Minimizing Impacts of Drilling

Technologies that can minimize the environmental impacts of drilling

Directional Drilling

Most Fayetteville Shale wells are drilled directionally, with long extended-reach sections. Wellheads do not need to be located directly above the natural gas resources being produced. This allows much more flexibility in choosing an environmentally friendly location for the surface facilities.

Drilling Multiple Wells from the Same Well Pad

Another benefit of directional drilling is that multiple wells can be drilled from a single well pad. Therefore, the total number of drill pads in a field can be reduced. Drilling multiple wells from the same well pad also reduces the number of trips by heavy vehicles across unimproved county roads. Drilling rigs do not need to be moved as many times, and the large number of vehicles required for fracturing jobs can remain at the well site to fracture several wells at a time.

Use of Air Drilling Rigs for the Upper Sections of Wells

At most Fayetteville Shale wells, the upper sections of the wells are drilled using smaller drill rigs and air drilling technology. This minimizes the volume of drilling fluids needed for the full well and reduces the time that fluids are held in reserve pits.

Use of Environmentally Friendly Drilling Muds

Following completion of the upper hole sections by air drilling rigs, operators switch to more traditional drilling rigs using large volumes of drilling muds. When drilling conditions allow, operators should choose water-based muds (WBMs) or synthetic-based muds (SBMs) rather than oil-based muds (OBMs). WBMs and SBMs are more environmentally friendly than OBMs. Most Fayetteville Shale wells are drilled using WBMs. When WBMs are used for drilling, the drill cuttings are placed in the reserve pit. At the end of the drilling job, the cuttings are stabilized with fly ash and are then buried in place after all liquids have been removed. The used WBMs are disposed of using land application.

Closed-Loop Drilling Waste Systems

When operators choose to use oil-based muds (OBMs) for better drilling performance, they should provide a closed-loop drilling waste system (typically this includes a series of tanks) rather than using a reserve pit. At the end of the drilling job, the OBMs are typically recycled, and the cuttings should be hauled offsite for disposal.

Reserve Pits and Other Pits

Operators should construct reserve pits and other pits that are intended to store oily materials using suitable natural or synthetic liner material. During times when pits are actively holding drilling fluids, cuttings, and other oily substances, fencing should be placed around the pit perimeters to keep livestock and wildlife from entering the pits. At the end of the drilling job, the reserve pit should be closed by removing any accumulated fluids. The liner should be removed to the extent possible, and the pit solids should be covered with clean dirt, regarded to natural contours, and revegetated.

Operators should consider constructing other pits to collect non-oily stormwater runoff and other relatively clean water. Segregation of "clean" and "dirty" fluids helps to minimize waste volumes. Liners are not necessarily needed for the clean water pits.

Temporal and Spatial Offsets for Threatened and Endangered Species

Additional protection for threatened and endangered species can be provided by constructing drilling operations in locations that avoid identified nesting or breeding locations or locations of populations of threatened or endangered species. Likewise, drilling activities can be postponed to avoid certain times of the year, when threatened and endangered species are mating, nesting, or rearing young. The U.S. Fish and Wildlife Service has proposed voluntary best management practices for protecting threatened and endangered species. These are described on the page containing regulatory requirements associated with drilling.

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Minimizing Environmental Impacts

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