Paper No. 175-9
Presentation Time: 10:45 AM
CONDUITS BENEATH US: CASE STUDIES OF ABANDONED OIL AND GAS WELLS AND THEIR IMPLICATIONS FOR MODERN DAY PRODUCTION IN ALBERTA AND SASKATCHEWAN
Much attention has been given in the literature to wells abandoned in the early to mid-1900s in relation to hydraulic fracturing of low porosity formations and carbon sequestration. However, there has been little attention given to conventional oil and gas production in reservoirs from which these abandoned wells originally produced. Modern oil and gas well regulations in Alberta and Saskatchewan are intended to protect aquifers containing potable groundwater, yet prior to the mid to late-1900s, many oil and gas wells were constructed under far less restrictive regulatory regimes. These regimes allowed for what today would be considered substandard well construction and abandonment practices. Poorly constructed wells with compromised integrity can cause numerous problems relating to groundwater quality, quantity, and public safety. Presently in Alberta and Saskatchewan, the occurrence of surface casing vent flow and gas migration is used as an indicator of well integrity problems, but records in Alberta only extend back to 1985 while semi-consistent reporting of measurement records in Saskatchewan did not truly begin until the 2000s. The integrity of older abandoned wells in both provinces must be estimated using available historical records. Where these older wells penetrate formations undergoing enhanced oil recovery operations such as waterflooding, or other activities such as CO2 sequestration, or hydraulic fracturing, the likelihood of fluids traveling up older compromised wellbores and impacting potable water sources is amplified. This study first provides insight into early well construction practices and the historical regulatory environment that may have unintentionally contributed to a greater risk of well integrity failure. Then identifies the ways in which the spatial distribution of historically abandoned wells coincides with modern day activities, ultimately suggesting that subsurface development in conventional fields with historical development should be given greater scrutiny.