Experimental Study on Chemical Flooding for Enhanced Oil Recovery in Low-Permeability High-Pour-Point Heavy Oil Reservoirs

As the largest domestic production base for heavy oil and high-pour-point oil, the Liaohe Oilfield has now entered the “dual-high” development stage. High-pour-point heavy oil is a special type of crude oil characterized by high viscosity, high resin and asphaltene content, and high wax content. Unlike conventional light oil, coupled with the low permeability of the reservoir and small pore-throat radius, the interaction between low-permeability reservoirs and the physical properties of high-pour-point heavy oil results in low efficiency in traditional water flooding. There is an urgent need to establish a chemical flooding system suitable for this block. The target block has an average reservoir permeability of 76.3 mD and an average pore-throat radius of 2.64 μm. Laboratory studies were conducted through experiments on the injectivity of low-molecular-weight polymers into the reservoir, evaluation of viscosity reducers, and the systematic construction of a chemical flooding system combined with digital simulation technology. Digital core simulation technology was used to optimize polymer concentration, viscosity reducer concentration, and slug size. Experimental results show that JN-1 can significantly reduce crude oil viscosity, achieving a viscosity reduction rate of over 93%. The composite viscosity-reducing flooding notably enhances oil recovery, increasing it by 11.8% compared to water flooding. The research findings demonstrate that the JN-1 viscosity reducer and low-molecular-weight polymer flooding system provide an important theoretical basis and technical guidance for the development of actual reservoirs, offering potential to promote the efficient exploitation of high-pour-point heavy oil in low-permeability reservoirs.