Study On Seepage Characteristics Of Underground Fluids In Heavy Oil Reservoir Of Es₃²⁺³Ⅲ In Liu 1 Fault Block Of Liuzan Oil Field

The heavy oil reservoir of the Es₃²⁺³Ⅲ oil group in the Liu-1 fault block of Liuzan oil field is the main block of the Liuzan Oilfield.Typical problems such as wax precipitation,high injection pressure and rapid rise of water-cut during the waterflood development are encountered.These are caused by the complicated seepage characteristics of oil and water phase.Therefore,this article studies the high-pressure properties and seepage characteristics of reservior fluids,in order to provide a theoretical basis for the development of water injection in heavy oil reservoirs and CO₂ stimulation in later stage.Firstly,the PVT properties of heavy oil,formation gas and non-condensate gas system were studied.The effects of temperature,dissolved gas-oil ratio,and gas type on the viscosity,density and volume fraction of heavy oil were analyzed,the PVT maps of formation oil ang non-condensate gas system were established.Secondly,the crude oil composition was analyzed.The mechanism of the formation of viscous oil viscosity was analyzed by the wax precipitation characteristic parameters.A model for stimulating the PVT properties of crude oil was established by using crude oil components,and a method for predicting the wax apparent temperature of the degassed heavy oil and formation oil viscosity-temperature curve was established.Finally,the indoor long-core lab test was used.The physical simulation method of core water flooding was used to study the relative permeability curves and recovery rules of water injection development in heavy oil reservoirs,and the template for oil and water two-phase threshold pressure gradients at different water cuts was established.The design of a conventional heavy oil water flooding was followed by non-condensate gas injection.The indoor experiments have verified the reliability of the PVT rule for heavy oil and non-condensable gas systems;and studied the effect of parameters such as gas injection volume,throughput cycle,well-soaking time,gas injection velocity,and bottomhole pressure on CO₂ huff and puff recovery.This paper clarifies the high-pressure physical properties of reservior fluids and non-condensable gas systems in Liuzan Oilfield,oil-water two-phase threshold pressure gradient and the reasonable parameters of CO₂ huff and puff after water flooding which are important for guiding heavy oil development in Liuzan Oilfield.