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.

On Temperature-Falloff Interpretation in the Circulation Phase of the Steam-Assisted-Gravity-Drainage Process

SPE Journal ◽  
2019 ◽  
Vol 24 (03) ◽  
pp. 1002-1015 ◽  
Author(s):  
Mazda Irani ◽  
Sahar Ghannadi
Keyword(s):  
Steam Injection ◽  
High Viscosity ◽  
Time Profile ◽  
Gravity Drainage ◽  
Oil Sand ◽  
Steam Assisted Gravity Drainage ◽  
In Situ Conditions ◽  
Reservoir Conditions ◽  
Industry Practice ◽  
The Right

Summary Steam-assisted gravity drainage (SAGD) is the preferred method to extract bitumen from Athabasca oil-sand reservoirs in western Canada. Bitumen at reservoir conditions is immobile because of high viscosity, and its saturation is typically large, which limits the injectivity of steam at in-situ conditions. In current industry practice, steam is circulated within injection and production wells. In theory, wells should be converted to SAGD production mode after a period when bitumen is mobile and communication is established between the injector and the producer. Operators use temperature-falloff data to predict successful conversion time. But temperature-falloff data are evaluated qualitatively, and there is not an analytical/numerical framework in which one can use such data. Although the bitumen heating sounds simple, approach wells are failing after steam injection because of steam breakthrough or sand production. Most of these wells are periodically returned to circulation/bullheading to ramp up production rates and heal the hot spots. Most of such failures are associated with early conversion to full SAGD, which shows the need to formulate an analytical/numerical framework to predict the right timing for conversion to full SAGD. In this presentation, the time of flight (ToF) is effectively used to convert spatial variations of temperature into time response of temperature variation at the well sandface. ToF defines the time an oil droplet needs to travel through a medium—more specifically, from its current location to the well sandface. By solving the heat transfer and Darcy's law simultaneously, the ToF is converted to a relationship of the temperature vs. time profile at the producer. This approach has been applied to SAGD well pairs with different geology, and the temperature-falloff trends are presented.

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.

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

An Investigation into Current Sand Control Testing Practices for Steam Assisted Gravity Drainage Production Wells

Eng ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 435-453
Author(s):  
Omar Kotb ◽  
Mohammad Haftani ◽  
Alireza Nouri
Keyword(s):  
Fluid Flow ◽  
Testing Procedure ◽  
Gravity Drainage ◽  
Steam Assisted Gravity Drainage ◽  
Mcmurray Formation ◽  
Sand Control ◽  
Production Wells ◽  
Brine Chemistry ◽  
And Performance ◽  
The Impact

Sand control screens (SCD) have been widely installed in wells producing bitumen from unconsolidated formations. The screens are typically designed using general rules-of-thumb. The sand retention testing (SRT) technique has gained attention from the industry for the custom design and performance assessment of SCD. However, the success of SRT experimentation highly depends on the accuracy of the experimental design and variables. This work examines the impact of the setup design, sample preparation, near-wellbore stress conditions, fluid flow rates, and brine chemistry on the testing results and, accordingly, screen design. The SRT experiments were carried out using the replicated samples from the McMurray Formation at Long Lake Field. The results were compared with the test results on the original reservoir samples presented in the literature. Subsequently, a parametric study was performed by changing one testing parameter at a test, gradually making the conditions more comparable to the actual wellbore conditions. The results indicate that the fluid flow rate is the most influential parameter on sand production, followed by the packing technique, stress magnitude, and brine salinity level. The paper presents a workflow for the sand control testing procedure for designing the SCD in the steam-assisted gravity drainage (SAGD) operations.

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.

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