Optimization of Geological Environments for Carbon Dioxide Disposal in Saline Aquifers in the United States - Final Report

High permeability sandstones of the Frio Formation east of Houston, Texas, were selected to test the feasibility of using carbon capture and storage (CCS) in geologic formations as a method to reduce atmospheric buildup of greenhouse gases. The Frio Brine pilot study was based on two small-volume and short-duration CO2 injections into two previously unperturbed brine-bearing sandstone beds typical of the region. These injections were designed to answer key questions about CCS using a process of intensive multiphysics monitoring, pre-, syn-, and post-injection monitoring, and then history-matching to test the correctness of numerical models of flow and geochemical changes. The first test, conducted in September 2004, injected about 1,600 tons of CO2 at a depth of 5,050 ft (~1,540 m) below the surface over 10 days and collected observations over 18 months. The second injection, in September 2006, injected more slowly, about 250 tons over 5 days, into thicker sandstone at 5,400 ft (~1,650 m) below the surface. The injection period was brief, and the formation was on the flank of a steeply dipping structural compartment, resulting in monitoring over 5 years and lasting well into the post-injection phase of plume stabilization. This provided the experience and measurements of a complete project that will be helpful in predicting the performance of large-volume injections potentially lasting decades. The site was closed at the end of the experiment in May 2009.