T174 Earthquakes and Deformation in Eastern North America and Other Continental Interiors: What We Know, What We Don’t, What We Think, and Which Is Which? (Posters)

Tuesday, 6 November 2018
9:00 AM - 6:30 PM
Halls J-K

GEOSPATIAL ANALYSIS OF THE INFLUENCE OF WASTEWATER DISPOSAL ON THE RECENT SEISMICITY IN OKLAHOMA

Paper number: T174-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Seismic records indicate that frequency of earthquakes in Oklahoma has significantly increased since late 2008, and evidence suggests the rise is most likely caused by wastewater disposal. Previous research focused on the analysis of volume injection data. In this study, we investigate the characteristics of the earthquakes themselves and their locations relative to the injection wells and the geologic environment. We study how these earthquakes have evolved over time focusing on where and how often they occur, with special considerations to their depths and magnitudes, in order to identify patterns that can help predict future damaging events. Our investigation considers three time periods, each representing a notable change in hydraulic fracturing development, including (1) the shale reservoir extraction, (2) the advances in horizontal drilling technology, and (3) the profitability in US oil and natural gas markets. Our preliminary results indicate that not only does the increase in earthquakes coincides with the increase in injection wells, but also their locations cluster heavily around saltwater disposal (SWD) wells. One discovery is a three-year lag between peak number of SWD injection wells in 2012 and peak number of earthquakes in 2015. Most of the earthquakes have small magnitudes (~Mw2), but Mw4 earthquakes also occurred, and in year 2016, three Mw5 earthquakes were recorded. Most likely the three-year lag is due to the rate and time in which wastewater is injected and how it affects strain accumulation along faults near the injection wells. As our investigation continues, we will consider the depths in which these injection wells are drilled because recent earthquakes are commonly occurring at 5-6 km depth. We will consider also the volume and the rate of injection, as well as the well placement geometry and orientation relative to the nearby faults as this can cause fluid migration and thus can lead to stress redistribution in the surrounding area.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-322111

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