--> Abstract: Dolomitization in Reflux, Mixing, Geothermal, and Hydrothermal Systems: Developing Predictive Diagenetic Concepts with Reactive Transport Models, by Yitian Xiao, Gareth D. Jones, Fiona F. Whitaker, and Sean A. Guidry; #90078 (2008)

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Dolomitization in Reflux, Mixing, Geothermal, and Hydrothermal Systems: Developing Predictive Diagenetic Concepts with Reactive Transport Models

Yitian Xiao1, Gareth D. Jones1, Fiona F. Whitaker2, and Sean A. Guidry3
1ExxonMobil Upstream Research Company, Houston, TX
2Dept. of Earth Sciences, University of Bristol, Bristol, United Kingdom
3ExxonMobil Development Company, Houston, TX

The accurate prediction of the geometry of subsurface dolomite bodies, their connectivity and the associated distribution of petrophysical properties, is a fundamental challenge in carbonate reservoir characterization. Reactive transport models facilitate quantitative, process-based investigations of dolomitization and related diagenetic reactions in 2D and 3D. The presentation will highlight new results and key conclusions from simulations of four distinctly different dolomitization mechanisms: 1) brine reflux, 2) mixing zone and sub mixing zone, 3) geothermal circulation and 4) fault controlled hydrothermal circulation. Simulations provide new insights on the spatial distribution and dynamic behavior of: A) geometry of dolomite bodies generated by different styles of subsurface fluid flow; B) sensitivity to and hierarchy of geological controlling parameters; C) spatial and temporal relationships between dolomitization and associated diagenetic minerals including anhydrite cements and Mississippi Valley Type (MVT) mineralization; D) effect of hydrothermal fluid induced dolomite recrystallization and anhydrite dissolution; and E) criteria to help identify the distribution of high permeability dolomite “sweet spots”. When integrated with conventional subsurface data and stratigraphic, geochemical, and structural framework, reactive transport models of dolomitization can be used to evaluate a broad range of geological scenarios and provide predictive concepts for exploration and new / mature field developments. In particular, the state-of-the-art simulations allow the analysis and 3D visualization of the spatial and temporal evolution of the dolomite body that can translate into alternative “process-based” well correlation methods and strategies for populating diagenetic bodies and their petrophysical properties in geological models / reservoir flow simulations.

 

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