NATURAL TRACER FOR SECONDARY RECOVERY WATER INJECTION PROCESS

摘要

All natural water sources are "labeled" by a unique ratio of strontium isotopes (<8><7>Sr/<8><6>Sr). In accordance with the invention, the strontium isotope ratio for oil bearing formation water and for seawater which is to be injected into the formation is determined. The strontium isotope ratio of the produced water is then monitored at regular intervals and, when the strontium isotope ratio changes to that of the injected water, water injection breakthrough is delimited. The strontium isotope ratio thus serves as a natural tracer for seawater injection.