Colorado suspends oil and gas wastewater disposal well after quake
US workers change pipes at Consol Energy horizontal gas drilling rig (AFP)

(Reuters) - Disposal of wastewater from oil and gas drilling into a Colorado well was ordered halted this week after seismic activity was detected in the area, state regulators said on Tuesday.

The Colorado Oil and Gas Conservation Commission ordered High Sierra Water Services to stop disposing wastewater for 20 days into the well in Weld County after seismologists detected a small 2.6-magnitude temblor on Monday. That came after a 3.4-magnitude earthquake shook the area on May 31.

It is the latest in a string of events linking oil and gas operations with seismic activity in the United States as energy drilling increases, but likely the first instance of its kind in quake-prone Colorado, a spokesman for COGCC said.

"We believe it is probably the first time," that seismic activity has been linked to wastewater disposal, he said.

Hydraulic fracturing, or fracking, is an increasingly common oil and gas production technique that involves pumping millions of gallons of water underground to release oil and gas. Much of that water comes back to the surface after drilling and is disposed of in large underground wells.

There were about 145,000 of these wells in the United States in 2012 and 309 in Colorado, according to the Colorado Geological Survey.

Both fracking and wastewater disposal have been linked to increased seismic activity in states where energy production is on the rise.

Recent small earthquakes in Ohio were likely triggered by fracking, state regulators said in April, establishing a new link that went beyond just the impacts of disposal wells.

According to a Colorado Geological Survey report from 2012, Colorado is "world famous" for triggered, or induced, earthquakes. Nearly 200 quakes with magnitude 2.8 to 3.4 were recorded between 2007 and 2009 in the Paonia area, largely due to coal mining activity, the CGS said.

(Reporting by Edward McAllister; Editing by Eric Walsh)