Experimental study on the transport, gelation, and flow diversion effects of low initial viscosity profile control agents: Taking the reservoir geology and fluids of Bohai S Oilfield as an example

The main oilfields in Bohai Sea have entered the development stage of "high water cut, high recovery degree", and it is urgent to adopt technical measures of "stabilizing oil and controlling water" through fluid diversion. During the construction of profile control, it is required that the mixture of polymer and crosslinking agent must have good injectability, characterized by low initial viscosity, to avoid damaging non-target layers. Meanwhile, it is required that the mixture can undergo crosslinking reactions in the reservoir. It intends to study the transport performance and flow diversion effect of two polymer crosslinking agent mixtures using multi pressure points long cores and heterogeneous cores within the layers. The results show that compared with the existing lotion polymer mixture, the new polymer mixture has lower initial viscosity, and smaller polymer molecular aggregate size, enabling it to easily penetrate deep into the high-permeability zones of cores (reservoirs). Additionally, the aggregate is weakly damaged by core pore shear, resulting in better gelation performance. The new polymer mixed fluid forms a significant crosslinking reaction in the core, and has a strong retention effect of "increasing resistance and reducing permeability", achieving better fluid flow diversion, and leads to a greater increase in profile control recovery.