Poststack inversion of the Hussar low frequency seismic data

Patricia E. Gavotti and Don C. Lawton and Gary F. Margrave and J. Helen Isaac

ABSTRACT

The Hussar experiment was carried out in September 2011 with the purpose of acquiring low frequency seismic data to be used in inversion methods. Three wells located close to the seismic line, and a dynamite-source dataset acquired with three-component 10 Hz geophones were used for a post-stack inversion test with commercial software. Several low-frequency cut-off filters applied to the data were tested with the one from 3-5 Hz been selected as the optimum. The resultant impedance reflects lateral changes that were not present in the initial model and therefore come from the seismic reflections. Impedance changes in the target zone are not as precise as expected possibly due to limitations with seismic resolution compared to impedance logs. However, the inverted impedance shows the general trend and relative variations, which would allow monitoring changes in the reservoir as variations in the rock properties occur. A final inversion was performed to simulate traditional approaches when the low-frequency component is absent in the seismic data. Filtered seismic-data (10-15-60-85 Hz) and an initial model with a 10-15 Hz cut-off were used for this test. The results at the well locations show a good match but the lateral variation and character of the events resemble more the initial model character.

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