DAS hybrid surveys with conventional

Part 9 — DAS and emerging technology

Learning objectives

Describe the fit of DAS + conventional receivers
Compare deployment and channel-count economics
List representative hybrid surveys in production use
Recognise that the DAS strip adds dense sampling along one transect

Pure-DAS surveys are rare. Real deployments mix DAS with conventional OBN, OBC, cable, or node patches. The conventional patch delivers broad 3D coverage with full azimuth. The DAS line — along existing fibre infrastructure — adds ultra-dense 1 m sampling along one specific transect.

When the hybrid wins

Two scenarios pencil out cleanly. First: a pipeline right-of-way that needs ongoing surveillance (leak detection, landslide monitoring). The DAS on the pipeline fibre is effectively free; a coarse OBN patch alongside gives 3D context. Second: a producing reservoir where a monitor well already has cemented fibre for VSP work. A cable or node patch over the reservoir plus the well’s DAS gives dense vertical sampling exactly where drilling is planned, with surrounding 3D context from the patch.

Economics

Conventional receiver install cost: $3,000–$ 15,000 per station depending on terrain. DAS marginal cost: a $50–$ 150 k interrogator plus already-installed fibre. For a 4 km transect, DAS channel density (4000 channels at 1 m) would cost tens of millions in conventional receivers but ≤ role="main" aria-label="Lesson content" tabindex="-1"50 k in DAS hardware. The capital trade-off favours DAS overwhelmingly along any transect where the fibre exists.

Real-world deployments

PGS “Apollon” (North Sea, 2022) combined streamer + DAS for pre-stack-depth-migration imaging. Aramco Ghawar passive DAS with 4C geophone reference receivers. Shell Ormen Lange OBN + DAS on the pipeline fibre (2021–2023). Equinor Johan Sverdrup permanent OBN PRM augmented with behind-casing DAS in all monitoring wells. The pattern: conventional for azimuth, DAS for dense along-line sampling.

References

Mougenot, D. (2013). MEMS-based 3C accelerometers for land seismic acquisition. The Leading Edge, 32(4), 388–396.
Vermeer, G. J. O. (2002). 3-D Seismic Survey Design. SEG Geophysical References 12.
Berg, E., Svenning, B., Martin, J. (2010). OBN technology — recent developments. EAGE Workshop on Permanent Reservoir Monitoring.