Distribution and Presence of Polymers in Porous Media
In order to better utilize the residual polymers formed after polymer flooding, the distribution and the presence of the polymers after polymer flooding were studied. This paper studied the vertical and plane distribution of the hydrophobically-associating polymer in addition to measuring the parameters after polymer flooding, which is important for numerical reservoir simulation. The results showed that the polymers mainly enter into the high permeability zone and distribute in the mainstream
... in the mainstream line area with only a small portion in the wing area. Based on the comparison of various experimental methods, double-slug experiments were chosen to measure the inaccessible pore volume and retention, which is considered to be the most accurate, most time-consuming and most complex method. Following this, we improved the processing method of experimental data by reducing it to one experiment with two parameters. At the same time, we further enhanced the accuracy of the experimental results. The results show that at 1750 mg/L, the inaccessible pore volume of the polymer is 25.8%. When the detention is 68.2 µg/g, the inaccessible pore volume constituted 22% of the total polymer, with the other 77.7% being the dissolved polymer. Moreover, the static adsorption and dynamic detention were measured, with the results showing that the static adsorption is larger than dynamic detention. Therefore, in the numerical reservoir simulation, using the static adsorption capacity instead of the dynamic detention is unreasonable. The double-slug method was chosen since it is more accurate for the determination of various parameters. Meanwhile, in order to enhance the accuracy of results, we improved the treatment of data. weight  , injection rate  and so on. Clarifying the distribution of polymers can provide the criteria for the next step to fully utilize the residual polymer. The presence     of polymers in porous media can be divided into two parts: polymers in the inaccessible pore volume (VIP) or polymers in the accessible pore volume. The latter has two states: detention  (including adsorption and captation) and dissolved polymers, which is shown in Figure 1 . The inaccessible pore volume occurs primarily because polymer molecules are large relative to solvent molecules and pores in the reservoir rock  . The VIP for polymer flooding has both positive and negative effects [19, 20] . It is known that VIP affects the rate of movement of polymer molecules through the medium. It is also probable that solvent interactions affect the flow and dispersion of solvent in which the polymers are dissolved. Table 1 shows a model  , which depicts the serious impact of VIP on the polymer flooding development index and on deciding follow-up operations. However, due to the complexity of the experiment, the VIP is hardly measured with the requirement for adjustment of parameters in the numerical models. If the VIP is not chosen to be a suitable value, it will lead to an inaccurate prediction of the polymer breakthrough time  . Energies 2017, 10, 2118 3 of 13 VIP and dynamic retention of the polymer at the same time. This study has significance in guiding the numerical simulation of polymer and dynamic monitoring.