--> Abstract: Sand Tectonics: a Reservoir-Scale Process Similar to Basin-Scale Salt and Shale Tectonics; #90063 (2007)

Datapages, Inc.Print this page

Sand Tectonics: a Reservoir-Scale Process Similar to Basin-Scale Salt and Shale Tectonics

 

Imbert, Patrice1, Marine Perus2 (1) TOTAL CSTJF, 64000 Pau, France (2) Total Exploration and Production, Pau, France

 

Seismic and outcrop data have highlighted the role of sand injection as a reservoir-modifying agent, as a thief zone-maker in exploration or as a help to reservoir communication.

 

In a more general way, seismic observations in various basins indicate that sand injection can be just part of a much larger-scale remobilization of parent turbidite sandbodies after some burial. Such a deformation can be inferred from the behavior of the overlying strata in North Sea examples, where the seismic contrast between the sand and its cover is weak. Examples from the deep Gulf of Mexico give a much better insight into the process, thanks to a strong impedance contrast between the sands and shales, which makes it possible to map with confidence the top of the deformed sandstone.

Sand tectonics in areas of initial thick and confined sand (e.g. channel fills) results in the development of structures very similar to those obtained with salt tectonics, like turtle backs and rollovers (Gulf of Mexico). In areas of more extensive and thinner sand (e.g. turbidite lobes), it rather makes decollement levels above which sand pillows can develop (North Sea).

 

Sand tectonics may help resolve the old debate about the geometry of turbidite sands, usually flat-lying at the outcrop and on the seafloor, and commonly “bumpy” in subsurface. It could provide an alternative to the contourite hypothesis and the “sandy debris flow” paradigm that have been proposed to resolve the conflict between analogues and reservoirs: when and where thick sands are isolated.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California