Title

A Comparison of Stress Evolution in Single-Layer and Multi-Layer Buckle Folds

Abstract

Buckle folds of single-layer and multilayer sedimentary strata characterized are among the most common structural traps for hydrocarbon reservoirs. The spatio-temporal evolution of the stress state in folded reservoirs is of significant importance for the understanding and predicting patterns of fractures associated with buckle folds. This paper compares the evolution of the principle stress state associated with buckle folding by studying the deformation process of two different geometries: single-layer and multilayer buckle folds. A 3D finite element modeling approach is applied to simulate the buckle folding of single-layer and multilayer stacks with Maxwell visco-elastic rheology. It is concluded that the stress state within the folding layer(s) are determined by the buckling process, fold geometry and material parameters. This study shows that the presence of the competent layers has a governing influence on the amplification rate of fold amplitude and the evolution of the strain/stress field. The lowest magnitude of effective minimum principle stress is found at the top of the hinge of the bottom competent layer in the three-layer system and central competent layer in the five-layer system. Moreover, layer-parallel extensional strain and low magnitudes of layer-parallel principle stress is observed between the limb and the hinge of the central competent layer in the five-layer system. Little differential stress develops throughout the folding layer in the less competent layer(s). This study also shows that tensile fractures perpendicular and parallel to the fold axis at the hinge and in the limb can be explained by the developed overpressure in low permeability rock. In summary, this study shows that strain distribution and stress evolution within buckle folds are directly dependent on the number of competent layer(s) and the distribution of material parameters.

Meeting Name

49th US Rock Mechanics / Geomechanics Symposium (2015: Jun. 28- Jul. 1, San Francisco, CA)

Department(s)

Geosciences and Geological and Petroleum Engineering

Comments

14 pages

Keywords and Phrases

Cements; Fracture; Multilayers; Rock mechanics; 3D finite element model; Deformation process; Differential stress; Hydrocarbon reservoir; Low permeability rock; Spatiotemporal evolution; Strain distributions; Three-layer systems

International Standard Book Number (ISBN)

9781510810518

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2015 American Rock Mechanics Association (ARMA), All rights reserved.

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