Abstract: Environmental Impact and Regulatory Concerns for the Protection of a Freshwater Aquifer Impacted by a Gas Well Blowout in Northwest Louisiana

William H. Schramm, David T. McKenzie, Michael S. Kline

The Louisiana Department of Environmental Quality, Ground Water Protection Division (GWPD) is responsible for oversight of the investigation and remediation of unpermitted releases to the waters of the State. In March, 1994, a Sligo Field gas well blowout caused artificial artesian conditions in the shallow Wilcox aquifer resulting in flowing water wells near the drilling location. The eruption of sand and formation water created a crater around an old abandoned well south of the active rig and a collapse crater north of the rig.

The company, in cooperation with the GWPD, began an investigation of the environmental impacts of the blowout. An electric log run in a stratigraphic boring and newly installed monitor wells were used to determine the sand/shale distribution and to assess the extent of contamination in the aquifer. Monitor wells and nearby water supply wells were sampled for BETX. Only the wells nearest to the blowout showed constituents above regulatory limits. The well, positioned between the blowout and residential wells, showed no BETX.

This paper will present the continued investigation and remedial activities planned for this site. They include additional wells or borings to delineate the horizontal area impacted by the blowout and evaluation of pump and treat methods to establish hydrologic control of the Wilcox Aquifer in the immediate area. Periodic testing of the residential and monitor wells will ensure that appropriate efforts are made to protect the local residents.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas