Masters Theses

Keywords and Phrases

ABAQUS; Buckle Folds; Effective Stress Evolution; Finite Element Analysis; Fractures; Pericline

Abstract

"The spatial distribution of fracture sets associated with buckle folds has been well documented in field studies. There are difficulties, however, in placing accurate constraints on the timing of the initiation of individual fracture sets during the deformation history of the fold under in-situ conditions. This study investigates specific conditions that give rise to the initiation of various fracture sets in the hinge and limb of a pericline, based on an analysis of the effective stress evolution during the processes of buckling and erosional unloading. A 3D finite element modeling approach is used to simulate the effective stress evolution in single-layer folds with a Maxwell viscoelastic rheology, while including the influence of overburden stress, pore pressure, and a geologic strain rate. Several material properties and geometric features are varied to test their influence on fracture initiation. The modeling results show that fracturing is most heavily influenced by permeability, initial overburden thickness, and erosional unloading. Further analysis reveals that six fracture sets, which are observed in natural buckle folds, are also observed in the modeling results: outer arc tensile fractures, outer arc normal faults, and inner arc thrusts, all of which strike parallel to the fold axis, are determined to be common fracture sets; outer arc tensile fractures that strike perpendicular to the fold axis, and thrusts in the limb that strike roughly parallel to the fold axis are determined to be less common fracture sets that require low permeability (< 10-21 m2) folding layers in order to initiate; vertical conjugate shear fractures in the outer arc, where the fold axis bisects the acute angle between fracture planes, are determined to be a rare fracture set. Most importantly, the timing of initiation is determined for each set, thus providing the most difficult information to obtain from a field study on fold related fractures"--Abstract, page iii.

Advisor(s)

Eckert, Andreas

Committee Member(s)

Hogan, John Patrick
Nygaard, Runar

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Petroleum Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2016

Pagination

xiii, 170 pages

Note about bibliography

Includes bibliographical references (pages 161-169).

Rights

© 2016 Eli Jacob Steinbeck, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Folds (Geology)Fracture mechanics -- Mathematical modelsFinite element method

Thesis Number

T 10982

Electronic OCLC #

958294098

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