Effect of Polymer Degradation on Polymer Flooding in Heterogeneous Reservoirs

Abstract

Polymer degradation is critical for polymer flooding because it can significantly influence the viscosity of a polymer solution, which is a dominant property for polymer enhanced oil recovery (EOR). In this work, physical experiments and numerical simulations were both used to study partially hydrolyzed polyacrylamide (HPAM) degradation and its effect on polymer flooding in heterogeneous reservoirs. First, physical experiments were conducted to determine basic physicochemical properties of the polymer, including viscosity and degradation. Notably, a novel polymer dynamic degradation experiment was recommended in the evaluation process. Then, a new mathematical model was proposed and an in-house three-dimensional (3D) two-phase polymer flooding simulator was designed to examine both polymer static and dynamic degradation. The designed simulator was validated by comparison with the simulation results obtained from commercial software and the results from the polymer flooding experiments. This simulator further investigated and validated polymer degradation and its effect. The results of the physical experiments showed that the viscosity of a polymer solution increases with an increase in polymer concentration, demonstrating their underlying power law relationship. Moreover, the viscosity of a polymer solution with the same polymer concentration decreases with an increase in the shear rate, demonstrating shear thinning. Furthermore, the viscosity of a polymer solution decreased with an increase in time due to polymer degradation, exhibiting an exponential relationship. The first-order dynamic degradation rate constant of 0.0022 day−1 was greater than the first-order static degradation rate constant of 0.0017 day−1. According to the simulation results for the designed simulator, a 7.7% decrease in oil recovery, after a cumulative injection volume of 1.67 pore volume (PV) was observed between the first-order dynamic degradation rate constants of 0 and 0.1 day−1, which indicates that polymer degradation has a detrimental effect on polymer flooding efficiency.

Experimental and numerical simulation study on the flow characteristics and optimization of structural parameters of displacement agent in partial pressure tools

“…Moreover, the structure of the molecular chain changes at all times during the flow of the polymer solution in the partial pressure tool, resulting in the experimental results being larger than the numerical simulation results . Moreover, the higher the concentration of the polymer solution, the greater the viscosity loss rate of the solution under the action of the partial pressure tool, and the greater the viscosity loss rate of high‐concentration polymer solution with the increase of the flow rate …”

“…52,53 Moreover, the higher the concentration of the polymer solution, the greater the viscosity loss rate of the solution under the action of the partial pressure tool, and the greater the viscosity loss rate of high-concentration polymer solution with the increase of the flow rate. 54 Figures 8-10 show the velocity nephogram, velocity streamline, and velocity change of polymer solution in the partial pressure tool when the flow rate is 10 m 3 /d, respectively. It can be seen from Figures 8 and 10 that the color change of the velocity nephogram is the most obvious when the flow cross section of the polymer solution is the smallest (the distance between the outer cylinder and the throttling groove is the smallest), which indicates that the degree of velocity change is the largest and the velocity reaches the maximum value of 2.06 m/s at the smallest cross section.…”

Chemical-Enhanced Oil Recovery Using N,N-Dimethylcyclohexylamine on a Colombian Crude Oil

“…Despite homogenization, several mineral samples from various locations were analysed; this metal was not observed before the washing process. Knowing that Fe minerals, combined with oxygen, can degrade some chemicals like polymers that are currently injected in reservoirs [33], they need to be identified because their potential effects on amines are unknown. On the other hand, oxygen and silicon were softly diminished, perhaps because the washing process reduces the quantity of minerals based on silicon because several of them are present in solid material and can be removed as fines.…”

Enhancing the Performance of HPAM Polymer Flooding Using Nano CuO/Nanoclay Blend

“…Figure 5 shows that the viscosity decreases with an increasing shear rate for all the fluid systems, which suggests a pseudoplastic (or shear thinning) behavior [29]. The decrease in viscosity with an increasing shear rate may result from the shear degradation of the HPAM molecules [18,33] and/or from disentanglement and alignment of the polymer chains along the direction of shear. Except for nanohybrid systems 2 and 6, which had a lower content of CuO NPs and nanoclay, as explained earlier, all nanohybrid systems displayed higher viscosities than HPAM solution for all the different shear rates.…”