Development of a Doppler acoustic imaging system for borehole wall to evaluate fluid flow distribution around subsurface fractures

We are in the process of developing a doppler borehole televiewer (DBHTV) w hich quantitatively evaluates the permeability of independent subsurface fr actures in a borehole. The system employs an ultrasonic pulsed Doppler meth od, and is compatible with the conventional acoustic borehole imaging syste m 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 th e 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 Do ppler shift was examined using a laboratory experimental model. An attempt to locate the sampling volume and a method to quantitatively estimate the f low velocity by scanning the transducer are examined. This study shows that the location of permeable fractures. the distribution of fluid velocity an d the fluid volume can be visualized using the DBHTV.