Polymer flooding for improving sweep efficiency has been studied extensively in laboratory and tested in fields for conventional oils. From the literature, polymer flooding is not recommended for oils with viscosity higher than 200 mPa.s. Severe viscous fingering during waterflooding of heavy oil leaves a large amount of oil untouched in the reservoir. Polymer flooding could be a potential method for enhanced heavy oil recovery by improving the sweep efficiency. However, how a polymer flooding should be planned for a heavy oil reservoir to make it economically feasible has not been studied.This paper investigated the potential of polymer flooding for heavy oil reservoir using a heavy oil of 1,450 mPa.s. Tertiary polymer flooding tests were performed in both homogeneous and heterogeneous (channelled) sandpacks. Results in homogeneous sandpacks showed that there existed a viscosity range for the injected polymer solution, in which the oil recovery had an evident increase with the increase of polymer solution viscosity. When the viscosity of polymer solution was outside of this range, the increase in polymer solution viscosity resulted in only a small incremental oil recovery. It was also found that the earlier the polymer flooding was applied, the lower the polymer solution viscosity was required to have an obvious increase in tertiary oil recovery. Results in channelled sandpack tests showed that the existence of heterogeneity in porous media greatly lowered the tertiary oil recovery by polymer flooding. These laboratory results will be helpful for the planning of polymer flooding for heavy oil reservoirs.

The present research aims at the establishment of a novel methodology to analyze the responses of a nonlinear machining system subjected to cutting forces excitations. For a systematic analysis, a nonlinear dynamic cutting system is developed that includes the main factors affecting vibration in machining. A new cutting vibration model is established to reflect the realistic vibrations of both the workpiece and the cutting tool of a lathe-type machining system. Vibrations of the workpiece and the cutting tool in a turning system are investigated on the basis of a coupled cutting vibration system established in the research. The effects of the workpiece deflection on the vibration of the machining system are considered. Moreover, the influences of nonlinear electrical features of the machining system's drive motor on the cutting vibration response are also considered in quantifying the nonlinear cutting force and the relative displacements between the workpiece and cutting tool. A set of numerical investigations of the behavior of the nonlinear cutting system is also carried out with implementation of the proposed model.