Sunday, September 18, 2011

DEP inspections show more shale well cement problems

Published: September 18, 2011

At the recent Shale Gas Insight conference in Philadelphia, the CEO of one of the largest Marcellus Shale drilling companies in Pennsylvania was unequivocal in his message that methane contamination of drinking water supplies from faulty gas wells is at an end.

"Problem identified; problem solved," Chesapeake Energy's Chairman Aubrey McClendon declared.

But violations data released last week by the state Department of Environmental Protection show problems persist with the cemented strings of steel casing meant to protect groundwater from gas and fluids in Marcellus wells.

In August, DEP inspectors found defective or inadequate casing or cement at eight Marcellus wells, including Hess Corp.'s Davidson well in Scott Twp., Wayne County - the first casing violation found in the county where only a handful of Marcellus wells have been drilled.

During the first eight months of 2011, 65 Marcellus wells were cited for faulty casing and cementing practices - one more than was recorded in all of 2010.

Casing and cementing violations do not necessarily indicate that gas has migrated or will migrate into drinking water supplies, and methane is present in many water wells in Pennsylvania from natural pathways unrelated to gas drilling. But in the three dozen instances when methane has migrated into water supplies from gas wells in Northeast Pennsylvania, cement flaws have been identified by state regulators as a primary pathway for the gas.

In his comments at the conference, Mr. McClendon credited an "updated and customized casing system" included in stronger state oil and gas casing and cementing regulations for "preventing new cases of gas migration."

The increase in casing and cementing violations reflects the state's increased attention to the issue, especially since the regulations were updated in February. The steady pace of new violations - an average of eight new wells a month have been cited for casing, cement or leaking gas violations this year - also indicates the complexity of the problem in a state where the geology is neither uniform nor predictable.
DEP Secretary Michael Krancer, who was not present for Mr. McClendon's statement, said he could not respond to it directly when asked about it at the shale conference.

"One case of methane migration or well contamination is one case too many," he said.

Click to enlarge image

Most of the casing and cement violations recorded this summer became evident to inspectors when bubbles rose from between the cemented casing strings in water pooled at the well sites or when combustible gas was detected with meters at the surface, according to notes in the violation reports posted by the department online.

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