Use of tracers to evaluate and optimize scale squeeze treatment design in the Norne Field

When squeezing scale inhibitors into oil production wells the inhibitor should usually be uniformly placed in the open intervals to optimise squeeze lifetime. In wells with varying reservoir quality and/or significant cross flow, however, uniform placement is difficult to obtain. Flow diverters are frequently used to improve the chemical placement. In many cases it is of great interest to evaluate the squeeze performance and assess the actual placement and back production of inhibitor to gather well information and thereby be able to optimise the future squeeze designs. This can be particularly interesting in subsea wells where other kinds of data collection, such as production logging, is not feasible due to high intervention costs and high operational risk. This study suggests the use of tracers during squeeze treatments to evaluate the placement as an alternative to running PLT. The main purpose of this paper is to demonstrate the applicability of tracers, in this particular study the injection of a KCl slug in a producer well in the Norne Field, to evaluate the layer flow rate profile along the completion interval, which depends on each layer’s pressure and geological properties. The study consists first of verifying the layer flow rate profile predicted by a history matched reservoir model. Then based on this layer flow rate profile, a tracer injection programme was designed, which included two production stages at different rates. Finally, based on the reservoir model predictions it is identified that each layer is at different pressures, and this leads to a distinctive return profile. To evaluate the match between the observed and the simulation data, the layer flow rate profile from the reservoir model was used to populate a specialized near wellbore model for scale squeeze treatments. The match between the simulated and the observed data was good. However, the near wellbore model, in particular the layer flow rate profile, was further fine tuned. Finally, the fine tuned near wellbore model was used to optimize future treatments more accurately with the fine tuned layer flow rate profile.