"The hot-film, heated-sensor technique of fluid flow measurement has been developed and is being applied to well logging by the U.S. Bureau of Mines for evaluating in situ fracturing and retorting experiments in Green River oil shale. Wellbore fluid flow profiles and fluid entry or exit points are determined and recorded while raising or lowering the tool in cased or uncased wellbores. Downhole tools contain no electronics except a small, durable, temperature-compensated, hot-film anemometer flow sensor that withstands high velocity and temperature and is compatible with most wellbore environments. Hot-film flow logging, in combination with air injection and production, has proven to be a valuable formation evaluation tool for characterizing natural, hydraulic, and explosive fractures in Green River oil shale. Fracture depths, types (horizontal or vertical ), and flow characteristics within a system of wells used in an in situ combustion test have been determined before and after fracturing. Injection and production fluid flow profile les were also determined before ignition, during combustion, and after combustion termination. A miniature probe, for insertion into 1-inch-diameter holes, has been fabricated for underground mining applications. This device, attached to 1-inch tubular rods, is used to locate permeable gas -producing fractures that interconnect boreholes if gas (air) is injected into one of the holes. Potential applications of the hot-film flow logging technique include determining flow characteristics of gas production and storage wells, water supply and injection wells, ore bodies fractured for solution mining, and a fracture zone surrounding a nuclear chimney."