Abstract: A system for identifying and quantifying a fluid in a gas-oil separation plant conduit includes a first wellhead and a second wellhead, a first flowline, a first prospector spool apparatus and a second prospector spool apparatus, a header, and a collection point. The first and the second prospector spool apparatus each include a porous layer with a prospector molecule. The prospector molecule has chemical affinity for oil, gas, or water, and is configured to diffuse into fluid flow. A method includes providing a system, producing a first fluid from a first well and a second fluid from a second well, flowing the first fluid through the first prospector spool apparatus and the second fluid through the second prospector spool apparatus, allowing the first fluid and the second fluid to commingle, collecting a sample of and analyzing the commingled fluid to provide a quantitative and qualitative analysis.