乐安油田注汽后火烧油层开发参数敏感性研究

EFFECT OF DEVELOPMENT PARAMETERS ON IN-SITU COMBUSTION AFTER INJECTING STEAM IN LE'AN OIL FIELD

火烧油层开发效果的影响因素很多 ,但在油藏条件一定的情况下 ,可通过分析开发参数的敏感性并设计其合理值来提高火驱的经济效益。以乐安油田火烧试验区为例 ,在注蒸汽热采历史拟合及蒸汽驱预测的基础上 ,利用工程计算及数值模拟方法 ,研究了射孔层位、射开厚度、注气速度、燃烧方式、转湿烧时机、湿烧水气比等参数对火烧效果的影响 ,分析了火烧前缘推进速度 ,优选了开发参数。结果表明 ,底层射孔可减轻火线超覆 ,射开厚度大可提高地层吸气能力。由空气油比和采收率来确定分阶段变速率注气开采效果较好 ,最大注气速度为 80 0 0 0m3 /d。湿式燃烧能提高采收率 ,降低空气油比 ,其合理的转湿时机为燃烧距离达到 2 5 % ,水气比为 2 .0kg/m3 。预测结果与实际结果吻合较好 ,为火驱试验的现场实施提供了理论依据。

The influence factors for combustion drive development are very complex. But the economic benefits of oil development can be improved by means of analyzing the sensitivity of operational parameters and optimizing the parameters under a certain reservoir condition. Taking an experimental reservoir of Le'an oil field as an example, on the bases of steam soak history matching and steam flooding forecasting, the main parameters influencing on combustion development, including perforation, air injection rate, combustion type (dry or wet), water air ratio and the start time of water injection for wet combustion were investigated and optimized using engineering calculation method and numerical simulation. The frontal advancing rate was analyzed. According to the air to oil production ratio and oil recovery, it is concluded that the perforation on bottom bed can reduce the overlap of combustion front, and the big thickness of perforation can increase the capability of inspiration, and the variable air rate is better than constant injection rate. The wet combustion is superior to dry combustion in improving recovery and making the air to oil production ratio reduced. The optimized parameters include maximum air rate of 8×10 4 m 3 per day, water injection distance at combustion front equal to 25 percent of well space, and water air ratio of 2 kg/m\+3. The calculation results agree with the practical results and can provide a theoretical basis for actualizing lease experiment and enlarging test area.