Frequency Modulated Continuous Wave Analysis of Dynamic Load Deformation in Geomaterials

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This research advances the use of microwave radar to assess geomaterial properties by the novel application of frequency modulated continuous wave (FMCW) radar to uniaxially loaded sandstones in the laboratory. Here contrasts in reflection coefficient are interpreted to represent microfracture formation and cross-linking under compressive loading prior to through-going sample failure. The Darney and Red St. Bees sandstones are characterized via optical microscope, X-ray radiography and tomography and by SEM methods and are tested for FMCW response under uniaxial compressive loads, with results showing that FMCW interrogation in the K-band is highly sensitive to the progression of bulk axial shortening and material bulk composition. The results reported here present an external, non-contact radio-frequency sensing modality using microwave radar to evaluate the samples as they are deformed. These samples are sandstones chosen for their distinct petrophysical properties and their significant differences in textural heterogeneity and anisotropy. This novel sensing application yields repeatable and consistent results, which are currently verified for four laboratory-deformed sandstone samples, where characteristic spikes in reflection coefficient, Γ, are observed. These spikes, which have not been observed in any other sensing modality, and occurring approximately 20 seconds prior to macroscopic yield, were observed in all samples tested. This research offers new insights into the evolution of deformation and failure in a porous geomaterial, here sandstone, and represents a departure from the current practices of post failure analysis. The effects of these new measurands (and how they change as a function of load) can be used to recognize more clearly the step-wise evolution of the sample progression to bulk failure and potentially be developed to provide a precursor warning of imminent sample failure. By increasing understanding of the damage development this can help refine the associated geomechanical theory. Better theory underpinning better calculations and simulations of a geomechanical reservoir issue can be critical in managing key seal and trap properties of a reservoir, enabling the operator to make improved operational decisions, increasing field productivity and production efficiency.
Original languageEnglish
Title of host publicationOffshore Technology Conference 2020
Number of pages21
ISBN (Electronic)978-1-61399-707-9
DOIs
Publication statusPublished - 4 May 2020
EventOffshore Technology Conference 2020 - Houston, United States
Duration: 4 May 20207 May 2020
http://2020.otcnet.org/

Conference

ConferenceOffshore Technology Conference 2020
Abbreviated titleOTC 2020
CountryUnited States
CityHouston
Period4/05/207/05/20
Internet address

Keywords

  • geomaterials
  • sensing
  • frequency modulation
  • prediction
  • energy

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