Development of a Doppler Acoustic Imaging System for Borehole Wall to Evaluate Fluid Flow Distribution around Subsurface Fractures.

  • Saito Jin
    Graduate school of Engineering, Tohoku University, Sendai 980-8579, Japan
  • Niitsuma Hiroaki
    Graduate school of Engineering, Tohoku University, Sendai 980-8579, Japan

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Abstract

We are in the process of developing a doppler borehole televiewer (DBHTV) which quantitatively evaluates the permeability of independent subsurface fractures in a borehole. The system employs an ultrasonic pulsed Doppler method, and is compatible with the conventional acoustic borehole imaging system called borehole televiewer (BHTV). Using the DBHTV, back-scattered waves from fine particles in the borehole fluid such as drill mud or cuttings in a water filled borehole are detected along with the reflected waves from the borehole wall, and the Doppler shift of the back-scattered waves is used to estimate the fluid velocity. A method to estimate the distribution of Doppler shift was examined using a laboratory experimental model. An attempt to locate the sampling volume and a method to quantitatively estimate the flow velocity by scanning the transducer are examined. This study shows that the location of permeable fractures, the distribution of fluid velocity and the fluid volume can be visualized using the DBHTV.

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