Understanding Key Elements of Past Subsurface Fluid Releases to Better Inform Future Groundwater Monitoring

Penoyer, Pete

Understanding Key Elements of Past Subsurface Fluid Releases to Better Inform Future Groundwater Monitoring

Thursday, November 13, 2014: 5:30 p.m.

Pete Penoyer, Hydrogeologist , Water Resoruces Division- Aquatic Systems Branch, National Park Service, Fort Collins, CO

This presenter has determined that impacts to shallow groundwater from oil and gas development are best looked at in one of two ways. The first is conventional surface/near surface, primarily vadose zone releases/spills of fluids from oil and gas surface operations (tanks, gathering lines, drilling-related reserve pits, retention ponds, transportation accidents, etc.). These releases will typically behave similar to fluid releases by other industries. Largely driven downward by gravity, the groundwater industry has a long history dealing with such spills/releases through site characterization, standard monitoring practices, and remediation of any resulting groundwater plumes. The second category is subsurface releases of fluids that typically are driven upward from some depth under a pressure gradient or relative density difference of the contaminating fluid, or both. In the latter type of release the groundwater industry has much less experience in terms of understanding the numerous elements that may come into play. Often there is a lack of well drilling, installation, and operational information in addition to limited deeper subsurface geologic or seismic data that is not readily available due to the confidential and proprietary data nature of the E&P (upstream) industry.

This presentation attempts to briefly summarize what is understood about the local geology, migration pathways, primary COCs, drive mechanisms, wellbore integrity, etc. that may have been contributing factors to some alleged/documented release incidents. Those fluid releases of hydrocarbons/brine that have gained national notoriety (e.g., PA, OH, TX, WY, CO, ND) suggest the actual role played by the hydraulic fracturing process itself is largely unrelated and the focus on the induced fracture pathway through/beyond the target formation appears unwarranted (“frac outs” excepted). Only through a better understanding of such past documented subsurface fluid releases may future groundwater monitoring be best informed and focused to cost effectively detect subsurface releases to shallow groundwater.

Pete Penoyer, Hydrogeologist, Water Resoruces Division- Aquatic Systems Branch, National Park Service, Fort Collins, CO

Pete Penoyer has degrees in Geology (B.S. and M.S.) from Western Kentucky University and Oregon State University respectively, a Professional Degree in Hydrogeology from the Colorado School of Mines, and an Associate of Science Degree in Hazardous Materials Technology from Front Range Community College. He spent 15 years in the oil and gas industry as an Exploration Geologist for Shell Oil Co., Champlin Petroleum, and Mitchell Energy and Development Corp. He spent seven years with the Army Corp of Engineers Omaha District conducting/overseeing groundwater investigations at military installations and formerly used defense sites. Penoyer is currently employed by the National Park Service as a water quality team lead in the national program center supporting parks on a service-wide basis in their efforts to protect surface water and groundwater resources.