Study On Accelerating Dissolution Of The Hydrophobically Associating Polymer In Offshore Field

Polymer flooding technology is mature and low cost,and has been widely applied in onshore oil field at home and abroad.However,the reservoirs in the offshore field have high viscosity,strong shear ability and high salinity,and it is difficult for conventional linear polymer to meet the requirements for viscosity increasing,shear resistance and salt tolerance of the offshore field.Therefore,the researchers have developed hydrophobically associating polymers to adapt to the conditions of the offshore fields.Because of the small amount of hydrophobic groups on the main chain,which makes the solubility worse and the dissolution time is prolonged.The onshore oil field can achieve complete dissolution by increasing the number and volume of the ripening tank,but the area and space of the offshore platform are narrow and the bearing is limited,it is impossible to copy the usual allocation process in onshore oil field.Conventional linear polymers are still difficult to be widely applied to offshore platforms,and are even more difficult for hydrophobically associating polymers with poor solubility.Therefore,the problem of polymer dissolution is the bottleneck for application of polymer flooding to enhance oil recovery in offshore oilfield.In view of the existing instant method,it is still impossible to break the bottleneck for application of polymer flooding in offshore oilfield.This paper studied the effect of polymer dissolution rate of the hydrophobically associating polymer AP-P4 by conducting dissolution experiments.It is found that the dissolution of polymer can be accelerated by increasing the concentration of polymer,decreasing the particle size of the dry powder,increasing the temperature of water and increasing the speed of the agitator.Using grey correlation analysis method,it is found that the main influencing factors of polymer dissolution rate are temperature of water and the particle size of dry powder.The theoretical analysis and experimental study on reducing the size of polymer particles found that reducing the particle size of the swollen particles of AP-P4 is more better for the dissolution of the polymer than decreasing the particle size of the dry powder,and the smaller effect of reducing the size of swollen particles on the viscosity of the mother liquid.Therefore,reducing the size of swollen particles of AP-P4 is more suitable for accelerating polymer dissolution in offshore oilfield,and the size of swellen particle is 150?m.In the light of the method of reducing the particle size of the swelling particles,a forced-stretch water-infiltrating unit is designed,and the units with the same internal structure are combined by the coaxial parallel connection to form a coaxial parallel forced-swing water-penetrating quick-dissolving device.Then,the numerical simulationis is used to analyze whether the device can meet the requirements of the field,and the following recognition isobtained:(1)The static design shows that the device can meet the requirement of velocity in engineering.(2)The higher the solution viscosity,the greater the pressure loss of the instant unit,the smaller the flow velocity and the smaller the excess over-flow rate.However,as long as the solution viscosity is less than 20mPa·s,the over-flow rate of the unit will be greater than 12.29m3/h,which can meet the requirement of over-flow in the field.(3)The rotor speed and the cleaner have little effect on the flow capacity of the instant unit.Increasing the rotor speed will enhance the stretching effect of the instant unit on the swellen particles,and the main function of the cleaner is to disperse the flow state of the polymer solution in the device and avoid large-scale deposition of the swellen particles.(4)The combination of static design and dynamic simulation shows that the design of the instant unit can meet the requirements of the field.(5)The volume and weight of the device can be further reduced by the coaxial parallel connection of several units with the same internal structures.(6)It is suitable for offshore oilfields to increase the concentration of polymer and to use coaxial parallel structure forced-stretch water-infusion quick-dissolution device to reduce the size of swollen particle.