47 research outputs found
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Distributed fibre optic strain sensing of an axially deformed well model in the laboratory
Well integrity is crucial in enabling sustainable gas production from methane hydrate reservoirs and real-time distributed monitoring techniques can potentially facilitate proper and timely inspection of well integrity during gas production. In this research, the feasibility of distributed fibre optic strain monitoring with Brillouin optical time domain reflectometry/analysis (BOTDR/A) for well monitoring was examined by conducting a laboratory test on a well model subjected to axial tensile deformation, which occurs due to reservoir compaction during gas production. First, the validity of the proposed experimental methodology is assessed by a finite element analysis and theoretical modelling of a well subjected to reservoir compaction. A 3 m long well model is developed from the modelling and is instrumented with different types of fibre optic cables to measure the distributed strain development during tensile loading. Results show that the proposed well model and loading scheme can satisfactorily simulate the axial tensile deformation of the well in the laboratory condition. BOTDR is capable of capturing the tensile strain development of the well model accurately within the limitation of the spatial resolution of the BOTDR measurement. To enable accurate distributed strain monitoring of well deformation with BOTDR/A, the following issues are discussed: tightly buffered coating layers around optical fibre cores through mechanical compression and/or chemical adhesion, and a small number of coating layers
Role of water in complexation of 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) with Li+ and K+ in hydrophobic 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ionic liquid
Antitumor activity of polysaccharide fractions prepared from some strains of basidiomycetes.
Fully Developed Laminar Fluid Flow and Heat Transfer in an Eccentric Annulus With an Axially Moving Core
An Analysis on Convective Heat Transfer of Film Boiling from a Finite-Size Horizontal Plate Facing Downward
Elastic wave validation of large concrete structures repaired by means of cement grouting
Injection of repair agent (grout) into boreholes is a repair technique commonly applied to deteriorated concrete structures, ensuring that interconnected cracks and voids are eliminated. The repair effect is evaluated from the increase in the pulse velocity between before and after grouting. Measured velocities after grouting, however, unexpectedly led to a remarkable decrease in the case of a 70-year old dam. This resulted in a doubt about the efficiency of repair. Through investigation, it was concluded that the velocity decrease was attributed to the initial low stiffness of the cement grouting agent due to insufficient hydration in cold environments where the structure is located. Theoretical investigation based on multiple scattering theory is performed, as the filling material acts as a scatterer in the concrete matrix. It is found that the pulse velocity of the structure is lower than that of the initial damaged condition before the repair agent becomes hardened up to an adequate level of stiffness. Accordingly, the amount of the agent injected into the structure was strongly correlated with the velocity decrease after grouting. As a result, the velocity decrease was observed in the repaired dam. Further validation was conducted after a period of 2 years in the same structure with exactly the same sensor arrangement as before. It is clarified that, the velocity distribution measured is in remarkable agreement with that predicted in the theory just after grouting