吐哈油田稠油油藏优化注气吞吐降黏实验研究

HUFF AND PUFF VISBREAKING EXPERIMENT IN TUHA OILFIELD HEAVY OIL RESERVOIR

针对吐哈深层稠油油藏常规方法难以有效开发的问题,通过PVT仪测试了搅拌状态下稠油注天然气、氮气和二氧化碳互溶后的黏度变化规律,测试了天然气和二氧化碳与英4井P3cf稠油配制的动溶稠油流体在不同混溶压力、不同实验温度条件下的原油黏度变化规律。在无搅拌条件下测试了天然气、二氧化碳静态混溶降黏效果。在此基础上,应用填砂管开展了注CO2吞吐提高稠油采收率的研究。结果表明,氮气、天然气、二氧化碳对英4井稠油的降黏率分别为56.8%、98.1%、99.7%,二氧化碳的降黏效果最好。静态混溶实验显示在各自的混溶周期内,二氧化碳的溶解气量远远高于天然气,意味着二氧化碳更能有效地降低地层稠油黏度,提高地层稠油的流动性能;填砂管吞吐实验说明多孔介质中天然能量自然衰竭实验的采出程度为3.86%,三轮次二氧化碳气体与稠油静溶吞吐实验累积采出程度增加了21.74%。

Aiming at the difficult development problems in Tuha deep heavy oil reservoirs by using conventional methods,the change laws of heavy oil viscosity were tested under stirring condition after injecting natural gas,nitrogen and carbon dioxide by using PVT instrument,and the experiment on crude oil viscosity change rules was also done by injecting natural gas and carbon dioxide in soluble heavy oil fluid under different miscibility pressure and different experimental temperature conditions.The visbreaking effects of heavy oil under static miscible natural gas and carbon dioxide were tested. On this basis,the sandpack tube huff and puff experiment improved heavy oil recovery ratio by injecting CO2. Research results showed that the visbreaking rates of nitrogen gas,natural gas and carbon dioxide in Ying 4well heavy oil were 56. 8%,98. 1% and 99. 7% respectively,the visbreaking rate of carbon dioxide was best. And the dissolved gas volume of carbon dioxide was higher than that of natural gas,carbon dioxide could effectively reduce the heavy oil viscosity,increase the f heavy oil flow property.