Recent studies linked wastewater disposal to the increase in earthquakes. Approximately 2,195 earthquakes shook Oklahoma last year, while oil production in the state has more than tripled over the past five years.
The gas industry has been blamed for causing seis- mic activity. Earthquakes have progressively increased since 2008. The U.S. geological survey has associated the increase in earthquakes with oil and gas production. However, earthquakes are being linked to the wastewater disposal rather than fracking. The waste- water is deposited into wells deep below the surface. It is unknown how much wastewater a formation can hold before it begins to affect pressure, according to University of Tulsa’s study.
“Fracking is the deliberate fracturing of rocks in the subsurface to initiate flow of liquids,” said Peter Michael, Department of Geosciences chairman at the University of Tulsa. “But it is the injection of wastewater, an unwanted byproduct of petroleum and natural gas production, back into the earth that is causing the earthquakes.”
Wastewater is the salty, toxic water which is held in wells deep under the ground, but is not stored near drinking water. As of October 2015, oil businesses have produced 419,000 barrels of oil per day, according to the U.S. Energy Information Administration.
Six earthquakes were recorded on Jan. 19. Forty-one were recorded in the last week, 221 in the past month and 2,195 in 2015. It is possible for earthquakes to happen near unknown faults lines, but Bryan Tapp, University of Tulsa professor of geosciences, noticed the trend happening near wastewater wells.
“We’re now seeing as many as 2,847 active shifts a year, and they’re not in traditional areas—they’re in areas of oilfield activity,” said Tapp, in a research study. “The pumping of wastewater into these disposal wells is almost certainly inducing all of these earthquakes.”
The Richter scale was not invented until 1935, and the earliest record of an earthquake wasn’t documented until 1897. There is not enough history recorded for earthquakes to compare with this development. Another explanation for the recent surge of earth- quakes in Oklahoma is a part of earth’s tectonic cycle, but the link to wastewater wells and earthquakes cannot be denied. Michael believes with “99.9 percent certainty” wastewater is to blame.
“Almost all earthquakes are associated with the boundaries of tectonic plates, where the plates converge, or slide past each other. There are rare instances of earthquakes occurring within tectonic plates.
There is no time and place on earth, except for other water injection areas, that has experienced this level of earthquake activity far from a plate margin,” said Michael. “Moreover, the earthquakes are almost all fairly close to injection wells. The timing of the earthquake activity, starting several years ago, coincides with a substantial increase in the pumping of wastewater underground.”
The majority of Oklahoma revenue comes from the oil and gas industry. The state economy reflects its prosperity. Additional research is needed to study the link, but the overall goal is to reduce the risk of creating more earthquakes while safely disposing of toxic wastewater.
“It will be necessary to monitor the volumes, locations and pressures of the wastewater in the wells themselves, but also in remote wells that are not being injected,” said Michael. “The disposal operators should be required to provide all of their information in terms of volumes and pressures. This information should be guaranteed to be accurate and it should be readily available. There should also be a greater effort to map faults in the state.”