Minimization of Negative Impact of Well Cementing on Productive Horizons by Utilization of Swellable Packers

Avoiding of negative impact of slurry contact with productive sections by utilization of swellable pakers well completion systems as a key solution for depleted reservoirs. Results are compared to previously used classic well completion method with production casing cementing The new method of the well completion is based on a long period and many wells operations within Svyrydivske field in Dnipro-Donets Basin (here and after DDB). Precise selection of hybrid, oil and water based elastomers and correct placement in the appropriate hole zones for water and sectional isolation together with oil based mud utilization during drilling have provided stable production in depleted reservoirs and have minimized negative consequences from water filtration. The results achieved and the well completion method are described in detail to allow readers to replicate all results in a comparable geological conditions in DDB. Current well completion method has a couple of outstanding results achieved: –well integrity barrier is based on sufficient differential pressure provided by swellable packers;–reliable long term water isolation of all detected water contained intervals;–the production sections are not polluted by slurry filtrated water;–increased production rate comparing to cemented wells;–no risks of slurry loss during well cementing. This technology has been successfully implemented in both vertical and deviated wells on 4.5″ (114.3 mm) casing OD, in the interval 5100-5450 meters, bottom hole temperature 120-135°C. The differential pressure provided by swellable packer is up to 10,000 PSI (68.9 MPa). Fluid reactive packers are ready to expand and isolate highly cavernous hole sections and keep differential pressure sustainably. To achieve the best results with this well completion method, it is also important to use reliable gas tight casing connections and know precise reservoir characteristics. That is why the technology is recommended to be customized for well known brownfield reservoirs with high rate of depletion. The main benefit of the well completion method is a proved and safe technical solution for mainly depleted deep gas and condensate deposits in DDB (Ukraine) with sensitive economics