During the period from April 22 to May 3, 2017, the area around Rangely, Colorado, home to the Rangely oil field, has experienced three earthquakes.  These earthquakes have ranged from 2.8 to 3.5 on the Richter scale, as confirmed by the United States Geologic Survey (USGS). The largest of the quakes, on April 22nd was reported to have “felt like an explosion”, with shaking felt throughout the town of 2,000, and some businesses reporting alarms going off, but little to no damage to property.

The area experiences natural tectonic events on an irregular basis, related to deep crustal adjustment and minor surface movement.  The recent earthquakes near Rangely were tracked to between four and six km (2.5 to 3.5 mi) depth, well below the main Rangely field producing reservoirs (Weber Fm) at just over one mile in depth.  The field has been producing since the 1940’s, with over 800 million barrels of oil extracted.

During the decades of production, oil has been produced through mechanisms of primary drainage, followed by secondary recovery utilizing water floods, and today is being injected with CO2 to further enhance the production capacity, and keep the field economically viable.  In addition, there have been many years of wastewater disposal of produced water associated with oil production going back into the ground.

So, there is the question.  Are these earthquakes natural tectonic events, or induced events caused by oil extraction, water disposal and flooding, and injected CO2?  We don’t have a definitive answer, but it is curious how often this oil town shakes.

USGS Earthquake Data, 2017