Monitoring of geological carbon sequestration (GCS) sites will primarily depend upon the tools and technology developed over many decades in support of the oil and gas industries for ensuring the safe injection and storage of CO2 in the subsurface. For more than thirty years CO2 has been compressed and transported in pipelines for injection as part of enhanced oil recovery projects. However, the aims of CO2 injection for carbon sequestration have significant differences from EOR injections, where the motivation is enhanced production. While the regulatory environment that will govern CO2 storage in the subsurface is still evolving, operators of GCS sites will need to demonstrate protection of drinking water resources, accountability of the volume injection and permanence for the CO2 emplaced. The US Department of Energy has coined the acronym MVA to describe the requirement to monitor the movement of CO2 into, through, and out of the targeted geologic storage area, verify the location of CO2 that has been placed in geologic storage, and account for the CO2 that has been transported to a geologic storage site. To accomplish this, advanced well-based technologies will be needed to meet regulatory and technical requirements. Recent demonstration projects have incorporated permanently emplaced sensors including pressure, distributed fiber-optic, temperature, seismic, electrical resistivity, and geochemical sampling to name a few. These are often installed so that they are compatible with periodic wireline operations. In this paper we will examine integrated well-based monitoring programs that were part of CO2 storage demonstration programs and will discuss requirements for future commercial installations.