High Resolution VSP Detection of Point Bar Structures within Bituminous Sands

Abstract

The connectivity between SAGD pair-wells is the key for success of SAGD processes. The bituminous sands of Corner field situate in middle McMurray, where tidal influenced meandering fluvial point bar dominate the deposits. Thus, to characterize the internal structure of point bar deposit is essential to optimize SAGD production in Corner field. The aim of this thesis is to investigate correspondences between point bar internal structures and VSP responses. Since VSP preserve higher frequency than surface seismic thus VSP data would provide more precise identification and characterization of internal structures if we can recognize them from data. These investigations are done by comparing actual data, synthetic data and targets part in the model. Prior to the comparisons, we need to build a model that preserves the characteristics of our targets in subsurface as accurate as possible. We decompose the segment of logging data corresponding to the thickness of point bar deposits into a function which is able to represent the influence of gravity on deposition and a function that is able to imply the affect of current. After examining relation between borehole and inclined units of point bar structure, two scaled functions are combined in a way which can produce structures of point bar deposits. As soon as a realistic model is constructed, VSP simulations proceed. Based on the comparison of plane wave source VSP data with the model, it is found that variation of travel-time difference between two levels indicate heterogeneities between these levels. Since finite difference used in this thesis is based on acoustic wave propagation, only travel-time is investigated. While if an elastic modeling is available, the results will be more fruitful with respect to amplitudes variation and wave conversion.