Geomechanical Effects on the SAGD Process
- Patrick Michael Collins (Petroleum Geomechanics Inc)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- August 2007
- Document Type
- Journal Paper
- 367 - 375
- 2007. Society of Petroleum Engineers
- 4.3.4 Scale, 1.14 Casing and Cementing, 1.2.1 Wellbore integrity, 2.2.2 Perforating, 5.5 Reservoir Simulation, 1.2.2 Geomechanics, 1.10 Drilling Equipment, 2 Well Completion, 5.5.2 Core Analysis, 2.4.3 Sand/Solids Control, 5.4.6 Thermal Methods, 5.4.11 Cold Heavy Oil Production (CHOPS), 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.2 Reservoir Fluid Dynamics, 5.2.1 Phase Behavior and PVT Measurements, 1.6 Drilling Operations, 1.6.9 Coring, Fishing, 5.8.5 Oil Sand, Oil Shale, Bitumen, 3 Production and Well Operations, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 4.2 Pipelines, Flowlines and Risers, 5.3.9 Steam Assisted Gravity Drainage
- 6 in the last 30 days
- 2,494 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 5.00|
|SPE Non-Member Price:||USD 35.00|
Steam-assisted gravity drainage (SAGD) is a robust thermal process that has revolutionized the economic recovery of heavy oil and bitumen from the immense oil-sands deposits in western Canada, which have 1.6 to 2.5 trillion bbl of oil in place. With steam injection, reservoir pressures and temperatures are raised. These elevated pressures and temperatures alter the rock stresses sufficiently to cause shear failure within and beyond the growing steam chamber. The associated increases in porosity, permeability, and water transmissibility accelerate the process. Pressures ahead of the steam chamber are substantially increased, promoting future growth of the steam chamber. A methodology for determining the optimum injection pressure for geomechanical enhancement is presented that allows operators to customize steam pressures to their reservoirs.
In response, these geomechanical enhancements of porosity, permeability, and mobility alter the growth pattern of the steam chamber. The stresses in the rock will determine the directionality of the steam chamber growth; these are largely a function of the reservoir depth and tectonic loading. By anticipating the SAGD growth pattern, operators can optimize on the orientation and spacing of their wells.
Core tests are essential for the determination of reservoir properties, yet oil sand core disturbance is endemic. Most core results are invalid, given the high core-disturbance results in test specimens. Discussion on the causes and mitigation of core disturbance is presented.
Monitoring of the SAGD process is central to understanding where the process has been successful. Methods of monitoring the steam chamber are presented, including the use of satellite radar interferometry. Monitoring is particularly important to ensure caprock integrity because it is paramount that SAGD operations be contained within the reservoir.
There are several quarter-billion-dollar SAGD projects in western Canada that are currently in the design stage. It is essential that these designs use a fuller understanding of the SAGD process to optimize well placement and facilities design. Only by including the interaction of SAGD and geomechanics can we achieve a more complete understanding of the process.
Geomechanics examines the engineering behavior of rock formations under existing and imposed stress conditions. SAGD imposes elevated pressures and temperatures on the reservoir, which then has a geomechanical response. Typically, the SAGD process is used in unconsolidated sandstone reservoirs with very heavy oil or bitumen. In-situ viscosities can exceed 5 000 000 mPa•s [mPa•s º cp] under reservoir conditions.
These bituminous unconsolidated sandstones, or "oil sands,?? are unique engineering materials for two reasons. Firstly, the bitumen is essentially a solid under virgin conditions, and secondly, the sands themselves are not loosely packed beach sands. Instead, they have a dense, interlocked structure that developed as a result of deeper burial and elevated temperatures over geological time. In western Canada, the silica pressure dissolution and redeposition over 120 million years developed numerous concave-convex grain contacts (Dusseault 1980a; Touhidi-Baghini 1998) in response to the additional rock overburden and elevated temperatures. As such, these oil sands are at a density far in excess of that expected under current or previous overburden stresses. Furthermore, once oil sands are disturbed, the grain rotations and dislocations preclude any return to their undisturbed state.
Oil sands, by definition, have little to no cementation. As such, their strength is entirely dependent upon grain-to-grain contacts, which are considerable in their undisturbed state. These contacts are maintained by the effective confining stress. Any reduction in the effective confining stress will result in a reduction in strength. Because the SAGD process increases the formation fluid pressure, it reduces the effective stresses and weakens the oil sand.
|File Size||1 MB||Number of Pages||9|
Aherne, A. and Birrell, G. 2002. Observations Relating toNon-Condensable Gasses in a Vapour Chamber: Phase B of the Dover Project.Paper SPE 79023 presented at the SPE International Thermal Operations and HeavyOil Symposium and International Horizontal Well Technology Conference, Calgary,4-7 November. DOI: 10.2118/79023-MS.
Bachu, S. and Underschultz, J.R. 1993.Hydrogeology of Formation Waters, Northeastern Alberta Basin. AAPG Bull.77 (10): 1745-1768.
Birrell, G. 2001. Heat transfer ahead ofa SAGD steam chamber: a study of thermocouple data from Phase B of theUnderground Test Facility (Dover Project). Paper 2001-088 presented at theCanadian Intl. Petroleum Conference, Calgary, 12-14 June.
Butler, R.M. 1997. Thermal Recovery ofOil and Bitumen, second printing. Calgary: GravDrain.
Chalaturnyk, R.J. 1996. Geomechanics ofthe steam assisted gravity drainage process in heavy oil reservoirs. PhDdissertation, Dept. of Civil Engineering, U. of Alberta, Edmonton, Alberta,Canada.
Chalaturnyk, R. and Li, P. 2001. When isit important to consider geomechanics in SAGD operations? Paper 2001-46presented at the Canadian Intl. Petroleum Conference, Calgary, 12-14June.
Chhina, H.S., Luhning, R.W., Bilak, R.A.,and Best, D.A. 1987. A horizontal fracture test in the Athabasca Oil Sands.Paper presented at the 38th Annual Technical Meeting of the Petroleum Soc. ofCIM, Calgary, 8-10 June.
Collins, P.M. 1994. Design of theMonitoring Program for AOSTRA's Underground Test Facility, Phase B Pilot. J.Cdn. Pet. Tech. 33 (3): 46-53.
Collins, P.M. 2002. Injection Pressures for GeomechanicalEnhancement of Recovery Processes in the Athabasca Oil Sands. Paper SPE79028 presented at the SPE International Thermal Operations and Heavy OilSymposium and International Horizontal Well Technology Conference, Calgary, 4-7November. DOI: 10.2118/79028-MS.
Collins, P.M. 2007. The False Lucre ofLow-Pressure SAGD. J. Cdn. Pet. Tech. 46 (1): 20-27.
Cox, J.W. 1983. Long axis orientation inelongated boreholes and its correlation with rock stress data. Paper presentedat the SPWLA 24th Annual Logging Symposium, Calgary, 27-30 June.
Dusseault, M.B. 1980a. Sample disturbancein Athabasca oil sand. J. Cdn. Pet. Tech. (April-June 1980) 85-92; paper80-02-06.
Dusseault, M.B. 1980b. The behaviour ofhydraulically induced fractures in oil sands. In Underground RockEngineering: 13th Canadian Rock Mechanics Symposium, Toronto, 28-29 May,CIM Special Volume 22, 36-41; published by the Canadian Inst. of Mining andMetallurgy, Montreal.
Dusseault, M.B. and Rothenburg, L. 2002.Deformation analysis for reservoir management. Oil & Gas Science andTechnology—Revue de l'IFP 57 (5): 539-554.
Dusseault, M.B. and van Domselaar, H.R.1982. Unconsolidated Sand Sampling in Canadian and Venezuelan Waters. Paperpresented at the Second Intl. Conference. on Heavy Crudes and Tar Sands,UNITAR, Caracas, 7-17 February.
Eaton, S. 2002. 4-D from the heavens:satellite-borne time-lapse radar measures production-induced ground movement.Nickle's New Technology Magazine 8 (6): 5-7.
Ito, Y. and Suzuki, S. 1996. NumericalSimulation of the SAGD Process in the Hangingstone Oil Sands Reservoir. Paper96-57 presented at the 47th Annual Technical Meeting of the Petroleum Soc. ofCIM, Calgary, 10-12 June.
Ito, Y., Ichikawa, M., and Hirata, T.2000. The growth of the steam chamber during the early period of the UTF PhaseB and Hangingstone Phase I projects. Paper 2000-05 presented at the CanadianIntl. Petroleum Conference, Calgary, 4-8 June.
O'Rourke, J.C., Chambers, J.I., Suggett,J.C., and Good, W.K. 1994. UTF Project Status and Commercial Potential—AnUpdate, May 1994. Paper 94-40 presented at the 48th Annual Technical Meeting ofthe Petroleum Soc. of CIM and AOSTRA, Calgary, 12-15 June.
Oldakowski, K. 1994. Stress inducedpermeability changes of Athabasca oilsands. MSc dissertation, Dept. of CivilEngineering, U. of Alberta, Edmonton, Alberta, Canada.
Roche, P. 2005. Listening to thereservoir: Shell uses microseismic, time-lapse seismic and surface tiltmetersto monitor steam movements at Peace River. Nickle's New TechnologyMagazine 11 (1): 28-30.
Stancliffe, R.P.W. and van der Kooij,M.W.A. 2001. The use of satellite-based radar interferometry to monitorproduction activity at the Cold Lake heavy oil field, Alberta, Canada. AAPGBull. 85 (5): 781-793.
Touhidi-Baghini, A. 1998. AbsolutePermeability of McMurray Formation Oil Sands at Low Confining Stresses. PhDdissertation, Dept. of Civil Engineering, U. of Alberta, Edmonton, Alberta,Canada.
Touhidi-Baghini, A. and Scott, J.D. 1998.Absolute permeability changes of oil sand during shear. Paper presented at the51st Canadian Geotechnical Conference, Edmonton, Alberta, Canada, 4-7October.
Wong, R.C.K. 2004. Effect of SampleDisturbance Induced by Gas Exsolution on Geotechnical and Hydraulic PropertiesMeasurements in Oil Sands. Paper 2004-071 presented at the Canadian Intl.Petroleum Conference, Calgary, 8-10 June.