SAGD开发伴生气影响数值模拟分析

Analysis of the Effect of Associated Gas in SAGD Development by Numerical Simulation

蒸汽辅助重力泄油（SAGD）是一种能够大幅提高超稠油采收率的开发技术,蒸汽在蒸汽腔内加热原油过程中因水热裂解反应会产生各种气体,如甲烷、二氧化碳和硫化氢。运用CMG公司的STARSII数值模拟软件来模拟SAGD操作中气体的变化过程,描述SAGD开发过程中伴生气对数值模拟结果的影响,得到描述SAGD开发中伴生气产生主要过程的模拟结果。针对油藏实际建立理论模型进行数值模拟,模拟的主要气体组分包括硫化氢、二氧化碳和甲烷,通过模拟气体产量随时间的变化,确定伴生气的存在增加了油-气-水过渡带的范围,导致蒸汽加热原油的效率降低,产油速度小于脱气原油模型;脱气原油模型运行时间约40min,含气原油模型运行时间约1h,两者相差不大。模拟过程加入伴生气使模拟产量更接近实际结果 ,因此建议在进行SAGD开发数值模拟时要充分考虑伴生气的产出。

Steam assisted gravity drainage（SAGD） is a development technique for enhancing oil recovery of super heavy oil greatly.When the steam heats the crude oil in the steam chamber,various gases may be produced because of aquathermolysis,such as methane,carbon dioxide and hydrogen sulfide.STARSII numerical simulation software of the CMG company was applied to the simulation on the process of gas variation in the SAGD,and to the description of the effect of associated gas in SAGD development on the numerical sim-ulation result.And the simulation results of the main generation process of the associated gas in the SAGD development were described as well.Numerical model was established based on real reservoir conditions,in which the main gas components are the hydrogen sulfide,carbon dioxide and methane.The change of gas production with time was simulated,and the existing of associated gas made the range of oil-gas-water transition zone larger.So the efficiency of steam heating on the oil dropped and oil production rate was less than that by the degassed crude model.Simulation time of the degassed crude model and gas-bearing crude model was about 40 min and 1 h respectively with few differences.When the associated gas was injected during the simulation,the simulated production was more close to the actual results.So it is recommended to consider the effect of the associated gas in SAGD development by the numerical simulation.