A device and method for imaging, measuring and identifying multiphase fluid flow in wellbores using phased array Doppler ultrasound. The device includes a radially-configured or ring-shaped ultrasound transducer that when deployed in a well in Doppler mode can measure the velocity of radially flowing fluids in the wellbore and generate a 3D image of radial flow in the wellbore, including flowback into the wellbore after fracturing operations, or flow leaving the wellbore during water injection operations. The ring-shaped ultrasound transducer can also simultaneously operate in a B-mode to generate a B-mode image of the wellbore liner upon which the Doppler image can be overlaid. The device may also include a forward facing ultrasound transducer either instead of or in place of the ring-shaped transducer for obtaining information and images on axial flow in the wellbore in Doppler mode, and the location of phase boundaries and phase locations in B-mode.