Effects of residual resistance factor in the mobility control of the polymer flooding

Abstract

To broaden the application of the polymer flooding in complex reservoirs, the residual resistance factor (RRF) is sought to make up for the limitations of high‐viscosity polymer flooding. First, the polymer solution rheology, adsorption and retention behaviors were mathematically characterized, and subsequently substituted into the equation of motion of the aqueous phase to build a mathematical model of the polymer flooding percolation. Second, based on the built numerical model, the formation process of seepage resistance and pressure propagation characteristics of polymers with a high RRF in the porous media were investigated. Lastly, the effects arising from viscosity and RRF on the flow control of the polymer flooding were explored by comparing the injection capacity, crude oil utilization and profile control capacity of different permeable formations at different development stages. As revealed by the results, the RRF was found to be more favorable than the “viscosity” parameter in improving the injection capacity at the polymer flooding stage. Moreover, it was found to slow down the water‐cut increase at the subsequent water flooding stage and reduce the difference between the oil recovery rate and injection pressure at different stages. Furthermore, the viscosity was primarily adopted to facilitate oil recovery of medium and high‐permeability formations by increasing the oil replacement efficiency, while the RRF was primarily dependent on the regulation of interlayer water absorption differences, thus mobilizing the remaining oil under the low‐permeability formations.

Simulated evaluation of the degradation of hydrophobically associative polymers in the formation

“…13,[20][21][22][23] The polymer solution will undergo adsorption and retention during the process of flooding, which makes the permeability of the water phase in the seepage channel decrease, [24][25][26] which has the effect of controlling the rate of increase of water content and ultimately improves the recovery of crude oil. [27][28][29] The physical chemistry of polymers has been studied in detail by many scholars for their ability to enhance the recovery of crude oil. [30][31][32][33][34][35][36] For polymer flooding to enhance crude oil recovery, researchers in the field have focused on: (1) Polymer solution viscosity.…”

“…Polymer flooding is mainly used to increase the viscosity of the replacement phase by injecting polymer solution into the formation, 15‐19 which decreases the viscosity ratio of oil and water phases and then achieves the effect of controlling the rate of increase of water content in the extraction fluid 13,20‐23 . The polymer solution will undergo adsorption and retention during the process of flooding, which makes the permeability of the water phase in the seepage channel decrease, 24‐26 which has the effect of controlling the rate of increase of water content and ultimately improves the recovery of crude oil 27‐29 …”

Experimental Study on Early Polymer Injection Timing of Heavy Oil Reservoir in Bohai Sea

“…[19].The concrete steps are as follows:(1) The sand pack is vacuumed and saturated with the synthetic brine. Porosity is calculated based on the weight difference before and after the sand pack is saturated with brine.…”