Optimisation of Steam Assisted Gravity Drainage [SAGD] for Improved Recovery from Unconsolidated Heavy Oil Reservoirs

2011 ◽  
Vol 367 ◽  
pp. 403-412 ◽  
Author(s):  
Babs Mufutau Oyeneyin ◽  
Amol Bali ◽  
Ebenezer Adom
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Oil Industry ◽  
Steam Injection ◽  
Thermal Capacity ◽  
Thermal Recovery ◽  
Viscosity Reduction ◽  
Gravity Drainage ◽  
Steam Assisted Gravity Drainage ◽  
The Impact

Most of the heavy oil resources in the world are in sandstone reservoir rocks, the majority of which are unconsolidated sands which presents unique challenges for effective sand management. Because they are viscous and have less mobility, then appropriate recovery mechanisms that lower the viscosity to the point where it can readily flow into the wellbore and to the surface are required. There are many cold and thermal recovery methods assisted by gravity drainage being employed by the oil industry. These are customised for specific reservoir characteristics with associated sand production and management problems. Steam Assisted Gravity Drainage (SAGD) based on horizontal wells and gravity drainage, is becoming very popular in the heavy oil industry as a thermal viscosity reduction technique. SAGD has the potential to generate a heavy oil recovery factor of up to 65% but there are challenges to ‘’realising the limit’’. The process requires elaborate planning and is influenced by a combination of factors. This paper presents unique models being developed to address the issue of multiphase steam-condensed water-heavy oil modelling. It addresses the effects of transient issues such as the changing pore size distribution due to compaction on the bulk and shear viscosities of the non-Newtonian heavy oil and the impact on the reservoir productivity, thermal capacity of the heavy oil, toe-to-heel steam injection rate and quality for horizontal well applications. Specific case studies are presented to illustrate how the models can be used for detailed risk assessment for SAGD design and real-time process optimisation necessary to maximise production at minimum drawdown. Nomenclature

Numerical Simulation of Thermal Solvent Replacing Steam under Steam Assisted Gravity Drainage SAGD Process

2010 ◽  
Author(s):  
Weiqiang Li ◽  
Daulat D. Mamora
Keyword(s):  
High Temperature ◽  
Oil Recovery ◽  
Oil Sands ◽  
Steam Injection ◽  
Thermal Recovery ◽  
Production Performance ◽  
Gravity Drainage ◽  
Steam Assisted Gravity Drainage ◽  
Recovery Technique ◽  
Simulation Results

Abstract Steam Assisted Gravity Drainage (SAGD) is one successful thermal recovery technique applied in the Athabasca oil sands in Canada to produce the very viscous bitumen. Water for SAGD is limited in supply and expensive to treat and to generate steam. Consequently, we conducted a study into injecting high-temperature solvent instead of steam to recover Athabasca oil. In this study, hexane (C6) coinjection at condensing condition is simulated using CMG STARS to analyze the drainage mechanism inside the vapor-solvent chamber. The production performance is compared with an equivalent steam injection case based on the same Athabasca reservoir condition. Simulation results show that C6 is vaporized and transported into the vapor-solvent chamber. At the condensing condition, high temperature C6 reduces the viscosity of the bitumen more efficiently than steam and can displace out all the original oil. The oil production rate with C6 injection is about 1.5 to 2 times that of steam injection with oil recovery factor of about 100% oil initially-in-place. Most of the injected C6 can be recycled from the reservoir and from the produced oil, thus significantly reduce the solvent cost. Results of our study indicate that high-temperature solvent injection appears feasible although further technical and economic evaluation of the process is required.

Feasibility Study on Development of Heavy Oil Reservoir by Steam-Nitrogen Assisted Gravity Drainage

2013 ◽  
Vol 827 ◽  
pp. 224-231 ◽  
Author(s):  
Han Sheng Mu ◽  
Yi Ning Ning Wang ◽  
Zhuang Zhang ◽  
Zhong Ya Zhou ◽  
Ying Xue Liu
Keyword(s):  
Heavy Oil ◽  
Oil Industry ◽  
Steam Injection ◽  
Gravity Drainage ◽  
Gas Oil ◽  
Theory Analysis ◽  
Steam Assisted Gravity Drainage ◽  
Engineering Theory ◽  
Cumulative Production ◽  
Very High

Currently, the primary method for developing extra heavy oil is the steam assisted gravity drainage (SAGD) characterized by high recovery factor and gas-oil ratio. However, in the course of application of this technology, because the whole reservoir needs to be heated to a very high temperature, too much steam is needed, and simultaneously, the loss of heat of reservoir is also increased. For the purpose of exploiting the extra heavy oil more economically, a SAGP technique, the steam and gas push, is put forward in the oil industry world. This paper takes the adding of nitrogen as an example, conducts reservoir engineering theory analysis, numerical simulation study and physical modeling study, and concludes that when adopting SAGP technique, it is unnecessary to increase the temperature of the whole reservoir to a very high value; compared with SAGD, although the cumulative production of SAGP declines to some extent, the steam injection volume is only 68% of that of SAGD, which indicates that SAGP exploitation technique can save steam and thus reduce the production cost compared with SAGD.

Mathematical Modeling of Steam Assisted Gravity Drainage

2005 ◽  
Vol 8 (05) ◽  
pp. 372-376 ◽  
Author(s):  
Serhat Akin
Keyword(s):  
Mathematical Model ◽  
Heavy Oil ◽  
Steam Injection ◽  
Viscosity Reduction ◽  
Gravity Drainage ◽  
Heavy Oils ◽  
Production Well ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage ◽  
Wide Range

Summary A mathematical model for gravity drainage in heavy-oil reservoirs and tar sands during steam injection in linear geometry is proposed. The mathematical model is based on the experimental observations that the steam-zone shape is an inverted triangle with the vertex fixed at the bottom production well. Both temperature and asphaltene content dependence on the viscosity of the drained heavy oil are considered. The developed model has been validated with experimental data presented in the literature. The heavy-oil production rate conforms well to previously published data covering a wide range of heavy oils and sands for gravity drainage. Introduction Gravity drainage of heavy oils is of considerable interest to the oil industry. Because heavy oils are very viscous and, thus, almost immobile, a recovery mechanism is required that lowers the viscosity of the material to the point at which it can flow easily to a production well. Conventional thermal processes, such as cyclic steam injection and steam-assisted gravity drainage(SAGD), are based on thermal viscosity reduction. Cyclic steam injection incorporates a drive enhancement from thermal expansion. On the other hand, SAGD is based on horizontal wells and maximizing the use of gravity forces. In the ideal SAGD process, a growing steam chamber forms around the horizontal injector, and steam flows continuously to the perimeter of the chamber, where it condenses and heats the surrounding oil. Effective initial heating of the cold oil is important for the formation of the steam chamber in gravity-drainage processes. Heat is transferred by conduction, by convection, and by the latent heat of steam. The heated oil drains to a horizontal production well located at the base of the reservoir just below the injection well. Based on the aforementioned concepts, Butler et al. derived Eq. 1 assuming that the steam pressure is constant in the steam chamber, that only steam flows in the steam chamber, that oil saturation is residual, and that heat transfer ahead of the steam chamber to cold oil is only by conduction. One physical analogy of this process is that of a reservoir in which an electric heating element is placed horizontally above a parallel horizontal producing well.

scholarly journals 3D experimental investigation on enhanced oil recovery by flue gas assisted steam assisted gravity drainage

2021 ◽  
pp. 014459872110065
Author(s):  
Lei Tao ◽  
Xiao Yuan ◽  
Sen Huang ◽  
Nannan Liu ◽  
Na Zhang ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Flue Gas ◽  
Physical Simulation ◽  
Thermal Recovery ◽  
Production Performance ◽  
Experimental Result ◽  
Gravity Drainage ◽  
Steam Assisted Gravity Drainage

Flue gas assisted steam assisted gravity drainage (SAGD) is a frontier technology to enhance oil recovery for heavy oil reservoirs. The carbon dioxide generated from the thermal recovery of heavy oil can be utilized and consumed to mitigate climate warming for the world. However, most studies are limited to merely use numerical simulation or small physical simulation device and hardly focus on large scale three-dimensions experiment, which cannot fully investigate the enhanced oil recovery (EOR) mechanism of flue gas assisted SAGD, thus the effect of flue gas on SAGD production performance is still not very clear. In this paper, large-scaled and high temperature and pressure resistant 3D physical simulation experiment was conducted, where simulated the real reservoir to a maximum extent, and systematically explored the EOR mechanisms of the flue gas assisted SAGD. Furthermore, the differences between the steam huff and puff, SAGD and flue gas assisted SAGD are discussed. The experimental result showed that the production effect of SAGD was improved by injecting flue gas, with the oil recovery was increased by 5.7%. With the help of thermocouple temperature measuring sensors, changes of temperature field display that flue gas can promote lateral re-development of the steam chamber, and the degree of reservoir exploitation around the horizontal wells has been increased particularly. What’s more, the addition of flue gas further increased the content of light components and decreased the content of heavy by comparing the content of heavy oil components produced in different production times.

Understanding the Steam-Hammer Mechanism in Steam-Assisted-Gravity-Drainage Wells

SPE Journal ◽  
2013 ◽  
Vol 18 (06) ◽  
pp. 1181-1201 ◽  
Author(s):  
Mazda Irani
Keyword(s):  
Water Hammer ◽  
Thermal Recovery ◽  
Viscosity Reduction ◽  
Gravity Drainage ◽  
Water Drainage ◽  
Steam Quality ◽  
Recovery Method ◽  
Steam Assisted Gravity Drainage ◽  
Production Tubing ◽  
Injection Phase

Summary Steam-assisted gravity drainage (SAGD) is one of the successful thermal-recovery techniques applied in Alberta oil-sands reservoirs. When considering in-situ production from bitumen reservoirs, viscosity reduction is necessary to mobilize bitumen, thereby flowing toward the production well. Steam injection is currently the most effective thermal-recovery method. Although steamflooding is commercially viable, condensation-induced water hammer (CIWH) resulting from rapid steam-pocket condensation can be a challenging operational problem. In steamflooding, steam is injected through a well down to the reservoir, warming it to temperatures of 150 to 270°C (302 to 518°F) to liquefy the bitumen inside the reservoir (Garnier et al. 2008; Xie and Zahacy 2011). The liquefied bitumen then drains to a lower well through which it is produced to the surface. In this process, steam pockets can become entrapped in subcooled condensate inside either the injection or the production tubing, causing a rapid collapse of the steam pocket. This type of rapid condensation is commonly referred to as "steam hammer." In this study, three different scenarios are explored to better understand steam-hammer situations in SAGD wells. These scenarios are at injectors or producers during the startup phase (or circulation phase), in the injection tubing during the injection phase, and in the production tubing during the injection phase. Modeling each of these scenarios indicates that a steam-hammer occurrence is likely in two of the three scenarios, but that its incidence can be mitigated. The likely scenarios for a steam-hammer occurrence are in either the injection or the production tubing during the startup phase, and in the injection tubing during the injection phase. Steam-hammer occurrences during the circulation period can be controlled by lowering the injection pressure and controlling water drainage into the reservoir. Flow shocks that occur as a result of countercurrent flow limiting (CCFL) are very likely to take place in the injection tubing during the injection phase but can be controlled by injecting at a higher steam quality. The least likely scenario for a steam-hammer occurrence is in the production tubing during the injection phase. This is because the produced (or breakthrough) steam temperature would need to be more than 20°C higher than the produced-liquid temperature to start a water-hammer condition.

scholarly journals Experimental study on the mechanism and development effect of multi-gas assisted steam huff and puff process in the offshore heavy oil reservoirs

2021 ◽  
Author(s):  
Jie Fan ◽  
Zuqing He ◽  
Wei Pang ◽  
Daoming Fu ◽  
Hanxiu Peng ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Steam Injection ◽  
Thermal Recovery ◽  
Oil Reservoirs ◽  
Viscosity Reduction ◽  
Oil Viscosity ◽  
Enhanced Production ◽  
Heavy Oil Reservoirs ◽  
Water Gas ◽  
Development Mechanism

AbstractMulti-gas assisted steam huff and puff process is a relatively new thermal recovery technology for offshore heavy oil reservoirs. Some blocks of Bohai oilfield have implemented multi-gas assisted steam huff and puff process. However, the development mechanism still requires further study. In this paper, high-temperature high-pressure (HTHP) PVT experiments and different huff and puff experiments of sand pack were carried out to reveal the enhanced production mechanism and evaluate the development effect of multi-gas assisted steam huff and puff process. The results indicated that viscosity reduction and thermal expansion still were the main development mechanism of multi-gas assisted steam huff and puff process. Specifically, CO2 easily dissolved in the heavy oil that made it mainly play the role of reducing oil viscosity, N2 was characteristics of small solubility and good expansibility, and it could improve formation pressure, increase steam sweep volume and even reduce the heat loss. Meanwhile, injecting multi-gas and steam could break the balance of heavy oil component that made the content of resin reduce and the content of saturates, aromatics and asphaltene increase so as to further reduce the viscosity of heavy oil. Compared with steam huff and puff process, multi-gas assisted steam huff and puff process increased the recovery by 2–5%. The optimal water–gas ratio and steam injection temperature were 4:6 and 300℃, respectively. The results suggested that multi-gas assisted steam huff and puff process would have wide application prospect for offshore heavy oil reservoirs.

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