Figure 111 shows the pattern of injection and production wells where the tracer test was run.

FIG. 110. Tracer records in well 3.

FIG 111. Wells 20-2 and 21-3.

Up to two years after the tracer injection, only three wells had detected tracer breakthrough: wells 12-3, 13-4 and 13. The simulation for the well 13-4 using the parameters provided by the oil company is shown as a black line in Fig. 112.

To obtain a better fit to the experimental data of well 13-4, the layer thickness was reduced from 55.5 m to 3.2 m, resulting in the curve given in Fig. 113. However, the simulation predicted a very significant production of tracer in well 14-4, which did not occur.

A similar situation appears in the mesh of well 20-2. It is possible to fit the tracer record of well 13-3, but the simulator predicts significant tracer production in well 13-2, which is absent (Figs 114 and 115).

A scenario which assumes strong anisotropy along the direction between wells 21-3 and 13-4 (or wells 20-2 and 12-3) is proposed. However, in this case, in the simulation there is tracer production in wells 14-3 and 13-2 (tracer response was undetected in these wells). In consequence, the only way to avoid tracer production in wells 14-3 and 13-2 is to assume that the injectors located to the south of these wells have higher water injection rates.

For example, if the injection water flow rates of the injectors located to the south are duplicated, it is possible to obtain a good fit for the tracer record of well 13-4. A satisfactory fit of simulated response and experimental data (for wells 12-3 and 20-2) was obtained (Fig. 116).

FIG. 113. Tracer records in the well 3 with the new, reduced, thickness layer.

FIG. 114. Streamlines in well 21-3 mesh.

days after injection FIG. 115. Experimental and simulated tracer records for well 13-4.

a = 13 m h =18 m

FIG. 116. Experimental and simulated tracer records for well 12-3.

Case application 4: Interpretation of tracer experiments in laboratory model of non-boundary conditions