November 7, 2011
Characterization Well Drilling Progress
Significant progress has been made in drilling the geologic characterization well in Morgan County. The well will not only benefit the FutureGen 2.0 project, but will also add to the scientific understanding of the Illinois geology. After completion and quality assurance, the results of the drilling effort will be shared with the Illinois State Geologic Survey and the public.
Drilling began on October 5. Initially, a 30-inch bit was used to drill down to the bedrock. At this depth a 24-inch steel casing was cemented into the hole. This initial casing isolates all drilling and testing from the surface geology, thereby protecting the surface geology and any shallow groundwater. Drilling then proceeded with a smaller bit to a depth of about 570 feet. At that point, a 16-inch steel casing was cemented into the hole. This second casing runs all the way to the surface and provides a second level of environmental protection and stabilized the wellbore.
The drill team is now using a 14-3/4 bit and as of November 1, at 7:00 AM, the drill bit reached 2,718 feet. Drilling speed varies, depending on the hardness of the rock formation at a particular depth. Currently, around 100 feet of rock is being drilled through each day. Intermittently, drilling pauses for various geologic tests, changing drill bits, or other engineering activities. The team predicts that the target geologic formation—the Mount Simon sandstone—will be reached in December. To date, the drilling rate has been right on schedule. The final borehole depth is estimated to be around 5,100 feet. A core sample of several of the formations will be extracted to verify the suitability of the rock to store CO2. No actual injection of CO2 will occur in this borehole as it is only for geologic characterization.
The team wants to confirm the physical properties, including the thicknesses and the porosity, of the different rock formations. It is important to the success of the project to have an impermeable rock layer—often a shale referred to as the caprock—above the target storage formation. This caprock is needed to ensure that the CO2, which is ultimately injected into sandstone called the Mount Simon, is retained in that formation. The cap rock—called the Eau Claire—will also be sampled. These properties, as well as a number of others, will be characterized as part of the drilling operation.