FRACTURE RESERVOIR CHARACTERIZATION BY FIBER-OPTIC DISTRIBUTED TEMPERATURE LOG
One of the important features of the fiber-optic distributed temperature log is its ability to acquire continuous, instantaneous and simultaneous temperature profile along the entire wellbore. Series of successive temperature profiles sampled every one minute or so enable to analyze transient temperature phenomena, which may pertain to important reservoir properties. For example, when change of rate occurred to the fluid flow such as due to water injection, the temperature profile over the section exhibits transient phenomena associated with the fluid flow. The characteristics of the phenomena depend on several factors including the flow profile which itself exhibits transient nature depending on fluid compressibility, permeability and reservoir extent, the original temperature profile, the temperature of injected fluid and that of the reservoir fluid flowing into the wellbore, the degree of rate alteration, well geometry, flow regime and etc.
Interactions of hydrogen and deuterium with silica optical fibers: A review
This paper reviews all the interactions of hydrogen and deuterium with silica-based optical fibers. Included in the discussion are H 2 overtone absorption, OH formation, increased UV and IR absorption, radiation effects on H 2 -treated fibers, the gas-in-glass laser and applications, the reduction of OH absorption by isotope exchange OH → OD and other isotope-exchange related effects, and applications of isotope exchange and substitution for diagnostic purposes. Also included is a description of common sources of H 2 in materials used in fiber and cable manufacture, and countermeasures against hydrogen generation and intrusion into the fiber.
Behavior of hydrogen molecules adsorbed on silica in optical fibers
It is shown that molecular hydrogen weakly adsorbed on silica in optical fibers has a dipole moment and is active in infrared spectra. This causes a loss increase at 1.3 and 1.55 μm, which are the attractive wavelengths for optical fiber communication systems. In addition, it is shown that the loss spectra are also related to the fundamental SiO 4 tetrahedral vibrations rather than the rotation of hydrogen molecules from the observation of the loss spectra in silica glass fibers containing hydrogen molecules and deuterium molecules. It is also shown that the loss is reversible and that the reversibility is promoted with temperature.