Time-lapse lithology prediction in the Nelson Field

摘要

This paper presents a method of lithology and porefill prediction applied to the monitoring of fluid movements and reservoir characterization in the Nelson field. The method combines amplitude vs. offset (AVO) analysis and seismic inversion. The study utilizes 1990 and 1997 vintages of seismic. The Nelson field is a simple four-way dip closure located over the Forties-Montrose high. Oil is trapped in Palaeocene Forties Fm turbidite sands at a depth of approximately 7300 ft. Sands are generally of good quality, with porosities averaging 23%, and the oil API is 38. The field shows a strong AVO effect, characterized by a dimming of the offset amplitudes and a phase reversal at far offset. These conditions are very favourable for a 4D' study.