Mary Johns

Diffraction imaging enhancement using spectral decomposition for faults, fracture zones, and collapse feature detection in a Middle East carbonate field

Diffraction imaging is demonstrated in this case study to improve horizontal resolution over conventional reflection imaging. Edge enhancement, using spectral decomposition on diffraction imaged data, further enhances the capabilities of detecting faults, fracture zones, and collapse features improving the spatial resolution and edge detection for higher resolution seismic interpretation. Spectral decomposition also provides an effective tool for separating low-frequency reflection data noise from diffraction imaged data, improving the interpretability of the diffraction imaged data. This case study also demonstrates that edge enhancement using spectral decomposition improves the ability of spatially correlating the edges of collapse features, detected with diffraction imaged data, to drilling mud losses in carbonates. Detecting overburden collapse features with diffraction imaging could provide economic benefits, avoiding encounters with high perm zones, preventing mud loss expenses and increased drilling time, from days to weeks, and controlling the well.

A field study of azimuthal seismic anisotropy in fractured carbonates at Canyon Lake, central Texas

Many important hydrocarbon fields worldwide produce from fractured carbonate reservoirs. For those fields, azimuthal seismic anisotropy potentially provides a means to map fracture orientation and distribution in the subsurface.

P-Wave Seismic Anisotropy In a Fractured Carbonate Reservoir: A Case Study From EastTexas

Summary We present a case study where we calculated P-wave seismic anisotropy for a land, 3D seismic survey at a gas field in east Texas. We calculated the azimuthal AVO (AzAVO) and azimuthal velocity (AzNMO) anisotropy. We compared the results with interpreted faults, fractures from oriented core, image logs, present day stress, and a dipole sonic log. High- anisotropy anomalies align with faults on the flanks of the structure. Low seismic anisotropy characterizes the crest of the structure, and may be an artifact of an associated amplitude shadow. Locally, orientations predicted from seismic anisotropy agree with our subsurface fracture observations. Full quantitative fracture interpretation is restricted, however, by signal noise, local reduction in inversion quality by an amplitude artifact, and limited subsurface fracture correlation.

Azimuthal AVO Workflow And Evaluation At an East Texas Fractured Reservoir

Summary We applied azimuthal anisotropy of amplitude versus offset (AzAVO) inversion technique to land 3D seismic data at an east Texas gas field. In general, AzAVO provides geologically interpretable anisotropy anomalies that correlate with previously interpreted faults and also correlate with the few subsurface data (FMI and cross-dipole sonic) that we have. The inversion quality is affected by signal/noise in the data and the application of random noise attenuation in the pre-processing enhances the results. We are encouraged to have developed an integrated workflow for the processing and interpretation of azimuthal seismic anisotropy.