Studies on the Secondary Structure of Partially HydrolyzedPoly(acrylamide) in the Process of Chemical Oil Recovery

The secondary structure parameters of partially hydrolyzed poly(acrylamide)(HPAM) in the process of chemical oil recovery have been determined by means of GPC-light scattering cooperation. It was found that the mean molecular mass of HPAM had decreased to 4 to 8 times, the molecular mass distribution of HPAM became broad. It has been deduced that the molecular mass decrease of HPAM results from the HPAM degradation and the mechanical degradation is a determinant because the molecular mass distributions of HPAM after degradation were narrower than the results estimated with the random degradation theory. The chain flexibility somewhat decreased when HPAM solution flowed in underground sandstones in the period of 6 to 8 months, that is, (S 2 n/M n) 1/2 increased from original 0.065 to 0.075 for HPAM in flooding 2 and 4 years and 0.081 for 6 years, which maybe imply HPMA further hydrolyzed under the underground weak basic condition of the oilfield.