双水平井超稠油SAGD循环预热启动优化研究

蒸汽辅助重力泄油是开发超稠油的一项前沿技术，其启动技术主要有蒸汽吞吐预热启动和循环预热启动。相对于蒸汽吞吐，注蒸汽循环预热启动吸汽加热均匀，启动平稳，但是配套循环预热管柱结构复杂，预热参数优化困难，循环预热机理仍需进一步研究。运用离散化井筒模型，对双水平井SAGD启动的三个阶段循环预热、压差对流、转入SAGD进行了优化设计，得到了合理的循环预热注汽速度、注汽干度、注汽环空压力、注汽压差产生时机和压差大小，为下步SAGD先导试验的顺利实施提供了可靠的依据。

STUDY ON SAGD TECNOLOGY FOR ULTRA HEAVY OIL IN DUAL HORIZONTAL WELLS

Steam assisted gravity drainage is an advanced technique to develop extra heavy oil.Nowadays,there are two methods to start up SAGD process.One is cyclic steam stimulation and the other is circulation steam.Relative to cyclic steam stimulation,steam injected cycle preheating is more uniform and more stable to start up SAGD process.However,the completion string structure to apply circulating steam is complicated.It is difficult to attain optimizing parameters of startup Phase.In terms of a fully coupled discretized wellbore model,circulating phase′s parameters are optimized during three phases of initial circulation phases,pressure differential phase and converted full SAGD phase.Reasonable parameters about steam rate,steam quality,steam pressure and chance and magnitude of pressure differential are attained.