1. INTRODUCTION
Hydraulic fracturing or fracking is a technique which has been used for the production of “unconventional” gas. “Unconventional” gas, is widely distributed in the rockbed or soil layer rather than being present in concentrated underground locations,and can be tapped in a cost-effective manner using special techniques like hydraulic fracturing. It is widely accepted that about 60-80% of the existing wells in the United States will require hydraulic fracking in order to remain functional.. It is believed that fracturing will help to extend the productivity of the older oil and gas fields, and helps to recover natural gas from sources which were once believed to be completely inaccessible, for instance tight shale formations.
Fracking is different from traditional natural extraction methods which have been used over the years. Traditional natural gas wells are significantly less deep than fracking wells, by about thousands of feet and are essentially at depths which do not interfere with surface or subsurface water resources . Fracking also requires up to hundred times the quantity of water required by traditional
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Large quantities of water are required to complete the drilling process, along with heavy drilling equipment and machinery. Figure 1 illustrates the various steps involved in the extraction of natural gas using hydro fracking.
a) DRILLING: The process of fracking involves the drilling of a vertical well to the desired depth, and then a ninety degree turn is made and the drilling continues horizontally for a several thousand feet into the soil formation which contains the untapped natural gas. In order to prevent the contamination of aquifers and prevent the seepage of hydrocarbons out from the well, a surface casing is installed. The open space between the wall of the bore and the casing is then filled up, by pumping cement down into the casing.A temporary wellhead is