Dynamic Reservoir Characterization Of Naturally Fractured Reservoirs From An Inter-Well Tracer Test

After field redevelopment in the Sherrod Unit of the Spraberry Trend Area, an inter-well tracer test was conducted at the field scale in order to understand the fracture system, which forms preferential flow paths for better management of waterflooding. The test consisted of 13 injection wells and more than 110 producing wells that were sampled, with each injector having its own unique tracer.

A wide range of tracer responses was observed in terms of tracer recovery, breakthrough time, and tracer velocity. Additional noise on tracer data was noticed due to reinjection of produced water. In this study, a comprehensive workflow is presented for dynamic reservoir characterization of naturally fractured reservoirs from an inter-well tracer test by incorporation of analytical interpretation, streamline simulation, and streamline-based optimization techniques. Categorized tracer responses were mapped according to analytical analysis, and dominating flow trends were detected in E-W and NE-SW directions before the simulation study. The constructed three-phase, dual-porosity model was simulated by a streamline simulator. Certain parameters in the model were modified based on high tracer response until a reasonable match was obtained for an inverted nine-spot pattern and breakthrough time of the injected tracer. Once the model became capable of matching historical field production, a 1-year prediction run was conducted for optimization. Cumulative oil production was increased by 8,000 bbl by allocating more water toward efficient producers, and 10,000 bbl less water was produced for the optimized case.