Study Of The Technology Of Water Shut Off And Enhanced Oil Recovery By Nitrogen

Gas drive is the important technology of enhancing oil recovery.In this paper for heavy oil,we study the mechanism and applicable conditions of reservoir of the nitrogen huff and puff technology to enhanced oil recovery by using the method based on physical model and numerical simulation.Firstly,there is a study on oil-water relative permeability change rule and oil-water distribution characteristics after nitrogen huff and puff by using single sand pack and parallel double sand pack experiment.Secondly,there is a study on reservoir adaptability water off and enhanced oil recovery by nitrogen by using sand pack physical model experiment,analyzing the stimulation effect of the reservoir of different permeability,viscosity,and level difference.Finally we made a optimization of production parameters of water off and enhanced oil recovery by nitrogen by numerical simulation.Research results show that injection nitrogen can increase the energy of the near bore;Dispersed nitrogen slug not to overlap,only continuous gas reaches a certain scale after back to produce floating up effect;Gas injection in high water cut part of the bottom water can be advanced more uniform,and the gas concentration near the well can better suppress the fingering of the water.Numerical simulation results show that the technology of water off and enhanced oil recovery by nitrogen for high permeability reservoir has a good effect of increasing oil production;For higher temperature and lower viscosity thermal recovery wells has a good effect of controlling water cut and increasing oil production;The greater heterogeneity of reservoir,the worse effect of controlling water cut and increasing oil production.Optimum parameters of nitrogen stimulation is: the cycle injection rate being from 28800 m3 to 144000 m3,the injection pressure in 6 mpa,the range of gas injection rate from 2400 to 2800 m3 /d,soak time within two days,the biggest cycle oil increment in second soak,then cycle oil increment gradually reducing.