Reservoir description and development of a mature oil field

The Mishovdag oil field is located in the southwest of Baku, Azarbaijan. Th e sandstone reservoirs consisting of five middle Pliocene age Horizons I, I I, Ill, IV, and XII provide 40% of total total oil production from the Sirv an oil field region. The reservoir trap is an anticline, and its size is ap proximately 15 x 5 km. Since its discovery in 1956, 516 wells had been dril led and 198 of them are still producing from successive layers of sandstone formations. This study was conducted to describe Horizon I of Block-9, prepare input da ta for a modeling study, and suggest development scenarios for this block. From this point of view, it was aimed to properly describe the reservoir pr operties with the use of core and, mainly, well log data. In this respect t hese data set were evaluated to define the reservoir. According to field reports, seven producing layers were present in Horizon I of Block-9. From the results of further analysis on well logs, it was rec ognized that the reported seven layers were not continuous within Block-9 s o, for modeling studies, these sandstone layers could be grouped under thre e main sand layers, namely, S1, S2, and S3, that were separated by two clay zones. The results of the the modeling study showed that oil production wa s mainly from level S3 and level S1 was less swept by water injection. The oil saturation distribution at three levels at the end of 39 years of produ ction indicated that there wets still recoverable oil in levels S1 and S2. No free gas could be observed in any of the levels because the pressure mai ntenance provided by water injection caused free gas to redissolve in oil.