Optimization Of CO₂ Huff And Puff Mining Scheme

The basic principle of CO₂ huff and puff oil recovery technology is:when CO₂dissolves in formation crude oil under high pressure,it will reduce the viscosity of crude oil,and the volume of crude oil will also expand,which will increase the internal kinetic energy of crude oil and help reduce the capillary resistance of flowing crude oil.improving the flow capacity of crude oil.In addition,the CO₂ dissolved gas dissolved in crude oil can be partially separated and vaporized under the action of high temperature and high pressure of the formation,which can be converted into pressure energy of the formation.The reduction of reservoir pressure can free CO₂ in crude oil,drive crude oil into the wellbore,and thus lead to the so-called“dissolved gas flooding”.In actual situations,the well layout method during the development of oil and gas reservoirs can be either horizontal wells or vertical wells.According to the experience summed up by many scholars:In this paper,taking two specific well areas in an oilfield in my country as an example,according to the results of laboratory experiments,the phase change of crude oil before and after CO₂ injection will be fitted and calculated,and the component simulation PVT will be given.parameter.A typical numerical simulation model is established based on the depletion production performance data of the respective well types of the two well areas.The method of numerical simulation is used to discuss the best layout of the two wells.After selecting the appropriate well types for the two well areas,the design of the carbon dioxide huff and puff scheme is further carried out,including the optimal design of relevant parameters such as injection volume,injection speed,and soaking time.The analysis shows that:1.For the reservoir with relatively thin effective thickness,it is suitable to use horizontal well development,because the length of horizontal well is relatively long,after the implementation of fracturing,the effective development of the reservoir area can be achieved;for the relatively large effective thickness It is suitable to use vertical wells for development of oil reservoirs,because vertical wells have better depth effect,and after fracturing,the effective development of the reservoir area can be realized.2.For the injection volume and injection speed of CO₂ gas,the models of the two well areas show that the effect of implementing the huff and puff oil increase will increase with the increase of the injection volume and injection speed.The effect of oil will weaken with the increase of injection volume and injection rate;for bottom hole pressure,the models of both well areas show that the bottom hole pressure during production should not be too high,in case the pressure difference is too small to prevent The crude oil is driven to the wellbore;for the soaking time,the models of both wells show that soaking operation is not suitable.3.The final determined horizontal well huff and puff related parameters range:injection volume:124000m³ to 168000m³,injection rate:1400m³/d-1680m³/d,bottom hole pressure:3MPa-7MPa.The related parameters of vertical well huff and puff range:injection volume:1260000m³-1680000m³,injection rate:7000m³/d-8400m³/d,bottom hole pressure:3MPa-5MPa.