Coreflood experiments are an integral part of the selection and optimisation of scale inhibitor treatments, providing information on formation damage, inhibitor return profiles and dynamic retention isotherms. However, significant discrepancies can arise between core and field due to test methodology.
In a previous paper (SPE131131), we demonstrated that test methodology can have significant consequences for the comparative inhibitor returns, particularly with respect to oversaturation. The paper showed that many of the limitations can often be overcome through appropriate simulation techniques.
We extend this work and present further results of laboratory core flood tests specifically designed to examine the effect of core flood test methodology on the derived return isotherm, particularly examining the effect of injection of different volumes of main treatment ranging from ~ 0.5 pore volume (under saturated) to 20 pore volumes (over saturated) for a series of different generic scale inhibitors. This work clearly identifies the significant detrimental artefact of inhibitor oversaturation. This paper differs from the previous works (SPE 131131) in that examples are shown where core flood oversaturation can not be overcome with effective isotherm derivation and upscaling. This is due to significant differences in the isotherms derived as a function of the level of oversaturation with main treatment chemical. This paper will also demonstrate the impact of low concentrations of impurities and or the use of chemical blends when testing with poorly designed core flood tests.
Thus the paper directly addresses the procedures involved in core flooding, recommends approaches and test protocols which allow more appropriate product ranking and allow improved simulation from core to field.