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

CATEGORY: GROUNDWATER PROTECTION
Understanding Key Elements of Past Subsurface Fluid Releases to Better Inform Future Groundwater Monitoring

Type	Conference Paper
Author	Pete Penoyer
URL	https://ngwa.confex.com/ngwa/gqhf14/webprogram/Paper10132.html
Date	2014/11/13
Conference Name	NGWA Workshop — Groundwater Quality and Unconventional Gas Development: Is There a Connection?
Abstract	Author 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. Author summarizes 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.