一种新型稠油水平井注汽方法

针对水平井在注汽过程中,由于水平井段长,吸汽不均致使受热井段短,采收率低的问题,进行稠油水平井均匀注汽技术研究。根据分层注水原理,将单点注汽完善为多点注汽,通过孔眼限流,调整注汽剖面,保证水平段均匀受热,提高加热效率。应用油田统计数据,给出孔眼个数确定数学表达式,根据热学理论,建立水平段蒸汽干度分布模型及地层吸收热量与蒸汽干度降低损失热量平衡方程,确定了注汽孔眼直径,同时在注入工艺上进行改进,保证蒸汽正常注入。目前该技术已成功地在大庆油田第一口稠油水平井中应用,放喷阶段产油为该区块平均单井产油的7.3倍。测温曲线表明,水平段温度分布得到了很好的改善,实现了均匀注汽。

A New Steam Injection Method of Horizontal Well for Heavy Oil

Due to the long hole section and uneven seam absorption of horizontal well in the process of horizontal well steam injection, the being heated hole section is short as well as recovery is low. The uniform steam injection technology of horizontal well for heavy oil recovery was studied. Based on principles of separated layer water flooding, single point steam injection was improved to be multipoint steam injection. By limiting flow rate through steam injection hole, steam injection profile was regulated to ensure uniform heating of horizontal well section and to enhance heating efficiency. Using statistical data of oilfield, mathematical expression of steam injection hole number was derived. According to thermology theory, steam dryness fraction distribution model of horizontal well section as well as heat balance equation between formation absorption and heat lost due to dryness fraction of steam decreasing were established. The radius of steam injection hole was defined. Meanwhile, steam injection technology was improved to ensure regular steam injection. The technology was applied on the first horizontal well for heavy oil, and the oil production of blow off stage was 7.3 times as average single well production in the block. Temperature-sensing curves show that temperature distribution of horizontal well section was well improved and uniform steam injection was realized.