Development of HTS-SQUID System for a Monitoring System of CO2 Enhanced Oil Recovery

We have tried to develop an induction logging system for oil fields utilizing a high-temperature superconducting quantum interference device (HTS-SQUID). Enhanced oil recovery (EOR) technology utilizing carbon dioxide (CO
₂
) is a promising technique for efficient production of petroleum. To control the EOR, it is important to improve the accuracy of monitoring technique of CO
₂
injected into the oil reservoir. The HTS-SQUID has a potential to monitor CO
₂
behavior in crude oil reservoir because of its high sensitivity in a wide frequency range from dc to over 1 MHz. As the first step of the developments, we prepared a vessel for SQUID system by using carbon fiber reinforced plastic with pressure tightness of 70 MPa and thermal durability of 200 °C. By using the SQUID system placed at a depth of about 300 m in a steel-cased borehole filled with water, magnetic signals from a transmitter coil in another borehole were successfully measured.