URTeC: 2670481 Seismic Monitoring of Hydraulic Fracturing Activity at the Marcellus Shale Energy and Environment Laboratory (MSEEL) Site, West Virginia Abhash Kumar 1,2, *, Erich Zorn 1 , Richard Hammack 1 , William Harbert 1,3 1 National Energy Technology Laboratory, Department of Energy, Pittsburgh, PA; 2 AECOM; 3 Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA Copyright 2017, Unconventional Resources Technology Conference (URTeC) DOI 10.15530/urtec-2017-2670481 This paper was prepared for presentation at the Unconventional Resources Technology Conference held in Austin, Texas, USA, 24-26 July 2017. The URTeC Technical Program Committee accepted this presentation on the basis of information contained in an abstract submitted by the author(s). The contents of this paper have not been reviewed by URTeC and URTeC does not warrant the accuracy, reliability, or timeliness of any information herein. All information is the responsibility of, and, is subject to corrections by the author(s). Any person or entity that relies on any information obtained from this paper does so at their own risk. The information herein does not necessarily reflect any position of URTeC. Any reproduction, distribution, or storage of any part of this paper without the written consent of URTeC is prohibited. Summary Hydraulic fracturing is a well-established completion technique to extract significant volumes of natural gas from organic-rich shale, which would otherwise behave as impermeable formations. Diffusion of water outward from the newly created hydraulic fractures into the reservoir helps reactivate the preexisting faults and initiates shear failure on complex network of preexisting planes of weaknesses. Microseismic events recorded on downhole arrays are a manifestation of associated shear failure along both preexisting and newly created fractures. Some of the recent studies focused on energy balance calculations suggest that the cumulative moment of microearthquakes is a small portion of the moment release expected for the amount of fluid injected into the formation. This suggests some other sources of deformation in the reservoir rock, contemporaneous with microseismic activity that need to be considered to get a balance in the energy budget during hydraulic fracturing process. Recent findings on long period, long duration tremors suggest that “slow slip emission” along weaknesses that are misaligned with respect to the present day stress field is likely the dominant mechanism of deformation and plays a crucial role in reservoir stimulation. In Monongalia County, Morgantown, we carried out surface seismic monitoring of the hydraulic fracturing operation at an active well pad with five seismometers. Upon investigating the waveforms from surface monitoring, we identified 89 high-amplitude, impulsive events and 436 long period, long duration (LPLD) events, with highly emergent waveform characteristics. The time of occurrence of these observed LPLD events have no temporal correlation with the events reported in the regional earthquake catalogs and data from CEUSN stations, suggesting that these LPLDs are not weakened records of regional earthquakes. We observed a significant concentration of energy in the 0.8-3 Hz frequency range for these observed LPLD events. During various stages of hydraulic fracturing, LPLD events were found to occur most frequently when the pumping pressure and rate were at maximum values. As the main purpose of hydraulic fracturing operation is to stimulate oil and gas production from the less permeable reservoir, we compared the relative production contribution per stage to the frequency of occurrence of LPLD events. We found good correlation between the frequency of LPLD events and production data, highlighting the potential contribution of slow deformation processes and its effectiveness in the reservoir stimulation. Introduction Hydraulic fracturing of organic-rich shale and tight gas reservoirs is routinely performed to enhance the secondary permeability of the reservoir and increase access to trapped hydrocarbon resources. Application of this engineering technology involves the injection of millions of gallons of water at high pressure to establish a complex network of permeable fracture pathways that enhances hydrocarbon production from an otherwise low-permeability reservoir.