Analysis of field responses to low-salinity waterflooding in secondary and tertiary mode in Syria

Mahani, Hassan (Shell Intl E&P Co) | Sorop, Tibi (Shell) | Ligthelm, Dick Jacob (Shell Intl E&P BV) | Brooks, David (Shell Intl E&P Co) | Vledder, Paul (Syria Shell & AFPC) | Mozahem, Fadwa (Al Furat Petroleum Co.) | Ali, Younes (Al Furat Petroleum Co.)


Low-salinity water injection is an emerging IOR/EOR technique, applicable to mixed-to-oil-wet sandstone reservoirs. This paper describes the field response for two large fields: Omar (secondary flood) and Sijan (tertiary flood). The data were analyzed using analytical and numerical modelling tools. This included evaluation of scaling numbers, mixing and dispersion and calibration. Insight was obtained on relevant drive mechanisms.

The responses to low-salinity flooding differ for the two fields:
• In Omar, a dual-step water-cut development was observed, which is characteristic for a change in wetting state. Our interpretation is that in this field, viscous forces provide the dominant drive mechanism, which is favorable to low-salinity flooding. We were able to history match the low-salinity response using a simple conceptual model.
• In Sijan, the low-salinity flood appears to be still immature and breakthrough of low-salinity water has not (yet) been observed. The reasons for the muted response thus far are explored, including a rather strong buoyancy effect caused by the higher permeability of the block, and the significant effect of injectant mixing with the highly saline aquifer.

A proposal is made for a workflow on how to apply this analysis to future low-salinity flooding implementation in field cases.