[[:file:predicting-reservoir-system-quality-and-performance_fig9-31.png|Figure 2]] is an example density-neutron crossplot. Points 1–5 are from the log (Figure 9-30). Points 2, 3, and 4 are from a zone that shows crossover. Crossover occurs when the density log reads higher than the neutron log in a zone of the same lithology as the log matrix lithology, i.e., sandstone. Point 2 has the greatest crossover; Point 4, the least. Once completed, the well from which this log was taken showed Point 2 to be in a gas reservoir, Point 3 to be in light oil reservoir, and Point 4 to be in a zone with residual oil. | [[:file:predicting-reservoir-system-quality-and-performance_fig9-31.png|Figure 2]] is an example density-neutron crossplot. Points 1–5 are from the log (Figure 9-30). Points 2, 3, and 4 are from a zone that shows crossover. Crossover occurs when the density log reads higher than the neutron log in a zone of the same lithology as the log matrix lithology, i.e., sandstone. Point 2 has the greatest crossover; Point 4, the least. Once completed, the well from which this log was taken showed Point 2 to be in a gas reservoir, Point 3 to be in light oil reservoir, and Point 4 to be in a zone with residual oil. |