ABSTRACT:

Gupco is the Pioneer Company not only in Egypt but also in the Middle East that applies waterflood as secondary recovery method. Many successful examples have been done and still running to recover great amount of oil. Shoab Ali oil field waterflooding project is one of those many. Three reservoirs Belayim, Kareem/Rudeis and Nukhul are being waterflooded. Waterflood project started for Kareem/Rudeis zone in 1984 and later on captured the other two reservoirs. In spite of the project succeeded in increasing the recovery from the three reservoirs by 27%, 21% and 9% respectively, it caused many undesired effects. The present work introduces the recent work done in Shoab Ali field to study the waterflood challenges, which were experienced during the project life. These side effects are mainly formation plugging by bacterial contamination, H2S production, and low pumping pressure and rate. Therefore, reduction in the ultimate oil recovery was expected. Based on Shoab Ali field study in 1995 new structural interpretation was completed for better evaluation of its seven productive formations, new zonation of which leads to an aggressive work plan that started in 1996 to convert these waterflood side effects into opportunities of success. To treat bacterial contamination and H2S production, surface and down hole sterilization program was initiated with some workover jobs at injectors. The injection pattern was modified to stop injection in the plugged intervals or allow injection to new zonations. New pump was added to the system to increase the injection rate and pressure. Low oil rate producer was converted into injector to have better areal sweep effect. The anticipated incremental gain of 4.2 MMSTBO is expected at the end of the aggressive plan doubling the remaining recoverable reserves of the three reservoirs.

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