Impact of well configuration on performance of steam-based gravity drainage recovery processes.

摘要

The volume of heavy oil and bitumen in the oil sands deposits in Western Canada is similar to that of conventional crude oil in the Middle East. This resource is immense but is difficult and energy intensive to extract because the viscosity of the oil is high, typically over 100,000 to 1,000,000+ cP at original reservoir conditions. Current commercial thermal recovery processes used are Steam-Assisted Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS). These methods are both energy intensive and use large volumes of water to recover the oil. In this thesis, the focus is on SAGD-type processes. It has been demonstrated that operating strategy can be altered to improve SAGD performance but it is not clear how well configuration can be changed to improve recovery, energy intensity, thermal efficiency, water use, and flue gas emissions. This thesis examines the impact of position and geometry of steam injectors on the performance of SAGD-like processes in homogenous and heterogeneous reservoirs. Different injection well configurations including single horizontal (typical SAGD), offset SAGD, and vertical/horizontal well combinations have been evaluated by using a detailed, three-dimensional, geostatistically-populated, large-scale thermal reservoir simulation model derived from core and log data of the Dover pilot site. The research reveals how injection well configuration impacts energy delivery to the reservoir, thermal efficiency, and how it changes the evolution of the steam conformance zone and oil flow dynamics in the reservoir. The results suggest that vertical injectors have the potential to deliver steam more efficiently than a single horizontal injector.