Basin-Scale Hydrologic Impacts of CO2 Sequestration; Scaling Calculations using Sharp Interface Theory

Abstract

Rational For Study: 1) The Mt. Simon Formation represents a viable saline water saturated reservoir for CO2 sequestration in the Illinois Basin and environments. It is thick (500 - >2500 ft.) and potentially has sufficient porosity and permeability to store large volumes of CO2. 2) However, freshwater withdraws from the Mt. Simon in urban areas (~ 280 Million MT/year) are on the same order of magnitude as CO2 production across the Illinois Basin (~ 80 Million MT/yr). Freshwater withdraws have had a significant hydrologic impact (600 ft drawdown in Chicago area) at the regional scale. Will CO2 injection have a regional scale impact on the hydrology of the system by displacing brine in the regions currently saturated by freshwater? 3) High number of wells required to inject 80 Million MT/yr CO2 may result in well-well interference patterns, high deviatoric pressures (especially in the deep, low-permeability portions of the basin), and displacement of brines into other aquifers. 4) We ask the question: Is there an optimal place to locate most of the injection wells across the basin?