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A Diagenesis Model for Geomechanical Simulations: Formulation and Implications for Pore Pressure and Development of Geological Structures

Lookup NU author(s): Joshua Obradors Prats, Dr Mohamed Rouainia

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This is the final published version of an article that has been published in its final definitive form by American Geophysical Union, 2019.

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Abstract

©2019. American Geophysical Union. All Rights Reserved. Forward basin modeling is routinely used in many geological applications, with the critical limitation that chemical diagenetic reactions are often neglected or poorly represented. Here, a new, temperature-dependent, kinetic diagenesis model is formulated and implemented within a hydromechanical framework. The model simulates the macroscopic effects of diagenesis on (1) porosity loss, (2) sediment strength, (3) sediment stiffness and compressibility, (4) change in elastic properties, (5) increase in tensile strength due to cementation, and (6) overpressure generation. A brief overview of the main diagenetic reactions relevant to basin modeling is presented and the model calibration procedure is demonstrated using published data for the Kimmeridge Clay Formation. The calibrated model is used to show the implications of diagenesis on prediction of overpressure development and structural deformation. The incorporation of diagenesis in a uniaxial burial model results in an increase in overpressure of up to 9 MPa due to both stress-independent porosity loss and overpressure generated by disequilibrium compaction caused by a reduction in permeability. Finally, a compressional model is used to show that the incorporation of diagenesis within geomechanical models allows the transition from ductile to brittle behavior to be captured due to the increase in strength that results in an overconsolidated stress state. This is illustrated by comparison of the present-day structures predicted by a geomechanical-only model, where a ductile fold forms, and a geomechanical model accounting for diagenesis in which a brittle thrust structure is predicted.


Publication metadata

Author(s): Obradors-Prats J, Rouainia M, Aplin AC, Crook AJL

Publication type: Article

Publication status: Published

Journal: Journal of Geophysical Research: Solid Earth

Year: 2019

Volume: 124

Issue: 5

Pages: 4452-4472

Print publication date: 01/05/2019

Online publication date: 08/04/2019

Acceptance date: 02/04/2019

Date deposited: 14/06/2019

ISSN (print): 2169-9313

ISSN (electronic): 2169-9356

Publisher: American Geophysical Union

URL: https://doi.org/10.1029/2018JB016673

DOI: 10.1029/2018JB016673


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