Role of Microbes in the Smectite-to-Illite Reaction

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Abstract

Temperature, pressure, and time have been thought to control the smectiteto-illite (S-I) reaction, an important diagenetic process used for petroleum exploration.  We demonstrated that microorganisms can promote the S-I reaction by dissolving smectite through reduction of structural FE(III) at room temperature and 1 atmosphere within 14 days.  This reaction typically requires conditions of 300??  to 350??C, 100 megapascals, and 4 to 5 months in the absence of microbial activity.  These results challenge the conventional concept of the S-I reaction and of reaction kinetic models.