Some Recent Developments in SAGD

Abstract

Abstract Steam Assisted Gravity Drainage (SAGD) is being used increasingly for the recovery of bitumen and heavy oil in Canada. Four large SAGD projects are under construction in Athabasca and two others have been announced. These projects are expected to produce bitumen economically and with a recovery greater than 50%. Productivity will be close to 1000 B/d per well pair. There are also many successful smaller, and growing, projects and pilots in Athabasca, Cold Lake and Lloydminster. Because of the rising costs of fuel it is desirable to reduce steam requirements for SAGD. Means for doing this include cogeneration of steam and power, alternate fuels, choosing better reservoirs, improved heat recovery, and the newer related processes, SAGP and Vapex. In Steam Assisted Gravity Drainage (SAGD)(1), Steam and Gas Push (SAGP)(2), and Vapour Extraction (Vapex)(3) the oil isduced in viscosity and produced by gravity drainage to horizontalells placed low in the reservoir. As the oil drains, the vacatedreservoir pores are filled largely with gas/steam in SAGD, steam lus non-condensible gas in SAGP and solvent vapour plus noncondensible gas in Vapex. A common feature of the three processes is that the use of long horizontal wells combined with the reduced viscosity of the produced oil allows the production of oil with essentially no by-pass of free gas. In suitable reservoirs economic rates are achieved whereas with conventional wells or without adequate viscosity reduction there would be intolerable gas coning. High recoveries are obtained because of the systematic nature of the drainage. Since the author's earlier paper in this series(4) there has been a great increase in the interest in this subject and there are now many substantial field projects in various stages of planning and construction. Advanced Commercial SAGD Projects In Athabasca SAGD is at the stage where several major field projects to recover bitumen from Athabasca are either under construction or about to be. In most cases, the reservoirs are thicker than those that have been exploited previously and superior results are anticipated. The initial investment for large SAGD projects is of the order of $10,000 Canadian per B/d of capacity and the Steam Oil Ratio (SOR) is about 1.9 to 2.5. The supply costs for bitumen will probably be less than $10 Canadian per barrel, including return but excluding the fuel cost. This important cost is discussed later. Generally product lifting from the reservoir is by natural flow, a technique first demonstrated by Sceptre Resources and now used in several of the pilots. Four large commercial SAGD projects are described below. A recovery of over 50﹪ of the oil in place is expected in each. Figure 1 shows the approximate locations of the projects discussed below. Alberta Energy Company (AEC) Foster Creek (T70 R4 W4M)(5) This is a commercial expansion of AEC's pilot project, which produces 2,000 B/d from three SAGD well pairs.