Thermal-Plume fibre Optic Tracking (T-POT) test for flow velocity measurement in groundwater boreholes

Read, T.; Bense, Victor; Bour, Olivier; Borgne, Tanguy Le; Lavenant, Nicolas; Hochreutener, Rébecca; Selker, John S.

doi:10.5194/gid-5-161-2015

Cited by 5 publications

(1 citation statement)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, identification of active fractures under ambient flow conditions is much improved when the water column in the borehole is subjected to a rapid heating episode. DTS can also monitor heat movement and rate of heat dissipation due to vertical flow inside an open borehole, which can be used for locating transmissive fractures and for determining water flow rates in the borehole (Banks et al, ; Freifeld et al, ; Hurtig et al, ; Leaf et al, ; Read et al, , ; Sakaguchi & Matsushima, ; Sellwood et al, , ; Yamano & Goto, ). However, Pehme et al () clearly showed that open‐hole temperature profiles can mask many active fractures and it is well‐known that hydraulic cross connection can alter the natural flow conditions of an aquifer.…”

Section: Introductionmentioning

confidence: 99%

Groundwater Flow Quantification in Fractured Rock Boreholes Using Active Distributed Temperature Sensing Under Natural Gradient Conditions

Maldaner

Munn

Coleman³

et al. 2019

Water Resources Research

View full text Add to dashboard Cite

Detection and quantification of groundwater flow in fractures is challenging due to its irregular distribution and fine scale, requiring intensive and depth‐discrete field data collection along boreholes. This study presents a new method using fiber optic active distributed temperature sensing (A‐DTS) in sealed boreholes to efficiently quantify depth‐discrete flow rates along the full length of a bedrock borehole. The method combines field data and numerical modeling to quantify groundwater flow rates under natural gradient conditions, which is important for assessing groundwater flow and contaminant transport. An empirical relationship between enhanced heat dissipation and groundwater flow rates is determined using a numerical model of groundwater flow and heat transport for a system of idealized parallel plate fractures in a homogeneous porous rock with negligible flow through the rock matrix. The empirical relationship is applied to a detailed profile of apparent thermal conductivity measured using A‐DTS that combines the effect of rock thermal properties and groundwater flow. In zones with no flow, the A‐DTS‐derived apparent thermal conductivity matches the laboratory effective rock thermal conductivity values measured independently. Local increases of A‐DTS apparent thermal conductivity relative to the rock matrix thermal conductivity can be used to estimate groundwater flow rates using the empirical relationship. The results are in reasonable agreement with straddle pacer tracer dilution tests in the same borehole, which helps to validate the approach. This new approach allows identification of active flow zones and quantification of flow rates and can be efficiently applied in single or multiple boreholes.

show abstract

Section: Introductionmentioning

confidence: 99%

Groundwater Flow Quantification in Fractured Rock Boreholes Using Active Distributed Temperature Sensing Under Natural Gradient Conditions

Maldaner

Munn

Coleman³

et al. 2019

Water Resources Research

View full text Add to dashboard Cite

show abstract

Distributed Temperature Sensing as a downhole tool in hydrogeology

Bense

Read

Bour

et al. 2016

Water Resources Research

Self Cite

110

View full text Add to dashboard Cite

Distributed Temperature Sensing (DTS) technology enables downhole temperature monitoring to study hydrogeological processes at unprecedentedly high frequency and spatial resolution. DTS has been widely applied in passive mode in site investigations of groundwater flow, in‐well flow, and subsurface thermal property estimation. However, recent years have seen the further development of the use of DTS in an active mode (A‐DTS) for which heat sources are deployed. A suite of recent studies using A‐DTS downhole in hydrogeological investigations illustrate the wide range of different approaches and creativity in designing methodologies. The purpose of this review is to outline and discuss the various applications and limitations of DTS in downhole investigations for hydrogeological conditions and aquifer geological properties. To this end, we first review examples where passive DTS has been used to study hydrogeology via downhole applications. Secondly, we discuss and categorize current A‐DTS borehole methods into three types. These are thermal advection tests, hybrid cable flow logging, and heat pulse tests. We explore the various options with regards to cable installation, heating approach, duration, and spatial extent in order to improve their applicability in a range of settings. These determine the extent to which each method is sensitive to thermal properties, vertical in‐well flow, or natural gradient flow. Our review confirms that the application of DTS has significant advantages over discrete point temperature measurements, particularly in deep wells, and highlights the potential for further method developments in conjunction with other emerging hydrogeophysical tools.

show abstract

Comparative application and optimization of different single-borehole dilution test techniques

2020

View full text Add to dashboard Cite

Single-borehole dilution tests (SBDTs) are a method for characterizing groundwater monitoring wells and boreholes, and are based on the injection of a tracer into the saturated zone and the observation of concentration over depth and time. SBDTs are applicable in all aquifer types, but especially interesting in heterogeneous karst or fractured aquifers. Uniform injections aim at a homogeneous tracer concentration throughout the entire saturated length and provide information about inflow and outflow horizons. Also, in the absence of vertical flow, horizontal filtration velocities can be calculated. The most common method for uniform injections uses a hosepipe to inject the tracer. This report introduces a simplified method that uses a permeable injection bag (PIB) to achieve a close-to-uniform tracer distribution within the saturated zone. To evaluate the new method and to identify advantages and disadvantages, several tests have been carried out, in the laboratory and in multiple groundwater monitoring wells in the field. Reproducibility of the PIB method was assessed through repeated tests, on the basis of the temporal development of salt amount and calculated apparent filtration velocities. Apparent filtration velocities were calculated using linear regression as well as by inverting the one-dimensional (1D) advection-dispersion equation using CXTFIT. The results show that uniform-injection SBDTs with the PIB method produce valuable and reproducible outcomes and contribute to the understanding of groundwater monitoring wells and the respective aquifer. Also, compared to the hosepipe method, the new injection method requires less equipment and less effort, and is especially useful for deep boreholes.

show abstract

Thermal-Plume fibre Optic Tracking (T-POT) test for flow velocity measurement in groundwater boreholes

Cited by 5 publications

References 17 publications

Groundwater Flow Quantification in Fractured Rock Boreholes Using Active Distributed Temperature Sensing Under Natural Gradient Conditions

Groundwater Flow Quantification in Fractured Rock Boreholes Using Active Distributed Temperature Sensing Under Natural Gradient Conditions

Distributed Temperature Sensing as a downhole tool in hydrogeology

Comparative application and optimization of different single-borehole dilution test techniques

Contact Info

Product

Resources

About