Onshore Unconventional Hydrocarbon Development Induced Seismicity and Innovations in Managing Risk–Day 2: Proceedings of a Workshop (2018) / Chapter Skim
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3 Advances and Challenges in Addressing the Risk of Induced Seismicity
3 Advances and Challenges in Addressing the Risk of Induced Seismicity
Pages 13-30
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From page 13... ...
. PANEL PRESENTATIONS Causality Assessment Approach: Integrating Geomechanics and Reservoir Analysis to Understand Induced Seismicity in Kansas Tandis Bidgoli, Kansas Geological Survey Kansas has seen a marked increase in seismicity in the state since about 2013, Bidgoli began.
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From page 14... ...
The data showed that while the two counties dispose of similar volumes of saltwater by injection, Ellis County has no associated seismic activity while Harper County does. Bidgoli suggested this response is due to the fact that Ellis County disposes of the water in nearly three times the number of wells as those in Harper.
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From page 15... ...
Top: simulation for 2011 shows relatively low pore pressure change in the subsurface. Middle: simulation for 2014 shows greater change in pore fluid pressure beneath an area that shows increased seismic activity.
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From page 16... ...
Collaboration on the part of industry and the regulatory community is necessary to provide access to some of these data sets, which can then be employed to inform better decisions. Operational Factors to Mitigate Hydraulic Fracture Induced Seismicity Shawn Maxwell, IMaGE In 2012, only two cases of hydraulic fracture induced seismicity had been documented in the United Kingdom and in Oklahoma, Maxwell said.
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From page 17... ...
Potential actions include slowing the injection rate or volume, pausing or ceasing the injection activity for a given time period, skipping particular stages of the hydraulic fracturing activity, and/or changing the type of fluid being used for the hydraulic fracture well completion. Maxwell then elaborated on a few of these approaches and described how the use of microseismic monitoring data is integral to understanding the reservoir that is being hydraulically fractured and to informing what types of actions can be taken to mitigate the hazard of induced seismicity.
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From page 18... ...
Lower figure shows earthquake activity in western Canada, the vast majority of which is due to geological causes. The three hydrocarbon reservoirs which have had induced seismic activity are identified.
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From page 19... ...
. These types of models can be used as a tool to examine the relative effects of what takes place along a fault when the input parameters are changed (e.g., fault orientation, changes in the stress field along the fault, changes in the position of the hydraulic fracture relative to the fault, skipping a hydraulic fracture stage when seismic activity is detected)
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From page 20... ...
Changes in the stress field along the fault can thus be used to anticipate response of the fault system to various operational parameters, allowing more informed approaches to mitigating the potential risk of a larger seismic event. A final approach Maxwell discussed that has potential to manage the risk of inducing felt seismic events with hydraulic fracturing involves changing the viscosity of the fluids used in the hydraulic fracture project.
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From page 21... ...
Beginning in 2013, natural gas production activity in the Horn River Basin decreased significantly, as did the seismic activity, due to declining natural gas prices; in the same period, production of oil from the Montney began to increase. In 2014, more seismic events in the Montney appeared to be related to hydraulic fracturing with some events still related to wastewater disposal and the BCOGC began to develop a more comprehensive regulatory review process that could address issues related to induced seismicity throughout the province.
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From page 22... ...
occur in the Rocky Mountains and are due either to natural tectonic activity or to mining and are not discussed further. Seismic events in the Montney and Horn River Basin have been further classified according to the interpreted cause of the events: enhanced oil recovery (EOR; dark blue circles)
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From page 23... ...
As of the date of his presentation, Venables indicated that 10 wells had been shut in due to induced seismic activity or reservoir pressures above specified levels; two wells were allowed to continue but with a continuous seismic monitoring program. The expansion of the seismic data set in British Columbia has allowed additional research into the similarities and differences between events, and between areas that are more seismically active or appear to be aseismic despite being in regions where hydraulic fracturing takes place.
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From page 24... ...
Geological Survey Over the past six to seven years, seismologists in the United States have shifted some of their research focus from tectonically-driven seismic activity on the West Coast to induced seismicity taking place in the central and eastern United States, Leith began (Figure 3.9)
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From page 25... ...
The focus in the last five years on trying to understand the hazard posed by induced earthquakes allowed the USGS to issue its first one-year hazard forecast in 2016 for 21 areas of past and ongoing induced seismicity. Using the example hazard forecast map from the Oklahoma-Kansas area (Figure 3.11)
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From page 26... ...
What Mark Zoback presented earlier in his talk, Leith said, is an excellent example of how to extend this type of forecast to be more immediately applicable on a month by month basis and to try to take into account what is known in the subsurface in terms of permeability of rock formations. He summarized the risk factors for inducing seismic events from fluid injection to include: total fluid volume being injected, rate of injection, depth of injection, bottom-hole pressure,6 proximity of injection to crystalline basement rocks, and access to faults well-oriented for failure in the ambient stress field.
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From page 27... ...
Furthermore, the community interested in these issues does not have an area to conduct controlled injections by which the effects of changing injection parameters could be directly tested. He discussed the value of having an induced seismicity test site which would allow characterization and modeling of subsurface geology, geophysics, and hydrology in four dimensions (including time)
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From page 28... ...
Bidgoli responded that some work is taking place with respect to measuring surface deformation in Kansas over the sites of wastewater disposal wells and a site where CO2 is being injected as part of an enhanced oil recovery project to see if any crustal deformation is measurable due to fluid injection at depth. InSAR data is being used as part of this work.
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From page 29... ...
One participant noted that the British Columbia example demonstrates that hydraulic fracturing can trigger fault seismic events; however, these events seem to have been infrequent in U.S. hydraulic fracturing areas.
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From page 30... ...
In areas such as Pennsylvania where most of the produced water is recycled and not injected into disposal wells, triggering earthquakes is minimized through water management. Elsewhere, when large volumes of salt water elsewhere are disposed through injection, our evolving understanding of induced seismicity can be continuously communicated to regulators and industry so that they can incorporate the information appropriately in their approaches to minimize the risk.
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