低渗油藏单井N2吞吐效果影响因素实验研究

三塘湖油田储层渗透率低,原油黏度高,单井产量低,注水难.为了提高单井产能,考虑注入气体,但是常规气驱用气量大.且易出现腐蚀、指进等问题,故考虑采用N2吞吐采油.分析了N2吞吐提高采收率机理,设计出储层条件下的单井模拟实验,研究单井N2吞吐采油的生产规律及其影响因素.使用三塘湖油田含气原油在长岩心物理模型上进行了一系列室...

Experiment research on influence factors of N2 huff-puff for single well in low permeability reservoir

The reservoir permeability in Santanghu Oilfield is very low,the flow seepage resistance is big,the viscosity of crude oil is very high,the single well production rate is very low and it is very difficult for waterflooding development.In order to improve the single well productivity,the gas injection is considered.However,the gas consumption is really huge under the condition of the ordinary gas flooding and it is easy to come with the problems of corrosion and fingering.So the nitrogen huff-puff is considered to increase oil recovery.This paper analyzed the principle for nitrogen huff-puff to increase oil recovery,designed the single well simulation experiments under the reservoir condition and studied the production disciplines and influence factors of single well.By using the crude oil from Santanghu Oilfield,we conducted series of simulation tests to study the influence of periodical injection,downhole pressure and multistage depressurization on periodical recovery degree on the long core physical model,acquiring the curves of huff-puff period-periodical recovery degree and injection-production relationship.The results show that the periodical injection and downhole pressure are the most important factors on the periodical recovery degree.Increasing the periodical nitrogen injection rate and decreasing the downhole pressure can improve the oil recovery degree.Two-stage depressurization can get better economic gain and the number of huff-puff periods can not exceed 3.This research is valuable for the program design of nitrogen huff-puff.