes to measure for reservoir prediction.

By retaining a wide temporal bandwidth with frequencies in our target zone in the 100-hertz range, maximum information can be extracted from our seismic sections in the interpretation stage. Within this Rose Run subcrop area of Ohio, seismic remnant indicators include: rollover of reflectors above, reflector sag below, and event pull-up at the unconformity with an associated amplitude anomaly. With a reference well for calibration, measurement of these indicators is used to estimate sand presence and thickness.