特低渗透油藏注空气开采效果数值模拟研究

NUMERICAL SIMULATION ON AIR INJECTION IN ULTRA-LOW PERMEABILITY RESERVOIR

根据大庆外围油田实际地质资料,采用CMG-STARS数值模拟软件建立了注空气采油的三维油藏数值模拟模型,根据物理、化学实验结果及相关资料确定了原油与空气发生氧化的化学反应方程式及相关参数,进而通过对注空气低温氧化前缘推进过程、产出油气组成和最佳注气强度的研究预测了特低渗透油藏注空气开采效果。模拟结果表明,注空气后,在近井地带可形成低温氧化带,氧化带宽度为3 m左右。注入15年后,氧化带推进到100 m左右。低温氧化前缘最高温度达300℃左右。采油井在注气不同阶段产出油气的组分差异很大。为了维持油层稳定的燃烧、保证较高氧气利用率、取得最佳经济效益,合理注气强度应在1 000 m3/d·m左右。

According to the actual geological data of Daqing peripheral oilfield,a three- dimensional numerical reservoir model for air injection was established by using CMG- STARS numerical simulation software. On the basis of physics,chemistry experimental results,the chemical reaction equation of oil and air oxidation and the relevant parameters were determined.Then the effect of air injection in ultra- low permeability reservoir was numerical simulated and predicted. The simulation results show that,after air injection,low temperature oxidation zone can be formed in the near wellbore area,and the oxidation zone width is about 3 m. After injecting for 15 years,the oxidation zone moves forward about 100 m,the maximum temperature of low temperature oxidation front is up to 300℃. In the different stages of air injection,the component of oil and gas output is in great difference. In order to maintain stable reservoir combustion,high oxygen utilization rate,best economic benefits,the reasonable gas injection intensity should be at 1000 m^3/ d·m.