Oilfield sustained-release tracers based on different binding forms and their controlled-release mechanism

Abstract

The problem of water breakthrough in horizontal wells is serious, so it is urgent to use sustained release tracers predict and monitor the time and position of horizontal wells. In this paper, the physically bonded epoxy resin-based slow-release tracer and the chemically bonded isocyanate-linked sustained release tracer were prepared using sulfosalicylic acid as the core material. The release and key characteristics of the two sustained-release tracers at different temperatures and salinities were discussed by observing the morphological changes and release curves. The results showed that both the sustained release rate and cumulative release were positively correlated with temperature and salinity, and the epoxy resin-based sustained release tracer had obvious burst release phenomenon due to physical blending. Isocyanate-linked slow-release tracers greatly reduce burst release. The cumulative release of the isocyanate-linked slow-release tracer at 85 °C is about 1%, while the cumulative release of the epoxy resin-based slow-release tracer is about 3%. Obviously, the chemical combination is better than the physical combination. At the same time, the possible controlled release mechanism was confirmed, and the controlled release mechanism of the epoxy resin sustained-release tracer was mainly tracer diffusion. The controlled release mechanism of the isocyanate slow-release tracer is the synergistic effect of polymer degradation and tracer diffusion, and its explanation is helpful for the sustained release tracer system required for horizontal well effect monitoring.