← Back to Sessions

Distinguishing the Causal Factors of Induced Seismicity in West Texas: Hydraulic Fracturing Versus Wastewater Disposal

Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip II

Type: Oral

Date: 4/19/2021

Presentation Time: 06:00 PM Pacific

Description: 

Identifying the direct cause of elevated seismicity rates in areas of multiple oil and gas activities has always been a challenging issue that is lacking a homogeneous response. A good example, is the Delaware basin, in West Texas, where the seismicity has been gradually increasing since 2009. In this study, we are examining the recent surge in the area expanding the framework presented in Grigoratos et al. (2020; 10.1785/0120200079) to daily hydraulic fracturing (HF) operations and pressure-driven modeling of wastewater disposal (SWD). Our analysis hindcasts seismicity rates of M ≥ 1.5 events after 2017 on a 5km grid using volume and pressure data as input, and compares them against the null hypothesis of tectonic loading. In the end, each block is assigned a p-value between 0 and 1, indicating our statistical confidence for the causal relationship of each human activity. Our results indicate that more seismicity clusters than previously identified are associated with HF. In the center of Reeves county, in particular, HF is associated with a uniform array of more than thirty 5km blocks, and is not limited to scattered sequences as in other parts of the state. Furthermore, although shallow SWD is linked to several sequences, it is not responsible for the vast majority of events, as previously reported. Finally, large parts of the Delaware basin, especially around the city of Pecos, are affected by both oil and gas activities, with better depth resolution needed to fully decouple causality.

Presenting Author: Iason Grigoratos

Student Presenter: No

Authors