| 摘要 |
<p>The present invention relates to a downhole tool for determining flow velocity of fluid in an inside of a borehole or borehole casing. The downhole tool comprises a tool housing extending along a longitudinal axis and having a circumference which is perpendicular to the longitudinal axis, said tool housing being adapted to be lowered into the inside of the borehole or borehole casing, a longitudinal transducer transmitting a probing signal substantially longitudinally from an end part of the tool housing into a fluid flowing in said borehole or borehole casing so that the transmitted probing signal is exposed to reflective entrained surfaces in the flowing fluid, and the longitudinal transducer receiving a reflected signal reflected substantially from reflective entrained surfaces in the fluid flowing in said well along a longitudinal direction towards the end part of the tool housing, and whereby a flow velocity of the fluid may be extracted from consecutive received signals (RS) by application of the Doppler principle, a plurality of electrodes arranged spaced apart around the longitudinal axis in the periphery of the tool so that the fluid flows between the electrodes and a borehole wall or borehole casing wall, and a measuring means for measuring the capacitance between two electrodes in all combinations giving n*(n-1)/2 capacitance measurements for n electrodes, wherein the downhole tool has a space between every two electrodes, which space is substantially filled up with a non-conductive means in order to determine properties of the fluid, of which the flow velocity is extracted.</p> |
