Study On Selection Method Of Oil Displacement Formula Of Daqing Crude Oil-betaine Emulsion

At present,the majority of domestic oil fields have entered the third stage of exploitation,the commonly used surfactants are divided into two categories: anionic type and non-ionic type,which have higher environmental requirements,strong dependence on alkali,alkali will produce many adverse effects,so it is urgent to develop better physical and chemical properties of surfactants.Taking the ternary system of heavy alkyl benzene sulfonate strong base and petroleum sulfonate weak base as the best indoor standard system,through the evaluation and analysis of the emulsification performance and oil displacement effect of the standard system,the evaluation method of the ternary system emulsification performance and oil displacement effect was established,and the emulsification performance parameters and oil displacement effect were compared and analyzed.The evaluation standard of betaine binary flooding formula suitable for pore structure characteristics of Daqing M block was established.At the same time,the pore structure characteristics of M block reservoir are tested,and the formation pore throat data are obtained.Secondly,under the same condition,different compound types of betaine surfactants were evaluated and analyzed,and the preliminary screening was carried out,and the sensitivity parameters of different compound types of betaine surface binary system oil displacement effect were obtained.Then,according to the size of betaine emulsion particle size in the binary system of oil displacement partition experiment,obtained the matching ratio of emulsion particle size and pore radius and formula screening method,and again verify the emulsion sensitive parameters,obtained the best betaine emulsion oil displacement formula.The results show that:(1)The pore structure characteristics of cores show that the pore structure parameters of cores with similar porosity and permeability have little difference.(2)The standard experimental study on the performance evaluation of betaine emulsion shows that the smaller the interfacial tension is,the better the oil recovery is;The lower the water fraction,the better the chemical flooding effect.The lower the emulsion stability index is,the slower the droplet polymerization rate is,and the better the oil displacement effect is.In a certain viscosity range,the chemical flooding recovery increases with the decrease of the viscosity of crude oil.As the particle size of emulsion decreases,the recovery rate of chemical flooding increases.(3)In betaine main agent oil displacement system,emulsion viscosity is the sensitive parameter of emulsification performance.There is a negative correlation between emulsion viscosity and chemical flooding recovery.The emulsion viscosity is also the sensitive parameter of betaine main agent and assistant(1)system.The main sensitive parameter of emulsion performance of betaine main agent and auxiliary agent(2)system is the interfacial tension value.The sensitive parameter of emulsion performance of betaine main agent and auxiliary agent(3)system is emulsion stability index.(4)Research on oil displacement formula screening method: The ideal range of pore particle ratio(the ratio of average pore radius to particle size)is 3.11 to 4.24.The optimal formula of betaine emulsion oil displacement is betaine type and surfactant concentration of A7/0.3% system,B6/0.1% system and B8/0.2% system.