Time - Lapse Impedance Inversion at Popeye Field , Offshore Gulf of Mexico

I grant The Pennsylvania State University the non-exclusive right to use this work for the University's own purposes and to make single copies of the work available to the public on a not-for-profit basis if copies are not otherwise available. ______________________ Tin-Wai Lee iii ABSTRACT Time-lapse (4D) inversion is a stand-alone method that does not require prior time-lapse seismic processing because amplitude and phase differences in the input seismic data are accounted for within the inversion procedure itself. After 4.5 years of gas production, the impedance of the G-sand in the RM reservoir compartment increases by 6% and the gas-water contact is interpreted to move about 800 m westward and 90 m vertically upwards. These results are comparable to Gassmann fluid substitution forward modeling (8 % increase) and a volumetric drainage model (700 m westward). This time-lapse inversion method relies on wavelet estimation techniques to derive appropriate wavelets for the inversions.