基于非稳态热传导的SAGD开发指标预测模型

根据传热学和热采理论，利用程序设计的方法，对考虑边界效应的SAGD（蒸汽辅助重力泄油）非稳态热传导模型和开发关键指标解析解及开发指标的快速预测进行了研究。研究结果表明：(1)现有的非稳态热传导模型对传热外边界的温度假设存在局限性，根据能量守恒原理修正传热外边界条件，建立传热深度与累积传热量的解析关系，可定量计算上覆和下伏地层的热损失；(2)在巴特勒经典SAGD产量模型基础上，推导的蒸汽腔上升及横向扩展阶段和下压阶段的产水量、油汽比和蒸汽热利用率等解析模型，可实现SAGD特定开发阶段或全生命周期开发关键指标的快速预测；(3)通过与实际指标对比，井组生产6.4 a预测油汽比和含水率的符合率均在95%以上，证实了解析模型和程序设计的可靠性；(4)根据准噶尔盆地风城油田重32井区油藏参数，预测分析的不同油层厚度条件下SAGD蒸汽热利用率和关键开发指标表明，蒸汽热利用率大于35%、油汽比大于0.15对应油层厚度应大于12 m。

SAGD production performance prediction model based on unsteady heat transfer

According to the theories of heat transfer and thermal recovery，the SAGD (steam-assisted gravity drainage) unsteady heat transfer model and the analytical solutions of key development indexes were derived， which were taken into account for boundary effect. The rapid prediction of development indexes was realized by using the program design method. The results show that: (1) The existing unsteady heat transfer models have limitations on the temperature assumption of the outer boundary of heat transfer. According to the principle of energy conservation，the outer boundary condition of heat transfer was modified，and the analytical relationship between the heat transfer depth and the accumulated heat transfer was established，which can be used to quantitatively calculate the heat loss of the overburden and underburden. (2) On the basis of Butler’s classical SAGD production model，the analytical models of water production，oil-steam ratio and steam heat utilization ratio in the steam chamber rising stage，lateral expansion stage and downward expansion stage were derived respectively，which can realize the rapid prediction of key indicators in the specific development stage or the whole life cycle of SAGD. (3) By comparing with the actual production indexes of the well group in 6.4 years，the coincidence rates of predicted oilsteam ratio and predicted water-cut are above 95%，which confirms the reliability of the analytical model and the program design. (4) According to the reservoir parameters of Zhong 32 well area in Fengcheng oilfield of Junggar Basin，the predicted and analyzed SAGD steam heat utilization rate and key development indicators under different oil layer thickness conditions show that when the steam heat utilization ratio is greater than 35% and the oilsteam ratio is greater than 0.15，the corresponding oil layer thickness should be greater than 12 m.