T176 Advancements in Energy Geology: The Best of American Association of Petroleum Geologists Technical Talks 2018

Tuesday, 24 September 2019
8:00 AM - 12:00 PM
Room 127ABC, North Building

PRECAMBRIAN BASEMENT TECTONICS BENEATH A CCS SITE, ILLINOIS BASIN

Paper number: T176-7
Program: Technical Sessions
Time: 9:20 AM – 9:35 AM

Authors

Abstract

Characterization of Precambrian basement tectonics using 3D seismic data is critical for fully constraining the geology of a carbon capture and storage (CCS) site. Our study applies state-of-the-art visualization and attribute analysis to a 3D seismic volume of the basement complex that underlies the Illinois Basin-Decatur Project CCS site. The most successful interpretative techniques used include geo-body analysis, X-directed (east-west, cross-line) amplitude change, and co-rendering (e.g., amplitude with semblance), integrated with gradient analysis. The 3D volume reveals a strong reflector deep within the basement complex that is interpreted to be a mafic sill, disrupted by a coherent pattern of structural discontinuities. The discontinuities, which have a mutually orthogonal northwest-northeast trend, could have formed as part of the intrusion process, as post-emplacement tectonic faults, or a combination of both. Our preferred interpretation is that discontinuities are small faults with varying senses of offset. The most prominent of these is a narrow, well-defined northwest-striking crest or flexure in the igneous sill reflector. Injection-induced microseismicity describes a conspicuous pattern of northeast-trending clusters of events, some of which nucleated in the uppermost part of basement, directly over this crest. This distribution of seismic events is proposed to be controlled, in part, by fracture zones related to the crest and associated discontinuities in the mafic sill. These fractures would be oriented in directions to be critically stressed, resulting in microseismicity following pore pressure increases.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-333708

© Copyright 2019 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.