Integrated Liquid/Steam Multiphase Flow Sensors for Geothermal Applications

Abstract

Renewable energy resources are a viable option for aiding in the decrease of carbon emissions that are produced from the use of fossil fuels. Of the various renewable energy options, this study will focus on geothermal energy, specifically steam wells. Steam wells are holes drilled into the ground for the purpose of accessing and extracting water from underground reservoirs. This water can be heated using a few different methods to create steam. One associated challenge is how to determine the conditions inside the steam well, specifically monitoring the present phases. This study proposes the use of fiber optic sensors to detect the multiphase flow. The Department of Energy (DOE) is interested in creating steam wells, and the purpose of the research is to determine the capabilities of fiber optic sensors developed by NanoSonic Inc. to operate effectively in the detection of a multiphase environment. The fiber optic sensors will be externally mounted to a bubble column along with a digital camera. Data collected from both methods such as bubble diameter, velocity, and volume (air percentage) will be compared. The camera serves as a rudimentary calibration method. Three flow conditions are chosen for examination: plug flow, transition flow, and bubble flow. For this study, plug flow is a singular bubble which has a diameter nearly equivalent to that of the bubble column (2 inches). Bubble flow is much smaller bubbles that travel together, but don't combine to form a larger bubble. Transition flow is between these two conditions; it is a cluster of smaller bubbles on the verge of combining into one plug bubble. After data collection, Matlab R2024a will be used for calculation and analysis. The equation for velocity is derived as outlined in published works using the same camera-based velocimetry estimation method. Additional calibration for the method comes from a published study that derived a general equation for bubble rising velocity in conditions that algin with those in this research.