Waveform Classification as a Pseudo for Reservoir Thickness

Abstract

In an incised channel lacustrine shoreface environment the thickness of the incised channels is unknown away from well control. The thickness often varies over short distances and is the predominant control on reservoir quality, as the best reservoir is in the channels and not the shoreface. A common practice in reservoir modelling is to use an empirical relationship between channel thicknesses to derive width ratios. However, this cannot indicate where other channel bodies are in the area of interest. This study created a relationship between waveform classifications and thickness. The absence of an upper peak-trough within the seismic trace was considered to be indicative of where the upper reservoir unit, incised channels, were present. A relationship was defined whereby the more prominent the upper peak-trough, the more shoreface preserved. Using this method, it is proposed that erosion, and subsequent channel fill, controls the presence of the upper peak-trough. Therefore, waveform classification schemes can be used as a probability map in the static model to control the channel thickness and distribution. The resultant models matched thickness of the upper incised channels at the wells and provide realistically geological models which are able to predict thickness away from well control. At the present, work is ongoing to understand what the waveform represents at wells with a poorer match.