蒸汽辅助重力泄油开发过程及机理研究综述

蒸汽辅助重力泄油(Steam-assisted gravity drainage,SAGD)技术是开采沥青/稠油油藏的一种行之有效的技术,尽管SAGD技术的概念看起来很简单,但在为理解这一过程而建立的理论中存在着诸多缺陷.实际上,SAGD是一个多物理过程,涉及同时传热传质,具体可分为注蒸汽循环预热阶段、蒸汽腔纵向扩展阶段、蒸汽腔横向扩展阶段以及蒸汽腔下降阶段等4个阶段.SAGD技术的开发机理包括蒸汽降黏、重力泄油、地质力学效应、热效应、蒸汽腔的聚并融合作用以及原地乳化作用等.其中部分机理存在争议,且机理间可能存在相互耦合的作用,未来应继续通过室内实验、数值模拟等手段进一步深入探究其耦合机理,为更好地理解、优化、设计SAGD开发过程打下坚实基础,从而在实际应用时充分考虑各项机理的综合作用,为SAGD开发提供更为可靠的评价、预测和设计手段.同时也应从充分理解常规SAGD的开发过程与机理出发,更合理地扩展SAGD开发的变种形式.

Review of Research on Recovery Process and Mechanism of Steam-assisted Gravity Drainage

Steam-assisted gravity drainage (SAGD) is an effective technique to develop asphalt/heavy oil reservoirs. Although the concept of SAGD seems quite simple, there are many flaws in the theories established to understand this process. In fact, SAGD is a multi-physical process involving simultaneous heat and mass transfer. Specifically, it can be divided into four stages: stage of loop preheating by steam injection, vertical expansion stage of steam chamber, horizontal expansion stage of steam chamber and descend stage of steam chamber. And the recovery mechanism of SAGD includes steam viscosity reduction, gravity drainage, geomechanical effects, thermal effects, steam chamber coalescence and in-situ emulsification effects. Some of above mechanism are controversial, and the coupling effects among them may exist. In the future, more laboratory experiments and numerical simulations should be carried out for further exploration of such coupling mechanism, so that we can better understand, optimize and design the development process of SAGD. Therefore, the comprehensive effect of various mechanisms can be fully considered in actual application scenarios, so as to provide more reliable approaches of evaluation, prediction and design for SAGD process. Simultaneously, it is necessary to fully understand the recovery process and mechanisms of conventional SAGD, so that more reasonable variant forms of SAGD can be established.