Geological CO2 Storage

Overview

Fossil fuels will continue to meet a large fraction of global energy demand for the foreseeable future. Progressive energy companies have recognized that prudent precautionary measures to mitigate the effect of combustion emissions are required now. CO2 capture and geologic storage offer a new set of options for reducing greenhouse gas emissions that can complement strategies of improving energy efficiency and increasing the use of non-fossil energy resources. In fact, geological sequestration is likely to be the only option that will allow us to remove CO2 in large enough quantities over short enough times to make a difference.

A critical issue for geological storage is ensuring that the captured and stored CO2 does not escape from the host formation. This Industrial Associates Project addresses a potentially game-changing approach to preventing escape, namely, sequestering the CO2 in physical and chemical forms whose immobility is assured over geologic time. Harnessing extensive experience in subsurface flow and transport, we will develop new concepts and technology, carrying out state-of-the-art simulations to evaluate the feasibility and reliability of subsurface storage schemes. The results will provide essential input for decisions by governments, industry and regulators on the role of storage in global environmental and energy policy.

Project Goals

The goals of this project are to answer questions such as:

  • What is the ideal target formation for geological storage?
  • Which rock/fluid properties are crucial in evaluating storage options?
  • What time scales are needed to move injected CO2 into permanently stored forms?
  • What measurements would provide verification that CO2 is stored permanently?
  • What are the modes and probabilities of CO2 leakage?

Gas Saturation Profiles

Examples of Key Findings

  • Buoyancy Flow Reduces Mobile CO2
  • Residual Gas Saturation Determines Mobile CO2
  • Well Completion Can Avoid Seal Integrity Issues
  • After injection ends, natural processes reduce the amount of mobile CO2
    • Dissolution into brine
    • Gravity driven flow
    • Mineralization

 

  • Time required to eliminate mobile CO2 depends on petrophysical properties of aquifer
    • Residual gas saturation
    • Average permeability
    • Relative permeability (especially hysteresis)
    • Anisotropy