Transport of Temperature Nanosensors Through Fractured Tight Rock: An Experimental Study

Abstract

Abstract The goal of this research was to develop methods for acquiring reservoir temperature data within the formation and to correlate such information to fracture connectivity and geometry. Existing reservoir-characterization tools allow temperature to be measured only at the wellbore. Temperature-sensitive nanosensors would enable in-situ measurements within the reservoir. Such detailed temperature information enhances the ability to infer reservoir and fracture properties and inform reservoir engineering decisions. This study provides the details of the experimental work performed in the process of developing temperature nanosensors. Specifically, particle mobility through fractured media was investigated. The transport of silica particles through fractured rock was investigated. Experimental results showed that the recovery of the particles was dependent on the particle size and suspension concentration. It was observed that the recovery of the 2 μm particles following their injection into fractured greywacke core was affected adversely by suspension concentrations (decreasing recovery with increasing suspension concentration). Increasing concentration of the 2 μm particles resulted in more pronounced aggregation, which led to trapping by straining. Conversely, the recovery of the 5 μm and polysize particles increased with increasing suspension concentration. The particle size has a direct effect on its recovery. By comparison, the recovery of 5 μm particles was about an order of magnitude higher than that of the large particles (> 5 μm). The controlling mechanisms for transport of silica particles were also identified. Among all, transport by gravitational sedimentation (gravity settling) was prominent. Results also showed that the existence of the fracture facilitated the particle transport. Particles were found to flow with the fast-moving streamlines within the fracture. The dominance of particle transport by advection or diffusion was examined using the Peclet number. The high Peclet numbers indicated advection-dominated transport.