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Basin-Scale Inelastic Deformation: Pore Pressure and Stress Implications
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
Summary
Most sedimentary rocks experience some form of inelastic deformation and compaction being enhanced by horizontal stresses at convergent margins. Existing published studies using basin modeling techniques in structurally complex regions often show inaccurate pressure predictions typically due to elastic assumptions and lack of non-vertical deformation and stress. This work uses an evolutionary geomechanical approach to model seals with evolving properties as a function of stress and fracture formation. We use a synthetic model to investigate basin-scale effects of fracturing on fluid flow and pore pressure evolution. The model captures fracture opening, closing, and potential reactivation in response to mechanical criteria as well as the system response when tectonic shortening is present. We are able to model realistic mechanical behavior of low-permeability shales in relation to complex compaction, various overpressure conditions, fracturing, and tectonic shortening. Though we study a simplified, synthetic geometry, our model results are geologically realistic and insightful. An example without tectonic loading demonstrates dissipation mechanism via natural fracturing at the location where pressure and stress condition exceed the elastic limit. An example with tectonic shortening predicts a consistent deformation zone and preferred flow orientation in relation to compressive forces.
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