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Abbott B.W.,CNRS Ecosystems, Biodiversity, and Evolution Laboratory | Baranov V.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Mendoza-Lera C.,IRSTEA | Nikolakopoulou M.,Naturalea | And 17 more authors.
Earth-Science Reviews | Year: 2016

Protecting or restoring aquatic ecosystems in the face of growing anthropogenic pressures requires an understanding of hydrological and biogeochemical functioning across multiple spatial and temporal scales. Recent technological and methodological advances have vastly increased the number and diversity of hydrological, biogeochemical, and ecological tracers available, providing potentially powerful tools to improve understanding of fundamental problems in ecohydrology, notably: 1. Identifying spatially explicit flowpaths, 2. Quantifying water residence time, and 3. Quantifying and localizing biogeochemical transformation. In this review, we synthesize the history of hydrological and biogeochemical theory, summarize modern tracer methods, and discuss how improved understanding of flowpath, residence time, and biogeochemical transformation can help ecohydrology move beyond description of site-specific heterogeneity. We focus on using multiple tracers with contrasting characteristics (crossing proxies) to infer ecosystem functioning across multiple scales. Specifically, we present how crossed proxies could test recent ecohydrological theory, combining the concepts of hotspots and hot moments with the Damköhler number in what we call the HotDam framework. © 2016 The Authors Source


Daley T.M.,Lawrence Berkeley National Laboratory | Miller D.,Silixa | Freifeld B.M.,Lawrence Berkeley National Laboratory | Dodds K.,BP CCP
76th EAGE Conference and Exhibition 2014, Workshops | Year: 2014

As part of a C02 storage project at Citronelle, Alabama, VSP data was acquired with a short string of tubing-deployed, wall-locking, geophones (18atl5m spacing) and a long (3 km) fiber, also tubing-deployed. We will show data examples comparing geophone and DAS attributes such as spectral response, signal-to-noise ratio and ground motion sensitivity comparison. Source


Madsen K.N.,Statoil | Dummong S.,Statoil | Kritski A.,Statoil | Finfer D.,Silixa | Gillies A.,Silixa
2nd EAGE Workshop on Permanent Reservoir Monitoring: Current and Future Trends | Year: 2013

In a collaborative project between Silixa, Weatherford and Statoil, simulatneous multiwell VSP data were successfully acquired using intelligent Distributed Acoustic Sensing (iDAS). The iDAS enables the use of an optic fibre as a massive seismic sensor array. In this field trial the iDAS was retrofitted to existing fibres installed for other purposes. Simultaneous measurements were carried out using 4 iDAS units retrofitted to fibres in three different wells coming up to the same platform. Several seismic lines were shot, e.g. one above each of the well tracks, while listening in the well directly below the shots and also in neighbouring wells at an angle to the shot line. All three wells were producing during the trial and the downhole seismic data were acquired without disturbing the well operations. Consequently data hold information about the flow in the well in addition to the seismic information. Source


Daley T.M.,Lawrence Berkeley National Laboratory | Freifeld B.M.,Lawrence Berkeley National Laboratory | Ajo-Franklin J.,Lawrence Berkeley National Laboratory | Dou S.,Lawrence Berkeley National Laboratory | And 7 more authors.
Leading Edge | Year: 2013

Distributed acoustic sensing (DAS) is a relatively recent development in the use of fiber-optic cable for measurement of ground motion. Discrete fiber-optic sensors, typically using a Bragg diffraction grating, have been in research and development and field testing for more than 15 years with geophysical applications at least 12 years old (Bostick, 2000, and summary in Keul et al., 2005). However, developments in recent years have sought to remove the need for point sensors by using the fiber cable itself as a sensor (Mestayer et al., 2011; Miller et al., 2012). © 2013 © 2013 by The Society of Exploration Geophysicists. Source


Madsen K.N.,Statoil | Dummong S.,Statoil | Parker T.,Silixa | Finfer D.,Silixa | And 3 more authors.
Borehole Geophysics Workshop II - 3D VSP: Benefits, Challenges and Potential | Year: 2013

Simultaneous multiwell VSP data have been acquired using fibre optic cables in producing wells as distributed acoustic sensors. The measurement apparatus was retrofitted to the fibre optic cables installed for other purpose with completion of the wells. Data were acquired with no other instrumentation in the well and without disturbing the normal operation of the wells. Source

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