Field Tests of Geomechanical Models of Natural Rock Deformation, 20-R8057

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Principal Investigators
David A. Ferrill
Kevin J. Smart
Alan P. Morris
Ronald N. McGinnis

Inclusive Dates:  04/01/09 – 10/01/10

Background - The permeability architecture of many geologic formations is controlled largely by faults and fractures. Predicting the abundance and distribution of these geologic structures in the subsurface is important to a wide range of areas, including oil and gas exploration and production, groundwater resource analysis, nuclear waste isolation, CO2 sequestration, geothermal energy production, and acid gas disposal. This project explored the important problem of relating strain and stress calculated through finite element modeling of geological deformation to actual deformation mechanisms in rock at the micro- to macro-scale, and the associated partitioning of strain between different mechanisms. This understanding is key to predicting fractures in rock (e.g., orientations and spacing of fractures).

Approach - Project tasks included finite element modeling to numerically simulate laboratory deformation tests of experimentally deformed rock cylinders for which published data exists, together with an integrated structural geological and geomechanical analysis of the oil-field scale Bargy anticline in eastern France.

Accomplishments - Project accomplishments included (i) replicating experimental laboratory testing of limestone cylinders using finite element modeling, (ii) developing a unique data set for an oil-field analog structure that spans deformation from the microstructural scale to the macrostructural scale, (iii) matching the macroscale structural geometry as well as outcrop- and smaller-scale deformation using finite element modeling, and (iv) publishing the modeling and analysis results to demonstrate these capabilities to prospective clients. Analysis led to an important scientific connection with well known and widely relied upon experimental results, producing advances in numerical techniques that will be of strong interest to scientists and engineers that use rock mechanics results for applied problems, largely in the oil industry. Via the field application to the Bargy anticline, a real-world field example was developed that provides a compelling analog for a large number of anticlinal oil fields with Cretaceous carbonate reservoirs, including some of the world's largest oil fields in the Middle East, and several structures in the Arabian Gulf and Iraq that SwRI recently investigated for commercial clients. This rigorously analyzed and geomechanically simulated field example in Europe, published and presented at international conferences, has already led SwRI researchers to develop and teach a new structural geology field course and expanded project work from oil industry clients.

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