Abstract: A system and methods for the inspection of a well borehole and the formation around said borehole. The system includes a coiled tubing unit for injecting flexible coiled tubing into a wellbore through a wellhead, a pump and valves for control of injection of fluids such as water, nitrogen, light-hydrocarbons, natural gas, and carbon dioxide through the coiled tubing into the wellbore, and a sensor for visually inspecting and/or acoustically examining the wellbore and a region around the sensor within a slug of fluid injected into the wellbore from the coiled tubing. The method includes the steps of injecting coiled tubing having an inspection sensor into a wellbore to a selected location, injecting an optically transparent or acoustically homogenous fluid into the wellbore through the coiled tubing to form a slug of such fluid around the sensor, and transmitting signals from the sensor representative of well conditions to the surface.