Linked polymer solutions (LPSs)

consisting of partially hydrolyzed polyacrylamide and aluminum citrate for enhanced oil recovery

were prepared and their flowing and diverting behavior in an unconsolidated sand pack was investigated by the core flooding method in the present study.Using a mixture of a polymer solution and a crosslinker solution prepared prior to injection

the experiments were conducted in a sand pack holder of 1500 mm in length and 40 mm in I D

filled with unconsolidated quartz sands.The effects of interstitial velocity and LPS injection amount on the plugging location were studied by on-line measurements.The results showed that LPSs flowed through the sand pack in plug-flow.During the LPS injection

frequent pressure fluctuations took place and finally gave rise to non-uniform plugging at certain positions in the sand pack

where abrupt increase in pressure drop appeared.The distance from the inlet to the place where significant plugging occurred increased nonlinearly with increasing interstitial velocity.It was found that most possibly there existed a critical LPS injection amount

above which plugging would happen.