Texas RRC: Oil, Gas Production Not to Blame for Well Water Contamination
Water contamination from explosive gas in the water supply of a North Texas neighborhood cannot be linked to nearby drilling, the Texas Railroad Commission (RRC) said in a recent report.
The investigation began after seven property owners in the neighborhood contacted the RRC about rising levels of methane in their water wells. An eighth property owner also found an increase of chloride in two water wells.
In its finding that there was an insufficient link between the contamination of well water in the Silverado on the Brazos (Silverado) neighborhood in southern Parker County and drilling in the nearby Barnett Shale, the RRC, which regulates the state’s oil and gas industry, noted that the contamination has worsened in five of the eight private water wells it tested in September 2013, compared to the contamination measured in the same wells in 2010 and 2011. However, the RRC geologist, Peter Pope, concluded that there was not sufficient evidence to reach a conclusion that drilling in the nearby Barnett Shale “caused or contributed to methane contamination beneath the neighborhood.”
In its report, the RRC said that “the occurrence of natural gas in the complainants’ water wells may be attributed to processes unrelated to recent Barnett Shale gas production.”
The RRC provided several factors that led to its conclusion:
- Surface casings of nearby Barnett Shale wells are sufficiently deep to isolate useable quality groundwater. Records show that surface casing cement was circulated to ground surface at each well.
- Bradenhead pressures were either absent or sufficiently low when monitored so as not to be considered threat to surface casing integrity based on the RRC’s Bradenhead Pressure Management Guidance procedure.
- Records submitted to the RRC, including cement bond logs, show that tops of production casing cement occur in excess of 600 feet above the productive zones in each well.
- Mechanical Integrity Tests (MITs) performed by Range Resources Corp. on the Teal 1-H and Butler 1-H wells revealed no leaks in the production casing of each well, according to expert testimony provided at the January 2011 hearing.
- Plugging records for the Carrizo Mund-Lipscomb 1-H well show that cement plugs were placed across the fresh water interval.
- Hydraulic fracturing was performed in the Barnett Shale which occurs at approximately 5,700 feet below ground surface.
- The base of the aquifer and the Barnett Shale are separated by approximately 5,300 feet of geological strata. Seismic reflection data submitted by Range Resources to the RRC do not show the presence of faults above the Barnett Shale beneath the neighborhood.
The possible cause of well water contamination in or near the area was previously investigated in late 2010 and early 2011. That earlier investigation found that there was no relationship between the contamination and production activity in the Barnett Shale. However, that investigation revealed a shallow source of natural gas, the Strawn formation, which “occurs beneath the neighborhood at depths as shallow as 200 feet before ground surface (bgs) based on information submitted to the RRC.”
Previously, using fingerprint-like analysis of the methane in water wells, independent scientists in separate studies said that the methane found in the well water originated from a well formerly owned by Range Resources in Fort Worth, according to the Lubbock Avalanche-Journal. Range Resources denied the allegations.
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