--> Eocene – Lower Miocene Reservoir Facies Presence and Source to Sink Seismic Evidence, East Mexican Perdido Fold Belt

AAPG ACE 2018

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Eocene – Lower Miocene Reservoir Facies Presence and Source to Sink Seismic Evidence, East Mexican Perdido Fold Belt

Abstract

As part of a regional play analysis evaluation on the eastern sector of the Mexican Perdido Fold Belt (MPFB), seismic facies and attribute evaluation were carried out to identify possible reservoir facies on the Eocene to Miocene interval, allowing us to recognize several units of interest.

The lower and middle Eocene sequence has several levels of thick, long lasting, meandering channel complexes in ensembles ranging from 5-10 km of width, and individual channels laterally migrating toward the east, reaching up to 400 m in width. Most channels are trending south-north with sediment transport inferred coming from the south, contrary to the belief of sediment carried from the Alaminos Canyon at that time. The upper Eocene sequence is made of subparallel, wavy, divergent, hummocky, irregular, and discontinuous low frequency reflectors that could represent mass transport complexes, locally covered by isolated meandering channels, ~300 m in width (southwestern sediment source). The uppermost part of this sequence has significant amount of meandering channels, laterally merging each other, forming belts of up to 1500 m. Associated to the channels there are several fan morphologies inferred as lateral overbank splay fans of up to 50 km2 in surface.

The Oligocene sequence is characterized by continuous and parallel reflectors to the east and hummocky and chaotic clinoforms to the west. Isolated narrow meandering channels with north-east bifurcation patterns are present in the upper portion of this unit.

Lower Miocene unit has a wide range of reflection patterns: parallel, divergent and chaotic, most of them onlaping toward the west. One of the main features observed here is a unique complex of north trending, braided channels of greater widths and thickness than those of older complexes, some of them having more than 1200 m of channel width and more than 50 km long, probably representing a main distributary channel.

From the seismic evidence observed in the eastern portion of the MPFB, channels, levees and overbank splay fans (associated to the channels) are some of the main reservoir facies in the area. Even though there is a large structural control on the sediment distribution in the area, most of the Tertiary sediment supply came from southern - southwestern sources. The interest of this last interpretation relies on the impact that sandstone composition has on reservoir quality; factor that could represent a difference between north and south sectors of the PFB.