稠油油藏水平井双管注汽井筒蒸汽参数分布规律

Distribution of steam parameters along horizontal wellbore with simultaneous dual-tubing injection technique in heavy oil reservoirs

为准确预测水平井双管注汽井筒内蒸汽热力参数分布规律,提高地层受热均匀程度,基于水平井双管管柱结构特点以及长短管同时注汽技术,建立水平井双管注汽井筒与储层耦合数学模型,并采用全隐式有限差分法和迭代算法对模型进行求解。运用该模型预测水平井井筒沿程蒸汽参数分布规律,对比短管注汽、长管注汽和双管注汽方式下地层受热均匀程度。研究结果表明:蒸汽压力降幅和温度降幅主要发生在长管内,最大降幅分别为61.71 kPa和1.59℃;蒸汽干度降幅主要发生在环空内,最大降幅为21.91%;且蒸汽压力、温度和干度从环空跟端到分隔器和从环空趾端到分隔器上的降幅几乎一样;双管注汽方式下地层受热最均匀,相比短管注汽,双管注汽在注汽结束时可将蒸汽腔发育均匀程度提高14.75%,因此,使用双管注汽技术能有效提高地层受热均匀程度。

To accurately predict the steam thermophysical parameters and improve the formation heating uniformity along the wellbore during the dual tubing injection process,a coupled reservoir and wellbore model was developed based on the structural characteristics of dual tubing horizontal wellbore and simultaneous dual tubing injection technique.The proposed model was solved by using a fully implicit difference method and iterative algorithm.With this model,the distribution of steam thermophysical parameters along the wellbore can be calculated,and the formation heating uniformity between the short tubing injection technique,long tubing injection technique and simultaneous dual-tubing injection technique was compared.The results show that the decline range of steam pressure and steam temperature mainly occur in the long tubing,and the maximum decline range of steam pressure and steam temperature are 61.74 kPa and 1.59℃,respectively.However,the decline range of steam quality mainly occurs in the annulus,the maximum decline range of steam quality is 21.91%.In addition,the decline range of the steam pressure,steam temperature and steam quality from the heel point to the landing position of the packer and from the toe point to the landing position of the packer in the annulus are almost equal.The best formation heating uniformity can be achieved under the condition of simultaneous dual tubing injection technique.Compared with the short tubing injection technique,the uniformity of the steam chamber can be improved by 14.75%with simultaneous dual tubing injection technique.Therefore,adopting simultaneous dual tubing injection technique can effectively improve the formation heating uniformity.