Abstract
Rules of thumb that are used in the industry for polymer flooding projects, tend to limit the distance over which HPAM polymers can be transported in pipelines without undergoing significant degradation. However, in sensitive environments such as offshore facilities where footprint minimization is required, centralization of the polymer hydration process and longdistance transport may be desirable. More reliable rules are required to design the pipe network and to estimate mechanical degradation of polymers during transport in turbulent conditions.
In this work, we present evidence in the form of both empirical, large-scale pipeline experiments as well as theoretical development refuting the claim that polymer pipeline transport is limited by mechanical degradation. Our work concludes that mechanical degradation occurs at a critical velocity which increases as a function of pipe diameter. Provided the critical velocity is not reached in a given pipe, there is no limit to the distance over which polymer solution can be transported.
In addition, the drag reduction of viscous polymer solutions was measured as a function of pipe length, pipe diameter, fluid velocity and polymer concentration. An envelope was defined to fix the minimum and maximum drag reductions expected for a given velocity on larger pipes. For pipes with diameter varying between 14″ and 22″ at a velocity higher than 1 m/s, the drag reduction percentage is anticipated to be between 45 and 80%. A more refined model was developed to predict drag reduction with less uncertainty.
In conclusion, classical design rules applied for water transport (fluid velocity <3m/s) can be applied to the design of a polymer network. Therefor, for tertiary polymer projects, the existing water injection network should be compatible with the mechanical requirements of polymer transportation.
