CHALLENGES TO ORPHANED WELL INTEGRITY FROM WASTEWATER INJECTION (Invited Presentation)

Orphaned and abandoned wells in regions subject to injection of wastewater from unconventional oil and gas production are at increased risk of compromised integrity and have the potential to serve as conduits for injected fluids to aquifers and to the surface. In the Permian Basin region of west Texas and southeast New Mexico, where 40% of U.S. oil is currently being produced, water produced with unconventional development is up to 5x that of oil, and must be recycled or re-injected for permanent disposal into shallower or deeper reservoirs. More than 10 million barrels per day of fluid is injected for disposal, nearly two-thirds of which is into shallow (~5,000 ft) reservoirs, below usable quality water but in strata through which thousands of legacy wells were drilled. This provides an opportunity to understand the link between injection, pressurization of shallow subsurface strata, and the nature of the hazard posed to orphaned wells. Here we (1) document the scale, and stratigraphic and spatial trends in shallow injection, (2) show evidence of pressurization of shallow injection reservoirs through modeled and measured data including InSAR surface deformation, hydrogeological modeling, and recorded pressure data, (3) show how areas with increased pressure and surface elevation changes correspond to wells with surface flows of effluent and other integrity challenges, and (4) highlight case studies to show how these data can be used to identify areas with increased risk of challenges to orphaned well integrity.