Mechanism Experimental Study Of EOR In Deep Heavy Oil Reservoir By Natural Gas/Disoxidation Air Injection

LKQ oilfield is a deep glutenite viscous crude reservoir with strong heterogeneity.During the water injection development,there are some problems such as high-speed of water breakthrough and low efficiency of displacement because of the influencing factors of water sensitivity,high crude oil viscosity and low dissolved-gas.This paper focuses on oversea literature investigation and physical experiment,which lies at the base of these displacement problems.We work to find the optimal mining method on basis of mechanism of heavy oil recovery by natural gas/disoxidation air injection and the feasibility of gas injection.This paper has completed the evaluation of reservoir phase state characteristics,gas injection characteristics,single and double tube core gas injection sensitivity evaluation and analysis of effection,thus we got the following conclusions and suggestions:(1)By conducting the inflation and compatibility experiment of natural gas/disoxidation air with deep viscous crude,we found the two injected-gas had not been miscible with the formation of heavy oil.However,natural gas is better in the compatibility,reducing the viscosity of crude oil and rising the saturation pressure with the deep heavy oil.(2)the development of the single core injection and water flooding experiments shows under the condition of injecting the same displacement multiple,the oil displacement efficiency of water flooding is much lower than that of the natural gas injection,and more effectively than that of the injected disoxidation air.(3)By launching the single-tube long-core injection natural gas experiment,the gas injection parameters and the injection method are obtained.First,taking the gas injection measures earlier and maintaining the high injection pressure and controlling the reasonable injection rate will improve the efficiency of oil displacement effectively.Second,in the process of the target reservoir waterflooding development,converting to gas,gas water alternative drive or increasing gas injection slug size can significantly improve oil displacement efficiency at the early and middle times of producing water,but the effect of natural gas injection is not ideal.Third,In the fracturing group experiment,the effect of increasing oil and water control by natural gas huff-puff is better than that of disoxidation air,but the effect is not obvious in the experiment of non fracturing group.(4)The physical simulation experiments of three kinds of double-tube parallel long core are carried out.The experimental results show that,in the process of double-pipe parallel water flooding,because the long core with high permeability gives priority to the water flooding,the efficiency of flood control is different in the long core with low permeability.The efficiency of flooding of high-permeability pipes are not much different however the low-permeability long cores are quite different.Second,natural gas is easy to break because of the increment of double pipe heterogeneity and in the long core with high permeability,the effect of enhancement oil recovery is obvious by taking the natural gas huff-puff.