Abstract
Non-uniformity of the steam-assisted gravity drainage (SAGD) steam chamber significantly decreases the development of heavy oil reservoirs. In this study, to investigate the steam conformance in SAGD operations, a wellbore model is developed for fluid flow in dual-string horizontal wells. Then, a three-dimensional, three-phase reservoir model is presented. Next, the coupled wellbore and reservoir model is solved with a fully implicit finite difference method. Finally, the effects of the injector wellbore configuration, steam injection ratio and injection time on the steam conformance are investigated. The results indicate that under different injector wellbore configurations, the closer the differences between the pressure drop from the landing position of the short string to the heel of the wellbore and the pressure drop from the landing position of the short string to the toe of the wellbore, the better is the steam conformance. The smaller the difference in the steam injection rate between the long and short injection strings, the higher is the uniformity of the steam chamber. The injector annular pressure profile uniformity is consistent with the steam conformance. Creating a more uniform steam pressure in the annulus of the injector improves the uniformity of the steam chamber. The steam conformance decreases with increasing injection time, so the optimization method of steam chamber uniformity should be adjusted according to different injection times.
Highlights
Heavy oil is an important energy source [1,2,3,4], and Steam-assisted gravity drainage (SAGD) is an effective technology for the economic recovery of heavy oil [5,6,7,8]
When the wells are converted to steam-assisted gravity drainage (SAGD) operation after circulation, steam is injected down the short deriving numerical model are asboth follows: and long the strings in the injector, and strings in the producer are used for production (Figure 2b)
The well configuration in the developed model is a dual-string well configuration; the fluid flow behaviour in the cases of the heel point injection mode and the toe point injection mode can be simulated by the developed model
Summary
Heavy oil is an important energy source [1,2,3,4], and Steam-assisted gravity drainage (SAGD) is an effective technology for the economic recovery of heavy oil [5,6,7,8]. Successful field testing of the SAGD process has demonstrated that the dual-string completion improve chamber conformance [16].chamber This completion scheme injectionscheme points in scheme hasthe thesteam potential to improve the steam conformance [16].offers. Dong developed a physical model experimentally study steam conformance with single-string well configuration and a dual-string well configuration. Of model and a wellbore model was not considered, and the injection and production performance thedual-string coupling of a reservoir model and a wellbore model was not considered, and the injection and dual horizontal wells has not been studied. The focus of the study is to propose a numerical model to investigate the steam conformance along the dual-string horizontal wells in SAGD operations. Uniformity of the steam chamber, and reasonable suggestions are given to improve the steam chamber conformance
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