SUSTAINABILITY IN THE MINERAL AND ENERGY SECTORS by SHEILA DEVASAHAYAM KIM DOWLING and MANOJ K. MAHAPATRA

Author:SHEILA DEVASAHAYAM, KIM DOWLING and MANOJ K. MAHAPATRA
Language: eng
Format: epub
Publisher: CRC Press

FIGURE 20.7 Water use by region for hydraulic fracturing in the United States. (Adapted from Gallegos, T. et al. 2015. Water Resources Research, 51(7): 5839–5845.)

The advantages of the larger hydraulic fracturing efforts is that more oil and NG can be produced per well. Based on current estimates of a yield of 50–170 million cubic meters of NG per well, the actual water use per MMBTU is not much different than conventionally produced NG, about 8 L/MMBTU versus 5 L/MMBTU. While data are more widespread for shale oil development with hydraulic fracturing, the trends suggest similar results, that the water use intensity is likely to be the same or even less than for conventional oil extraction. These values are both presented in Table 20.5. Therefore, while the newer nontraditional oil and NG extraction technologies seem to use more water, the overall water use intensity has not changed. But locally, the high volume of shale gas and shale oil wells drilled in such a short period in some regions could have significant impacts on local water resource sustainability.

The biggest environmental issue documented with hydraulic fracturing is poor surface completions through shallow fresh groundwater aquifers, and surface water contamination from surface water pits. Figure 20.8 shows a typical horizontal well drilling pad in the eastern United States, showing the typical surface disposal and mud pits (GWPC, 2009). This type of drilling pad layout is also typical of conventional oil and gas well development such that the operations of conventional and nonconventional extraction are very similar. If these surface pits are not lined or maintained properly, they can leak or spill fracked or produced water into surface water systems. Disposal of the hydraulic fracturing flow back and produced water, because of the high salt content generated on contact with the shales, continues to be a major environmental and cost concern for its disposal and reuse.

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