Water management in unconventional oil and gas development – The issues and their optimization

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Introduction The U.S. natural gas industry, and by extension the industry globally has borne witness to tremendous change over the past decade. During this period, U.S. natural gas production levels have risen from a twenty year low of 18 Tcf (510 Bcm ) in 2005, to an all-time high of 24 Tcf (680 Bcm) in 2012 . At the same time, natural gas prices have fallen to levels not seen since the period immediately following the U.S. gas market deregulation in the mid-nineties. The underlying driver of these dynamics has been the very rapid growth in the production of unconventional natural gas resources, and in particular shale gas resources – historically considered unrecoverable. Technical advances in the areas of drilling and reservoir stimulation have been the key to unlocking shale gas. Today’s shale gas is largely sourced from wells drilled with horizontal bores that have been subjected to large-scale hydraulic fracture stimulation. The combined efficacy of these technologies in enabling gas production from shale formations (and indeed other low permeability reservoir settings) is such that their development has led to enormous upward revisions in the assessed scale of the total recoverable natural gas resource in the United States. Today, analysis by organizations including the U.S. Energy Information Administration (EIA), and the Potential Gas Committee (PGC) suggest that the likely recoverable U.S. shale gas resource is in the 800-1,000 Tcf (23-28 Tcm) range. This contrasts with the National Petroleum Council (NPC) 2003, assessment that estimated the shale resource at 35 Tcf (1 Tcm). The prospect of a much larger and indeed lower-cost domestic natural gas resource in the U.S. is having major impacts on both the U.S. and intern... ... middle of paper ... ...mental processes involved in hydraulic fracturing remains the same. A fluid is injected (water is the commonly used) into the well bore at a sufficient rate to generate a pressure differential between the well bore and the reservoir. This causes stresses around the well bore to increase beyond the tensile strength of the rock, at which point it splits or “fractures”. Assuming a sufficient pumping rate is maintained, it is possible to ”grow” these fracture both in terms of width and length, such that they propagate away from the well bore into the surrounding formation. Generally speaking, once pumping ceases the induced fractures would close. So in order to keep fractures open, a proppant material must be placed in the fractures. This is achieved by transporting the proppant down hole as part of the slurry comprising of the proppant and the fracturing fluid itself.

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