Thread: Fiber‐Optic Cable deployment

Started: 2022-05-03 18:24:16
Last activity: 2022-05-09 15:10:27
Marco Olivieri
2022-05-03 18:24:16
Dear All,

We have been offered to deploy our own fiber‐optic cable besides one
telecom company deployment that will connect a town to a village (about 8
km long). We expect to use it for seismic monitoring purposes with DAS. As
far as we know they will use a standard method i.e. dig an 8 km long
trench, bury a pvc duct and insert the fiber‐optic cable in it.

The question is: Would it be better to insert our cable in the pvc duct
besides the telecom one or to have it buried directly to the ground (out of
pipe)? Do you know any paper or technical report that discusses this task?
Please respond to me directly and I will compile responses for those
interested.

Any hint would be appreciated.
Thanks
Marco Olivieri

  • Peter Hubbard
    2022-05-03 10:49:55
    This seems like a controversial topic! I personally find a tight buffered
    cable and direct burial provides the best mechanical coupling to the soil
    and thus the highest fidelity strain measurements. Please see these two
    manuscripts currently being reviewed that detail this type of installation
    and show example cables.

    https://www.preprints.org/manuscript/202204.0268/v1

    https://arxiv.org/abs/2202.04779

    Best,

    Peter

    On Tue, May 3, 2022 at 9:26 AM Marco Olivieri (via IRIS) <
    das-bounce<at>lists.ds.iris.edu> wrote:

    Dear All,

    We have been offered to deploy our own fiber‐optic cable besides one
    telecom company deployment that will connect a town to a village (about 8
    km long). We expect to use it for seismic monitoring purposes with DAS. As
    far as we know they will use a standard method i.e. dig an 8 km long
    trench, bury a pvc duct and insert the fiber‐optic cable in it.

    The question is: Would it be better to insert our cable in the pvc duct
    besides the telecom one or to have it buried directly to the ground (out of
    pipe)? Do you know any paper or technical report that discusses this task?
    Please respond to me directly and I will compile responses for those
    interested.

    Any hint would be appreciated.
    Thanks
    Marco Olivieri

    ----------------------
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    Acoustic Sensing Research Coordination Network, please go to:
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    Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
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    • Jonathan Ajo-Franklin
      2022-05-03 13:22:43
      Agree on the "out of the conduit" if possible. Only potential downside
      is mechanical damage which is more likely without the PVC. We tried 4
      cables using direct burial including fully SS encapsulated, an
      anti-rodent cable (with steel tape surrounding the gel-filled core),
      and 2 types of tactical. The responses were surprisingly similar in
      the 5-25 Hz range but the light tactical was much simpler to deploy
      (lighter, no shape memory). We have yet to have major rodent problems
      with our cables but I'm sure there will be a first at some point!

      https://www.nature.com/articles/s41598-017-11986-4.pdf

      We did have one difficult experiment involving fiber in double-walled
      conduit and I wasn't thrilled by the data quality (although it was
      processable).

      https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2018GL081195

      Cheers - J.



      On Tue, May 3, 2022 at 1:02 PM Peter Hubbard (via IRIS)
      <das-bounce<at>lists.ds.iris.edu> wrote:

      This seems like a controversial topic! I personally find a tight buffered cable and direct burial provides the best mechanical coupling to the soil and thus the highest fidelity strain measurements. Please see these two manuscripts currently being reviewed that detail this type of installation and show example cables.

      https://www.preprints.org/manuscript/202204.0268/v1

      https://arxiv.org/abs/2202.04779

      Best,

      Peter

      On Tue, May 3, 2022 at 9:26 AM Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu> wrote:

      Dear All,

      We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

      The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
      Please respond to me directly and I will compile responses for those interested.

      Any hint would be appreciated.
      Thanks
      Marco Olivieri

      ----------------------
      Distributed Acoustic Sensing - For more information on the Distribution Acoustic Sensing Research Coordination Network, please go to: https://www.iris.edu/hq/initiatives/das_rcn
      Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe: das-unsubscribe<at>lists.ds.iris.edu

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      --
      Dr. Jonathan Ajo-Franklin

      ja62<at>rice.edu
      JBAjo-Franklin<at>lbl.gov

      Professor (Geophysics)
      Dept. of Earth, Environmental, and Planetary Sciences
      Rice University, MS-126
      6100 Main Street, Houston, TX 77005

      Visiting Faculty, Geophysics Dept.
      Energy Geosciences Division
      Earth and Environmental Sciences Area
      Lawrence Berkeley National Laboratory
      #1 Cyclotron Road, MS 74R0120
      Berkeley, CA 94720
      Cell : (510)-735-4350


      • Francisco López Torres
        2022-05-03 21:59:35
        Hello all.

        I share the vast majority of the comments of the speakers who have
        intervened in the debate before me.

        The experience of more than 30 years in fiber optic installations of our
        parent company, FIBERCOM, and the knowledge that we at Aragón Photonics
        Labs have acquired in DAS sensing infrastructures the last 10 years have
        allowed us to develop a cable specially designed for this use.

        I attach a product sheet for reference (sorry for being in Spanish).

        This cable is designed for sensing, but can of course also be used for
        telecommunications, although the small number of fibres does not make it
        particularly suitable for trunking.

        There are several manufacturers offering similar cables, some developed
        specifically for DAS and others simply ruggedised cables. It is important
        to analyse the details of the characteristics of each cable to see if they
        are really the best choice for DAS.

        In our opinion, there are three main aspects to take into account when
        choosing the cable and the installation technique:

        - It is preferable for the cable to be directly buried rather than
        inside a tube. A burial of between 20 and 50 cm is more than sufficient,
        but the depth is usually determined by the conditions of the environment
        (soil material, human and other activities in the vicinity, etc.)
        - The cable that is directly buried must be resistant to external
        aggressions (rodents, humans, etc.). Metal reinforcements are usually the
        best option (strips, layers, rods...), the stronger the better.
        - The loose tube is the best choice to protect the optical fibre in
        these circumstances, but it is very important that this tube has
        thixotropic gel so that the mechanical waves can propagate effectively to
        the fibre from the outside of the cable.

        I hope this information will be useful to you.

        Best regards.

        Francisco M. López
        *BC*
        [image: logo APL]
        [image: icono APL]
        f.lopez<at>aragonphotonics.com [image: icono correo]
        +34 976 359 972 <+34976359972> [image: icono telefono]
        www.aragonphotonics.com [image: icono web]
        Prado 5, local 50009 Zaragoza, Spain https://goo.gl/maps/ftAc7DQmHFfBE7vL8
        [image: icono direccion]


        El mar, 3 may 2022 a las 20:47, Jonathan Ajo-Franklin (via IRIS) (<
        das-bounce<at>lists.ds.iris.edu>) escribió:

        Agree on the "out of the conduit" if possible. Only potential downside
        is mechanical damage which is more likely without the PVC. We tried 4
        cables using direct burial including fully SS encapsulated, an
        anti-rodent cable (with steel tape surrounding the gel-filled core),
        and 2 types of tactical. The responses were surprisingly similar in
        the 5-25 Hz range but the light tactical was much simpler to deploy
        (lighter, no shape memory). We have yet to have major rodent problems
        with our cables but I'm sure there will be a first at some point!

        https://www.nature.com/articles/s41598-017-11986-4.pdf

        We did have one difficult experiment involving fiber in double-walled
        conduit and I wasn't thrilled by the data quality (although it was
        processable).

        https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2018GL081195

        Cheers - J.



        On Tue, May 3, 2022 at 1:02 PM Peter Hubbard (via IRIS)
        <das-bounce<at>lists.ds.iris.edu> wrote:

        This seems like a controversial topic! I personally find a tight
        buffered cable and direct burial provides the best mechanical coupling to
        the soil and thus the highest fidelity strain measurements. Please see
        these two manuscripts currently being reviewed that detail this type of
        installation and show example cables.

        https://www.preprints.org/manuscript/202204.0268/v1

        https://arxiv.org/abs/2202.04779

        Best,

        Peter

        On Tue, May 3, 2022 at 9:26 AM Marco Olivieri (via IRIS) <
        das-bounce<at>lists.ds.iris.edu> wrote:

        Dear All,

        We have been offered to deploy our own fiber‐optic cable besides one
        telecom company deployment that will connect a town to a village (about 8
        km long). We expect to use it for seismic monitoring purposes with DAS. As
        far as we know they will use a standard method i.e. dig an 8 km long
        trench, bury a pvc duct and insert the fiber‐optic cable in it.

        The question is: Would it be better to insert our cable in the pvc duct
        besides the telecom one or to have it buried directly to the ground (out of
        pipe)? Do you know any paper or technical report that discusses this task?
        Please respond to me directly and I will compile responses for those
        interested.

        Any hint would be appreciated.
        Thanks
        Marco Olivieri

        ----------------------
        Distributed Acoustic Sensing - For more information on the Distribution
        Acoustic Sensing Research Coordination Network, please go to:
        https://www.iris.edu/hq/initiatives/das_rcn
        Topic home: http://ds.iris.edu/message-center/topic/das/ |
        Unsubscribe: das-unsubscribe<at>lists.ds.iris.edu

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        --
        Dr. Jonathan Ajo-Franklin

        ja62<at>rice.edu
        JBAjo-Franklin<at>lbl.gov

        Professor (Geophysics)
        Dept. of Earth, Environmental, and Planetary Sciences
        Rice University, MS-126
        6100 Main Street, Houston, TX 77005

        Visiting Faculty, Geophysics Dept.
        Energy Geosciences Division
        Earth and Environmental Sciences Area
        Lawrence Berkeley National Laboratory
        #1 Cyclotron Road, MS 74R0120
        Berkeley, CA 94720
        Cell : (510)-735-4350


        ----------------------
        Distributed Acoustic Sensing - For more information on the Distribution
        Acoustic Sensing Research Coordination Network, please go to:
        https://www.iris.edu/hq/initiatives/das_rcn
        Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
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  • Daniel DANSKIN
    2022-05-03 16:35:28
    Out of the duct.
    I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
    All other duct installations have poor signal compared to direct bury.

    I'm sure every other vendor will say the same.

    Dan


    Get Outlook for Androidhttps://aka.ms/AAb9ysg
    ________________________________
    From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu>
    Sent: Tuesday, May 3, 2022 5:25:36 PM
    To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
    Subject: [IRIS][das] Fiber‐Optic Cable deployment

    Dear All,

    We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

    The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
    Please respond to me directly and I will compile responses for those interested.

    Any hint would be appreciated.
    Thanks
    Marco Olivieri

    -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com --

    • FangDad Fabulous
      2022-05-03 11:56:21
      Hi Marco:

      In order the maximize coupling to the ground we always did a direct bury of a gel filled fiber. If you place it in conduit you may get a situation in which the fiber is suspended in air and vibrates like a guitar string in the conduit introducing severe noise. If you can place you conduit and then backfill a bit you should have better coupling….

      I’d recommend reaching out to Dan Costley at US Army ERDC for publications and reports on best practices.

      Good luck!

      Best,

      Jason

      —————————-
      Jason McKenna
      (601) 618 4969

      On May 3, 2022, at 11:46 AM, Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu> wrote:

      
      Out of the duct.
      I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
      All other duct installations have poor signal compared to direct bury.

      I'm sure every other vendor will say the same.

      Dan


      Get Outlook for Android
      From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu>
      Sent: Tuesday, May 3, 2022 5:25:36 PM
      To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
      Subject: [IRIS][das] Fiber‐Optic Cable deployment

      Dear All,

      We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

      The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
      Please respond to me directly and I will compile responses for those interested.

      Any hint would be appreciated.
      Thanks
      Marco Olivieri
      -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com --


      ----------------------
      Distributed Acoustic Sensing - For more information on the Distribution Acoustic Sensing Research Coordination Network, please go to: https://www.iris.edu/hq/initiatives/das_rcn
      Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe: das-unsubscribe<at>lists.ds.iris.edu

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    • NEAL E LORD
      2022-05-03 16:51:48
      Hi all,

      Pick a cable which won't be cut by rodents.

      -Neal
      ________________________________
      From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu>
      Sent: Tuesday, May 3, 2022 11:44 AM
      To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
      Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

      Out of the duct.
      I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
      All other duct installations have poor signal compared to direct bury.

      I'm sure every other vendor will say the same.

      Dan


      Get Outlook for Androidhttps://aka.ms/AAb9ysg
      ________________________________
      From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu>
      Sent: Tuesday, May 3, 2022 5:25:36 PM
      To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
      Subject: [IRIS][das] Fiber‐Optic Cable deployment

      Dear All,

      We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

      The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
      Please respond to me directly and I will compile responses for those interested.

      Any hint would be appreciated.
      Thanks
      Marco Olivieri

      -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com --

      • Scott W Tyler
        2022-05-03 17:44:15
        Well, that is easier said than done!! But braided steel overlay works well, as does low cost “flat drop” cable from AFL that has fiberglass strength elements, which most rodents don’t like.
        Not sure if they are producing single mode flat drop tho.

        Dr. Scott Tyler
        Foundation Professor
        University of Nevada, Reno
        styler<at>unr.edu<styler<at>unr.edu>
        http://scotttylerhydro.com/
        http://www.ctemps.orghttp://www.ctemps.org/

        From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu>
        Sent: Tuesday, May 03, 2022 9:56 AM
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
        Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

        Hi all,

        Pick a cable which won't be cut by rodents.

        -Neal
        ________________________________
        From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
        Sent: Tuesday, May 3, 2022 11:44 AM
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
        Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

        Out of the duct.
        I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
        All other duct installations have poor signal compared to direct bury.

        I'm sure every other vendor will say the same.

        Dan


        Get Outlook for Androidhttps://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Faka.ms%2FAAb9ysg&data=05%7C01%7Cstyler%40unr.edu%7C438e90070a734226412c08da2d26bfbe%7C523b4bfc0ebd4c03b2b96f6a17fd31d8%7C0%7C1%7C637871941696779787%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=V3P%2BZQC3WqReNdWCNApLEZ53pfn70Ad4QCIng0pjg9Q%3D&reserved=0
        ________________________________
        From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
        Sent: Tuesday, May 3, 2022 5:25:36 PM
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
        Subject: [IRIS][das] Fiber‐Optic Cable deployment

        Dear All,

        We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

        The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
        Please respond to me directly and I will compile responses for those interested.

        Any hint would be appreciated.
        Thanks
        Marco Olivieri

        -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com<cybersecurity<at>asn.com> --

      • Kurt Feigl
        2022-05-03 17:45:54
        All,

        I agree with Dan that good coupling to the soil and rock is essential. I agree with Neal that protecting from rodents is also essential. The key words are "StrataJac® encapsulation" and "rodent deterrent additive". Please find below some information about the 9000 meters of cable deployed at Brady Hot Springs, Nevada as part of the PoroTomo project. If this information is helpful, then please cite the appropriate references.

        Best,

        Kurt


        The (horizontal) surface cable is a ruggedized military type cable that is rodent resistant with acrylate-coated fibers rated to 85°C, as shown in Figure 15. The cable was laid into the trench as five separate cable lengths and spliced together using “direct-bury” splice enclosures. The cable was tested for fiber integrity and the trench backfilled using a skid-steer loader.



        [cid:26099de5-2f11-4b9c-b9c1-fb2160b8b4c5]



        Typical optical cables contain several bundled fibers within outer protective layers. Two types of cable were used at Brady. The trenched cable was a tight-buffered construction with a polymer jacket, the borehole cable was a fiber in metal tube (FIMT) based construction. Each cable contained several of both types of fiber: multimode (MM), used for DTS, and singlemode (SM), used for DAS. For each installation a pair of MM fibers were joined at the far end with a u-bend termination to allow a double-ended DTS configuration. The upper right photo in Figure 1 shows the splicebox at the terminus of the trench. A similar spliced pair of SM fibers were used for the borehole DAS installation (DASV) which was recorded over an interval that included both the wellhead and the turnaround splice with about 10 extra channels at each end (an aid to matching DTS and DAS channels with well geometry).



        Miller, Douglas E., Thomas Coleman, Xiangfang Zeng, Jeremy R. Patterson, Elena C. Reinisch, Michael A. Cardiff, Herbert F. Wang, Dante Fratta, Whitney Trainor-Guitton, and Clifford H. Thurber. "DAS and DTS at Brady Hot Springs: Observations about coupling and coupled interpretations." In Proceedings of the 43rd Workshop on Geothermal Reservoir Engineering, Stanford, CA, USA, pp. 12-14. 2018. http://erlweb.mit.edu/sites/default/files/Miller%20DAT%20and%20DTS%20at.pdfhttp://secure-web.cisco.com/1inWmo1EpKWa2g9M1iVVx4Kudgwh7HZP5341qhSC945n3BX7YnWRZCQZFVc8u1kQA7i3FK-eaDQn0QYI3du80a7vtKK5TQGiq6AoDO1NzXYK-n3TFvzdM_JtKl2qnN7buve2COjei7-GjNNdISZ8N0055fyNdbZHhvibjiQXHOpanaRHaF9LNF_fihq4ZLpMpVgB3Ow1qq-tnG55MM6BnZW6I30sN8dVoMlX-UPQCKl-Ix1nMC815uA4OwxzxdU35q4FASCRXEps3HozEgYKQLRU1tEYv1zpM33IgiztXKvJMMUWfUaegbhYhEmGx8-Ow/http%3A%2F%2Ferlweb.mit.edu%2Fsites%2Fdefault%2Ffiles%2FMiller%2520DAT%2520and%2520DTS%2520at.pdf



        The (horizontal) surface cable is a ruggedized polyurethane jacketed military type cable that is rodent-resistant with acrylate-coated fibers rated to 85°C. To install the cable, we dug a trench approximately 100 cm deep using a Ditch Witch-style trencher (Figure 4.12). The bottom surface of the trench was leveled and smoothed using a tool attached to the trencher and manually using a hoe. The trenching process took approximately two weeks. The cable was laid into the trench as five separate cable lengths spliced together using “direct-bury” enclosures.

        [cid:1df461d7-b929-4644-99da-2a0d7184f55b]

        https://www.osti.gov/biblio/1499141https://secure-web.cisco.com/1SIBGmReqQEnNWsqs5b1fzNuaZgcYdozKx6gnqYLRobaB3mSikpNYmj0AHpptfFjx8uumnH7ZagAgednTa6AvfeuQo3yZGpz55YKCeVVd3Uv_EDbC1EYVc_BdzWKq2vCRTXO3oW6IlzUeitqszkqQVk9M89vvfxAWHkCgKivxcOGkKwrsgKnTYlUS-zdMJHpiNKkuAk1rXMyX9v0UV8VTUdtE7wvBubuMJ7trx-5DamDXf0Q1kdOIqPykCE5UIHgKApRlyo18jwJ8CvGRc0Y1PfIqSw1SlZB-6hWU1m4TOqaLB2a9fFpv2lxjl2nQIPz7/https%3A%2F%2Fwww.osti.gov%2Fbiblio%2F1499141

        Feigl, K. L., and L. M. Parker (2019), PoroTomo Final Technical Report: Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, Medium: ED; Size: 176 p. pp, ; Univ. of Wisconsin, Madison, WI (United States). https://www.osti.gov/servlets/purl/1499141





        Kurt Feigl (he/him/his)
        Professor
        Department of Geoscience
        University of Wisconsin-Madison
        1215 West Dayton Street
        Madison, WI
        53706 USA


        http://geoscience.wisc.edu/feigl

        ________________________________
        From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of NEAL E LORD (via IRIS) <das-bounce<at>lists.ds.iris.edu>
        Sent: Tuesday, May 3, 2022 11:55
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
        Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

        Hi all,

        Pick a cable which won't be cut by rodents.

        -Neal
        ________________________________
        From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu>
        Sent: Tuesday, May 3, 2022 11:44 AM
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
        Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

        Out of the duct.
        I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
        All other duct installations have poor signal compared to direct bury.

        I'm sure every other vendor will say the same.

        Dan


        Get Outlook for Androidhttps://aka.ms/AAb9ysg
        ________________________________
        From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu>
        Sent: Tuesday, May 3, 2022 5:25:36 PM
        To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
        Subject: [IRIS][das] Fiber‐Optic Cable deployment

        Dear All,

        We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

        The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
        Please respond to me directly and I will compile responses for those interested.

        Any hint would be appreciated.
        Thanks
        Marco Olivieri

        -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com --

        Attachments
        • Douglas E Miller
          2022-05-04 00:40:13
          Interrogator monitors the fiber extremely well so it’s all about coupling fiber to your signal of interest and then separating that signal from nuisance signal. However, one guy’s nuisance is another guy’s key to interpretation of the mixed response.

          You may want to consider backfilling (cable outside PVC) with a slurry (e.g. bentonite) that will harden to enhance cable to ground coupling. PVC conduit will be a guide of some sort for signal that will couple to ground & cable.

          DTS acquired simultaneously with DAS from the same cable will show heterogeneity of soil & soil-cable coupling. DTS is better resolved spatially (less resolved temporally) than DAS.


          Douglas E Miller
          Research Affiliate
          Department of Earth, Atmospheric and Planetary Sciences, MIT
          77 Massachusetts Ave 54-211

          demiller<at>mit.edu<demiller<at>mit.edu>
          203 733 6751 (cell)
          http://www.mit.edu/~demiller





          On May 3, 2022, at 1:56 PM, Kurt Feigl (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> wrote:

          All,

          I agree with Dan that good coupling to the soil and rock is essential. I agree with Neal that protecting from rodents is also essential. The key words are "StrataJac® encapsulation" and "rodent deterrent additive". Please find below some information about the 9000 meters of cable deployed at Brady Hot Springs, Nevada as part of the PoroTomo project. If this information is helpful, then please cite the appropriate references.

          Best,

          Kurt

          The (horizontal) surface cable is a ruggedized military type cable that is rodent resistant with acrylate-coated fibers rated to 85°C, as shown in Figure 15. The cable was laid into the trench as five separate cable lengths and spliced together using “direct-bury” splice enclosures. The cable was tested for fiber integrity and the trench backfilled using a skid-steer loader.



          <image.png>



          Typical optical cables contain several bundled fibers within outer protective layers. Two types of cable were used at Brady. The trenched cable was a tight-buffered construction with a polymer jacket, the borehole cable was a fiber in metal tube (FIMT) based construction. Each cable contained several of both types of fiber: multimode (MM), used for DTS, and singlemode (SM), used for DAS. For each installation a pair of MM fibers were joined at the far end with a u-bend termination to allow a double-ended DTS configuration. The upper right photo in Figure 1 shows the splicebox at the terminus of the trench. A similar spliced pair of SM fibers were used for the borehole DAS installation (DASV) which was recorded over an interval that included both the wellhead and the turnaround splice with about 10 extra channels at each end (an aid to matching DTS and DAS channels with well geometry).



          Miller, Douglas E., Thomas Coleman, Xiangfang Zeng, Jeremy R. Patterson, Elena C. Reinisch, Michael A. Cardiff, Herbert F. Wang, Dante Fratta, Whitney Trainor-Guitton, and Clifford H. Thurber. "DAS and DTS at Brady Hot Springs: Observations about coupling and coupled interpretations." In Proceedings of the 43rd Workshop on Geothermal Reservoir Engineering, Stanford, CA, USA, pp. 12-14. 2018. http://erlweb.mit.edu/sites/default/files/Miller%20DAT%20and%20DTS%20at.pdfhttp://secure-web.cisco.com/1inWmo1EpKWa2g9M1iVVx4Kudgwh7HZP5341qhSC945n3BX7YnWRZCQZFVc8u1kQA7i3FK-eaDQn0QYI3du80a7vtKK5TQGiq6AoDO1NzXYK-n3TFvzdM_JtKl2qnN7buve2COjei7-GjNNdISZ8N0055fyNdbZHhvibjiQXHOpanaRHaF9LNF_fihq4ZLpMpVgB3Ow1qq-tnG55MM6BnZW6I30sN8dVoMlX-UPQCKl-Ix1nMC815uA4OwxzxdU35q4FASCRXEps3HozEgYKQLRU1tEYv1zpM33IgiztXKvJMMUWfUaegbhYhEmGx8-Ow/http%3A%2F%2Ferlweb.mit.edu%2Fsites%2Fdefault%2Ffiles%2FMiller%2520DAT%2520and%2520DTS%2520at.pdf



          The (horizontal) surface cable is a ruggedized polyurethane jacketed military type cable that is rodent-resistant with acrylate-coated fibers rated to 85°C. To install the cable, we dug a trench approximately 100 cm deep using a Ditch Witch-style trencher (Figure 4.12). The bottom surface of the trench was leveled and smoothed using a tool attached to the trencher and manually using a hoe. The trenching process took approximately two weeks. The cable was laid into the trench as five separate cable lengths spliced together using “direct-bury” enclosures.
          <image.png>
          https://www.osti.gov/biblio/1499141https://secure-web.cisco.com/1SIBGmReqQEnNWsqs5b1fzNuaZgcYdozKx6gnqYLRobaB3mSikpNYmj0AHpptfFjx8uumnH7ZagAgednTa6AvfeuQo3yZGpz55YKCeVVd3Uv_EDbC1EYVc_BdzWKq2vCRTXO3oW6IlzUeitqszkqQVk9M89vvfxAWHkCgKivxcOGkKwrsgKnTYlUS-zdMJHpiNKkuAk1rXMyX9v0UV8VTUdtE7wvBubuMJ7trx-5DamDXf0Q1kdOIqPykCE5UIHgKApRlyo18jwJ8CvGRc0Y1PfIqSw1SlZB-6hWU1m4TOqaLB2a9fFpv2lxjl2nQIPz7/https%3A%2F%2Fwww.osti.gov%2Fbiblio%2F1499141
          Feigl, K. L., and L. M. Parker (2019), PoroTomo Final Technical Report: Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, Medium: ED; Size: 176 p. pp, ; Univ. of Wisconsin, Madison, WI (United States). https://www.osti.gov/servlets/purl/1499141




          Kurt Feigl (he/him/his)
          Professor
          Department of Geoscience
          University of Wisconsin-Madison
          1215 West Dayton Street
          Madison, WI
          53706 USA

          http://geoscience.wisc.edu/feigl
          ________________________________
          From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of NEAL E LORD (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
          Sent: Tuesday, May 3, 2022 11:55
          To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
          Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

          Hi all,

          Pick a cable which won't be cut by rodents.

          -Neal
          ________________________________
          From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
          Sent: Tuesday, May 3, 2022 11:44 AM
          To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
          Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

          Out of the duct.
          I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
          All other duct installations have poor signal compared to direct bury.

          I'm sure every other vendor will say the same.

          Dan


          Get Outlook for Androidhttps://aka.ms/AAb9ysg
          ________________________________
          From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
          Sent: Tuesday, May 3, 2022 5:25:36 PM
          To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
          Subject: [IRIS][das] Fiber‐Optic Cable deployment

          Dear All,

          We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

          The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
          Please respond to me directly and I will compile responses for those interested.

          Any hint would be appreciated.
          Thanks
          Marco Olivieri
          -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com<cybersecurity<at>asn.com> --

          ----------------------
          Distributed Acoustic Sensing - For more information on the Distribution Acoustic Sensing Research Coordination Network, please go to: https://www.iris.edu/hq/initiatives/das_rcn
          Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe: das-unsubscribe<at>lists.ds.iris.edu<das-unsubscribe<at>lists.ds.iris.edu>

          Sent from the IRIS Message Center (http://ds.iris.edu/message-center/)
          Update subscription preferences at http://ds.iris.edu/account/profile/


          • Barry Freifeld
            2022-05-03 21:14:21
            Doug et al.,

            Thanks for the interesting discussion of buried DAS fiber. I take exception
            to the idea of using a backfill material that will harden to enhance ground
            coupling. My experience is that you want to minimize acoustic impedance
            contrast between the native formation and the DAS cable backfill material.
            The simplest way to achieve that is to use native materials, unless they
            could be damaging to the cable. In that case a small amount of sand can be
            used to surround the cable and then covered with native compacted
            materials.

            Best Regards,
            Barry

            _____________________________________________
            Barry Freifeld, Ph.D.
            Class VI Solutions, Inc.
            711 Jean St.
            Oakland, CA 94610
            cell (510) 520-2618
            bmfreifeld<at>classvisolutions.com


            On Tue, May 3, 2022 at 8:59 PM Douglas E Miller (via IRIS) <
            das-bounce<at>lists.ds.iris.edu> wrote:

            Interrogator monitors the fiber extremely well so it’s all about coupling
            fiber to your signal of interest and then separating that signal from
            nuisance signal. However, one guy’s nuisance is another guy’s key to
            interpretation of the mixed response.

            You may want to consider backfilling (cable outside PVC) with a slurry
            (e.g. bentonite) that will harden to enhance cable to ground coupling. PVC
            conduit will be a guide of some sort for signal that will couple to ground
            & cable.

            DTS acquired simultaneously with DAS from the same cable will show
            heterogeneity of soil & soil-cable coupling. DTS is better resolved
            spatially (less resolved temporally) than DAS.









            *Douglas E Miller Research Affiliate Department of Earth, Atmospheric
            and Planetary Sciences, MIT 77 Massachusetts Ave 54-211 demiller<at>mit.edu
            <demiller<at>mit.edu> 203 733 6751 (cell) http://www.mit.edu/~demiller
            http://www.mit.edu/~demiller*





            On May 3, 2022, at 1:56 PM, Kurt Feigl (via IRIS) <
            das-bounce<at>lists.ds.iris.edu> wrote:

            All,

            I agree with Dan that good coupling to the soil and rock is essential. I
            agree with Neal that protecting from rodents is also essential. The key
            words are "StrataJac® encapsulation" and "rodent deterrent additive".
            Please find below some information about the 9000 meters of cable deployed
            at Brady Hot Springs, Nevada as part of the PoroTomo project. If this
            information is helpful, then please cite the appropriate references.

            Best,

            Kurt

            The (horizontal) surface cable is a ruggedized military type cable that is
            rodent resistant with acrylate-coated fibers rated to 85°C, as shown in
            Figure 15. The cable was laid into the trench as five separate cable
            lengths and spliced together using “direct-bury” splice enclosures. The
            cable was tested for fiber integrity and the trench backfilled using a
            skid-steer loader.


            <image.png>



            Typical optical cables contain several bundled fibers within outer
            protective layers. Two types of cable were used at Brady.* The trenched
            cable was a tight-buffered construction with a polymer jacket,* the
            borehole cable was a fiber in metal tube (FIMT) based construction. *Each
            cable contained several of both types of fiber: *multimode (MM), used for
            DTS, and *singlemode (SM), used for DAS.* For each installation a pair of
            MM fibers were joined at the far end with a u-bend termination to allow a
            double-ended DTS configuration. The upper right photo in Figure 1 shows the
            splicebox at the terminus of the trench. A similar spliced pair of SM
            fibers were used for the borehole DAS installation (DASV) which was
            recorded over an interval that included both the wellhead and the
            turnaround splice with about 10 extra channels at each end (an aid to
            matching DTS and DAS channels with well geometry).


            Miller, Douglas E., Thomas Coleman, Xiangfang Zeng, Jeremy R. Patterson,
            Elena C. Reinisch, Michael A. Cardiff, Herbert F. Wang, Dante Fratta,
            Whitney Trainor-Guitton, and Clifford H. Thurber. "DAS and DTS at Brady Hot
            Springs: Observations about coupling and coupled interpretations." In *Proceedings
            of the 43rd Workshop on Geothermal Reservoir Engineering, Stanford, CA, USA*,
            pp. 12-14. 2018.
            http://erlweb.mit.edu/sites/default/files/Miller%20DAT%20and%20DTS%20at.pdf
            http://secure-web.cisco.com/1inWmo1EpKWa2g9M1iVVx4Kudgwh7HZP5341qhSC945n3BX7YnWRZCQZFVc8u1kQA7i3FK-eaDQn0QYI3du80a7vtKK5TQGiq6AoDO1NzXYK-n3TFvzdM_JtKl2qnN7buve2COjei7-GjNNdISZ8N0055fyNdbZHhvibjiQXHOpanaRHaF9LNF_fihq4ZLpMpVgB3Ow1qq-tnG55MM6BnZW6I30sN8dVoMlX-UPQCKl-Ix1nMC815uA4OwxzxdU35q4FASCRXEps3HozEgYKQLRU1tEYv1zpM33IgiztXKvJMMUWfUaegbhYhEmGx8-Ow/http%3A%2F%2Ferlweb.mit.edu%2Fsites%2Fdefault%2Ffiles%2FMiller%2520DAT%2520and%2520DTS%2520at.pdf



            The (horizontal) surface cable is a ruggedized polyurethane jacketed
            military type cable that is rodent-resistant with acrylate-coated fibers
            rated to 85°C. To install the cable, we dug a trench approximately 100 cm
            deep using a Ditch Witch-style trencher (Figure 4.12). The bottom surface
            of the trench was leveled and smoothed using a tool attached to the
            trencher and manually using a hoe. The trenching process took approximately
            two weeks. The cable was laid into the trench as five separate cable
            lengths spliced together using “direct-bury” enclosures.
            <image.png>
            https://www.osti.gov/biblio/1499141
            https://secure-web.cisco.com/1SIBGmReqQEnNWsqs5b1fzNuaZgcYdozKx6gnqYLRobaB3mSikpNYmj0AHpptfFjx8uumnH7ZagAgednTa6AvfeuQo3yZGpz55YKCeVVd3Uv_EDbC1EYVc_BdzWKq2vCRTXO3oW6IlzUeitqszkqQVk9M89vvfxAWHkCgKivxcOGkKwrsgKnTYlUS-zdMJHpiNKkuAk1rXMyX9v0UV8VTUdtE7wvBubuMJ7trx-5DamDXf0Q1kdOIqPykCE5UIHgKApRlyo18jwJ8CvGRc0Y1PfIqSw1SlZB-6hWU1m4TOqaLB2a9fFpv2lxjl2nQIPz7/https%3A%2F%2Fwww.osti.gov%2Fbiblio%2F1499141

            Feigl, K. L., and L. M. Parker (2019), PoroTomo Final Technical Report:
            Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology,
            Geodesy, and Hydrology, Medium: ED; Size: 176 p. pp, ; Univ. of Wisconsin,
            Madison, WI (United States). https://www.osti.gov/servlets/purl/1499141




            Kurt Feigl (he/him/his)
            Professor
            Department of Geoscience
            University of Wisconsin-Madison
            1215 West Dayton Street
            Madison, WI
            53706 USA

            http://geoscience.wisc.edu/feigl
            ------------------------------
            *From:* das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on
            behalf of NEAL E LORD (via IRIS) <das-bounce<at>lists.ds.iris.edu>
            *Sent:* Tuesday, May 3, 2022 11:55
            *To:* Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
            *Subject:* Re: [IRIS][das] Fiber‐Optic Cable deployment

            Hi all,

            Pick a cable which won't be cut by rodents.

            -Neal
            ------------------------------
            *From:* das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on
            behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu>
            *Sent:* Tuesday, May 3, 2022 11:44 AM
            *To:* Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
            *Subject:* Re: [IRIS][das] Fiber‐Optic Cable deployment

            Out of the duct.
            I have only seen one instance where duct improved DAS signal and this was
            a waterlogged duct!
            All other duct installations have poor signal compared to direct bury.

            I'm sure every other vendor will say the same.

            Dan


            Get Outlook for Android https://aka.ms/AAb9ysg
            ------------------------------
            *From:* das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu> on
            behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu>
            *Sent:* Tuesday, May 3, 2022 5:25:36 PM
            *To:* Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
            *Subject:* [IRIS][das] Fiber‐Optic Cable deployment

            Dear All,

            We have been offered to deploy our own fiber‐optic cable besides one
            telecom company deployment that will connect a town to a village (about 8
            km long). We expect to use it for seismic monitoring purposes with DAS. As
            far as we know they will use a standard method i.e. dig an 8 km long
            trench, bury a pvc duct and insert the fiber‐optic cable in it.

            The question is: Would it be better to insert our cable in the pvc duct
            besides the telecom one or to have it buried directly to the ground (out of
            pipe)? Do you know any paper or technical report that discusses this task?
            Please respond to me directly and I will compile responses for those
            interested.

            Any hint would be appreciated.
            Thanks
            Marco Olivieri
            -- This email was sent to you by someone outside of ASN. Be careful of
            attachments and links. Report suspicious emails to cybersecurity<at>asn.com
            --

            ----------------------
            Distributed Acoustic Sensing - For more information on the Distribution
            Acoustic Sensing Research Coordination Network, please go to:
            https://www.iris.edu/hq/initiatives/das_rcn
            Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
            das-unsubscribe<at>lists.ds.iris.edu

            Sent from the IRIS Message Center (http://ds.iris.edu/message-center/)
            Update subscription preferences at http://ds.iris.edu/account/profile/



            ----------------------
            Distributed Acoustic Sensing - For more information on the Distribution
            Acoustic Sensing Research Coordination Network, please go to:
            https://www.iris.edu/hq/initiatives/das_rcn
            Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
            das-unsubscribe<at>lists.ds.iris.edu

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            • Douglas E Miller
              2022-05-04 11:55:33
              Barry,

              Your point is well taken.

              I wonder what published comparisons of backfill strategy are now available.

              I imagine that in specific cases such as the one in question a comparison of two or three alternatives could be made at the site prior to the main installation.

              Keep in mind that the impact of impedance contrast is sensitive to the volume of contrasting material as well as to the slip condition at all material interfaces (including those within the cable).

              Best regards,
              Doug

              Douglas E Miller
              Research Affiliate
              Department of Earth, Atmospheric and Planetary Sciences, MIT
              77 Massachusetts Ave 54-211

              demiller<at>mit.edu<demiller<at>mit.edu>
              203 733 6751 (cell)
              http://www.mit.edu/~demiller

              On May 4, 2022, at 12:20 AM, Barry Freifeld (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> wrote:

              Doug et al.,

              Thanks for the interesting discussion of buried DAS fiber. I take exception to the idea of using a backfill material that will harden to enhance ground coupling. My experience is that you want to minimize acoustic impedance contrast between the native formation and the DAS cable backfill material. The simplest way to achieve that is to use native materials, unless they could be damaging to the cable. In that case a small amount of sand can be used to surround the cable and then covered with native compacted materials.

              Best Regards,
              Barry

              _____________________________________________
              Barry Freifeld, Ph.D.
              Class VI Solutions, Inc.
              711 Jean St.
              Oakland, CA 94610
              cell (510) 520-2618
              bmfreifeld<at>classvisolutions.com<bmfreifeld<at>classvisolutions.com>


              On Tue, May 3, 2022 at 8:59 PM Douglas E Miller (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> wrote:
              Interrogator monitors the fiber extremely well so it’s all about coupling fiber to your signal of interest and then separating that signal from nuisance signal. However, one guy’s nuisance is another guy’s key to interpretation of the mixed response.

              You may want to consider backfilling (cable outside PVC) with a slurry (e.g. bentonite) that will harden to enhance cable to ground coupling. PVC conduit will be a guide of some sort for signal that will couple to ground & cable.

              DTS acquired simultaneously with DAS from the same cable will show heterogeneity of soil & soil-cable coupling. DTS is better resolved spatially (less resolved temporally) than DAS.


              Douglas E Miller
              Research Affiliate
              Department of Earth, Atmospheric and Planetary Sciences, MIT
              77 Massachusetts Ave 54-211

              demiller<at>mit.edu<demiller<at>mit.edu>
              203 733 6751 (cell)
              http://www.mit.edu/~demiller





              On May 3, 2022, at 1:56 PM, Kurt Feigl (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> wrote:

              All,

              I agree with Dan that good coupling to the soil and rock is essential. I agree with Neal that protecting from rodents is also essential. The key words are "StrataJac® encapsulation" and "rodent deterrent additive". Please find below some information about the 9000 meters of cable deployed at Brady Hot Springs, Nevada as part of the PoroTomo project. If this information is helpful, then please cite the appropriate references.

              Best,

              Kurt

              The (horizontal) surface cable is a ruggedized military type cable that is rodent resistant with acrylate-coated fibers rated to 85°C, as shown in Figure 15. The cable was laid into the trench as five separate cable lengths and spliced together using “direct-bury” splice enclosures. The cable was tested for fiber integrity and the trench backfilled using a skid-steer loader.



              <image.png>



              Typical optical cables contain several bundled fibers within outer protective layers. Two types of cable were used at Brady. The trenched cable was a tight-buffered construction with a polymer jacket, the borehole cable was a fiber in metal tube (FIMT) based construction. Each cable contained several of both types of fiber: multimode (MM), used for DTS, and singlemode (SM), used for DAS. For each installation a pair of MM fibers were joined at the far end with a u-bend termination to allow a double-ended DTS configuration. The upper right photo in Figure 1 shows the splicebox at the terminus of the trench. A similar spliced pair of SM fibers were used for the borehole DAS installation (DASV) which was recorded over an interval that included both the wellhead and the turnaround splice with about 10 extra channels at each end (an aid to matching DTS and DAS channels with well geometry).



              Miller, Douglas E., Thomas Coleman, Xiangfang Zeng, Jeremy R. Patterson, Elena C. Reinisch, Michael A. Cardiff, Herbert F. Wang, Dante Fratta, Whitney Trainor-Guitton, and Clifford H. Thurber. "DAS and DTS at Brady Hot Springs: Observations about coupling and coupled interpretations." In Proceedings of the 43rd Workshop on Geothermal Reservoir Engineering, Stanford, CA, USA, pp. 12-14. 2018. http://erlweb.mit.edu/sites/default/files/Miller%20DAT%20and%20DTS%20at.pdfhttp://secure-web.cisco.com/1inWmo1EpKWa2g9M1iVVx4Kudgwh7HZP5341qhSC945n3BX7YnWRZCQZFVc8u1kQA7i3FK-eaDQn0QYI3du80a7vtKK5TQGiq6AoDO1NzXYK-n3TFvzdM_JtKl2qnN7buve2COjei7-GjNNdISZ8N0055fyNdbZHhvibjiQXHOpanaRHaF9LNF_fihq4ZLpMpVgB3Ow1qq-tnG55MM6BnZW6I30sN8dVoMlX-UPQCKl-Ix1nMC815uA4OwxzxdU35q4FASCRXEps3HozEgYKQLRU1tEYv1zpM33IgiztXKvJMMUWfUaegbhYhEmGx8-Ow/http%3A%2F%2Ferlweb.mit.edu%2Fsites%2Fdefault%2Ffiles%2FMiller%2520DAT%2520and%2520DTS%2520at.pdf



              The (horizontal) surface cable is a ruggedized polyurethane jacketed military type cable that is rodent-resistant with acrylate-coated fibers rated to 85°C. To install the cable, we dug a trench approximately 100 cm deep using a Ditch Witch-style trencher (Figure 4.12). The bottom surface of the trench was leveled and smoothed using a tool attached to the trencher and manually using a hoe. The trenching process took approximately two weeks. The cable was laid into the trench as five separate cable lengths spliced together using “direct-bury” enclosures.
              <image.png>
              https://www.osti.gov/biblio/1499141https://secure-web.cisco.com/1SIBGmReqQEnNWsqs5b1fzNuaZgcYdozKx6gnqYLRobaB3mSikpNYmj0AHpptfFjx8uumnH7ZagAgednTa6AvfeuQo3yZGpz55YKCeVVd3Uv_EDbC1EYVc_BdzWKq2vCRTXO3oW6IlzUeitqszkqQVk9M89vvfxAWHkCgKivxcOGkKwrsgKnTYlUS-zdMJHpiNKkuAk1rXMyX9v0UV8VTUdtE7wvBubuMJ7trx-5DamDXf0Q1kdOIqPykCE5UIHgKApRlyo18jwJ8CvGRc0Y1PfIqSw1SlZB-6hWU1m4TOqaLB2a9fFpv2lxjl2nQIPz7/https%3A%2F%2Fwww.osti.gov%2Fbiblio%2F1499141
              Feigl, K. L., and L. M. Parker (2019), PoroTomo Final Technical Report: Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, Medium: ED; Size: 176 p. pp, ; Univ. of Wisconsin, Madison, WI (United States). https://www.osti.gov/servlets/purl/1499141




              Kurt Feigl (he/him/his)
              Professor
              Department of Geoscience
              University of Wisconsin-Madison
              1215 West Dayton Street
              Madison, WI
              53706 USA

              http://geoscience.wisc.edu/feigl
              ________________________________
              From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of NEAL E LORD (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
              Sent: Tuesday, May 3, 2022 11:55
              To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
              Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

              Hi all,

              Pick a cable which won't be cut by rodents.

              -Neal
              ________________________________
              From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Daniel DANSKIN (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
              Sent: Tuesday, May 3, 2022 11:44 AM
              To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
              Subject: Re: [IRIS][das] Fiber‐Optic Cable deployment

              Out of the duct.
              I have only seen one instance where duct improved DAS signal and this was a waterlogged duct!
              All other duct installations have poor signal compared to direct bury.

              I'm sure every other vendor will say the same.

              Dan


              Get Outlook for Androidhttps://aka.ms/AAb9ysg
              ________________________________
              From: das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu> <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>> on behalf of Marco Olivieri (via IRIS) <das-bounce<at>lists.ds.iris.edu<das-bounce<at>lists.ds.iris.edu>>
              Sent: Tuesday, May 3, 2022 5:25:36 PM
              To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu<das<at>lists.ds.iris.edu>>
              Subject: [IRIS][das] Fiber‐Optic Cable deployment

              Dear All,

              We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

              The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
              Please respond to me directly and I will compile responses for those interested.

              Any hint would be appreciated.
              Thanks
              Marco Olivieri
              -- This email was sent to you by someone outside of ASN. Be careful of attachments and links. Report suspicious emails to cybersecurity<at>asn.com<cybersecurity<at>asn.com> --

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  • Philippe Jousset
    2022-05-03 20:43:02
    Ciao Marco,

    We have some experience of setting up conventional telecom cable
    (multimode and single mode fibres) in volcanic scoria (Etna volcano,
    Italy). We could perform quite convincing studies as shown in

    https://se.copernicus.org/articles/12/993/2021/ and

    https://www.nature.com/articles/s41467-022-29184-w

    In both cases, cables were dug in 10 cm to 30 cm depth directly in the
    scoria, without any duct or anything, to increase coupling.

    Thanks all for interesting discussion.

    All best,

    Philippe


    On 5/3/22 18:25, Marco Olivieri (via IRIS) wrote:
    Dear All,

    We have been offered to deploy our own fiber‐optic cable besides one
    telecom company deployment that will connect a town to a village
    (about 8 km long). We expect to use it for seismic monitoring purposes
    with DAS. As far as we know they will use a standard method i.e. dig
    an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable
    in it.

    The question is: Would it be better to insert our cable in the pvc
    duct besides the telecom one or to have it buried directly to the
    ground (out of pipe)? Do you know any paper or technical report that
    discusses this task?
    Please respond to me directly and I will compile responses for those
    interested.

    Any hint would be appreciated.
    Thanks
    Marco Olivieri

    ----------------------
    Distributed Acoustic Sensing - For more information on the Distribution Acoustic Sensing Research Coordination Network, please go to: https://www.iris.edu/hq/initiatives/das_rcn
    Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe: das-unsubscribe<at>lists.ds.iris.edu

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    Update subscription preferences at http://ds.iris.edu/account/profile/

    --
    Dr. Philippe Jousset
    -
    EGU Seismology Division President
    -
    Helmholtz-Zentrum Potsdam
    Deutsches GeoForschungsZentrum GFZ
    Near-surface Geophysics
    Telegrafenberg, 14473 Potsdam, Germany
    Tel.: +49 (0) 331 288 1299
    Email: pjousset<at>gfz-potsdam.de
    http://www.gfz-potsdam.de/


  • kasey.aderhold@iris.edu
    2022-05-04 13:01:16
    Thank you, Marco, for starting off such a vigorous discussion. I've given
    all timezones a fair shot at this and kept responses open, but I would like
    to encourage folks to respond directly to one another now.

    Given that this is a topic of interest, however, please get in touch with
    me directly at kasey<at>iris.edu if you would like to be involved in a
    discussion or panel on fiber emplacement techniques in the near future.

    Cheers,
    Kasey

    On Tue, May 3, 2022 at 12:29 PM Marco Olivieri (via IRIS) <
    das-bounce<at>lists.ds.iris.edu> wrote:

    Dear All,

    We have been offered to deploy our own fiber‐optic cable besides one
    telecom company deployment that will connect a town to a village (about 8
    km long). We expect to use it for seismic monitoring purposes with DAS. As
    far as we know they will use a standard method i.e. dig an 8 km long
    trench, bury a pvc duct and insert the fiber‐optic cable in it.

    The question is: Would it be better to insert our cable in the pvc duct
    besides the telecom one or to have it buried directly to the ground (out of
    pipe)? Do you know any paper or technical report that discusses this task?
    Please respond to me directly and I will compile responses for those
    interested.

    Any hint would be appreciated.
    Thanks
    Marco Olivieri

    ----------------------
    Distributed Acoustic Sensing - For more information on the Distribution
    Acoustic Sensing Research Coordination Network, please go to:
    https://www.iris.edu/hq/initiatives/das_rcn
    Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
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    --

    Kasey Aderhold, Ph.D.
    Project Associate | IRIS Instrumentation Services
    202-407-7019 | kasey<at>iris.edu | (she/her)
    Currently teleworking M-F, 10am-6pm ET

    • Marco Olivieri
      2022-05-09 15:10:27
      Dear All,
      I would like to thank you for the detailed responses I got for my question.
      We now have a clear view of how to approach the deployment and also on how
      to choose the proper cable.

      Since this discussion could be of some interest to other people I created a
      summary with all the responses I received.
      These can be found at this link:
      https://docs.google.com/document/d/1mT6EkzBkWKAyaIGnCmn4JxI0xj9mjz6b_TSvBu-gcr8/edit?usp=sharing

      I almost anonymized the answers, leaving only the first name and removing
      family name and email. Hope this is ok

      regards
      Marco




      Il giorno mer 4 mag 2022 alle ore 19:05 Kasey Aderhold (via IRIS) <
      das-bounce<at>lists.ds.iris.edu> ha scritto:

      Thank you, Marco, for starting off such a vigorous discussion. I've given
      all timezones a fair shot at this and kept responses open, but I would like
      to encourage folks to respond directly to one another now.

      Given that this is a topic of interest, however, please get in touch with
      me directly at kasey<at>iris.edu if you would like to be involved in a
      discussion or panel on fiber emplacement techniques in the near future.

      Cheers,
      Kasey

      On Tue, May 3, 2022 at 12:29 PM Marco Olivieri (via IRIS) <
      das-bounce<at>lists.ds.iris.edu> wrote:

      Dear All,

      We have been offered to deploy our own fiber‐optic cable besides one
      telecom company deployment that will connect a town to a village (about 8
      km long). We expect to use it for seismic monitoring purposes with DAS. As
      far as we know they will use a standard method i.e. dig an 8 km long
      trench, bury a pvc duct and insert the fiber‐optic cable in it.

      The question is: Would it be better to insert our cable in the pvc duct
      besides the telecom one or to have it buried directly to the ground (out of
      pipe)? Do you know any paper or technical report that discusses this task?
      Please respond to me directly and I will compile responses for those
      interested.

      Any hint would be appreciated.
      Thanks
      Marco Olivieri

      ----------------------
      Distributed Acoustic Sensing - For more information on the Distribution
      Acoustic Sensing Research Coordination Network, please go to:
      https://www.iris.edu/hq/initiatives/das_rcn
      Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
      das-unsubscribe<at>lists.ds.iris.edu

      Sent from the IRIS Message Center (http://ds.iris.edu/message-center/)
      Update subscription preferences at http://ds.iris.edu/account/profile/



      --

      Kasey Aderhold, Ph.D.
      Project Associate | IRIS Instrumentation Services
      202-407-7019 | kasey<at>iris.edu | (she/her)
      Currently teleworking M-F, 10am-6pm ET


      ----------------------
      Distributed Acoustic Sensing - For more information on the Distribution
      Acoustic Sensing Research Coordination Network, please go to:
      https://www.iris.edu/hq/initiatives/das_rcn
      Topic home: http://ds.iris.edu/message-center/topic/das/ | Unsubscribe:
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  • Chris Minto
    2022-05-04 13:13:10
    Hi Marco

    Would recommend the FOSA publications on this topic – they sweep up a LOT of what has been said.

    https://www.fiberopticsensing.org/page/installation-considerations

    There isn’t one for seismic purposes but the other land based ones will suffice (e.g. pipelines)

    Other comments:


    * If gel filled – loose tube and NOT dry powder filled
    * Tight buffered will be excellent coupling but of course if over strained will have a higher risk of breakage
    * Sensitivity wise an unarmoured cable in a conduit has similar sensitivity to an armoured direct burial cable – some slight deltas

    Regards

    Chris



    Dr Chris Minto
    Engineering Director


    Mobile: +44 7500 782 508
    Email: chris.minto<at>optasense.com<chris.minto<at>optasense.com>

    From: das-bounce<at>lists.ds.iris.edu <das-bounce<at>lists.ds.iris.edu>
    Sent: 03 May 2022 17:26
    To: Distributed Acoustic Sensing <das<at>lists.ds.iris.edu>
    Subject: [IRIS][das] Fiber‐Optic Cable deployment

    Dear All,

    We have been offered to deploy our own fiber‐optic cable besides one telecom company deployment that will connect a town to a village (about 8 km long). We expect to use it for seismic monitoring purposes with DAS. As far as we know they will use a standard method i.e. dig an 8 km long trench, bury a pvc duct and insert the fiber‐optic cable in it.

    The question is: Would it be better to insert our cable in the pvc duct besides the telecom one or to have it buried directly to the ground (out of pipe)? Do you know any paper or technical report that discusses this task?
    Please respond to me directly and I will compile responses for those interested.

    Any hint would be appreciated.
    Thanks
    Marco Olivieri

21:50:13 v.ad6b513c