12.: Conclusions

In many early waterflood projects, chemistry issues were not recognized as key focus areas. Indeed, some of the issues—such as reservoir souring and low-salinity flooding—had not yet been identified. In current waterfloods, the situation has significantly improved, although a comprehensive understanding of the full impact of chemistry issues, and a subsequent optimization program, is often still missing. Chemistry issues have a significant impact on the operating cost to be borne by a waterflood development. This is often especially true if the full impact of the issues is not recognized at the outset and control has to be implemented on a remedial basis. Many of these issues will not only affect the operating cost but also can significantly affect the subsequent production and recovery profile. This does not apply only to low-salinity flooding, in which the chemistry is specifically manipulated to influence recovery. Recovery can also be negatively influenced by reservoir souring if, for example, the produced H₂S levels reach the point at which producers have to be shut in because materials limits have been reached.