水平井提高油砂SAGD井组后期开发效果研究

Study on Improving Oil Sand SAGD Well Group Development Effect at Later Stage Using Horizontal Well Assistance

蒸汽辅助重力泄油(SAGD)是开采超稠油的一项先进技术。尽管学者们在井眼轨迹控制、注汽操作参数优化、均匀注采及注溶剂提高采收率等方面进行了深入研究,但是SAGD开发后期井组间仍存在大量剩余油未动用。为进一步提高SAGD开发效果,提出采用辅助水平井的措施。在辅助水平井与SAGD井组数值模拟机理模型基础上,分析讨论了辅助水平井横向和纵向位置、长度、启动时间以及注气量对开发效果的影响。研究结果表明:辅助水平井应平行于SAGD生产井,且位于生产井组间1/2处;当SAGD水平井组为400 m时,得到了辅助水平井最优注采参数,即长度为250 m,注气量为150~175 t/d;当SAGD井组蒸汽腔突破(发育到顶或者到顶后横向扩展)时启动水平井辅助。此外,基于机理模型参数优化结果,论证了辅助水平井对实际稠油SAGD井组开采后期的增油效果明显。

Steam Assisted Gravity Drainage(SAGD) technology is one of the advanced technologies for developing extra-heavy oil and oil sand. In the past four decades, a great deal of researches had been studied, including the wellbore trajectory control, optimization of the SAGD cycle preheating operation parameters, uniform injection and production and solvent injection to improving recovery, et al. However, there are still a large number of remaining oil between the SAGD well group in the later stage. To improve the development effect of the SAGD well group, a mechanism numerical simulation model of using an assistant horizontal well for improving SAGD well group was first established. Then the location and the injection/production operation parameters of the assistant horizontal well were analyzed and discussed. The results showed that the assistant horizontal well should be located at middle of the SAGD well group, and should be parallel to SGAD production well. When the horizontal well length of SAGD group is 400 m, the optimum injection and production parameters of the auxiliary horizontal well are obtained(eg, the length is 250 m and the injection rate is 150~175 t/d). And the assistant horizontal well should be started when the steam chamber of the SAGD well group breaks. In addition, it was proved that the assistant horizontal well has obvious stimulation effect on the actual SAGD well group in the late production period based on the parameters optimization results of the mechanism model.