SpecialReport: Completion Technology concept. The returns of water tracers injected with PGT were compared with the returns of water tracers pumped on FIGURE 4 Horizontal Refracture with PGT and Proppant Tracers surface into the same stages as a control. Each cluster in a traced stage used the same unique tracer to better compare with the surface injection water tracer. The control tracer curves and the PGT curves followed in trend, indicating that the system successfully has injected tracer without pumps on surface. The PGT system returns were lower in value because of the lower tracer injection volumes. This proof of concept provided the framework to move forward with other experiments and case studies for PGT. FIGURE 5 Vertical Refracture with PGT and Post-Frac Temperature Survey Case Studies The first case study focuses on a pair of adjacent Marcellus wells in the Appalachian Basin. The operator wanted toe-side flow assurance diagnostics to be sure that the approximately two-mile long laterals were open to flow during flowback operations, and also for a period of about 50-60 days later when an adjacent pad was being fractured. PGT was used for every cluster in two stages in the toeside of each well, with each stage having its own unique tracer. Figure 2 provides a graphical representation of the PGT returns. Each curve represents the returns of the clusters from each stage. One interesting note is that the fracture driven interactions from the offset pad fracturing can be seen in the returns profile of the 1H well (and to a lesser degree the 2H) around 50-60 days from initial flowback. This area is highlighted to show that three of the four curves dropped below minimum detection levels from the offset pad frac water diluting the water returns from the 1H and 2H wells. However, after about 60 days, the tracers returned to detectable levels after the offset fracture communication stopped and no longer diluted the returns in the 1H and 2H. Figure 3 shows renderings of the returns profile (left) and well-to-well communication (right) of the 1H and 2H. The larger-diameter disks represent the clusters from the highest-returning stages. In addition, the arrows represent the clusters from the two stages that were in communication. Arrow diameter is proportional to the magnitude of communication. The colors of the well segments, 76 THE AMERICAN OIL & GAS REPORTER GoTrace 1H PGT Water PGT Oil