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Microseismic monitoring
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Microseismic monitoring is used to observe small-scale earthquakes that may occur as a result of mining, fracking, geothermal activities, and underground natural gas storage. These earthquakes, sometimes known as microseismic events, are too small to be felt on the surface, and seismologists use geophones and other sensitive technologies to detect them. The goal of monitoring is to improve production techniques, increase an oil or gas well's productivity, reduce well completion costs, and determine whether fewer wells or fractures are needed to extract oil and gas.[1]
Background
- See also: Seismicity
Earthquakes are vibrations under the Earth's surface. The vibrations are caused by the release of energy after two blocks of earth slip along a fault line (a fracture that exists between two chunks of earth). Stress is a force that acts on a plane and exists within fault lines. When an earthquake occurs, pre-existing stress is released. As two pieces of earth slip past one another, the energy (stress) is released as seismic waves that travel out along the Earth's interior surface.[2][3]
Induced seismicity (or induced seismology) refers to seismic events that occur at higher than normal rates due to human activity. These events are generally smaller earthquakes, sometimes known as microseismic events, and can result from underground injection, oil and gas extraction, geothermal projects, mining extraction, underground nuclear tests, and the impoundment of reservoirs behind dams. These activities change the stress distribution or the volume of a rock mass (a large body of solid materials). The rock tries to transfer stress into other parts of the rockmass, resulting in slips along weak faults or fractures to produce microseismic activity.[4][5]
Procedure
Microseismic monitoring is used to determine when and where microseismic events occur and their size, usually in real time as oil and gas extraction occurs. Operators use technologies such as geophones, which can be placed near the Earth's surface or into drilled wells. These technologies produce images or video showing the growth of induced (human-caused) fractures and their interaction with natural fractures. Operators will observe microseismic activity during oil and natural gas production over time to detect any seismic patterns that correspond to specific production actions. The goal of monitoring is to improve production techniques, increase an oil or gas well's productivity, reduce well completion costs, and determine whether fewer wells or fractures are needed to extract oil and gas.[5][6][7]
See also
Footnotes
- ↑ Society of Petroleum Engineers, “Microseismic Monitoring: Inside and Out,” November 2009
- ↑ U.S. Geological Survey, "The Science of Earthquakes," accessed July 24, 2012
- ↑ U.S. Geological Survey, "How Earthquakes Happen," January 11, 2013
- ↑ U.S. National Academy of Sciences, "Induced Seismicity Potential in Energy Technologies," accessed February 22, 2017
- ↑ 5.0 5.1 ESG Solutions, "Microseismic Monitoring 101," accessed April 18, 2017
- ↑ Hess, "Microseismic Monitoring Offers Insight on the Subsurface," accessed April 18, 2017
- ↑ Halliburton, "Microseismic Monitoring," accessed April 11, 2017
