Snorre Low Salinity Water Injection - Core Flooding Experiments And Single Well Field Pilot

Abstract

Low salinity water (lowsal) flooding has been evaluated for increased oil recovery at the Snorre field. Core flooding experiments and a single well chemical tracer test (SWCTT) field pilot have been performed to measure the remaining oil saturation after sea water and after lowsal flooding.The laboratory core flooding experiments done at reservoir and low pressure conditions involved core material from the Upper and Lower Statfjord and Lunde formations. The core material from the Statfjord formations gave incremental recovery in the order of 2 % of original oil in place (OOIP) by injection of diluted sea water. Similar amounts were produced during following NaCl-based lowsal injections. The same trend was observed in the high and low pressure experiments. No significant response to lowsal flooding was observed for Lunde cores. No response was normally observed during alkaline injection.The SWCTT field pilot test was carried out in the Upper Statfjord formation. The average oil saturations after sea water injection, after lowsal injection and after a new sea water injection were determined; showing no significant change in the remaining oil saturation. The measured in-situ value of remaining oil saturation after sea water flooding was in agreement with previous SCAL experiments.The measured effect of tertiary lowsal flooding from core experiments was in agreement with the SWCTT. Both measurements indicated only low or no effect from lowsal injection.It has been suggested that lowsal flooding has a potential for improved oil recovery in all clayey sandstone formations containing crude oil. The results from this work indicate that the initial wetting condition is a crucial property for the effect of lowsal injection.