Hierarchical Analysis of Channelized Deep-Water Deposits, Carmelo Formation, Point Lobos State Reserve, Northern California

Springhorn, Steven¹, Morgan D. Sullivan², Michael Pyrcz³, Ryan Alward⁴, Margaret Skartvedt-Forte⁴, Bryan Demucha⁴, Sean Spaeth⁴, Nick Lawlor⁴ (1) California State University, Sacramento, CA (2) Chevron Energy Technology Company, Houston, TX (3) Chevron, Houston, TX (4) California State University, Chico, CA

The Paleocene to early Eocene strata of the Carmelo Formation were deposited in a confined slope channel system which incised into granodiorites of the Salinian basement. It is comprised of approximately 200 meters of complexly interstratified conglomerate, sandstone and shale which at first glance display no obvious organization. Based on detailed analysis, however, the Carmelo Formation can be subdivided into distinct channel elements which are bounded by avulsion events. Individual channel elements exhibit a predictable change from axis to margin in grain size and lithofacies type. Avulsion, which is the lateral shifting of a channel or lobe, controls the distribution of these characteristics and therefore the distribution of reservoir and non-reservoir facies. Individual channels are 10 to 20 meters thick and estimated to be 100's of meters in width. Based on this analysis, channels have width to thickness ratios of 15:1 to 20:1. Channel-axis deposits are dominated by tractively deposited, normally graded, clast supported conglomerate and lesser amounts of shale clast conglomerate. These deposits grade laterally into non-amalgamated, thick-bedded massive sandstones which represent channel off-axis deposits. The channel margin deposits consist of interbedded thick- to medium-bedded massive sandstones, thin-bedded sandstones and shales. Slump deposits are also locally present and are probably related channel margin failure. Facies proportions, bed thicknesses/lengths data and channel dimensions were also collected and analyzed. This information can be used to provide geostatistical data required to construct geologic (aquifer/reservoir) models to better understand and predict fluid flow in subsurface sandstones.