PETROGRAPHIC ANALYSIS OF THE LAMOTTE SANDSTONE: POTENTIAL FOR CARBON SEQUESTRATION

The Lamotte Sandstone, the basal Cambrian unit continuous throughout Missouri, is being investigated as a potential unit for shallow geologic carbon sequestration. Carbon sequestration is a technique that is currently being used by numerous countries in an attempt to limit the amount of carbon dioxide released into the atmosphere. A detailed petrographic analysis of the Lamotte Sandstone is one of the necessary factors to determine if it could be a viable reservoir for carbon sequestration.

The Lamotte Sandstone has a variable composition throughout the state, but detailed petrographic analyses have not been conducted at the potential injection sites. Thin sections are being created from samples taken approximately every ten feet from four separate cores, and a standard 1000-point count model analyses are being conducted. The data from a new core site in North-Central Missouri is consistent with previous analyses of the Lamotte in that it alternates between quartz arenite and quartz wacke. The dissimilarities are that there is an absence of carbonate at the top, and an absence of feldspar at the base. The porosity is variable with depth, with an apparent low porosity zone (8%) bounded by two high porosity zones (as high as 29%). Preliminary data suggests that petrographically the Lamotte Sandstone appears to be a suitable unit for storing a large quantity of injected carbon dioxide. Further investigation of additional sites will allow for a more detailed analysis regarding the suitability as a potential unit for carbon sequestration, as well as classifying the Lamotte Sandstone and understanding its complex history of deposition and diagenesis.