Enhanced oil recovery

EOR I pilot — Loudon Oil Field (Huff 'n Puff)
This immiscible CO2 EOR pilot was designed to inject CO2 into a prevalent Illinois Basin oil-bearing interval to directly measure CO2 sequestration mass, enhanced oil recovery, and CO2 injection rate.

The pilot formation was the Cypress Sandstone, a 1,500–ft deep, fine- to very fine- grained sandstone with 6–10 ft thick packages interbedded with shales. Typically this sandstone occurs as elongated bodies that may coalesce to form larger flow units; at this site, average permeability is 31 mD and average porosity is 16%. Injection and production plan follows:

  • Injected CO2 as a gas into the tubing-casing annulus of an oil producing well, injection period about one week at a rate of 5–10 tons per day
  • Shut in the well to allow CO2 to mix and dissolve in the oil, shut-in period one week
  • Produced the well to observe CO2, hydrocarbon gas, oil, and water production; incremental oil production about 100 barrels (after two months)

Project status:
  • Completed 43 tons cumulative injection
  • Well returned to active oil production

  • Oil production increased, rate peaked at 8 bopd with sustained oil rate of 1–2 bopd above the pre-CO2 injection rate
  • Water production decreased

Monitoring, verification, and accounting:
  • Conducted baseline, injection, and post-injection monitoring, including continuous in-zone pressure and temperature, gas content and liquid chemistry of the injection formation, cased-hole logging, vadose zone sampling, shallow groundwater quality monitoring, and shallow geophysical surveys
  • Conducted reservoir, geochemical, and groundwater flow modeling to verify operational and field efforts
  • Monitored the chemical composition of the formation brine for nearly two years after the initial injection of CO2
  • Assessed the impact of the injected CO2 on the chemical and mineralogical composition of the injection formation

MVA results:
  • Shallow groundwater quality has not been impacted by CO2 injection activities, based on water chemistry results
  • Residential sampling was important to address concerns of an adjacent neighbor
  • Vadose zone monitoring in the Illinois Basin may be limited by saturated soil conditions
  • Shallow geophysical techniques may also be limited by the site infrastructure (e.g. power lines, pipelines)

Midwest Geological Sequestration Consortium
Midwest Geological Sequestration Consortium
Advanced Energy
Technology Initiative

University of Illinois
615 E. Peabody Dr.
Champaign, IL 61820