Encapsulated radioactive tracer

摘要

Radioactive particles are provided for use in tracing the flow path in or near a well of fluids injected into the well. The particles include an element which can be made radioactive by bombardment with neutrons and a material to encapsulate the element. The encapsulant is preferably an organic polymer having a high softening temperature. The particles may be injected into a well in treating fluids and their location may be later determined by gamma ray logging of the well.