Identifier

etd-01052017-162808

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

Receiver angular coverage of microseismic sources occurring during hydraulic fracturing treatments is an important factor to consider when interpreting moment tensor inversion results. A horizontal receiver array can provide greater angular coverage of vertical failure planes than a vertical receiver array. The source orientation can be accurately determined if the array samples both sides of the failure plane. However, the compensated-linear-vector-dipole (CLVD) mechanism can be overestimated by up to ~40% for double-couple (DC) sources and the isotropic mechanism can be overestimated by ~70% for CLVD sources. Source mechanism constraints on the moment tensor inversion are used to mitigate the lack of angular coverage. The use of the deviatoric assumption decreases the error in the source mechanism to ~70% for DC sources and ~50% for CLVD sources however this introduces an error of ~55° in the strike of the CLVD source. Moment tensor inversion programs typically assume isotropic velocity models however rocks can have anisotropic seismic velocities. Inversion of sources occurring in anisotropic media but assuming an isotropic velocity model in the inversion results in source orientations with errors < 15° and up to 80% error in the resolved source mechanism.

Date

2016

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Lorenzo, Juan

DOI

10.31390/gradschool_theses.4582

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