Inflow Chemical Tracers: An Innovative Approach to Quantify the Zonal Contribution from Inaccessible Drains

Abstract Individual zonal inflow production profiling and monitoring is very challenging in multi-lateral wells due to accessibility limitations post completion, hence, inflow chemical tracers were chosen to be deployed for this well. A transient campaign was planned and carried out with the objective of quantifying the relative inflow production from each zone in each of the three laterals. Inflow chemical tracer systems were manufactured into a matrix and designed to provide 5 years of oil tracer and water tracer longevity (upon water breakthrough). The tracers were installed into externally vented tracer carriers which were then RIH with 3½" Inflow Control Valves in the mainbore and with 4½" in limited entry liners in the 3 laterals. The mainbore is fitted with 3 unique oil and 3 unique water tracer systems, whereas the laterals contained 7 unique oil tracer systems each, bringing the total installed tracers in the well to 24 oil and 3 water unique tracer systems. To be able to quantify the relative inflow contribution in individual zones of each lateral, the well needed to be shut in for a duration of 24 hours to allow tracer contact with the formation fluid. Once in contact, the tracer molecules are released from the matrix and accumulate in the wellbore. The movement of these tracers to the surface gives a chemical signal that carry information on the flow – a signal that is captured during surface sampling and subsequent analysis in a high-end tracer lab. The well was put on production with each lateral being opened sequentially, controlled by their respective ICV in the mainbore. High-frequency sampling was carried out where each ICV was kept open for an average duration of 12 hours allowing tracer production from each lateral. The tracer signals proved the arrival of all installed oil tracers’ signatures and peaks. Results indicate that all reservoir zones in all three laterals are contributing to oil production. A quantitative interpretation was performed to determine relative inflow contribution per monitored zone. The chemical inflow tracers were deployed in a smart multi-lateral well to enable production monitoring and surveillance of the laterals. This application is unique due to the limitation of other diagnostic methods in the market that can quantify flow inside a lateral.