Water/Land/Energy Nexus for Unconventional Energy in Texas
This presentation will focus on an aspect of the water-energy nexus that is discussed nearly daily in the media, specifically the use of hydraulic fracturing to produce natural gas and oil from shale and tight sandstone formations. The recent growth of exploration from these formations has yielded substantial quantities of natural gas and liquids (oil and gas condensates). This increased production is benefiting the US economy in many ways and reducing CO2 emissions to the lowest level in 20 years. These changes have become possible because of the development and widespread use of hydraulic fracturing technologies, particularly in horizontal wells. In Texas, since 2005, 31,000 horizontal wells have been drilled and stimulated using hydraulic fracturing, with the Barnett (Ft. Worth area; 13,860 wells), Eagle Ford (south Texas; 5375 wells) and Permian Basin (west Texas; ~3000 wells) representing the bulk of the exploration.
Because of this activity, Texas currently leads the Nation in gas and oil production. This increase in energy recovery comes at a cost to the environment, however, especially in the areas of water and land use. For example, the median water use to stimulate each well in the Barnett play traditionally has been ~10,600 m3 (2.8 Mgal), but more recently has increased ~17,000 m3 (4.5 Mgal) because of increases in lateral lengths. When normalized for lateral length, median water-use intensity for the Barnett play for horizontal wells is has remained ~12.5 m3/m (1000 gal/ft). In water-stressed areas like west and south Texas, the cumulative amount of water used in drilling activities in small communities can exceed all other water uses combined, even though unconventional energy exploration uses <1% of all water withdrawn in the State (by comparison, irrigated agriculture accounts for about 70% of water withdrawals).
Land impacts from above-ground activities (well pads, pipelines, truck traffic, etc.) can also be significant, and landscape fragmentation is now being studied. These issues will be discussed, as well as suggestions for reducing impacts to water and land resources.