Realistic and Promising Technology Measures for SAGD Projects at Low Oil Price

Abstract

Steam assisted gravity drainage (SAGD) process is widely used in super heavy oil and oil sands projects. These projects generally have higher steam to oil ratio and poor economy, partly because un-uniform steam chamber along the horizontal section forms and it is hard to adjust, affecting by reservoir heterogeneity including muddy interlayer and thief zones. Therefore, it is desirable to explore realistic and promising technology measures for SAGD projects at low oil price. In this paper, almost all the technology measures for SAGD projects were extensively and deeply investigated in terms of domestic and foreign reports, literatures and on-site experiences. The available research subjects include Xinjiang Fengcheng and Liaohe super heavy oil projects in China as well as ten oil sands project attached to eight corporations in Canada. Better yet, numerous statistics about technology application are reviewed well-by-well, and field application effects for some technologies were verified by deliberate numerical simulation. Many realistic and enforceable technology measures were systematically analyzed and recommended. Single or multiple stage dilation start-up process assisted by waste water or polymer injection enhanced start-up process significantly. Infilling well pairs or wedge well, and sidetracking horizontal well or fishbone well effectively tapped the unswept remaining oil by steam. The other technologies further improved steam chamber conformance including non-condensable gas co-injection, ICD/FCD technology, differentiated operating pressure strategy, nitrogen plus dispersant foam profile control and other remedial measures, etc. Besides, the present situation and foreground application were summarized and evaluated for several promising new technologies to be studied such as screening low cost mixed solvent to increase solvent recovery, warm solvent gravity drainage (Nsolv) process and in-situ upgrading process assisted by electrical heater or catalytic modification to reduce the capital cost of surface facility, etc. The paper contains some previously unpublished data of practical experiences, and the findings of this investigation add to the knowledge base information related to improving the SAGD performance and economy of super heavy oil or oil sands projects.