--> ABSTRACT: Predictive Evaluation of Sandstone Reservoir Quality Through Integration of Diagenetic Data from Natural and Experimental Systems, by R. E. Larese and D. L. Hall; #91021 (2010)

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Predictive Evaluation of Sandstone Reservoir Quality Through Integration of Diagenetic Data from Natural and Experimental Systems

LARESE, RICHARD E. and DON L. HALL

Lithologic data (e.g., core/cuttings) is often limited or nonexistent in deeper reservoir intervals comprising many plays in frontier and mature basins. In these instances, integration of natural and hydrothermal experimental rock-fluid data can aid in predictive evaluation and modeling of porosity-modifying diagenetic processes in deep sandstone reservoir systems. Laboratory simulation of chemical and physical diagenetic processes facilitates a better evaluation of the effects of clay/non-clay grain coatings, hydrocarbon "poisoning", overpressure and other phenomena on porosity reduction, preservation, and enhancement.

Depositional facies and original framework composition exert significant controls on the distribution of chlorite grain coats in several Gulf Coast and North Sea reservoirs. Here, optimum reservoir quality occurs in sandstones possessing ~5-13 vol percent chlorite. The chlorite coats effectively inhibit quartz cementation and appear to be sourced by in situ chemical alteration of roughly 3-8 vol percent lithic framework material. Experimental evidence suggests that liquid hydrocarbon effectively retards quartz and clay cementation as well as compaction processes in sandstone reservoir lithologies. Liquid petroleum appears to effectively retard pressure solution compactional effects under both oil-wet and water-wet conditions. Preliminary pressure solution experiments show a porosity loss of ~27 vol percent in oil-filled (oil wet) compacted sands versus ~85 vol percent in comparable water-filled specimens. Although liquid petroleum retards physical compaction effects in lithic-rich sandstones under oil-wet conditions, its effectiveness on the "poisoning" of ductile lithic deformation in water-wet sands is greatly dependent on interactive chemical stability of framework grains and timing of emplacement.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.