Solvent-aided Steam-Assisted Gravity Drainage in thin oil sand reservoirs

2010 ◽  
Vol 74 (3-4) ◽  
pp. 138-146 ◽  
Author(s):  
Ian D. Gates
Keyword(s):  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage

Overview of Performance and Analytical Modeling Techniques for Electromagnetic Heating and Applications to Steam-Assisted-Gravity-Drainage Process Startup

SPE Journal ◽  
2016 ◽  
Vol 21 (02) ◽  
pp. 311-333 ◽  
Author(s):  
Sahar Ghannadi ◽  
Mazda Irani ◽  
Rick Chalaturnyk
Keyword(s):  
High Viscosity ◽  
Gravity Drainage ◽  
Induction Medium ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage ◽  
Production Wells ◽  
Reservoir Conditions ◽  
Startup Time ◽  
Industry Practice ◽  
High Level

Summary Steam-assisted gravity drainage is the method of choice to extract bitumen from Athabasca oil-sand reservoirs in Western Canada. Under reservoir conditions, bitumen is immobile because of high viscosity, and its typically high level of saturation limits the injectivity of steam. In current industry practice, steam is circulated within injection and production wells. Operators keep the steam circulating until mobile bitumen breaks through the producer and communication is established between the injector and the producer. The “startup” phase is a time-consuming process taking three or more months with no oil production. A variety of processes could be used to minimize the length of the startup phase, such as electromagnetic (EM) heating in either the induction (medium frequency) or radio-frequency ranges. Knowledge of the size of the hot zone formed by steam circulation and of the benefits of simultaneous EM-heating techniques increases understanding of the startup process and helps to minimize startup duration. The aim of the present work is to introduce an analytical model to predict startup duration for steam circulation with and without EM heating. Results reveal that resistive (electrothermal) heating with/without brine injection cannot be a preferable method for mobilizing the bitumen in startup phase. Induction slightly decreases startup time at frequencies smaller than 10 kHz, and at 100 kHz it can reduce startup time to less than two months.

Drained/Undrained-Zones Boundary in Steam-Assisted-Gravity-Drainage Process

SPE Journal ◽  
2016 ◽  
Vol 21 (05) ◽  
pp. 1721-1742 ◽  
Author(s):  
Mazda Irani ◽  
Ian Gates
Keyword(s):  
Pore Pressure ◽  
Volume Change ◽  
Injection Pressure ◽  
Point Of View ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage ◽  
Shear Dilation ◽  
Temperature Front ◽  
Undrained Conditions

Summary Li et al. (2004) described three zones at the edge of steam chambers on the basis of drainage conditions: drained, partially drained, and undrained. In the drained zone, the pore pressure is controlled by injection pressure, and fluid mobility within this region is sufficient to drain additional pore pressures because of shear dilation and pore-fluid thermal expansion. The undrained zone lies beyond the partially drained zone and extends to virgin reservoir far beyond the chamber. In this zone shearing behaves under undrained conditions; by this, Li et al. (2004) mean no volume change occurs but shear lead to changes in pore pressure. Li et al. (2004) proposed that the boundaries of these zones are dependent on bitumen viscosity, which relates to the temperature distribution beyond the steam interface. Because drained/undrained conditions affect the geomechanics at the edge of the chamber, we investigate whether the assumption of Li et al. (2004) that there is no volume change within the sheared zone is correct and is supported by field data. Here, we establish the physics associated with the undrained zone at the edge of steam-assisted gravity-drainage steam chamber and explore the pressure front vs. temperature front of different oil-sand field projects. The results reveal that the drained zone governed by pressure-front advancement is greater in extent than the sheared zone. The thermodynamics of the undrained zone are discussed to derive a new theory for mechanothermal phenomena at the edge of the chamber. The results from the theory show that the drained zone extends beyond the temperature front and thus, from a geomechanical point of view, the system solely consists of the drained and partially drained zones.

Convection at the Edge of a Steam-Assisted-Gravity-Drainage Steam Chamber

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 503-512 ◽  
Author(s):  
Jyotsna Sharma ◽  
Ian D. Gates
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Relative Permeability ◽  
Convective Heat ◽  
Injection Well ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Production Well ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage

Summary Steam-assisted gravity drainage (SAGD) has become the preferred process to recover bitumen from Athabasca deposits in Alberta. The method consists of a lower horizontal production well, typically located approximately 2 m above the base of the oil zone, and an upper horizontal injection well located roughly 5 to 10 m above the production well. Steam flows from the injection well into a steam chamber that surrounds the wells and releases its latent heat to the cool oil sands at the edge of the chamber. This research re-examines heat transfer at the edge of the steam chamber. Specifically, a new theory is derived to account for convection of warm condensate into the oil sand at the edge of the chamber. The results show that, if the injection pressure is higher than the initial reservoir pressure, convective heat transfer can be larger than conductive heat transfer into the oil sand at the edge of the chamber. However, enhancement of the heat-transfer rate by convection may not necessarily imply higher oil rates; this can be explained by relative permeability effects at the chamber edge. As the condensate invades the oil sand, the oil saturation drops and, consequently, the oil relative permeability falls. This, in turn, results in the reduction of the oil mobility, despite the lowered oil viscosity because of higher temperature arising from convective heat transfer.

scholarly journals Monitoring of steam chamber in steam-assisted gravity drainage based on the temperature sensitivity of oil sand

2021 ◽  
Vol 48 (6) ◽  
pp. 1411-1419
Author(s):  
Yunfeng GAO ◽  
Ting'en FAN ◽  
Jinghuai GAO ◽  
Hui LI ◽  
Hongchao DONG ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage

A New Thermogeomechanical Theory for Gravity Drainage in Steam-Assisted Gravity Drainage

SPE Journal ◽  
2013 ◽  
Vol 18 (04) ◽  
pp. 736-742 ◽  
Author(s):  
M.. Cokar ◽  
M.S.. S. Kallos ◽  
I.D.. D. Gates
Keyword(s):  
Thermal Expansion ◽  
Oil Sands ◽  
High Viscosity ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage ◽  
Volumetric Expansion ◽  
Drainage Rate ◽  
In Situ Conditions ◽  
Effective Drainage

Summary Oil-sands reservoirs in western Canada hold more than 170 billion bbl of recoverable heavy oil and bitumen representing a significant source of unconventional oil. At in-situ conditions, the majority of this oil has essentially no initial mobility because of its high viscosity, which is typically in the hundreds of thousands to millions of centipoises. In steam-assisted gravity drainage (SAGD), steam injected into the formation heats oil at the edge of a depletion chamber, thus raising the mobility, ko/μo, of bitumen. Three main effects account for the increase of oil mobility. First, bitumen at steam temperature has viscosity typically less than 20 cp. Second, it is believed that shear, which is caused by thermal-expansion gradients, dilates the oil sand and causes enhanced permeability. Third, dilation at the chamber edge leads to smaller residual oil saturation (ROS). Because the production rate of SAGD is directly tied to the drainage rate of mobilized oil at the chamber edge, the thermogeomechanics of the oil sand at the chamber edge is a control on the performance of SAGD. In this study, a novel SAGD formula is derived that accounts for thermogeomechanical effects at the edge of the chamber. This paper couples dilation effects arising from thermal expansion into an analytical model for SAGD oil rate. The results reveal that volumetric expansion at the edge of the chamber plays a significant role in enabling effective drainage of bitumen to the production well.

Reservoir Simulation of Hydrogen Sulfide Production During a Steam-Assisted-Gravity-Drainage Process by Use of a New Sulfur-Based Compositional Kinetic Model

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 080-093 ◽  
Author(s):  
Simon V. Ayache ◽  
Violaine Lamoureux-Var ◽  
Pauline Michel ◽  
Christophe Preux
Keyword(s):  
Hydrogen Sulfide ◽  
Kinetic Model ◽  
Reservoir Simulation ◽  
Steam Injection ◽  
Laboratory Scale ◽  
Gravity Drainage ◽  
Production Data ◽  
Oil Sand ◽  
Oil Companies ◽  
Steam Assisted Gravity Drainage

Summary Steam injection is commonly used as a thermal enhanced-oil-recovery (EOR) method because of its efficiency for recovering hydrocarbons, especially from heavy-oil and bitumen reservoirs. Reservoir models simulating this process describe the thermal effect of the steam injection, but generally neglect the chemical reactions induced by the steam injection and occurring in the reservoir. In particular, these reactions can lead to the generation and production of the highly toxic and corrosive acid gas hydrogen sulfide (H2S). The overall objective of this paper is to quantitatively describe the chemical aquathermolysis reactions that occur in oil-sands reservoirs undergoing steam injections and to provide oil companies with a numerical model for reservoir simulators to forecast the H2S-production risks. For that purpose, a new sulfur-based compositional kinetic model has been developed to reproduce the aquathermolysis reactions in the context of reservoir modeling. It is derived from results gathered on an Athabasca oil sand from previous laboratory aquathermolysis experiments. In particular, the proposed reactions model accounts for the formation of H2S issued from sulfur-rich heavy oils or bitumen, and predicts the modification of the resulting oil saturate, aromatic, resin, and asphaltene (SARA) composition vs. time. One strength of this model is that it is easily calibrated against laboratory-scale experiments conducted on an oil-sand sample. Another strength is that its calibration is performed while respecting the constraints imposed by the experimental data and the theoretical principles. In addition, in this study no calibration was needed at reservoir scale against field-production data. In the paper, the model is first validated with laboratory-scale simulations. The thermokinetic modeling is then coupled with a 2D reservoir simulation of a generic steam-assisted gravity drainage (SAGD) process applied on a generic Athabasca oil-sand reservoir. This formulation allows investigating the H2S generation at reservoir scale and quantifying its production. The H2S- to bitumen-production ratio against time computed by the reservoir simulation is found to be consistent with production data from SAGD operations in Athabasca, endorsing the proposed methodology.

Predicting Geomechanical Dynamics of Steam-Assisted Gravity-Drainage Process. Part II: Modified Cam-Clay Model

SPE Journal ◽  
2020 ◽  
Vol 25 (06) ◽  
pp. 3366-3385
Author(s):  
Mazda Irani
Keyword(s):  
Monitoring Program ◽  
Test Facility ◽  
Elastic Behavior ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage ◽  
Heated Zone ◽  
Modified Cam Clay ◽  
Cam Clay

Summary In Part I of this study (Irani 2018), the geomechanical effects in the reservoir associated with steam-assisted gravity drainage (SAGD) steam chamber growth was evaluated on the basis of two core assumptions: reservoir yield behavior follows that of the Mohr-Coulomb (MC) dilative behavior, and the reservoir stress response follows that of a drained sand. In Part I, it was shown that although the dilative model nicely described the shearing and the sheared zone thickness at the front of the SAGD steam chamber, it could not predict the displacements associated with cold dilation in SAGD reservoirs, in which cold dilation refers to vertical displacement created in the zone ahead of the heated zone caused by isotropic unloading generated by the pore pressure increase and the increase in far-field horizontal stress. In cold dilation, the stresses do not reach the critical state line (CSL), which defines the yield surface and should, therefore, be analyzed considering elastic behavior. A modified Cam-Clay (MCC) model, however, can be used to describe the behavior of the oil sand in the cold dilation zone before reaching the CSL. In this study and as an extension to the results presented in Part I, strains developed in the reservoir during SAGD operation are calculated using an MCC model, and the associated oil rate enhancement and displacements are evaluated. The vertical strains and displacements are compared with measured values from the extensive monitoring program conducted at the Underground Test Facility (UTF) in the late 1980s. Two aspects of geomechanical effects are compared between the cap models (Part II) and dilative models (Part I): first, prediction of the sheared zone thickness and its effect on SAGD production enhancement, and second, prediction of vertical and horizontal displacements. It is shown that consideration of the material model effects on production rates are negligible for both models and that the MCC model can predict displacements in both the heated and cold zones of the reservoir reasonably accurately. Although dilative constitutive models can be used to predict horizontal and vertical displacements in the heated zone quite accurately, they lack the ability to predict the response in the “cold dilation zone.” Another main advantage of using an MCC model is that the MCC model provides a better description of a stress path and how the reservoir mobility can affect reservoir dilation, especially in the cold dilation zone.

Microfluidic Characterization of Steam-Bitumen Interactions During Steam Assisted Gravity Drainage Operations

2012 ◽  
Author(s):  
Thomas de Haas ◽  
Hossein Fadeai ◽  
David Sinton
Keyword(s):  
Surface Mining ◽  
Horizontal Wells ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Production Well ◽  
Rich Region ◽  
Steam Assisted Gravity Drainage ◽  
Deep Underground

In-situ recovery of heavy-oil and bitumen is used when reserves are too deep underground for conventional surface mining technologies. Steam assisted gravity drainage (SAGD) is process in which two horizontal wells, one vertically 5m above the other, are drilled into an oil-rich region. Steam is injected into the reservoir from the top well, and an oil steam-condensate mixture is pumped out the production well. The aim of this research is to physically model a section of oil sand in a SAGD operation. An array of micropillars fabricated into a glass microfluidic chip is used to represent the grains of sand. The chip was positioned vertically so that gravity plays a dominate role in drainage. Steam was pumped into the chip, reducing the viscosity of the oil and allowing oil and steam to flow under gravity to the outlet. The position of the steam front and the micro-scale interactions of the steam and oil were recorded over time.

On the Stability of the Edge of a Steam-Assisted-Gravity-Drainage Steam Chamber

SPE Journal ◽  
2013 ◽  
Vol 19 (02) ◽  
pp. 280-288 ◽  
Author(s):  
Mazda Irani ◽  
Ian Gates
Keyword(s):  
Heat Transfer ◽  
Diffusion Equation ◽  
Thermal Recovery ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Chamber ◽  
Steam Condensate ◽  
Steam Assisted Gravity Drainage ◽  
Pressure Diffusion ◽  
The Stability

Summary Steam-assisted gravity drainage (SAGD) is a successful thermal-recovery technique applied in oil-sand reservoirs in which the viscosity of the oil (bitumen) is typically in the hundreds of thousands to millions of centipoise. For the in-situ production from bitumen reservoirs, bitumen viscosity must be reduced to achieve the mobility required to flow toward the production well. Many factors influence the efficiency and rate at which bitumen is mobilized. The controlling feature of steam-based recovery processes is heat transfer from the steam chamber to the formation—the greater the heat flux, the larger the oil volume heated, and the higher the oil-drainage rate. Previous studies have demonstrated that instability at the steam-chamber edge can enhance heat transfer there by creating limited-amplitude steam fingers that enlarge the heat-transfer area, thus leading to greater thermal efficiency of the recovery process. This, in turn, increases oil production. At this point, stability studies have focused on the instability between steam and oil at the edge of the chamber—none has examined the case between steam condensate and oil. In the research documented here, the stability between steam condensate and bitumen at the edge of the chamber is explored. Here, a steam-pressure diffusion equation at the moving chamber interface is derived. The perturbations of the pressure and condensate velocity are substituted into the pressure diffusion equation and Darcy's law to realize a linear-stability equation governing the growth of disturbances at the interface. The results show that the stability is controlled by moving-interface velocity and reservoir water-phase hydraulic diffusivity.

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