TRACER AND METHOD

摘要

The invention concerns a tracer material for tracing fluid flows from a hydrocarbon reservoir. The tracer material is a particulate tracer material comprising a plurality of particles of a porous particulate solid material, said particles having pores containing a tracer composition characterised in that a retaining material overlies said tracer composition in at least some of said pores. The retaining material retards the release of the tracer material so that the tracer is released at a more constant rate over a longer period than in the absence of the retaining material.