Downhole Enthalpy Measurement with Fiber Optics

Abstract

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 photo-sensors. 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.