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ABSTRACT: Transformation of Recent Sediments under Differential Confining Pressure

Y. Petzoukha, O. Selivanov, A. Fomin

Hydrocarbon generation models are based on the assumption that temperature is the most important parameter affecting source rock transformation. The pressure effect induced by tectonic stress in sedimentary basins has almost been neglected.

Our experiments simulated source rock alteration by mechanical activation and were conducted with recent sediments under differential confining pressure (up to 200 MPa) at room temperature. For a series of tested specimens on the stress-strain curves, the region of elastic and plastic deformations and shear failure was observed.

Remarkable qualitative and quantitative differences were noted in the deformed samples. The amount of hydrocarbons in free lipids increased six times. Distribution of normal and isoprenoid alkanes was changed. Differential confining pressure at room temperature initiated significant stereochemical rearrangements in steranes and hopanes and promoted isomerization and maturation.

The results of this study have revealed that organic reactions with the mineral matter present are sensitive to rock deformations which occur within sedimentary basins and have implications for applied petroleum geochemistry.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990