This paper gives guidelines for geophysically detecting the two most common materials of interest in E&P environmental studies, produced water and crude oil. Techniques for locating buried metal objects such as buried casing heads and pipelines are also discussed. Produced water can easily be detected with several electrical techniques. The choice of technique generally depends on the depth of investigation. Crude oil can sometimes be detected remotely with ground-penetrating radar but there is no technique that can be used routinely. Magnetic or conductivity measurements usually are the most effective for locating buried metal.