The production-time-series analysis has three reservoir characterization objectives: (1) to determine the initial reservoir drive mechanism, (2) to understand the effects of previous reservoir production strategies, and most importantly, (3) to understand how the reservoir architecture has influenced fluid flow. The combined influence of these three factors creates the reservoir’s production history. Knowledge of their relative effects is critical in characterizing the reservoir and determining reserve growth potential. To achieve the objectives of production-time-series analysis, five main tasks must be accomplished, preferably in the order listed below:

1. Analyze initial and spatial time variation of fluid chemistry.
2. Analyze initial conditions for fluid contacts from completion, workover, logs, and pressure.
3. Graph production and annotate with production strategy history.
4. Map and analyze time-series history of fluid production.
5. Determine flow direction of injected and encroaching fluids.

In this module, we will examine tasks one and two, analyzing changes in fluid chemistry and initial fluid contact conditions. Module 13 covers the last three tasks to be accomplished when performing production-time-series analysis of a reservoir.