One of the most intractable environmental challenges for onshore oil and gas development is the drilling of the first 500 to 1,000 feet of the top hole (i.e., the vertical portion of unconventional wells).  This section passes through fresh (drinking) water.  A portion of whatever medium clears cuttings while drilling the top hole is driven into the most permeable parts of the fresh water aquifer, however impermeable.  Although casing is used to protect groundwater, there is a period during which the borehole is open before each casing set is cemented in place.  This period includes drilling, flushing, and cleaning the borehole wall.  The casing string through fresh water may include as many as three concentric steel pipes: the conductor casing, the coal string, and the surface casing.   Commonly, an air drill is used to construct the top hole largely because the rate of penetration is faster than when a rotary drill is used with a mud-based drilling fluid.  Three problems emerge with the use of air.  The first is high pressure air which stirs groundwater, particularly along joints, and this causes turbidity in local water wells.  Second, methane in the top 1,000 feet is common and mobilized by high pressure air and this causes the concentration is methane in local water wells to increase.  Third, when methane and bacteria are mixed by high pressure air, the bacteria may well use the methane as a source for electrons which are then collected by both iron and manganese oxides.  Reduced iron and manganese appear in local water wells where mixing with oxygen causes precipitation and the concomitant rusty orangish brown (iron) or dark gray (manganese) drinking water.  In Pennsylvania, these three physical processes turned local citizens against industry and, hence, become the primary enablers of the global pushback against fracking.    <br/>

Environmental issues associated with drilling Marcellus gas wells through fresh water aquifers

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.