Calibration and Deployment of an Electromagnetic Flowmeter for Cross-Hole Hydrogeologic Experiments
Physical and Biological Sciences
EART 195: Senior Thesis (Senior Capstone)
(Note: I ran out of room for the Title of Project. The title should read: "Calibration and Deployment of an Electromagnetic Flowmeter for Cross-Hole Hydrogeologic Experiments Using Borehole Observatories.")
An industrial electromagnetic flowmeter was modified for long term autonomous deployment on a subseafloor borehole observatory (CORK) on the eastern flank of the Juan de Fuca Ridge, in order to measure the flow rate of fluid out of the volcanic crust as part of a cross-hole experiment. Prior to deployment, the flowmeter was calibrated using two methods: in a tank with a pump at rates of 0.5 to 1.2 L/s, and on a wireline at sea at rates of 0.5 to 5.2 L/s. During deployment on the seafloor, the flow rate of fluid out of the volcanic crust is expected to be in the range of 1 to 20 L/s. Reference flow rate and apparent flow rate from calibration are correlated and highly linear. The calibration results indicate the "true" flow rate of fluid out of the volcanic crust can be obtained by increasing the apparent totalizer flow rate by 7%. Much of this 7% offset is associated with correcting for the measured inner diameter of the flowmeter. The flowmeter was deployed for one year starting in Summer 2011. The storativity and transmissivity of the volcanic crust will be calculated from the results of the cross-hole experiment. The pressure response at CORKs surrounding the deployment site is estimated using the expected flow rate.
