The Growth of the Steam Chamber During the Early Period of the UTF Phase B and Hangingstone Phase I Projects

Abstract

Abstract Based on temperatures measured in observation wells of the UTF Phase B project, the behaviour of the rising steam chamber when it reached impermeable layers was studied using a numerical thermal simulator. Results indicated that steam could rise by detouring the impermeable layers when they exist within the channel sands. The extension of these impermeable layers is generally less than 10 m in diameter. Most of these impermeable layers became permeable after one to one and a half years of heating with steam. When steam reached shaly sands in the upper part of the reservoir, steam rise was terminated. However, in some instances, it rose slowly after one to one and a half years of heating. Steam generally stopped to rise at few metres from the bottom of the point bar sands. However, a significant amount of bitumen could be produced from these sands. In the Hangingstone reservoir, Japan Canada Oil Sands Limited (JACOS) began initial steam circulation in April 1999 and the regular SAGD operation in July 1999. The early oil production volumes were close to our expectations. An extended understanding of the rising mechanism of the steam chamber is achieved by a comparison of the performances obtained in the Hangingstone and UTF reservoirs. Markedly different characteristics between each were detected, which can be caused by the variance in geomechanical behaviour of the tar sands. Introduction The steam assisted gravity drainage (SAGD) process has been successfully tested at the UTF (Underground Test Facility) project initiated in 1988. The project consisted of a small scale test (Phase A) with three pairs of 50 m horizontal wells, a commercial scaledpilot test (Phase B) with three pairs of 500 m horizontal wells, and Phase D where wells were drilled from the surface. The performance of these tests has been reported(1-3). Japan Canada Oil Sands Limited (JACOS) has participated in the UTF project since 1992, and acquired field data. Numerical history matches were conducted for all of these phases. For example, 10,990 grids were used to match the history of all three pairs of the Phase B project. In addition to the history match of well performances, flow resistance of the annulus and tubing, the effect of gas injection, and other aspects were also studied from the data provided. The growth mechanism of the steam chamber, which is presented in this paper, is also included in these topics. The original recovery mechanism of the SAGD process described by Butler(4, 5), is based on energy flow by thermal conduction, and drainage of the heated oil by gravity. Ito and Suzuki(6) proposed the importance of convective heat transfer in the SAGD process via numerical simulation. An equation to calculate oil production rates was developed by Ito et al.(7) through a parametric study, involving a series of numerical simulation runs. A quantitative heating mechanism of the reservoir by conduction and convection was also evaluated(8, 9). The above mechanism is based on the process where it becomes mature and the steam chamber grows sideways.