Multicomponent & helically-wound DAS fibre — progress + full abstracts

Compiled 2026-06-30 from a multi-source, adversarially-verified search (21 confirmed claims) + targeted abstract retrieval. English only; full abstracts included.

Synthesis & maturity verdict

The problem. A straight glass DAS fibre is sensitive only to axial strain along its tangent — it is broadside-insensitive (blind to waves arriving perpendicular to the cable) and effectively single-component. This makes straight fibre unusable for surface reflection seismic (raypaths ⟂ cable) and unable to characterise multiple wave modes (no native Vs).

Two distinct goals — don’t conflate them:

Broadside sensitivity (so a horizontal surface cable can record reflections). Solved engineering. A helically-wound fibre is sensitive to broadside waves; sensitivity is tuned by the wrapping angle, with an optimum ≈ 30° for plastic cables (Kuvshinov 2016). The first broadside-sensitive cable was field-trialled in 2013 (Hornman et al.) and matched 3C accelerometers in all directions. Field-proven again at Groningen with straight + helical fibre (Al Hasani 2023).
Full multicomponent / shear (Vs) recovery (the whole 6C strain tensor). Still emerging. This is harder and subtler than broadside sensitivity.

The key, non-obvious result (the crux): Helical shaping alone does NOT recover shear. If the gauge length spans an integer number of helical winds (the normal case — typical gauge ~10 m ≫ helix period ~28 cm), the shear-strain terms cancel — the fibre stays shear-insensitive. Shear sensitivity is unlocked only when the gauge length drops below the helix period (~3 cm), at which point elastic-FWI Vp/Vs/density results become comparable to point-sensor geophones (Eaid, Keating & Innanen 2020). Such sub-period gauge lengths are “on the horizon” (5 cm systems emerging; Silixa offers a 25 cm gauge). This is the single biggest gating constraint.

Full strain-tensor reconstruction. Rather than one clever fibre, combine multiple projections — e.g. 5 helical + 1 straight fibre → 6 strain projections → full 3D strain tensor in a least-squares sense (Ning & Sava 2018). Design is optimised via the condition number of the fibre geometry. Helical-winding strain reconstruction has since been pushed into anisotropic elastic RTM with non-regular variable-pitch windings (Zhang et al. 2024).

Elastic FWI with DAS. DAS strain data cannot feed conventional FWI directly — the receiver operator must be redefined to supply tangential strain using the fibre geometry (Eaid et al. 2023). Joint inversion of geophone + shaped-DAS data beats either alone for Vp/Vs/density. Validated on field VSP data (accelerometer + DAS) at the CaMI/Newell County CO₂ site, Alberta.

Field hardware maturity. CREWES (U. Calgary) built and buried a prototype multicomponent shaped-fibre array (“the pretzel”) in 2018; ran multi-azimuth walk-away VSP with co-located 3C geophones + accelerometers + fibre at Newell (2018–2019); and nine-component (9C) DAS acquisition on experimental multicomponent sensors continues (2024–2025). These remain experimental/prototype, not productised.

Manufacturers (commercial reality):

Company	Product	Engineered / helical?	Claim	Status
Silixa	Carina Sensing System + Constellation fibre	Engineered fibre (Silixa also sells helically-wound surface cables)	100× / 20 dB lower noise floor vs standard fibre; gauge length selectable 25 cm–30 m	Commercial
OptaSense (Luna)	QuantX interrogator	Standard single-mode fibre; “designed for engineered fibres”	100 km range, 50,000 ch, +15 dB noise floor, DC-to-Nyquist	Commercial
Others (AP Sensing, Febus, Aragón, NEC, Sintela…)	interrogators	mostly straight fibre	—	varies

Verdict — two-speed answer:

Broadside-sensitive / engineered fibre for surface seismic & sensitivity → commercially available & field-proven (Silixa Constellation; broadside cables since 2013). Not just emerging.
True multicomponent / shear-recovery helical DAS (9C, Vs from a single deployment) → still emerging / research-stage: needs sub-period gauge lengths (~3 cm) that are not yet standard, plus multi-fibre reconstruction; demonstrated in theory + synthetics + a few field prototypes (CREWES/Newell), not productised. The phrase “still emerging” is accurate specifically for the multicomponent/shear goal.

Papers — full abstracts

Theory & broadside sensitivity

Kuvshinov, B.N. (2016) — Interaction of helically wound fibre-optic cables with plane seismic waves. Geophysical Prospecting. 10.1111/1365-2478.12303

Distributed acoustic sensing is a novel technology for seismic acquisition. In this technology, strain changes induced by seismic waves impinging on an optical fibre are monitored. Due to the fact that glass is relatively rigid, straight glass fibres are not sensitive to broadside waves. We suggest using distributed acoustic sensing systems with fibres helically wound around cables. One increases the fibre sensitivity to broadside waves by decreasing the fibre wrapping angle (the angle between the fibre axis and the plane normal to the cable axis). The optimal wrapping angle is chosen to minimize the impact of Rayleigh waves on the signal measured. This angle depends on the cable Poisson ratio, and it is approximately equal to 30° for cables composed of plastic. For reliable detection of seismic waves, one needs a good mechanical contact between the cable and the surrounding medium. On the other hand, the sensitivity of distributed acoustic sensing systems to primary waves can be significantly reduced if the cable is placed in a cemented borehole.

Hornman, K., Kuvshinov, B., Zwartjes, P., Franzen, A. (2013) — Field Trial of a Broadside-sensitive Distributed Acoustic Sensing Cable for Surface Seismic. EAGE. 10.3997/2214-4609.20130383

Distributed Acoustic Sensing (DAS) for seismic applications is a relatively new technology. It is based on the measurement of strain by means of Rayleigh back-scattering by inhomogeneities in an optical fibre. DAS for seismic is promising, because the sensing cable does not require any power and it is potentially low-cost. In addition, the sampling along the cable can be adapted to the geophysical needs in the field by a setting in the Interrogator Unit. Successful seismic DAS applications have been shown earlier for Vertical Seismic Profiling. A limitation of current DAS cables is that they are insensitive in the broadside direction, perpendicular to the cable, making them unsuitable for reflection seismic with a horizontal cable, as used in surface seismic. In this paper we describe a novel DAS cable with broadside-sensitivity. Such a cable was manufactured and a field trial was carried out to validate the theoretical predictions of its angular sensitivity, by comparing this cable with 3C accelerometers. The results indicate that the cable is indeed sensitive in all directions - to our knowledge a first in the industry. This property enabled the acquisition of seismic reflection data at the surface with a horizontal DAS cable.

Adeniyi, A.B., Abdul Latiff, A.H., Adedeji, Z.O., Md Arshad, A.R. (2025) — Directional sensitivity of fibre optic cables for surface seismic reflection DAS: a review and potential solutions for enhanced sensitivity. Geomechanics and Geophysics for Geo-Energy and Geo-Resources. 10.1007/s40948-025-00972-0

Fibre optic distributed acoustic sensing (FO-DAS) technology is continually gaining attention in the seismic industry due to its cost-effectiveness, longer aperture sensing, minimal maintenance, and its capability to deliver seismic data with high spatial resolution for imaging subsurface stratigraphy and structures. This technology, which consists of an optoelectronic interrogator unit and fibre optic cables as sensors, has been deployed in various geophysical borehole investigations. However, its surface-deployment for subsurface imaging has been limited due to the sensor’s broadside insensitivity. This review significantly advances the understanding of FO-DAS technology, with a particular focus on surface-deployed fiber-optic cables for subsurface imaging. We provide an extensive review of innovative cable configurations, such as inertial member cables, sinusoidal and helical cables, which have been designed and deployed to overcome the broadside sensitivity limitations of straight surface-deployed cables. The potential of surface-deployed fibre optic technology for multicomponent sensing is also explored in detail. In addition, we propose improvements in cable design, cable materials and fibreglass refractive properties for enhanced sensitivity.

Multicomponent / full strain-tensor reconstruction

Ning, I. Lim Chen & Sava, P. (2018) — Multicomponent distributed acoustic sensing: Concept and theory. GEOPHYSICS 83(2). 10.1190/geo2017-0327.1

Distributed acoustic sensing (DAS) data are increasingly used in geophysics. Lower in cost and higher in spatial resolution, DAS data are appealing, especially in boreholes in which optical fibers are readily available. DAS has the potential to become a permanent reservoir monitoring tool with a reduced sensing time interval. To accomplish this goal, it is critical that DAS can record all wave modes to fully characterize reservoir properties. This goal can be achieved by recording the complete strain tensor consisting of 6C. Conventional DAS provides projections of these components along the optical fiber by observing deformation along the fiber. To obtain the entire 6C strain tensor, we have developed an approach using multiple strain projections measured along optical fibers with judiciously chosen geometry. We evaluate designs combining multiple helical configurations or a single helical configuration together with a straight optical fiber that allow access to multiple strain projections. We group multiple strain projections in a given spatial window to perform reconstruction of the entire strain tensor in a least-squares sense under the assumption that the seismic wavelength is larger than the analysis window size. We determine how optimal optical fiber parameters can be selected using a scan of the entire configuration space and analyzing the condition number associated with the geometry of the optical fibers. We develop our method through synthetic experiments using realistic fiber geometry and wavefields of arbitrary complexity.

Ning, I. Lim Chen & Sava, P. (2018) — High-resolution multi-component distributed acoustic sensing. Geophysical Prospecting. 10.1111/1365-2478.12634

Distributed acoustic sensing uses an optical fibre together with an interrogator unit to perform strain measurements. The usage of distributed acoustic sensing in geophysics is attractive due to its dense spatial sampling and low operation cost if the optical fibre is freely accessible. In the borehole environment, optical fibres for distributed acoustic sensing are often readily available as a part of other sensing tools, such as for temperature and pressure. Although the distributed acoustic sensing system promises great potential for reservoir monitoring and surface seismic acquisition, the single axial strain measurement of distributed acoustic sensing along the fibre is inadequate to fully characterise the different wave modes, thus making reservoir characterisation challenging. We propose an acquisition system using five equally spaced helical optical fibres and a straight optical fibre to obtain six different strain projections. This system allows us to reconstruct all components of the 3D strain tensor at any location along the fibre. Analysing the condition number associated with the geometry of the optical fibre, we can systematically search for the optimum design parameters for our configuration. Numerical examples demonstrate the effectiveness of our proposed method to successful reconstruction of the full strain tensor from elastic wavefields of arbitrary complexity.

Zhang, L., Zhao, Y., Liu, L., Niu, F. (2024) — Strain field reconstruction from helical-winding fiber DAS and its application in anisotropic elastic reverse time migration. GEOPHYSICS. 10.1190/geo2023-0354.1

Optical fiber-based distributed acoustic sensing (DAS) technology has been a popular seismic acquisition tool due to its easy deployment, wide bandwidth, and dense sampling. However, the sensitivity of straight optical fiber to only single-axis strain presents challenges in fully characterizing multicomponent seismic wavefields, making it difficult to use these data in elastic reverse time migration (ERTM). The helical-winding fiber receives projecting signals projected onto the fiber from all seismic strain field components and has the potential to reconstruct those strain components for ERTM imaging. Here, we give detailed mathematical principles of helical fiber-based DAS with crucial parameters such as pitch angle, gauge length, and rotating angle. At least six points of DAS responses are required in one or several winding periods to rebuild the strain fields within the seismic wavelength. The projecting matrix of conventional regular helical-winding fiber is singular and ill conditioned, which results in computation challenges for the inverse of the Hessian matrix for strain component reconstruction. To tackle this problem, we develop a nonregular variant pitch-angle winding configuration for helical fiber. Our winding design is validated using the rank and condition number of the projecting matrix. The recovered strain components from the DAS response are then used to backward propagate the receiver wavefields in ERTM with an efficient P/S decoupled approach. Two synthetic examples demonstrate the effectiveness of our approach.

Elastic FWI with shaped DAS fibre

Eaid, M.V., Keating, S.D., Innanen, K.A. (2020) — Multiparameter seismic elastic full-waveform inversion with combined geophone and shaped fiber-optic cable data. GEOPHYSICS. 10.1190/geo2020-0170.1

Distributed acoustic sensing (DAS) is a rapidly growing technology for seismic acquisition, with the potential to sample rarely available wavefield components in reservoir settings. How to best use the information that DAS supplies to estimate reservoir properties is an open question. Full-waveform inversion (FWI) of DAS data, alone or in combination with geophone data, is a natural possibility to pursue. A mixed formulation must accommodate particle velocity data and 1C measurements of strain or strain rate in the direction tangent to a fiber-optic cable, which itself may take on some characteristic shape. Expecting that these amplitude and directionality properties of DAS data will impact parameter resolution in FWI, especially when incorporating finite gauge lengths, we have developed two appraisal methods. The first is an analytic description of the relationship between the spatial period and the elastic-wave sensitivity within a helical-wound fiber (which builds on a symmetry class of fibers insensitive to shear strains). The second is an extension of scattering radiation pattern analysis to DAS sensors of arbitrary geometry. We then numerically analyze the FWI response. Using 2D simulations and several simple models including the Marmousi2, we analyze the effect that shaping of the DAS fiber has on parameter estimations, by comparing inversion results derived from straight and various coiled fibers in a horizontal well. Fiber geometry is observed to have important implications for the accuracy and fidelity of DAS-FWI parameter estimates. It is also clear that the complementary features of DAS and standard geophone data impact FWI. Simultaneous inversions of surface geophone and DAS data from horizontal wells convincingly outperform inversions from either data set alone.

Eaid, M.V., Keating, S.D., Innanen, K.A., Macquet, M. (2023) — Field assessment of elastic full-waveform inversion of combined accelerometer and DAS data in a VSP configuration. GEOPHYSICS 88(6):WC163. 10.1190/geo2023-0066.1

Seismic data are a significant facilitator for monitoring in carbon capture and sequestration projects, providing high-resolution images of fluid migration, using, for example, full-waveform inversion (FWI). Distributed acoustic sensing (DAS), a relatively novel technology for wavefield sampling, is well suited for this type of monitoring. Using noninvasive optical fibers, DAS allows for dense spatial sampling along the entire length of the wellbore, without disrupting operations. Permanently installed in the wellbore, typically behind casing, DAS offers highly repeatable and dense sampling of the transmitted wave modes crucial to seismic monitoring of injected carbon dioxide (CO₂). However, the DAS data consist of measurements of strain along the tangent of the fiber and therefore do not transfer directly to conventional FWI algorithms. Incorporation of DAS data in their native strain (or strain-rate) form in standard FWI algorithms requires changing the definition of the receiver sampling operator to use geometric information about the fiber to supply tangential strain measurements to the FWI residual. The theoretical developments are applied to invert field vertical seismic profile data acquired with DAS fiber and accelerometers at a CO₂ sequestration site in Newell County, Alberta. Our method incorporates DAS data and accelerometer data in one objective function and allows us to tune the relative importance we wish to place on each data set. This method also transfers to noncollocated sensors, for example, surface-deployed geophones and borehole fiber. The inverted models contain features expected from the geology of the field site, and data modeled in the inverted models compare favorably with the field data. The models are derived from data acquired prior to CO₂ injection, representing baseline models for future time-lapse studies.

Eaid, M., Keating, S., Innanen, K. (2020) — The role of fiber gauge lengths in elastic FWI of data from coiled DAS fibers. CREWES Research Report 32 (CRR202011). PDF

Distributed acoustic sensing offers distinct benefits for reservoir monitoring; the increased access it provides to borehole acquisition geometries can supply transmission data crucial to successful FWI on land. The properties of the fiber — its geometric shape and its gauge length, especially in relation to the geometry — have implications for parameter resolution in FWI. This paper explores the role of the fiber gauge length in FWI by examining (1) how it affects a given fiber’s sensitivity to each component of the strain field, and (2) how the relative sensitivity to these strain components affects multiparameter elastic inversion. Key result: if the gauge length contains an integer number of winds the shear-strain components cancel (the fiber is shear-insensitive); gauge lengths shorter than one wind period (a typical helix advances ≈27.6 cm/period; 5 cm gauge systems are emerging) unlock shear-strain sensitivity and markedly improve inversion, especially for Vs.

Innanen, K. (2017) — Geometrical parameterization of a helically-wound DAS fibre in a curved cable (acquisition research). CREWES / EAGE 2017. PDF

Introduces a geometrical parameterization of a helically-wound fibre encased in a cable whose axis itself may be arbitrarily curved, enabling full multicomponent elastic estimation from shaped fibre. Frames optimizing DAS fibre curvature to raise SNR and enable full multicomponent elastic estimation as an open acquisition research problem (DAS reduced sensitivity/SNR relative to clamped geophones noted as the key limiting issue).

Field prototypes / 9C / surface

Innanen, K., Lawton, D., Hall, K., Bertram, K., Bertram, M., Bland, H. (2018) — Design and deployment of a prototype multicomponent DAS sensor (“the pretzel”). CREWES Research Report (CRR201823). PDF

In 2016–2017 CREWES published analyses and applications of a geometrical model of fibre-optic (DAS) data for arbitrary fibre shapes, including a multicomponent estimation scheme based on combined use of varying fibre directions in a shaped cable. In 2018 a prototype shaped DAS fibre array (“the pretzel”) was buried to test these ideas. In October 2018 it was illuminated from several directions, and shot records were analyzed to assess whether commonly available directional sensitivity is sufficient to permit multiple components of strain to be estimated simultaneously.

Bevc, D., Nedorub, O., Hall, K.W., Bertram, K.L. (2019) — Simultaneous accelerometer and optical-fibre multi-azimuth walk-away VSP experiment: Newell County, Alberta. SEG. 10.1190/segam2019-3216606.1

CREWES conducted a high-resolution multi-azimuth walk-away three-component VSP survey at the Containment and Monitoring Institute’s Field Research Station (CaMI.FRS) in September 2018, primarily intended for full-waveform inversion and modelling studies. The FRS has three wells (geophysics, injection, geochemistry). The 2018 VSP had thirteen source lines (four at 10 m VP spacing, the rest at 60 m), an Inova Univib 1–150 Hz sweep, and — in addition to permanent 3C geophones and optical fibre — a string of Inova 3C VectorSeis accelerometers in the geophysics well from surface to bottom hole. First-break picks sorted by offset and azimuth confirm very weak HTI anisotropy at the FRS.

Al Hasani, M. & Drijkoningen, G. (2023) — Experiences with DAS using both straight and helically wound fibers in surface-deployed cables: a case history in Groningen, The Netherlands. arXiv:2304.04384 (submitted to GEOPHYSICS). 10.48550/arXiv.2304.04384

DAS has been limited for surface-seismic reflection due to the fiber’s decreased sensitivity when deployed horizontally. The authors deployed both straight and helically wound fibers in a trench in Groningen using seismic vibration sources. Helically wound fibers dampened surface-wave amplitudes predictably with wrapping angle; both engineered straight and helically wound fibers produced reflection images comparable to geophone data. The combined use of straight (SF) and helically-wound (HWF) fibre proved useful — SF showed better sensitivity in the shallower part, HWF in the deeper part.

Manufacturers (full specs)

Silixa — Carina® Sensing System + Constellation™ fibre. “Engineered fibre optic sensing system combining the extensive, high-density coverage of distributed sensors with sensitivity beyond that of point sensors.” Engineered Constellation fibres give two orders of magnitude lower noise floor (100× / 20 dB improvement) over standard fibres. Software-selectable gauge length 25 cm / 2 m / 10 m / 30 m; sensing range 15–60 km; 1 kHz amplitude spectral density down to 70 fε/√Hz at 30 m gauge; dynamic range 130 dB; sample spacing 25 cm–32 m. (Silixa also markets helically-wound surface cables for broadside/surface seismic.)

OptaSense (Luna Innovations) — QuantX DAS interrogator. 100 km range on standard single-mode fibre; 50,000 channels at 2 m spacing; adjustable gauge length; +15 dB noise-floor improvement over prior generation; DC-to-Nyquist flat response; quantitative phase + amplitude in real time. “Designed for engineered fibres and cables” but uses standard single-mode fibre (not specifically helically-wound).

More in the corpus

The scanned OnePetro corpus has ~50 further multicomponent / Vs / 9C papers with full abstracts in the local ~/literature/geophysics/scanned_corpus_full-abstracts.md — notably Hall, Innanen & Lawton (2025), “Nine component DAS acquisition on experimental multi-component sensors” (10.1190/image2025-4316702.1) and the coiled-DAS gauge-length FWI (10.1190/segam2020-3427798.1).