Title: Pressure monitoring of disposal reservoirs in North-Central Oklahoma: implications for seismicity and geostorage

Speaker:  Director  & State Geologist Dr. Nicholas W. Hayman

Location: Petroleum Alliance Building

                   500 NE 4th St #200

                   Oklahoma City, OK 73104

Dates: April 17, 2024
Time: 11:30 am - 1:00 pm
Cost: $25 Members $35 Non-members (lunch included)

Abstract: Subsurface pressures and fluid flow figure prominently in most investigations of induced seismicity. Moreover, disposal of industrial wastewater, storage of natural gas and/or hydrogen fuel, and future geological sequestration of carbon dioxide all depend on the pressure conditions within deep geologic reservoirs. To understand subsurface pressure conditions within a major regional disposal reservoir, the carbonate Arbuckle Group of Oklahoma, we monitored the water levels in 15 inactive injection wells.  The wells were monitored at 30-second intervals, with eight wells monitored since September 2016, and an additional seven from July 2017. All of the wells were monitored until early March 2020. Since 2016, 13 of the 15 wells showed a significant net decrease in well level (a.k.a. hydraulic head), proportional to near-borehole fluid pressure even considering decreasing regional injection volumes during this period. The well pressures responded to Earth tides and injections into nearby wells as well as to distal and proximal seismic waves, though responses varied between wells. We suggest that the variability in pressure responses is the result of non-homogeneous properties within the reservoir. Moreover, there appears to be a threshold injection rate above which monitoring well pressure becomes less sensitive to injections within <15 km. The data illustrate that Arbuckle hydrogeology is an out of equilibrium multi-scale, temporally dynamic system, with regionally heterogeneous porosity and permeability. The resulting pressure dynamics likely are important controls on seismic hazard and storage capacity.

Bio: Dr. Nicholas W. Hayman became the Director of OGS in July 2020. He has a background in science management courtesy of his time at the National Science Foundation as a Program Director. Prior to that Nick was a researcher at the University of Texas, Austin, Institute for Geophysics. There he participated and led many research projects, and supervised numerous students and postdocs, with support from the National Science Foundation, US Department of Energy, and energy industry sponsors. His primary research focus has been the many ways that deformation impacts the crust and upper mantle of the earth, from scales as small as nano-pores, to as large as active plate boundaries. His focus with the OGS is currently to serve both the region’s public, oil and gas industry, and prepare Oklahoma for the future of energy which is rapidly evolving on our dynamic planet.

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