<title>SCIIB pressure sensors for oil extraction applications</title>

Efficient and complete recovery of petroleum reserves from existing oil wells has proven difficult due to a lack of robust information that can monitor processes in the downhole environment. Commercially available sensors for measurement of pressure, temperature, and fluid flow exhibit lifetimes in the harsh downhole conditions, which are characterized by high pressure (up to 20 kpsi), temperatures up to 250 degree(s)C, and exposure to chemically reactive fluids. Development of robust sensors that deliver continuous, real- time data on reservoir performance and petroleum flow pathways will facilitate application of advanced recovery technologies, including horizontal and multi-lateral wells. We describe the development and fabrication of pressure, temperature, and flow sensors designed for the downhole environment, based on the Self-Calibrated Interferometric/Intensity-Based configuration, which combines the high sensitivity of interferometric sensors with the high-speed of intensity-based sensors. By splitting the output of a Fabry-Perot sensor into two channels with differing coherence, unwanted perturbations, such as source power fluctuations and variations in fiber loss, may be compensated. Results of laboratory tests of prototype sensors demonstrate excellent resolution and accuracy.