Lithological, petrophysical and seal properties of mass-transport complexes (MTCs), northern Gulf of Mexico

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: This is version 5 of this Preprint.


Download Preprint

Supplementary Files

Nan Wu , Christopher Aiden-Lee Jackson , Howard D. Johnson, David Hodgson


Mass transport complexes (MTCs) are one of the most sedimentologically and seismically distinctive depositional elements in deep-water depositional systems. Seismic reflection data provide spectacular images of their structure, size, and distribution, although a lack of borehole data means there is limited direct calibration between MTC lithology and petrophysical expression, or knowledge of how they may act as hydrocarbon reservoir seals. In this study, we evaluate the lithological and petrophysical properties, and seismic characteristics of three deeply-buried (>2300 m/7546 ft below the seabed), Pleistocene MTCs in the northern Gulf of Mexico. We show that: (i) MTC lithology is highly variable, comprising a mudstone-rich debrite matrix containing large (4.5 km3/1.08 mi3), deformed, sandstone-rich blocks; (ii) MTCs are generally acoustically faster and are more resistive than lithologically similar (i.e. mudstone-dominated) slope deposits occurring at a similar burial depth; (iii) MTC velocity and resistivity increase with depth, likely reflecting an overall downward increase in the degree of compaction; and (iv) the lowermost 15-30 m (49-98 ft) of the MTCs, which represent the basal shear zones, are characterised by relatively high P-wave velocity and resistivity values, likely due to shear-induced over-compaction. We conclude that detailed analysis of petrophysical data, in particular velocity and resistivity logs, may allow recognition of MTCs in the absence of high-quality seismic reflection data, including explicit identification of the basal shear zone. Furthermore, the relatively thick basal shear zone, rather than the overlying and substantially thicker MTC itself, may form the primary permeability barrier and thus seal for underlying hydrocarbon accumulations.



Earth Sciences, Engineering, Engineering Science and Materials, Geology, Physical Sciences and Mathematics, Sedimentology


Gulf of Mexico, MTCs, Petrophysical properties


Published: 2019-02-22 03:30

Last Updated: 2019-10-16 06:59

Older Versions

Academic Free License (AFL) 3.0

Add a Comment

You must log in to post a comment.


There are no comments or no comments have been made public for this article.