On the Relationship between Completion Design, Reservoir Characteristics, and Steam Conformance Achieved in Steam-based Recovery Processes such as SAGD

Abstract

Abstract With continuing decline of conventional crude oil reserves, there is higher demand for developing and producing heavy oil and bitumen resources. In Alberta, Canada, there are over 170 billion barrels of recoverable bitumen in oil sands. The two main thermal technologies being used to produce are Steam Assisted Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS). For Athabasca reservoirs, SAGD is the method of choice since the oil has low solution gas. One key factor that controls the success of these methods is steam conformance – the ability to control the distribution of steam within the oil column. In this research, thermocouple data from the Surmont SAGD pilot project together with reservoir geology are analyzed to examine steam conformance and its impact on process performance (oil rate, recovery factor, and steam to oil ratio). The data is analyzed to generate a simple correlation between reservoir geology and operating pressure to predict vertical steam conformance versus time. The results demonstrate that the reservoir geology, operating pressure, and well completion design all affect steam conformance in the reservoir. Also, the distribution of steam flow and pressure within the well impacts steam conformance in the reservoir. An analysis of the A wellpair of the Surmont SAGD pilot suggests that the distribution of steam flow in the well contributes largely to the non-uniform steam conformance along this wellpair.