We are a leader in determining and employing risk mitigation strategies such as seismic reviews of disposal wells, minimizing use of disposal wells in riskier areas and using temporary seismometers during hydraulic fracturing. We also participate in industry owned/operated seismic arrays.
While seismic events are rare in North Dakota, Marathon Oil will apply our prevention strategies if needed in our Bakken asset. Company subject-matter experts share our learnings with other operators and industry organizations to increase capacity to prevent and minimize induced seismicity industrywide.
We support scientific research into any links between seismicity and oil and gas activity, as well as regulatory oversight and information sharing to prevent and mitigate seismic activity potentially connected to our operations.
Marathon Oil sponsors or supports academic organizations and government agencies involved in research into seismicity and oil and gas operations. These include:
- Stanford Center for Induced and Triggered Seismicity. The center researches the physical processes responsible for induced and triggered seismicity, and develops a scientifically based framework and tools for seismic risk assessment and risk management.
- Oklahoma Corporation Commission (OCC). This agency makes guidance available for all operators to address seismicity concerns in the state.
- Oklahoma Coordinating Council (member, technical subcommittee). This council organizes state resources and activities to address seismicity.
- Center for Integrated Seismicity Research (CISR) at the University of Texas at Austin. CISR is a collaborative that collects high-quality data on earthquakes in Texas and conducts fundamental and applied research to better understand naturally occurring and potentially induced earthquakes and the associated risks.
- TexNet Seismic Monitoring Network. This state agency helps locate and determine the origin of earthquakes in Texas. Where earthquakes are possibly caused by human activity, TexNet helps prevent earthquakes from occurring the future.
Preventing Seismic Activity
Most injection wells aren’t associated with felt earthquakes, according to the USGS, which has found that a combination of many factors is necessary for injection to contribute to earthquakes that can be felt. In Oklahoma, the OCC has designated Areas of Concern where injection is restricted due to seismic activity.
Marathon Oil currently doesn’t own or operate any injection wells for wastewater disposal in targeted formations that have been linked to seismic activity in Oklahoma, or in areas with similar restrictions. We take precautions to prevent disposal of produced water from our sites into formations that have been linked to seismic activity. These include contracting with vetted third-party water haulers to dispose of produced water in approved disposal sites that don’t inject into targeted formations.
While seismicity associated with completion activity is rare, we monitor our completion sites in Oklahoma to mitigate seismic activity. Initiating mitigation activities promptly can significantly reduce or eliminate the likelihood of felt earthquakes that may be associated with well stimulation.
Marathon Oil co-founded the largest private seismic monitoring array in the world. This array of seismometers located across the STACK/SCOOP plays in Oklahoma allows us to constantly monitor operations and implement protocols to mitigate any seismicity that may occur as a result of our operations.
We follow the OCC’s Well Completion Seismicity Protocol, which requires operators to develop and implement a mitigation plan prior to completing any wells. Action is required for seismic events greater than or equal to 2.0 magnitude within 5 kilometers of the well, with requirements increasing as event magnitude increases. Under Marathon Oil’s mitigation plan, which is more stringent than the requirements in the OCC protocol, we:
- Conduct risk analysis as part of our pre-spud and pre-stimulation planning.
- Actively monitor seismic activity before, during and after well stimulation, using the private array of seismometers and publicly available data to accurately detect events.
- Maintain and exercise appropriate mitigation plans based on real-time monitoring of seismic activity, with immediate response and validation 24/7.
- Take early operational actions to mitigate pressure buildup.
- Respond following seismic activity within 5 kilometers of our hydraulic fracturing operations, whether the activity may be related to our operations or those of other operators.
- Notify OCC’s Induced Seismicity Department and confer with its staff members regarding any pause, suspension or resumption of fracturing.
As a result of Marathon Oil’s collaborative efforts with the OCC and our industry peers, there was only one seismic event greater than 2.5 magnitude in the vicinity of Marathon Oil’s operations that triggered the OCC guidelines in 2019.
Transferring Lessons Learned
Marathon Oil was instrumental in leading an effort to apply lessons learned from Oklahoma to the Eagle Ford, resulting in a substantial reduction in the number and magnitude of seismic events recorded through temporary monitors in that location.
Our approach is to be proactive and monitor our own and surrounding operations using data from available seismometer arrays. If seismic activity is detected, we select the mitigation measure that best meets our needs for safety, efficiency, effectiveness and cost.
There are no state protocols to mitigate seismic risk in South Texas. Our Eagle Ford asset analyzes data from regional public seismometer arrays and factors in our knowledge of local geology and drilling and completions activity to determine if we need to take preventive action. For specific predetermined operations, we deploy private arrays to provide real-time data that allows us to quickly take action if needed.
Few seismic events are reported in publicly available data in the New Mexico Delaware Basin, but low-level events are on the rise. With no state regulations pertaining to induced seismicity, we continue to evaluate the data and will take action if we detect any increase in seismic activity.
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