Shale Gas contains 70-90% methane and smalleramounts of other lighter hydrocarbons, and gases. The Shale gas is found deepinside, around 2 to 3 Km below the earth’s surface. Hydro Fracturing or Fracking is themethod by which shale gas is extracted from earth’s surface. In this process, afracking fluid is used which mainly consists of water and sand along with somechemicals. This fracking fluid is injected deep underground at high pressure toextract the natural gas from the shale rocks. Some of this fracking fluid comesback to the surface of the earth as flow back water.
Thereare some environmental risks and challenges associated with the production ofShale Gas. These are as follows. Contamination of Ground Water:The production of shale gas poses risk to contamination of ground water. There arelots of chances of contamination of groundwater by the methane gas present inshale gas, fracking fluid chemicals and dissolved contaminants in flowbackwater of fracking fluid. Increased fresh Water consumption:During production of Shale gas, each well needs about 10-20 million liters ofwater, 500 tons of sand and 50 tons of chemicals and about 60-80 % of thismixtures returns back to the surface as flowback water. Already India is facingshortfall of fresh water supplies for regular consumption and removing hugeamounts of water from the water table below the earth for production of shalegas will further aggravate the supplies of fresh water for regular consumption. Disposalof Flow back Water: Disposal of this flowback water isanother big challenge. The flowback water contain fracture fluid additives andchemicals which will contaminate the surface and subsurface water resources.
Hence special treatment is required to remove any chemicals present in itbefore disposing the same on the earth surface. They also contain trace amountsof naturally occurring radioactive materials which needs to be safely removedbefore disposal of the flowback water. Induced Seismicity:During the hydro fracking process, the fracking fluid is injected at very highpressure in to the earth’s crust and this may trigger earthquakes in thatregion. LocalImpacts: There may be many local issues like the volume oftruck traffic in the production region, noise problems, dust particles and landdisturbances in the region around.