Patent ID: 6614717
Filing Date: 2003-09-02
Classification: G01V

Abstract:
A method of determining and mapping the presence and the movement of the reservoir fluids that have different viscous properties, or mapping the changes in the viscous properties of the pore fluids in the reservoir rocks due to production and injection processes, comprising the steps of:(a) Using reflection seismic recording methods with a seismic vibratory source, that generates and transmits a low distortion seismic vibratory signal; this signal can be generated on the surface or in a wellbore, the reflected signals from the subsurface formations received by the surface receiver arrays, downhole receiver arrays or both and recorded using conventional seismic recording equipment; (b) Recording 2-D, 3-D or borehole seismic reflection data using standard field recording procedures, cross-correlating with the primary transmitted vibratory swept frequency signal and processing the primary cross-correlated data-set to generate the primary subsurface reflected image, the subsurface image generated by using the current and generally known standard 2-D or 3-D seismic processing methods that are known in the industry, and are used for seismic reflection reservoir imaging; (c) Using primary subsurface reflected image for conventional and standard structural interpretation of the reservoir, the methods of using different processing algorithms and interactive interpretation are known and practiced in the industry; (d) Computer-generating the synthetic pilot swept frequency signals, these pilot signals representing the higher order harmonics of the primary swept frequency signal, like the second, third, fourth and fifth harmonics, all having the same amplitude as the primary transmitted sweep signal; (e) Cross-correlating the recorded data with each of the synthetic harmonic frequency swept signals individually, thus making the number of cross-correlations that represent all the harmonics being investigated, thus generating a complete data set for each harmonic of the primary swept signal; (f) Processing each of these harmonic data sets to generate the seismic reflection subsurface image, using the same 2-D or 3-D processing parameters that were used for the primary seismic reflection imaging, thus creating full volume seismic reflection subsurface images for each harmonic of the primary swept signal; (g)Displaying the 2-D or 3-D images representing each of the harmonics being investigated, odd harmonic image highlighting the reservoir saturated with higher viscosity fluid, and even harmonic image highlighting the lower viscosity fluid in the reservoir.