Conventional Oil—The Forgotten Part of the Water‐Energy Nexus

Abstract

The impacts of unconventional oil and gas production via high‐volume hydraulic fracturing (HVHF) on water resources, such as water use, groundwater and surface water contamination, and disposal of produced waters, have received a great deal of attention over the past decade. Conventional oil and gas production (e.g., enhanced oil recovery [EOR]), which has been occurring for more than a century in some areas of North America, shares the same environmental concerns, but has received comparatively little attention. Here, we compare the amount of produced water versus saltwater disposal (SWD) and injection for EOR in several prolific hydrocarbon producing regions in the United States and Canada. The total volume of saline and fresh to brackish water injected into depleted oil fields and nonproductive formations is greater than the total volume of produced waters in most regions. The addition of fresh to brackish “makeup” water for EOR may account for the net gain of subsurface water. The total amount of water injected and produced for conventional oil and gas production is greater than that associated with HVHF and unconventional oil and gas production by well over a factor of 10. Reservoir pressure increases from EOR and SWD wells are low compared to injection of fluids for HVHF, however, the longer duration of injections could allow for greater solute transport distances and potential for contamination. Attention should be refocused from the subsurface environmental impacts of HVHF to the oil and gas industry as a whole.

Global Groundwater Sustainability, Resources, and Systems in the Anthropocene

“…Preservation of these deep waters is achieved by slow movement through low permeability strata (Ingebritsen & Manning, 1999;Neuzil, 1994) and negative buoyancy due to high salinities (Ferguson et al, 2018). Installation and operation of wells for water supply (Perrone & Jasechko, 2017) and by the energy industry (Jennifer C. McIntosh & Ferguson, 2019;Bridget R. Scanlon et al, 2017) have led to the mixing of waters of various depths and ages but the implications of such mixing to lithospheric processes at large scales is unclear.…”

Crustal Groundwater Volumes Greater Than Previously Thought

“…Considerations of such long time periods may also provide important insights into how the legacy of the Anthropocene might be preserved over deep time in the subsurface. These efforts are also urgently needed in the short term in the race for porosity between both conventional and emerging energy projects in the subsurface (Ferguson, 2013; McIntosh & Ferguson, 2019; Vengosh et al., 2014), waste isolation (Benson & Cole, 2008; Cherry et al., 2014), CO 2 sequestration (Benson & Cole, 2008), and protection of strategic water resources (Ferguson, McIntosh, Perrone, & Jasechko, 2018; Perrone & Jasechko, 2019).…”

Identification of Geochemical Processes During Hydraulic Fracturing of a Shale Gas Reservoir: A Controlled Field and Laboratory Water‐Rock Interaction Experiment

“…A nitrate desorption experiment was also conducted using deionized water and 2 mol/L KCl solution. The pressure was not considered in the WRI experiments because (1) during hydraulic fracturing and subsequent flowback, the changes in pressure are quite dynamic (Birdsell et al, 2015; Edwards & Celia, 2018; McIntosh & Ferguson, 2019) and (2) the impact of pressure on most wetness parameters is limited (Harrison et al, 2017; Morel & Hering, 1993; Zolfaghari et al, 2019). The cation exchange capacity (CEC) of the shale sample was measured by using the sodium acetate method strictly following U.S. EPA Method 9081.…”