Abstract
The sedimentary environment in Casabe field is a complex continental-fluvial deposit conformed by numerous stacked sandstone reservoirs intercalated with shales with high lateral and vertical heterogeneity. In that conditions Casabe has been under Waterflooding for 30 years with successful results due to an efficient vertical and areal sweep achieved through selective injection.
The successful in production increment also bring us a huge increment in produced water in a ratio of 1 BOPD to 6 BWPD. But, we notice that there where patterns with more than 90% of BSW in between of patterns below than 70% of BSW. Considering additional arguments evidence lead us to rethink our vertical distribution.
With the water channeling identification in mind our reservoir surveillance process was adjust going further in layer by layer analysis from the production-injection balance and the pore volume displaced to get an indicator of where water is going in order to come with a general or localized solution. All the analysis required gather and integrate information from tools like inter well tracers, PLTs, swabbing by layers, saturation logs, time lapse resistivity logs, and cement logs where there was an opportunity to run the tools.
After the identification of water recirculation (Bad Water) in zones with high permeability the immediate action to stop water recirculation and reduce produced water was blocking zones in 1) Producers: Water shut off and/or 2) Injectors.
In the long term, a more comprehensive solution for water channeling will be Water Conformance as the saturation logs shows there is still oil in those layers.
The results of the work done in 21 production wells was the reduction of produced water up to 300 BWPD per well achieving water cuts lower than 80%. Additionally and more important was the increment in oil production observed in the same wells as a consequence of vertical swept efficiency improved.
