Analyzing waterflood responses for Pekisko B

This paper focuses on the fluid communication and injection responses in th e Pekisko B Pool between January 1990 and September 1997. The analysis was based on responses of producers to changes in the injection rates. The stre ngth of oil response is measured as the correlation between the oil rate an d the injection rate. In a similar fashion, the strength of the total fluid responses is measured as the correlation between the total fluid rate and the injection rate. These responses and the corresponding time lags are pre sented in the form of special XY-diagrams. One form of these diagrams shows normalised responses of wells around each injector. The second form shows the long distance communication between injectors and producers that are ch aracterised by strong responses above the predefined level. Results indicate very good short and long distance communication between in jectors and producers. Waterflood responses can be segmented into three geo graphical areas: northern, central and southern. The oil responses correlat e strongly to the injection in the central part of the pool. Weaker respons es and longer time lag response was observed in the southern pool area, and strong interference between injectors was detected in the northern pool ar ea. A more detailed analysis, involving pressure data, geology and completi on intervals, demonstrate that the existing waterflood inefficiencies are r elated to inadequate injection volumes in the southern pool area and poor i njection well distribution in the northern part of the pool. The study prov ed that the applied methodology is very efficient in diagnosing the waterfl ood performance and helping to optimise waterflood design. This analysis very quickly identified communication or lack there of, which had only partially been understood through lengthy geological study of the pool. This method should be used in the early stages of study to very quic kly "zero in" on areas of difficulty due to complicated configuration or ge ological/depositional complexities.