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Gas Well/Water Well Subsurface Contamination - Plan for Investigation

Rick Railsback
[email protected]

With the advent of horizontal drilling and frac technologies which allow the commercial production of oil and gas from very low permeability rocks, onshore North America is undergoing a historic drilling boom. The industry is now drilling in areas never drilled before – densely populated and often with significant, beneficial use aquifers in the shallow subsurface. Is oil and gas drilling, fracing, and production endangering the nation's groundwater supplies? Are water wells and aquifers being contaminated with oil and gas, drilling mud, and/or frac fluids? Numerous tools and methods of investigation can be used to answer these questions: proximity; timing of the impact; other contaminant sources; oil and gas well records; pressure data from the gas well and water well; data on frac geometry; natural gas, condensate, and water composition; seismic data; cement bond logs; noise logs; temperature logs; gamma ray logs; radioactive tracers; pressure interference tests; and installation of monitoring wells. This review covers tools and methods which have been commonly used by industry for tracking the presence and the flow of fluids in the subsurface near wellbores. Effective use of these tools will solve the problem of whether or not an oil or gas well has contaminated a water well. Operators can utilize these tools to educate the public and landowners, promote and defend drilling programs, and in litigation support. The oil and gas industry also has the opportunity to technically educate the environmental consulting community, which is largely unfamiliar with these tools. The result will be a better understanding of how oil and gas is produced and why subsurface aquifers are rarely affected by oil and gas drilling and production.

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013