Understanding Pore Networks and Reservoir Quality in the Deeply Buried Eocene Wilcox Sandstone of the Texas and Louisiana Coast, USA Using Mercury Injection Capillary Pressure Analysis

摘要

Adatabase of mercury injection capillary pressure (MICP) analyses was assembled for Paleocene-Eocene Wilcox sandstones from Texas and Louisiana to investigate controls on reservoir quality and evolution of pore-network characteristics with increasing depth and temperature. Objectives of this paper are to (1) review the MICP analyses and relate them to porosity and permeability data, (2) integrate MICP data with thin-section petrography to explain relationships of pore types and pore-throat sizes, and (3) provide insights from MICP data on controls of permeability.As sandstones are buried to greater depths and temperatures, pore networks evolve from a mixture of primary interparticle macropores, secondary intraparticle macropores, and micropores to a pore network dominated by intraparticle macropores and micropores. This pore-network change with depth/temperature corresponds to an increase in micropore throats connecting pores, and, as a result, permeability decreases.As indicated by MICP and thin sections, both pore-throat radii and pore diameters are in the microscale range (≤10 microns for pores) in the deepest/hottest Wilcox sandstones. The relationship between interparticle pores and permeability is better than the relationship between total porosity and permeability. Thin-section point counts of interparticle macropores are an efficient method of calculating effective porosity, which should be used to calculate porosity/permeability transforms.