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Injectivity Experiences and its Surveillance in the West Salym ASP PilotNormal access

Authors: F.H.J. van der Heyden, E. Mikhaylenko, A.J. de Reus, D.W. van Batenburg, V.M. Karpan and Y. Volokitin
Event name: IOR 2017 - 19th European Symposium on Improved Oil Recovery
Session: Pilot & Field Cases
Publication date: 24 April 2017
DOI: 10.3997/2214-4609.201700243
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 4.02Mb )
Price: € 20

Summary:
ASP or polymer flooding in reservoirs with permeabilities below 100 mD has not been often applied due to the perceived and/or potential issues related to the injection of viscous polymer solution under those conditions. Poor injectivities become an even bigger issue if injection under matrix conditions is required. This is usually the case for pilot projects with relatively short inter-well distances to optimize response time, project costs and pilot duration. One of the major problems that could lead to injectivity deterioration is plugging of the formation in the near wellbore due to trapping of polymer molecules in smaller pores and polymer adsorption. The higher injected fluid viscosity due to polymer also leads to higher injection pressures. The injection pressure should, however, not exceed the formation breakdown pressure if matrix conditions are required. A proper flood design should achieve the compromise between polymer molecular weight, its concentration, viscosity of injected solution and injection pressure, and should include appropriate plans to mitigate injectivity loss. The paper describes the injectivity challenges experienced during water, ASP and subsequent polymer injection in the West Salym ASP pilot. The project is implemented in a sandstone reservoir with permeabilities in the range from 10 mD to 100 mD. Conventional waterflooding in West Salym is performed under fracturing conditions, hence it was recognized from the beginning that the injection of ASP and polymer solutions under matrix conditions in the pilot would be challenging. The paper provides the injectivity history for the pilot wells, describes the surveillance methods used, and provides details on the steps taken to improve the injectivity. New analysis approaches to effectively extract information contained in the real-time data that were developed for this project are also discussed. Overall, this paper will provide the reader with hands-on experience in injection of ASP and polymer solutions in reservoirs with permeabilities below 100 mD.


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