DOWNHOLE ENTHALPY MEASUREMENT WITH FIBER OPTICS
Studies investigating ways to measure enthalpy down hole have been in progress at Stanford University for the last three years. So far, the void fraction and the dispersed-phase velocity, which are the two essential factors required for calculation of flowing enthalpy, were determined by using resistivity and photosensors. Currently, research efforts have been oriented toward measuring down hole enthalpy by fiber optics. After discussing the applicability of using horizontal or vertical fiber tips, this paper describes the usage of normal reflection probe with the tip surface cut at a right angle to the fiber axis to investigate the void fraction initially in water-air flow then in water-steam flow. The calibration curve was obtained by correlating the void fraction given by the fractional flow ratio detector (FFRD) and the calculated local void fraction. Successful results were obtained for the slow bubble flow case. Future work includes determining the bubble velocity, and testing the device in a model wellbore.
Geothermal energy assessment
This section considers the magnitude of the energy contained in the rocks and in the fluids within a geothermal reservoir. Unlike oil and gas reservoirs in which the energy resource is the fluid itself, geothermal fluid has little inherent value and is simply a carrier of the energy. The principal value of a geothermal reservoir to a developer lies in the thermal energy it contains — the fluid is useful only in bringing that energy to the surface.
A computer based hot-film technique used for flow measurements in a vertical kerosene-water pipe flow
Abstract This paper presents the application of a hot-film anemometer based two-phase flow measurement technique to the investigation of the structure of a vertical pipe flow of a water-kerosene mixture. Experiments were carried out within the bubbly flow, spherical cap bubble and churn flow regimes. The results obtained show that the radial profile of the local volume fraction is uniform at low volumetric quality, β, but becomes wall peaked as β increases. The average oil drop size is uniform across the pipe and independent of β for values of β below 15%, but at higher values the drop size increases in the central region of the pipe. The velocity profile becomes more uniform as β increases from zero to about 15%, but then becomes steeper again at higher values of β, and the variation of the centreline turbulence intensity with β shows a local minimum for β ≈20%. The one-dimensional energy spectrum for the water-kerosene mixture flow is found to be composed of two power laws with exponents −1 at lower frequencies and −5 3 at higher frequencies, and the characteristic length scales associated with the continuous phase turbulence decrease substantially with increasing β.