Significance of Coupling of Distributed Fibre Optic Sensor Systems for Vertical Seismic Profiling

Abstract : Distributed Acoustic Sensing (DAS) is a new technology of seismic acquisition that relies on traditional fibre-optic cables to provide inline strain measurement. This acquisition system is largely used in vertical seismic profiling (VSP) surveys. Coupling is a key factor influencing data quality. While geophones and accelerometers are clamped to the borehole wall during VSP surveys, the fibre cable is either clamped and then cemented behind the casing, or attached with rigid clamps to the tubing, or loosely lowered into the borehole. The latter deployment strategy, also called wireline deployment, usually acquires the lowest level of signal but is regarded as the most cost-effective in particular for existing well installations. This PhD thesis addresses the problematic of coupling of DAS using wireline deployment. We develop numerical models that are used to analyse real data. The interpretation of these results allows us concluding that an immediate contact of the cable with the borehole wall with a computed contact force is required to provide good coupling conditions. Based on those findings, we propose solutions to further optimise DAS acquisitions. We numerically modify the contact force and the elastic properties of the DAS cable and show how these modifications can improve but also deteriorate data quality. Finally, we propose a coupling detection algorithm that is applied to real datasets and allows ensuring the acquisition of data with a high signal-to-noise ratio.
Document type :
Theses
Complete list of metadatas

Cited literature [129 references]  Display  Hide  Download

https://pastel.archives-ouvertes.fr/tel-01789878
Contributor : Abes Star <>
Submitted on : Friday, May 11, 2018 - 2:20:07 PM
Last modification on : Wednesday, May 15, 2019 - 10:19:08 AM
Long-term archiving on : Monday, September 24, 2018 - 1:18:00 PM

File

2017PSLEM042_archivage.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01789878, version 1

Citation

Sven Schilke. Significance of Coupling of Distributed Fibre Optic Sensor Systems for Vertical Seismic Profiling. Earth Sciences. PSL Research University, 2017. English. ⟨NNT : 2017PSLEM042⟩. ⟨tel-01789878⟩

Share

Metrics

Record views

178

Files downloads

57