NEW YORK Nov 4 Carbon dioxide injected into oil
and gas wells may have caused a series of minor earthquakes in
Texas long before the adoption of current hydraulic fracking,
according to a study published on Monday in a national science
The study, which analyzed 93 earthquakes that occurred
between March 2009 and December 2010, appears to be the first to
link earthquakes of magnitude 3 and above and carbon dioxide
injections in the Cogdell oil field near Snyder, Texas.
Tremors in the area that occurred between 1975 and 1982 were
previously linked to the injection of water into wells but the
same explanation could not be applied to earthquakes that
occurred in late 2000s, the paper's two authors said.
"The timing of gas injection suggests it may have
contributed to triggering the recent seismic activity," the
study said. "If so, this represents an instance where gas
injection has triggered earthquakes having magnitudes 3 and
The paper, authored by Wei Gan of the China University of
Geosciences in Beijing and Cliff Frohlich of University of Texas
in Austin, was published in the Proceedings of the National
Academy of Sciences. It relied on data gathered by six temporary
seismograph stations that were a part of the USArray program.
Recent studies, including a 2012 paper by one of the
authors, have linked fracking and wastewater disposal wells to
increased seismic activity in places like the Barnett Shale in
northern Texas and central Oklahoma.
This is the first publication to hint at a direct link
between enhanced oil recovery and seismic activity in Texas.
Carbon dioxide is injected into wells nearing the end of
life to enhance their output. It is a technique that is mostly
used in mature oil fields such as the Cogdell field, one of the
7,000 oil fields that make up the Permian Basin in West Texas.
Oil companies like Occidental Petroleum have
extensive carbon dioxide injection projects in the field. In
fact, Occidental's website says nearly 60 percent of its oil
production in West Texas and southeast New Mexico comes from
The abstractof the latest study can be found at: