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Experimental Flow-Through Study of Artificial Diagenesis in Sandstones

Rona J. Donahoe, Linda E. Leard

During petroleum reservoir development and production, various fluids are injected into well bores. Because these fluids differ compositionally from the reservoir rock pore fluids, induced fluid/rock interactions can range from none to extreme in their effect on reservoir rock properties. These induced reactions, considered artificial diagenesis, can be studied using a new low-temperature flow-through hydrothermal apparatus.

The flow-through apparatus is presented as an alternative to conventional high-temperature, high-pressure permeameters for studying water/rock interactions. This equipment is designed to study water/rock interactions under variable fluid-flow rate (0.0005-10 ml/min), temperature (50°-300°C), and pressure (50-500 bar) conditions; to allow in-situ measurements of permeability; and to accommodate packed column or 1-in. diameter core samples.

An experimental and computational study was conducted at 250°C to investigate the effects of fluid flow rate, fluid composition, and sandstone mineralogy on disaggregated sandstone sample alteration mineralogy and permeability. Three series of flow-through experiments were conducted with the following variables: (1) sandstone composition (quartzarenite, 2 arkose); (2) fluid composition (distilled, deionized water and aqueous solutions of HF/HCl and NaOH); and (3) fluid-flow rate (0.001-1 ml/min). Preliminary results from these experiments are presented. The variables listed above are discussed in terms of their effect on sandstone alteration mineralogy and permeability. In addition, computer chemical-equilibrium programs used to model these man-made diagenetic systems are evaluat d.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.