Geometry Determination of Channel-fill Deposit Induced by Turbidity Current: A Study from an Outcrop Analogue

Abstract

Channel system produced by turbidity current has been proved as one of the most prominent hydrocarbon reservoir. Nowadays, E&P industries are chasing deeper water environment to explore the potential hydrocarbon resources in the deep-water setting. Geoscientists find many challenges to characterize and to predict the geometry of the turbiditic deposit because of their complexities, diversities, and outcrop scarcities especially in Indonesia with tropical climate setting. This deep-water channel outcropped in Cipamingkis River, West Java, Indonesia is perfectly exposed along the southern part of meandering river. The objective of this research is to understand the geometrical characteristic of turbiditic channel and how it is generated by studying its outcrop as an analogue for subsurface hydrocarbon reservoir. This study discusses geometry determination and paleogeographical environment from the outcrop. From the field observation, we found that the turbidite facies is encased in muddy deposit of other associated facies. The turbidite facies composed of interbedded coarse-grained sandstones and very coarse-grained in the lower part with planar, cross-bedding, and cross-lamination sedimentary structure. The base of this facies is sharp or locally show erosional surface with burrows commonly observed in the middle or upper part of the facies. The dimension of this package is 360 cm thick with overall fining-upward pattern in the uppermost 100 cm. Overall geometry of the outcrop represents a lens of channel-fill deposit induced by turbidity current. The expected initial environment of this outcrop that we propose is on a deep water steeper slope with smoother relief and without any confining boundary instead of vertical stacked channels filling the incised valley. Further study on petrography, petrophysical analysis, biostratigraphy, and forward modelling will be needed in the future to be able to replicate turbidity process in deep water slope environment if it is induced by pure gravitational force or turbidity current as expected in previous publications. Question about the exact process to create those geometries will also be tested using flume tank experiment and computational fluid dynamics later on.

AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018