The art of well tying with new MATLAB tools

Heather J. E. Lloyd and Gary F. Margrave

ABSTRACT

To tie seismic data to well logs, four steps are required. The first step involves editing the sonic and density well logs, including de-spiking the logs, truncating any anomalous values and smoothing the logs to prevent stratigraphic attenuation. Since the velocities that seismic data experience are different then the velocities sonic tools measure a calibration step is needed. The most common way to do this is to use checkshot data, however when this data is not available the calibration can be computed from an attenuation (Q) estimate or by matching seismic events to event son the synthetic. The third step includes the calculation of the time-depth relationship using the calibrated sonic and the calculation of reflection coefficients from the sonic and density. In the last step the wavelet is estimated from the seismic data and phase rotations are applied to get good correlation between the seismic and the synthetic. A series of MATLAB tools have been developed to make the well-tying process easier and good synthetics obtainable in a short amount of time and are available in the CREWES Toolbox.

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