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Abstract
As part of the US DOE's Regional Carbon Sequestration Partnership program, the Midwest Geologic Sequestration Consortium has four active field demonstrations: two EOR pilots, one S/ECBM pilot, and one brine-saturated formation CO2 injection pilot.

The S/ECBM pilot injection period was seven months which ended in mid-January 2009. The pilot included four wells completed in a coal seam at 900 ft. The injection well and three monitoring wells are oriented in the face and butt cleat directions. About 100 tons of CO2 were injected at 0.50-0.75 tons/day. Results indicate the enhancement of methane gas production and sequestration of CO2 through competitive desorption. Presently, post-CO2 water injection pressure transient tests are being completed to identify changes in cleat permeability resulting from CO2 adsorption.

An immiscible (gas) CO2 EOR flood was started in May 2009 in a sandstone at 1900 ft. The injection rate was 20-25 tons/day. A water injection well was converted to a CO2 injection well. The well is centrally located between eight oil producing wells. CO2 injection ended in May 2010 with cumulative injection of about 7,200 tons. Twelve months of water injection are planned after CO2 injection. Several 100 barrels of incremental oil recovery have been measured; less than 5% of the injected CO2 has been produced.

A liquid CO2 EOR, inverted 5-spot pilot was started in September 2009 and injection continued through January 2010 until winter road restrictions were enforced. During this time 2,860 tons were injected at 25-30 tons/day. While road travel was restricted, 13,000 barrels of water were injected. CO2 injection resumed in May 2010 and is planned to continue through the summer. At the end of the first CO2 injection period, the pattern’s oil production rate increased 200% from its baseline.
The injection well of the deep saline formation test was drilled and completed in 2009. A verification well is scheduled to be drilled later in 2010. Injection is planned for 2011. The UIC permit process is near completion. This one million ton injection project will be in the Mt. Simon sandstone, the deepest sedimentary formation in the Illinois Basin. Injection rates of 1,100 tons/day are anticipated.

Introduction
The Midwest Geological Sequestration Consortium (MGSC) is one of seven regional partnerships selected by the U.S. Department of Energy (DOE) to determine the best regional approaches for capturing and storing carbon dioxide (CO2) that might otherwise contribute to global climate change. The MGSC is led by the Illinois State Geological Survey, in conjunction with the Indiana Geological Survey and the Kentucky Geological Survey, and covers Illinois, southwestern Indiana, and western Kentucky. This partnership was established to assess geological carbon sequestration options in the 60,000 mi2, oval-shaped, geologic feature known as the Illinois Basin (figure 1). Within the Basin are deep, less economic coal resources, numerous mature oil fields, and deep saline (brine-saturated) reservoirs with potential to store CO2. MGSC’s objective is to determine the technical and economic feasibility of using these geologic formations for long-term storage.

The MGSC is assessing the CO2 storage feasibility, capacity, and safety of these geological formations. Testing will focus on the ability of these types of reservoirs to serve as sinks for some of the 300 tons of annual CO2 emissions from fixed sources in the Illinois Basin (DOE, 2010). Four pilot field tests were conducted during the current DOE Phase II Validation, which is a 5-year effort (2005–2010) focused on demonstrating and validating promising geological sequestration opportunities. These pilot projects included the testing of the deeper and/or thinner coal seams to adsorb gaseous CO2, and the ability to enhance oil production or recovery from oil fields by CO2 flooding. The fifth field project is a large scale demonstration (DOE Phase III) that overlaps with the Phase II effort. The Phase III demonstration will inject CO2 into a deep saline formation at a depth of about 7,000 feet measured depth (MD).