Investigation of Stacked Three Dimensional Lobe Deposit Properties Using a Set of Experimental Transitional Flows

Abstract

Low permeability, muddy sandstone reservoirs in ultra-deepwater fan systems present considerable challenges for reservoir predictions at multiple scales. Understanding the spatial facies distributions in channelized lobe systems can be complex due to the variable sediment-flow types, from turbulent to transitional to laminar, that create them. A set of physical experiments were used to investigate the evolution of lobe properties associated with stacked three dimensional deposits. Multiple high concentration, clay-rich sand-laden transitional flows were released into an unconfined slope-basin setting. Individual flow events were distinguished by varying the color of the coarsest sand fraction. Twenty seven freeze core samples of the final deposit were used to explore the spatial distribution, relative thickness and degree of mixing of colored sand and mud. Grain size and sorting analysis of the unmixed and mixed layers of sand and mud at multiple locations in the deposit are used to identify vertical and horizontal trends. These trends are compared to the local topographic and deposit thickness variations. These experiments provide insight into the spatial facies distributions of muddy sandstones in lobe systems, with relatively clean sands occurring near the deposit axis and muddier sands at the margins.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015