Hyperbranched Copolymer as a Viscosity Reducer for Offshore Heavy Oil: From Optimization to Application

Thispaper discussed the selection of functional monomers and optimalsynthesis conditions for hyperbranched copolymer named as HVR, a novelpolymer flooding chemical, intended to enhance offshore heavy oilrecovery. The potential application of HVR as a polymer for oil displacementwas also evaluated. Through experiments and molecular simulations,functional monomers AOS and OP-10 for Bohai heavy oil were screenedout due to their high viscosity reduction rates for oil, both above90%. Moreover, the interaction energy calculation results suggestedthat AOS and OP-10 were more likely to spontaneously disperse asphalteneaggregation. Furthermore, the influence of various factors on thesynthesis of HVR was discussed using orthogonal design, and optimalsynthesis conditions were determined. The optimal conditions for HVRsynthesis are as follows: polymerization concentration of 30 wt %,initiator dosage of 1 wt %, initiation temperature of 50 & DEG;C,and system pH of 7; the sum of OP-10 and AOS accounts for 29.9 wt%, with a molar ratio of 1:1; the total amount of AM and AA accountsfor 79.9 wt %, with a mole ratio of 6.5:3.5; and 3.0 G PAMAM accountsfor 0.2 wt %. Moreover, HVR demonstrated good mobility control capacityand improved the recovery of heavy oil significantly in core floodingtests. Injecting a slug of 0.3 PV of HVR led to the additional recoveryof 21.96 and 16.04% for oil viscosities of 350 and 500 cP, respectively.Notably, HVR's additional recovery was over 7% higher thanthat of conventional hydrophobically associating polymer. These findingshighlight the potential of HVR as a novel polymer to enhance the heavyoil recovery.