The Pros and Cons of Various Dolomite Models: Some Work, Many Don’t

Hans G. Machel
EAS, Univ. of Alberta, Edmonton, AB, Canada

The so-called “dolomite problem” has several facets: (a) dolomites can form in many different diagenetic and hydrothermal settings; (b) data often permit more than one genetic interpretation; (c) dolomite is rare in Holocene sediments, yet abundant in older rocks; and (d) well-ordered, stoichiometric dolomite has never been successfully grown inorganically in laboratory experiments at near-surface conditions. These aspects lead to practical problems plaguing the petroleum industry, most notably: how much dolomite can be formed by any given process (or model), and what are the resulting geometry and porosity-permeability patterns in dolostone reservoirs, which are notoriously difficult to interpret and predict? ---

From a practical point of view, the “dolomite problem” can be solved to a degree that would enhance exploration success, and thus allow for more efficient development of dolostone reservoirs. Attaining these goals requires a comprehensive understanding and application of the involved disciplines, most notably crystallography, geochemistry, and hydrogeology. Many ambiguities in previous studies arose from a superficial understanding and lack of rigor in the application of these disciplines. A common result is that some dolomite models, such as the mixing zone and the hydrothermal dolomite models, are essentially useless in the prediction of dolostone reservoirs.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas