Figure 9. Horizontal well with unique FlowProfiler tracers injected into each of the 29 frac stages. Figure 10. Frac stages that are too far apart leave stranded crude oil in the reservoir. Tight-Oil Zone 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 29 28 27  26 25 24 23 6,000 feet 11 12 13 400 feet 14 Stranded crude oil Tight-Oil Zone 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 29 28 27  26 25 24 23 9,000 feet 6,000 feet