Designing a Novel NIR Spectroscopy-Based Sensor for Early Kick Detection in Harsh Environments

A blowout can be a fatal event, made more catastrophic when it occurs offshore where scale of operation is typically larger than onshore. Blowouts usually result when a drilling crew is unaware that reservoir fluids have entered riser from the formation. To reduce this risk, we are developing a chemical sensor that will alert the crew of an influx of any hydrocarbon when encountered in the well bore. For this reason, we set out to build a sensor that could be made a part of the lower marine riser package. To be part of an effective early warning system, the sensor should detect the presence of hydrocarbons present in the well bore within short time frames (seconds). Our sensor is based on NIR spectroscopy using fiber optic waveguides which would be located downhole where the environmental conditions are harsh, including high pressure and temperature. To protect the sensor under such conditions, we developed a sensor that is coated with a material that is hydrophobic/oleophilic. Our work investigated a suitable material and coating technique for the sensor. We found that the coating worked best when it was porous in nature to allow passage of hydrocarbons through it in a short time frame. We have successfully identified a minimum concentration of 2.5% of hydrocarbons in the simulated drilling fluid instantaneously. We also explored different techniques like Evanescence wave, absorbance, Raman, and transmission spectroscopy.