AAPG Bulletin, V. 82 (1998), No. 4 (April 1998), P. 637-648.

Porosity Prediction in Quartzose Sandstones as a Function of Time, Temperature, Depth, Stylolite Frequency, and Hydrocarbon Saturation¹

Per Arne Bjørkum,² Eric H. Oelkers,³ Paul H. Nadeau,² Olav Walderhaug,² and William M. Murphy⁴

©Copyright 1998.  The American Association of Petroleum Geologists.  All Rights Reserved
 

¹Manuscript received August 19, 1996; revised manuscript received April 14, 1997; final acceptance November 14, 1997.
²Statoil a.s, N-4035 Stavanger, Norway; e-mail: [email protected]
³Laboratoire de Géochimie, Université Paul Sabatier, 38 rue des Trente Six Ponts, 31400 Toulouse, France.
⁴Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238.

We thank Stephen N. Ehrenberg, Nils Einar Aase, Jacques Schott, and Jean Louis Dandurand for helpful discussions during the course of this study. Reviews by Sal Bloch, Raymond Siever, and David R. Turner led to significant improvements of the manuscript. Support from Statoil and the Centre National de la Récherche Scientifique are gratefully acknowledged.

Abstract

The variation of porosity in quartzose sandstones is calculated as a function of depth, temperature gradient, burial rate, stylolite frequency, and hydrocarbon saturation. Calculations were performed by considering the effects of both mechanical compaction and chemical compaction/cementation. This latter process dominates at temperatures greater than approximately 90°C and is due to quartz redistribution within the sandstone. Quartz redistribution stems from clay-induced quartz dissolution at stylolite interfaces, coupled with diffusional transport of aqueous silica into the interstylolite sandstone and precipitation on quartz surfaces as cement. Many model parameters are obtained from theoretical calculations or laboratory measurements, and few basin-dependent parameters are required to make porosity predictions. A set of porosity predictions is presented in porosity/depth figures. Close correspondence between computed results and measured porosities in cores from a variety of sedimentary basins demonstrates the accuracy of the predictions.