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.
DOWNHOLE ENTHALPY MEASUREMENT IN GEOTHERMAL WELLS
Advances have been made in the ongoing research to find a way to measure enthalpy downhole in geothermal wells. The project has thus far revolved around determining applicable ways to determine the presence of air vs. water, which could ultimately lead to an estimate of the void fraction and enthalpy. The measurement principles tested have been based on temperature, resistivity and optical transmissivity. Successful results utilizing cross correlation techniques have lead to quite accurate estimates of bubble velocity using both resistivity measurements and optical measurements. However, so far, temperature measurements have not proven to be successful. Preliminary testing based on resistivity properties of two phase flow for determination of void fraction has begun. Future work includes deriving correlations between void fraction and resistivity using a new electrode design which looks outward from an in-situ probe into the well bore. Finally, the possibility of cross correlating the signal from two such electrode setups (spaced a known distance apart) is being investigated in the hope of obtaining the vapor velocity.
Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves.
Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenza-3 virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, nonstressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.