Experimental Study On Combustion Gas Flow In Yingdong Oilfield

Enhancing oil recovery is the eternal theme of oil and gas field development, which runs through the whole process of oil and gas field development. Looking around the current situation of oil and gas field development at home and abroad, EOR technologies having applied to the field scale focus on chemical flooding, thermal flooding and gas injection, of which thermal flooding plays a leading role, application of chemical flooding is a little, and gas injection, especially hydrocarbon gas injection, is one EOR technology which has great potential and development prospects.Yingdong Oilfield, as the object of study, is characterized by large reservoir thickness, interlaced oil-gas distribution and abundant gas. By means of laboratory experiments and numerical simulations, we study on the feasibility analysis of hydrocarbon gas injection EOR for Yingdong Oilfield. We have carried out the gas injection expansion, slim tube test and long-core displacement test in laboratory.This paper analyzed the influence of hydrocarbon gas injection to fluid phase. Fluid expansion test show that hydrocarbon gas injection is effective. While injection increase, the saturation pressure of crude oil, solution gas-oil ratio and expansion capability increased, but the oil viscosity decreased at the same time.This paper determined the minimum miscibility pressure of hydrocarbon gas injection. Through slim tube test, the minimum miscibility pressure of hydrocarbon gas injection is31.8MPa, and it’s higher than formation pressure15.5MPa, so that it is immiscible displacement in Yingdong Oilfield.This paper evaluated the effective of different ways of gas injection. For high permeability group, through four long-core displacement tests about depletion, direct gas injection, water-alternating-gas (WAG) and WAG after water flooding, it shows WAG and WAG after water flooding is better. For low permeability group, through two long-core displacement tests about direct gas injection and WAG after water flooding, it shows WAG after water flooding is much better.This paper carried out the numerical simulation of reservoir gas injection. Compositional model was chosen for the gas injection numerical simulation of reservoir. The recovery effects of depletion, direct gas injection, WAG and WAG after water flooding were compared. The results showed that elastic energy of reservoir and recovery degree is low, the recovery degree of WAG is highest, which is up to35.85%.