A Joint Industry Project was undertaken to study releases representative of those that could occur on offshore installations involving well-stream fluids either at the wellhead or during processing. The project involved a programme of large-scale jet fire experiments to investigate releases involving mixtures of crude oil and gas (simulating 'live' crude) and water. Seven oil and gas companies and the UK Health and Safety Executive sponsored the work that was undertaken by Advantica and Shell Global Solutions at the Spadeadam Test Site, Cumbria, UK. The results demonstrate that the presence of water modifies, significantly, the size, shape, thermal characteristics and stability of a jet fire. For an equivalent release of fuel, the distance from the release point within which flame impingement could occur is slightly increased. However, the overall size of the flame, the temperatures within the flame and the overall heat loading to objects within the flame are reduced. The results also indicate that the flame is extinguished if the water content of the well-stream fluid reaches about 55% by mass. Some well-stream fluids contain a lot of water, in some cases up to 80% by mass, and these will not produce jet fires.