Study on long term retention of crosslinked polymer in core pores——by taking the core from Eh_3Ⅳ 5-11 of Shuanghe oilfield as an example

In order to further understand the long-term retention performance of crosslinked polymer in core pores and the influence on reservoir porosity and permeability damage, laboratory experiments were conducted on Ⅳ5-11 natural cores in Shuanghe oilfield. The change of porosity and permeability of different permeability cores after crosslinked polymer flooding was studied by means of CT scanning method. The results show core porosity and throat are full of crosslinked polymer after the injection of crosslinked polymer, and the core porosity and permeability decrease greatly. After standing for 12 months under the formation conditions, the crosslinked polymer will degrade, and the porosity and permeability can be recovered. The porosity and permeability in high-medium permeability cores are the best, and the recovery rate is above 90%, but the recovery degree in low permeability cores is poor. The experimental results further clarify the suitable reservoir conditions, and provide the basis for field profile control.