Research on mechanism and scale inhibition performance of PESA on SrSO4/BaSO4 in oilfield sewage

Key words:  polyepoxysuccinic acid  scale inhibition  relative molecular weight  barium sulfate/strontium sulfate  scale inhibition mechanism  oilfield sewage

Abstract:

The self-made polyepoxysuccinic acids (PESA) were prepared and the scale inhibition effect of the relative molecular weight on barium sulfate and strontium sulfate in the oilfield sewage were investigated. And the scale inhibition performance between PESA and traditional scale inhibitor was compared. The results show that the molecular weight of PESA has an obvious influence on the scale inhibition. PESA with different molecular weights and different concentrations are selected in terms of different concentrations of scale-forming ions and different kinds of scales. It is also found that PESA is an efficient scale inhibitor for strontium/barium sulfate. The relative molecular weight of 500-1000 and 2000 is feasible to oilfield sewage containing 500 mg/L and 1 000 mg/L Sr²⁺ respectively. The scale inhibition rate can be up to 95％ with 3-8 mg/L PESA. The scale inhibition performance of PESA is better than that of the traditional scale inhibitor for the oilfield. Moreover, the synergistic effect of PESA and PAA is found. Compared with the results obtained by PESA, the scale inhibition rate is improved for 20％, when PESA and PAA are at a ratio of 1∶3, and the total concentrationis 100 mg/L. The PESA inhibition mechanisms mainly are lattice distortion, charge dispersion and chelating solubilization.