AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Delineating Deepwater Depositional Patterns in a Foredeep Basin: An Integrated Study from North Chicontepec Basin, East-Central Mexico
(1) ConocoPhillips School of Geology and Geophysics, University of Oklahoma, Norman, OK.
(2) Cossey & Associates Inc, Durango, CO.
(3) Mexican Petroleum Institute (IMP), Mexico City, Mexico.
Chicontepec turbidites were deposited in an elongated foreland basin between the active Sierra Madre Oriental (SMO) fold thrust belt and Tuxpan Platform during the Paleocene and Eocene. An attempt has been made to unravel the complex spatial and temporal geologic patterns in the northern part of Chicontepec foredeep by integrating available 3D seismic data sets, well logs, core information with Chicontepec outcrops adjacent to the 3D seismic area.
Seismic attribute analysis provided clues about the depositional patterns in Chicontepec, but high frequency changes in depositional patterns were rarely captured due to limits in seismic resolution. Outcropping Chicontepec strata at the foothills of SMO, expose the deepwater patterns dominated by amalgamated and layered sheet sandstones generated from fine grained turbidites, mass transport complexes (MTCs) including slumps and debrites along with occasional channel fills and splays. Sediment thickness and the relative abundance of MTCs within the sedimentary column decreases significantly from west to east in the basin indicating the major sediment provenance was from the SMO fold and thrust belt. Conventional well logs were calibrated with the few available core gamma logs for log pattern recognition of proximal, mid and distal lobe, as well as channel facies. Detailed well log correlation based on these patterns and the analysis of isopach maps reveal several channelized turbidite deposits. While there was a dominant axial turbidite channel from NW to south during the deposition of Lower Chicontepec strata, most of middle Chicontepec deposition was associated with channel systems generated from SMO. Paleocurrent measurements in outcrop locations support this depositional evolution process. Some of the major channel systems are marked by steep increase in Th/K ratio at the base as seen from spectral core gamma ray logs. A few paleocurrent measurements and a single cross-bedding direction from image log interpretation invoke the possibility of flow pulses from the eastern Tuxpan platform. High carbonate mineral content in some core plugs close to the platform strengthens this assumption. Majority of the slumps were generated from SMO, but a few slumps with E-W direction were also found. These inputs from detailed geologic study along with acoustic and elastic impedance inversion will strengthen the seismic interpretation to build and quantify geologic patterns incorporating the areas having few or no wells.