--> Abstract: Constraints On Advective Mass Transfer During Burial Diagenesis, by K. Bjorlykke, F. A. Chuhan, and O. Lauvrak; #90928 (1999).

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BJORLYKKE, K., F. A. CHUHAN, O. LAUVRAK
Department of Geology, University of Oslo, Norway

Abstract: Constraints on Advective Mass Transfer during Burial Diagenesis

Transport of solids in pore water can be calculated as a function of the solubility of ions in equilibrium with the most Important mineral phases. Dissolution and precipitation due to fluid flow is then a function of the fluid flux and the solubility/temperature gradient. Integrated fluxes over time exceeding 106m3/m2 are required to precipitate 10% quartz cement. In the case of aluminum the required flux for significant mineral dissolution or precipitation is several order of magnitude higher. These fluxes are much higher than can be obtained from compaction driven flow unless the flow is focused by 3-4 orders of magnitude. It is therefore no known mechanism which can explain large scale dissolution or precipitation by advective flow except perhaps increase of extreme focusing. Mass transfer is difficult to calculate from petrographic observations and the advective component can not be distinguished from precipitation and dissolution due to diffusion. Changes in composition of sandstones and shales with depth can also be due to lateral facies changes. New data from Jurassic sequences from Haltenbanken and the North Sea show that precipitation of illite depend on the local availability of K-feldspar and kaolinite which are the main precursor minerals. The amount of quartz cement is a function of the temperature and the surface area available for quartz precipitation. In sandstone with grain coatings of chlorite or bitumen quartz cementation has been effectively prevented or reduced. Reservoir quality is therefore linked to provenance and early diagenesis and there is no evidence that fluid flow play a significant role.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas