Evaluating Changes in Water and Hydrocarbon Chemistry

The evaluation of spatial changes in water and hydrocarbon chemistry can aid in the recognition of reservoir compartmentalization and be used in the construction of a reservoir model. As pointed out by Smalley and England (1994), numerous reservoirs display spatial variations in both hydrocarbon and water composition. These variations occur because of heterogeneities within the reservoir as fluids migrated over time. When these spatial variations are delineated they can be used as evidence of fluid-flow connectivity or the presence of fluid flow barriers. See figure 1 below for examples.

Figure 1. Petroleum characteristics can vary within the same stratigraphic interval. An example is oil gravity which can display different characteristics between fault bounded reservoir campartments.