Diagenetic Controls on Permeability of the Ben Nevis/Avalon Sandstones, White Rose Field, Jeanne d’Arc Basin, Newfoundland, Canada

Leon S. Normore and Rudi O. Meyer
Memorial University of Newfoundland, St. John's, NF

The Aptian-Albian shoreface sandstones of the Ben Nevis/Avalon Formations contain up to three quarters of a billion barrels of oil in the White Rose and Hibernia Fields, with mean permeabilities on the order of < 1 to 300 mD. At the White Rose Field sediment grain size, poikilotopic calcite cement and quartz overgrowths are largely accountable for the reduction in porosity and permeability. Diagenetic evolution of the cements is investigated using core description, optical and cathodoluminescence petrography, digital image analysis, and carbon and oxygen isotopic compositions.

The objective of this study is to develop a knowledge of the paragenetic sequence during early and late diagenesis, relating timing and source of cements to attempt to predict cement distribution, its effect on reservoir-scale fluid connectivity and its use as a development and exploration tool at White Rose Field and potential extensions nearby. The study aims to test whether the source of calcite is provided by the underlying marlstone of the Fortune Bay Formation, or from accumulations of oyster banks and serpulid worm tubes, and associated event or lag concentrations.

Another aspect of this study is the evaluation of the stratigraphic distribution of quartz cement, detected with cathodoluminescence microscopy and quantified by digital image analysis. The abundance of quartz overgrowths is variable, but pervasive throughout the reservoir interval. Hence, in absolute terms, quartz may infill more pore space than all other cements becoming the governing factor for diagenetic reduction in permeability for the bulk of the reservoir.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005