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Are Higher HF Injection Rates More Prone to Triggering Seismicity? Data From Four North American Basins Say No.

Description: 

Wastewater-disposal wells with higher injection rates have for a long time been associated with a higher seismogenic potential (Weingarten et al. 2015; 10.1126/science.aab1345). In this study, we investigate if this is true also for hydraulic fracturing (HF) wells. Using the methods presented in Grigoratos et al. (2022; 10.1785/0220210320), we identified which HF stimulations induced detectable seismicity at a confidence level above 95% in Texas (Eagle Ford, Delaware Basin), Oklahoma and Canada (West Canadian Sedimentary basin). The framework uses a generalized version of the Seismogenic Index model (Shapiro et al. 2010; 10.1190/1.3353727) to hindcast the time-series of the seismicity rates above the magnitude of completeness on a 5 km grid and compare them against the null hypothesis of solely tectonic loading. In the end, each block is assigned a p-value, indicating the statistical confidence of its causal link with HF operations. For a HF well to be flagged as seismogenic it would have be inside a block with p < 0.05 and also within 5 km of an earthquake that occurred during or right after its stimulation period. Notably, across all basins, only 1 to 10% of the HF stimulations are usually responsible for all of the earthquakes linked to HF. We then checked whether their total injected volume or their average daily injection rate is higher than those who did not induce seismicity. The results for all the examined basins showed that the distributions of both seismogenic and non-seismogenic wells were essentially indistinguishable. We discuss possible physical reasons behind this novel finding and the major implications it has for hazard-mitigation strategies.

Session: Advances in Characterizing Seismic Hazard and Forecasting Risk in Hydrocarbon Systems

Type: Oral

Date: 4/18/2023

Presentation Time: 04:45 PM (local time)

Presenting Author: Iason Grigoratos

Student Presenter: No

Invited Presentation: 

Authors