Print this pageA Predictive Model for Turbidite Channel Element Dimensions and Fill Characteristics Relative to Equilibrium Gradient
Tim McHargue1, Julian Clark1, Nicholas Drinkwater2, Andrea Fildani1, H. Posamentier2, Michael Pyrcz2, and Morgan Sullivan2
1Chevron ETC, San Ramon, CA
2Chevron ETC, Houston, TX
Outcrop and subsurface examples of turbidite channels are highly variable but can be viewed as a continuum between two end-member populations with distinct characteristics. We suggest that these end-member populations reflect extremes of equilibrium gradient. In one end-member population, channel elements tend to be thick (>10m), with a low aspect ratio. Abandonment facies are thick (several meters), mud drapes are common, and channel fill is highly heterolithic. Because post-abandonment relief is high, avulsion frequency is low at the complex scale so elements are tightly clustered and display an organized, laterally offset stacking pattern that may include a strong aggradational component. This channel type is interpreted to have been deposited on a high equilibrium gradient. Conversely, the other end-member population of channel elements tends to be thin (a few meters), with a high aspect ratio. Abandonment facies are thin or absent and sands may over-fill channels and spill into inter-channel areas. Mud drapes are uncommon and channel fill typically is sand-rich and highly amalgamated. Because the post-abandonment relief of the channel is low, avulsion frequency tends to be high. Elements are loosely clustered and randomly laterally offset with little aggradation. This channel type is interpreted to have been deposited on a low equilibrium gradient. These two end-member models may be interpolated to characterize intermediate settings. In sparse well situations, these trends provide an a priori model for constraining channel dimensions, their stacking pattern / spatial distribution and their reservoir properties that may be updated by local information; thus, reducing uncertainty in reservoir assessment.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas