Single-Well SAGD Field Installation and Functionality Trials
- Grant Hocking (GeoSierra LLC) | Travis Wayne Cavender (Halliburton) | John Person (Halliburton Group Canada) | Timothy Hunter (Halliburton Technology Center)
- Document ID
- Society of Petroleum Engineers
- SPE Heavy Oil Conference Canada, 12-14 June, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 5.1.1 Exploration, Development, Structural Geology, 2.5.2 Fracturing Materials (Fluids, Proppant), 4.1.2 Separation and Treating, 2.4.3 Sand/Solids Control, 3 Production and Well Operations, 1.6 Drilling Operations, 3.1.2 Electric Submersible Pumps, 5.5 Reservoir Simulation, 5.1.5 Geologic Modeling, 1.14 Casing and Cementing, 5.4.6 Thermal Methods, 2.2.2 Perforating, 1.2.3 Rock properties, 2 Well Completion, 3.1 Artificial Lift Systems, 5.3.9 Steam Assisted Gravity Drainage, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 3.1.7 Progressing Cavity Pumps
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A vertical single-well steam-assisted gravity drainage (SAGD) injector/producer is proposed that consists of six vertical propped planes installed at varying azimuths throughout the pay thickness to minimize geological heterogeneities on system performance. Steam is injected at the top of the pay and liquids are extracted at the bottom. The well operates immediately in SAGD mode and is highly efficient because of the immediate drainage available from the propped vertical planes, the full gravity drainage height at startup, and a favorable steam pressure gradient. A field trial is presented of the installation of multi-azimuth vertical propped planes from two expanded split-casing sections in a sandy silt formation. Each casing section contained six vertical propped planes at multiple azimuths that were coalesced by pore-pressure relief between the casing sections. Downhole expansion and splitting of the 9 5/8-in. casing and cement quantified formation stiffness and strength, while downhole photographs and packer impressions showed the split casing in the locked-open position. Each wing was stimulated independently of the other wings with 12/20-mesh proppant injected using a highly crosslinked gel through a specialized treatment tool. Real-time active resistivity monitoring quantified the injected plane geometry from both subsurface and surface resistivity receivers. Hydraulic pulse interference tests quantified the hydraulic vertical connectivity of the vertical propped planes. The field trials showed conclusively that multiple vertical propped planes on various azimuths can be constructed from a single wellbore and the planes coalesced between casing sections spaced along the wellbore. The field trials demonstrated the functionality of the expanded casing and stimulation tools and showed that the vertical permeable propped planes could be constructed on azimuth with high in-placed permeability. The geometry of the injected planes was recorded in real-time using the active resistivity method. Following completion of the stimulations, surface excavations showed two of the vertical planes on azimuth with the multi-azimuth casing dilation planes. Following this successful field trial, heavy-oil and bitumen steaming trials are planned.
Shallow-field experiments demonstrated that vertical planes could be injected on azimuth in weakly cemented formations (Hocking 1996). Continuous permeable planes filled with an iron proppant—in some cases, kilometers in length—have been constructed using this technology for groundwater remediation at numerous sites (Hocking and Wells 2002). More recently, shallow-field experiments have demonstrated that multi-azimuth permeable planes can be installed from a single well in weakly cemented formations (Hocking et al. 2008). The technology is not limited by depth, but is limited to formation strength, being that it is applicable only in weakly cemented formations. This process has now been extended to depths greater than 500 m (Hocking et al. 2011a) and is proposed as a new thermally enhanced well-completion system for heavy-oil and bitumen recovery in unconsolidated sands where conventional thermal recovery methods, such as SAGD and cyclic steam stimulation (CSS), have limitations because of geological issues.
Stimulation of weakly cemented formations is not a fracturing process identical to what occurs in hard rocks because the weak formation has minimal strength and thus basically zero fracture toughness. Laboratory and near-surface experiments involving injection from a perforated casing have yielded random injected geometries that are not repeatable nor develop a vertical planar injected feature. Conversely, if the casing is dilated during or just before the injection process, repeatable consistent vertical planar-injected geometries are formed with control of the azimuth of the injected planes. To help ensure the process is controlled and repeatable, the method requires (1) a dilating casing system, (2) a highly viscous stimulating treatment fluid, and (3) control of the pumping rate. Once the vertical planes are initiated by the dilating casing, the propagating vertical planes remain on azimuth because of the formation's anelasticity and low horizontal-stress contrast.
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