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Date of Award
Campus Access Master's Thesis
Master of Science in Geophysics (MS)
Administrative Home Department
Department of Geological and Mining Engineering and Sciences
Committee Member 1
Seismic interferometry (SI) is a cost effective method to study a reservoir in a time-lapse survey. 2D finite difference modeling allows us to test different boundaries of noise and geophone locations in an attempt to optimize the geometry for high quality subsurface imaging before implementation in a real case study. Utilizing a crosswell geometry for ambient noise seismic interferometry should provide higher resolution seismic data of an area between two wells than a surface array given the same lateral extent. This conjecture was tested using 2D finite difference modeling of ambient noise and cross-correlation using both a surface and crosswell arrays in a simple anticline geological model. The area containing point-sources of noise is varied to determine if the crosswell geometry can more effectively utilize high angle noise.
Crosswell ambient noise seismic interferometry is plausible, however, cross-correlation is the limiting factor in this study. Cross-correlation is not an effective method to stack coherent reflection information from raw data obtained using a crosswell geometry. This is due to the geometrical complexity of point sources occurring randomly in space and time, with the close proximity of the lower part of the crosswell array to the noise boundary. The complexity causes reflection signals to be significantly different between geophones at the surface and those close to the noise boundary, which renders cross-correlation ineffective as it depends on the stacking of similar reflection signals. Additionally, the repeatability of such surveys is lessened, as the difference in location and time of point sources of noise between base and repeat surveys changes the geometry between source, receiver geophone and virtual shot geophone dramatically.
Crane, Garvie, "A SIGNAL ANALYSIS OF CROSSWELL SEISMIC INTERFEROMETRY USING 2D FINITE DIFFERENCE MODELING OF AMBIENT NOISE", Campus Access Master's Thesis, Michigan Technological University, 2016.