双水平井SAGD循环预热工艺研究与应用

The Study and Application of Circulation Steam Process in Dual-horizontal Well

蒸汽辅助重力泄油(SAGD)技术是开发超稠油的一项前沿技术,具有驱油效率高、采收率高的特点。该技术应用分为启动阶段和生产阶段。SAGD启动阶段应用的技术主要有蒸汽吞吐预热启动和循环预热启动。相对于蒸汽吞吐预热启动,注蒸汽循环预热启动加热均匀,启动平稳,有利于蒸汽腔的均匀扩散,蒸汽腔发育体积大,转入SAGD生产以后,生产效果好,采收率高。但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,尤其在工艺配套上,尚无满足循环预热试验要求的同注同采工艺技术,且国内尚无成功实施循环预热的先例可资借鉴。对循环预热工艺机理、注采参数设计、管柱结构进行研究,完成了为循环预热工艺配套的井下双管柱结构、无接箍长冲程抽油泵、注采一体双管井口等多项关键技术设备,现场应用表明,完全满足循环预热工艺要求。同时,得到合理的循环预热注汽量、注汽速度、注汽压力、采注比等预热参数,为下步SAGD试验的规模实施奠定了基础。

Steam assisted gravity drainage is an advanced technique for developing ultra heavy oil with the features of high-efficient oil displacement and high oil recovery efficiency.Its application has two stages：start- up and production.Nowadays,there are two methods applied in start-up SAGD process.One is cyclic steam stimulation and the other is circulation steam.Relative to cyclic steam stimulation,steam injection cycle preheating is more uniform and more stable to start up SAGD process ,which is favorable to uniform diffusion in steam chest.The effect will be good and oil recovery efficiency will be high after entering SAGD production for its big developmental volume of the steam chest.However,the completion string structure in the process of circulating steam is complicated.It is difficult to attain optimizing parameters at startup phase.The mechanism of circulation steam still needs for research further,especially on the matching technologies.The technology of injection and production at the same time needed for circulation steam should be researched because of no successful cases for references.The mechanism,injection-production parameter design and string structure of the circulation steam process are studied.Several key technologies and equipments are mature：downhole dual string structure,flush long stroke pump and integrated injection-production dual string head,which can meet the demands of the circulation steam process after the field application.Reasonable steam injection amount, steam injection rate,steam injection pressure,production-injection ratio and other parameters are obtained, which will pay the foundation for wide application of next SAGD experiments.