Large Erosional Slope Channels and the New Challenge; Low Relief Sandy Channel Levees

Mayall, Mike¹ (1) BP, Sunbury on Thames, United Kingdom

Large scale (1-3km wide, 50-200m thick) erosional channels are now extensively recognised on slope systems. The main components of these channels, the sinuosity, facies patterns, repeated history of cutting and filling and complexity of the internal stacking patterns are widely recognised. With increasing well log and core data, the characterisation of the reservoirs can be done with growing confidence. However there are an important range of issues which require further study, among which are - Sinuosity, there are clearly different types of sinuosity in channels, are they related? Is it important? How does the fill of levee channels differ from erosionally confined channels? What is backfilling – does it really exist? In addition to the large erosionally confined channels, smaller low-relief channel levees are becoming increasingly important. They are usually 5-30m thick and on seismic data often form a single trough-peak loop. These channels have axis which are tens to hundreds of metres wide and sandy levees which commonly extend hundreds of metres, or more, away from the channel axis. The channel axis is most commonly mud-filled but sandy axis also occur. Although this style of channel can be well imaged on seismic there are many challenges to effective development of the resources. Additionally there are few, if any, outcrop descriptions of this channel style. These types of channels are so common in slope systems that they must occur in outcrops but have yet to be identified.