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DEP Orders Chesapeake Energy To Evaluate All 171 Wells For Stray Methane Releases
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While the Department of Environmental Protection continues to monitor Chesapeake Energy’s progress in remediating stray methane gas in Wilmot Township, Bradford County, the agency announced this week it has directed the company to monitor all 171 of its Marcellus Shale natural gas wells for methane gas leaks.
On September 2, DEP received reports of bubbling water on the Susquehanna River. DEP and Chesapeake believe the culprit is gas migrating from six wells that are located on three well pads on the “Welles property,” which is approximately two to three miles northwest of the river.
“Ventilation systems have been installed at six private water wells. Water has been provided to the three affected homes and Chesapeake is evaluating and remediating each of its well bores within a four-and-a-half-mile radius of the gas migration, which is essential,” said DEP Secretary John Hanger.
DEP sampled six private water wells affected by the migration for compounds associated with natural gas drilling. Their analysis found methane levels in the water wells that fluctuated between non-detect and 4.4 percent, possibly as a result of barometric pressure in the atmosphere. No stray gas has been detected in the homes served by the water wells. DEP also found:
-- Methane concentrations ranging from 2.16 milligrams per liter and 55.8 mg/L.
-- The water met the drinking water standards established for barium, chloride and total dissolved solids.
-- Three wells exceeded the iron limit of 0.3 mg/L and all six wells exceeded the 0.05 mg/L limit for manganese.
The iron and manganese limits are secondary limits, which mean that the limits are established to prevent taste and odor issues.
DEP and Chesapeake individually sampled isotopic readings from the gas, which could help pinpoint which well is responsible for the gas migration. DEP expects its isotopic analysis to be complete next week while Chesapeake’s is expected sooner.
To help prevent against future migration issues, Secretary Hanger said DEP directed Chesapeake to evaluate each of its 171 wells in Pennsylvania that used the well casing procedures used in the six Wilmot Township wells—a procedure that was used exclusively in northeast Pennsylvania. Well casings are installed in a well bore to act as a barrier to the rock formations and maintain the well’s integrity.
To do so, the company is using equipment sensitive to sound and temperature. When the equipment finds an anomaly, the company is to correct it immediately by injecting cement behind the casing that seals off the formation, eliminating the route for gas to migrate.
Once the remediation work is performed, it will take up to two weeks to determine if it was successful, although it may take longer for the stray gas to dissipate.
The Welles property wells were drilled between December 2009 and March 2010, but have not been fractured, or “fracked,” and are not yet producing gas from the Marcellus Shale formation, leading the agency to believe that any stray gas migrating from these wells is from a more shallow formation.
On September 9 DEP issued Chesapeake a notice of violation for failing to prevent gas migration to fresh ground water and for allowing an unpermitted natural gas discharge into the state’s waters. DEP will determine future enforcement actions based in part on the speed with which Chesapeake eliminates the migrating gas.
“This situation perfectly illustrates the problem DEP is addressing through the improved well construction standards we have finalized,” said Secretary Hanger. “Chesapeake has assured me that all wells drilled by Chesapeake after July 31 conform to the regulations that the Environmental Quality Board will consider on October 12.”
If approved by the EQB, the Independent Regulatory Review Commission is expected to vote on the regulations in November.
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9/20/2010 |
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