Gas Tracer Technology to Improve Reservoir Understanding and Evaluate EOR Strategy, a Pilot Study in Kuwait

Abstract

This paper describes planning, implementation, and results of chemical gas tracers used in a gas injection pilot study in a heterogeneous multilayer reservoir, onshore Kuwait. The use of tracer for waterflooding is a common practice to understand and improve field performances. In contrast, tracing injected gas with chemical tracers is applied less frequently. This study presents the first implementation of gas tracers in a pilot study in Kuwait and is an early adaptation of tracers to investigate gas-based EOR in the Middle East. The pilot comprises of one injector completed in three target layers and seven producers, completed in similar or other different layers. Unique gas tracers were injected into isolated layers independently at different times to evaluate the injector-producer connectivity in each layer. The producers and re-injected gas were sampled for one year to evaluate gas tracers return. The recovered tracer masses were evaluated against the injected amount to provide information on connectivity and sweep efficiency. The main revelation from the gas tracer study is their distinct difference from what could be expected from a consideration of the water flow itself. A likely explanation for the difference is that the water and gas behave differently in the reservoir, which in turn leads a conclusion that gas enhances the production of oil by replacing oil in the reservoir volumes.