Detecting Vertical Movement of Fluid in Wells and Aquifers with High Resolution and Over Long Times Using Fiber Optics
Detecting Vertical Movement of Fluid in Wells and Aquifers with High Resolution and Over Long Times Using Fiber Optics
Presented on Tuesday, May 6, 2014
There are few methods by which high-resolution, in-situ characterization of flow in aquifers is possible. We present a new method which has the potential to quantify both lateral and vertical components of flow in wells and nearby aquifers with 2-meter resolution. The method is based on a novel heating system combined with temperature measurements using a fiber optic distributed temperature sensor (DTS) that provides temperatures each 0.25 m and the ability to detect relative differences of about 0.01 °C on a sub-hour time scale. The method has three phases. In phase one, the background temperature profiles are recorded from which the vertical profile of thermal diffusivity may be obtained. In the second phase the borehole is heated uniformly over the depths of interest. Based on differential in cooling, this provides data to estimate lateral flux with depth. A key innovation is the third phase in which we apply energy to localized short sections (0.5m) of the cable, or heated “dots,” that are equally spaced (2m) along the well. The vertical migration of these warmed zones relative to the heated “dotted line” provides data from which the vertical fluid flow can be estimated. The concept is demonstrated in a 600 m borehole which had 300 heated patches. The method allows for high-resolution detection over an entire well’s depth and can remain in place and operable for many years. Numerical simulations are presented which further illustrate expected behaviors.
John Selker
SelkerMetrics, LLC, Portland, OR
TBA
Frank Selker
SelkerMetrics, LLC, Portland, OR
Frank Selker, a Principal and Founder of SelkerMetrics, has applied distributed temperature sensing (DTS) and other temperature studies at a variety of sites to investigate the emergence of groundwater into surface waters. Sites have included refineries, manufacturing plants, Superfund sites, salt and freshwater bays, rivers and small streams. SelkerMetrics has developed new hardware for installing and handling DTS cable, including custom plows that reduce or eliminate the need for divers and obtain a more uniform burial as well as specialized equipment for retrieving and cleaning cable. SelkerMetrics has also developed proprietary analytics for evaluating the large volume of data DTS systems deliver, to better detect seeps. Prior to founding SelkerMetrics, Mr. Selker founded two other firms and was a senior consultant at Decision Focus Inc. Mr. Selker studied at Reed College and Stanford University.
