Gas Well Flaws Prevent Drilling

Wednesday, May 18, 2011 @ 12:05 PM gHale

Cabot Oil and Gas Corp. can not yet resume operations in a nine-square-mile area of Susquehanna County because there are persistent flaws in 22 of 43 of the company’s gas wells in the area, said officials at the Pennsylvania Department of Environmental Protection (DEP).

The agency halted Cabot’s operations in the section of Dimock Township in April 2010 after it found methane it attributed to faulty Cabot wells seeping into 18 drinking water supplies. In December, Cabot and DEP agreed to a $4.6 million settlement that opened the door for Cabot to resume drilling in the off-limits area by the end of April if it fixed the problem wells.

DEP Oil and Gas Regional Manager Craig Lobins said Cabot had not fully complied with the requirements of the settlement.

Pressure tests show gas is channeling between layers of cemented casing in 22 of the company’s gas wells. Gas in the space between strings of casing in a natural gas well, called the annular space, generally indicates the well has “defective, insufficient or improperly cemented casing,” Lobins said.

The gas in 14 of the wells is of most concern, Lobins said because it is present in the space between the outermost casing closest to water supplies and the next nested string of casing, indicating a leak or defective cement.

The channeled gas in the Cabot wells does not appear to be associated with just one method of well construction or one type of cement, he added.

Cabot said its operations did not cause the methane to seep into water supplies and has argued over two years of sometimes contentious correspondence with the DEP the gas occurs naturally in the aquifer.

Cabot spokesman George Stark said the company “fully believes our operations are in full compliance” with the state’s oil and gas regulations and has been working closely with the department to meet the terms of the settlement.

“We will respond to the points raised in the letter in an appropriate and timely manner and look forward to continuing this important dialogue,” he said.

In addition to the channeled gas in the 22 wells, the department found Cabot has not resolved violations issued in January for defective casing in three additional gas wells drilled about 400 feet north of the affected area, Lobins said. He also said Cabot had waited more than the required 24 hours to tell the department about gas pressure in the annulus of a well first deemed defective in 2009.

Cabot must conduct water monitoring to meet the terms of the December settlement. DEP has since stopped conducting its own routine monitoring of methane in the families’ water supplies.

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