Seismicity

Antero proactively addresses seismicity issues by carefully evaluating the location of disposal wells before use. Antero does not own or operate disposal wells, but uses properly permitted and operated third-party Class II UIC wells for produced water disposal. Third-party disposal wells are vetted in a rigorous selection process before wells are utilized for produced water disposal. The process begins with locating existing disposal wells close to Antero’s areas of operation. Potential disposal wells undergo a desktop audit first by the HSSE department, and a subsequent audit and assessment by our Geology department. A location that exceeds Antero’s risk tolerance is not authorized for use.

During the Geology department’s investigation, the disposal well’s proximity to known mapped faults or seismic events, proximity to other wells, and the targeted injection zone are assessed via USGS datasets. According to the USGS 2014 Seismic Hazard map, Antero’s operations are located in very low risk areas, meaning low risk of occurrence of the potential for horizontal acceleration. Per the USGS 2018 Short-term Induced Seismicity model, Antero’s area of operations is in the lowest (1%) chance of potentially minor-damage ground-shaking events. Additionally, Antero evaluates company wells within two miles of the third-party disposal well to identify open zones in common with the disposal well; in case of overlap, the company wells are recommended as a candidate for plugging. Additionally, during this assessment and audit process, Antero evaluates the planned injection interval of the third-party disposal well to understand where Antero wells are stratigraphically in relation to nearby wells and actively producing zones. If a location is approved by the Geology department, the Antero HSSE department conducts follow-up on site audits of the third-party disposal wells during the on-boarding process. Once the onsite audit is conducted and there are no findings of concern, Antero’s operational team is given the authorization to utilize the third-party well for produced water disposal.

In the Ohio Utica play, there have been reported instances of induced seismicity likely related to basement faults in connection with hydraulic fracturing and produced water disposal. The Ohio Department of Natural Resources (ODNR) has their own seismic monitoring array in place across the state. In areas where they have identified the potential for seismic activity, they may request operators to install additional monitoring equipment. As part of this program, there is a set of tiers that determine whether operations can continue, must be modified, or must be halted entirely. Antero has made arrangements with vendors to support this increased monitoring if it is deemed necessary by the ODNR. Monitoring of this nature includes a series of geophones and accelerometers that are localized around a specific completion activity. These sensors gather data continually and relay it to the vendor and Antero personnel for the data to be processed and managed. At this small scale, the resolution of the data is more precise than the statewide array. Although there is no known history of seismic activity across our area of operations, this monitoring capability is available to us in our operations areas in both West Virginia and Ohio.