Effect of polyacrylamide on flow characteristics of highly viscous oil-water annular flow
Aiming at the problem of flowability improvement of water annulus for heavy oil transportation in water ring,a simulation experiment method for heavy oil flow boundary layer under the action of water ring with anionic polyacrylamide(PAM)was proposed.On the basis of self-developed design of indoor visualization experimental loop device of heavy oil-water two-phase flow,taking 500#industrial white oil as simulated oil sample of Lyuda highly viscous oil,the flow regime characteristics and friction resistance properties of heavy oil-water annular flow before and after the addition of PAM in outer aqueous phase were investigated experimentally.The synergistic drag reduction effect of PAM on water ring lubrication was evaluated,and the mechanism of PAM on flow stability of water ring was analyzed.The experimental results showed that the presence of PAM had a significant effect on the flow pattern and resistance characteristics of heavy oil-water annular flow.After the addition of PAM,the region of annular flow reduced and changed to either stratified flow or plug flow,and when it transformed into stratified flow,the drag reduction effect of PAM was lost.As the oil superficial velocity varied from 0.23m/s to 0.90m/s,with the raise in water volume fraction,the drag reduction rate first increased rapidly and then decreased slowly.The maximum drag reduction rate in the test range reached 35%.The research results could provide a theoretical guidance and technical support for the technology optimization of heavy oil-water ring transportation,as well as a new concept and method for the flow improvement of heavy oil pipeline transportation.
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