scholarly journals Experimental Investigation and Numerical Simulation of Dynamic Characteristics for Multithermal Fluid-Assisted SAGD in Extraheavy Oil Reservoir

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 1) ◽  
Author(s):  
Zhenhua Xu ◽  
Xiaokun Zhang ◽  
Zhenyi Cao ◽  
Pengcheng Liu ◽  
Zhe Yuan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Oil Recovery ◽  
Comparative Investigation ◽  
Oil Reservoirs ◽  
Physical Parameters ◽  
Condensation Zone ◽  
Dissolved Carbon ◽  
Steam Chamber ◽  
Nitrogen Injection ◽  
Horizontal Expansion

Abstract Loss of the vast majority of heat and steam is an unavoidable problem encountered during conventional steam-assisted gravity drainage (SAGD) in extraheavy oil reservoirs. The noncondensate gas coinjection technique of reducing energy consumption and enhancing oil recovery can effectively solve this problem. Aiming at extraheavy oil with a high initial viscosity, the influence of noncondensate gases in multithermal fluids on the physical parameters of extraheavy oil was experimentally studied; the production characteristics and mechanism of multithermal fluid-assisted SAGD were studied through numerical simulation. A comparative investigation of the conventional SAGD and multithermal fluid-assisted SAGD injection schemes was conducted. The characteristics and mechanism of the steam chamber during the production processes were analyzed. The results show that a steam-gas-oil system forms in the steam chamber in the case of multithermal fluids. The steam chamber can be partitioned into four zones, and the flow of the oil mainly occurs in the steam condensation zone and the oil drainage zone. The injected multithermal fluids increase the horizontal expansion of the steam chamber, while the dissolved carbon dioxide reduces the residual oil saturation. Moreover, the nitrogen injection significantly reduces the heat loss and increases the heat utilization for multithermal fluid-assisted SAGD in developing extraheavy oil reservoirs.

scholarly journals Breccia interlayer effects on steam-assisted gravity drainage performance: experimental and numerical study

2021 ◽  
Author(s):  
Qichen Zhang ◽  
Xiaodong Kang ◽  
Huiqing Liu ◽  
Xiaohu Dong ◽  
Jian Wang
Keyword(s):  
Numerical Simulation ◽  
Oil Recovery ◽  
Oil Sands ◽  
Numerical Study ◽  
Middle Part ◽  
Experimental Results ◽  
Production Performance ◽  
Peak Oil ◽  
Steam Chamber ◽  
The Impact

AbstractCurrently, the reservoir heterogeneity is a serious challenge for developing oil sands with SAGD method. Nexen’s Long Lake SAGD project reported that breccia interlayer was widely distributed in lower and middle part of reservoir, impeding the steam chamber expansion and heated oil drainage. In this paper, two physical experiments were conducted to study the impact of breccia interlayer on development of steam chamber and production performance. Then, a laboratory scale numerical simulation model was established and a history match was conducted based on the 3D experimental results. Finally, the sensitivity analysis of thickness and permeability of breccia layer was performed. The influence mechanism of breccia layer on SAGD performance was analyzed by comparing the temperature profile of steam chamber and production dynamics. The experimental results indicate that the existence of breccia interlayer causes a thinner steam chamber profile and longer time to reach the peak oil rate. And, the ultimate oil recovery reduced 15.8% due to much oil stuck in breccia interlayer areas. The numerical simulation results show that a lower permeability in breccia layer area has a serious adverse impact on oil recovery if the thickness of breccia layer is larger, whereas the effect of permeability on SAGD performance is limited when the breccia layer is thinner. Besides, a thicker breccia layer can increase the time required to reach the peak oil rate, but has a little impact on the ultimate oil recovery.

An Investigation Into Propagation Behavior of the Steam Chamber During Expanding-Solvent SAGP (ES-SAGP)

SPE Journal ◽  
2019 ◽  
Vol 24 (02) ◽  
pp. 413-430
Author(s):  
Zhanxi Pang ◽  
Lei Wang ◽  
Zhengbin Wu ◽  
Xue Wang
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Physical Simulation ◽  
Heat Losses ◽  
Oil Reservoirs ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Experimental Conditions ◽  
Steam Chamber ◽  
Heavy Oil Reservoirs

Summary Steam-assisted gravity drainage (SAGD) and steam and gas push (SAGP) are used commercially to recover bitumen from oil sands, but for thin heavy-oil reservoirs, the recovery is lower because of larger heat losses through caprock and poorer oil mobility under reservoir conditions. A new enhanced-oil-recovery (EOR) method, expanding-solvent SAGP (ES-SAGP), is introduced to develop thin heavy-oil reservoirs. In ES-SAGP, noncondensate gas and vaporizable solvent are injected with steam into the steam chamber during SAGD. We used a 3D physical simulation scale to research the effectiveness of ES-SAGP and to analyze the propagation mechanisms of the steam chamber during ES-SAGP. Under the same experimental conditions, we conducted a contrast analysis between SAGP and ES-SAGP to study the expanding characteristics of the steam chamber, the sweep efficiency of the steam chamber, and the ultimate oil recovery. The experimental results show that the steam chamber gradually becomes an ellipse shape during SAGP. However, during ES-SAGP, noncondensate gas and a vaporizable solvent gather at the reservoir top to decrease heat losses, and oil viscosity near the condensate layer of the steam chamber is largely decreased by hot steam and by solvent, making the boundary of the steam chamber vertical and gradually a similar, rectangular shape. As in SAGD, during ES-SAGP, the expansion mechanism of the steam chamber can be divided into three stages: the ascent stage, the horizontal-expansion stage, and the descent stage. In the ascent stage, the time needed is shorter during ES-SAGP than during SAGP. However, the other two stages take more time during nitrogen, solvent, and steam injection to enlarge the cross-sectional area of the bottom of the steam chamber. For the conditions in our experiments, when the instantaneous oil/steam ratio is lower than 0.1, the corresponding oil recovery is 51.11%, which is 7.04% higher than in SAGP. Therefore, during ES-SAGP, not only is the volume of the steam chamber sharply enlarged, but the sweep efficiency and the ultimate oil recovery are also remarkably improved.

New Insights Into Steam/Solvent-Coinjection-Process Mechanism

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 867-877 ◽  
Author(s):  
Raman K. Jha ◽  
Mridul Kumar ◽  
Ian Benson ◽  
Edward Hanzlik
Keyword(s):  
Oil Recovery ◽  
Saturation Temperature ◽  
Solvent Mixture ◽  
Condensation Temperature ◽  
Reservoir Properties ◽  
Condensation Zone ◽  
Process Mechanism ◽  
Heated Oil ◽  
Steam Chamber ◽  
Lower Viscosity

Summary We present results of a detailed investigation of the steam/ solvent-coinjection-process mechanism by use of a numerical model with homogeneous reservoir properties and various solvents. We describe condensation of steam/solvent mixture near the chamber boundary. We present a composite picture of the important phenomena occurring in the different regions of the reservoir and their implications for oil recovery. We compare performances of various solvents and explain the reasons for the observed differences. An improved understanding of the process mechanism will help with selecting the best solvent and developing the best operating strategy for a given reservoir. Results indicate that as the temperature drops near the chamber boundary, steam starts condensing first because its mole fraction in the injected steam/solvent mixture (and hence its partial pressure and the corresponding saturation temperature) is much higher than the solvent's. As temperature declines toward the chamber boundary and steam continues to condense, the vapor phase becomes increasingly richer in solvent. At the chamber boundary where the temperature becomes equal to the condensation temperature of both steam and solvent at their respective partial pressures, both condense simultaneously. Thus, contrary to steam-only injection, where condensation occurs at the injected steam temperature, condensation of steam/solvent mixture is accompanied by a reduction in temperature in the condensation zone and the farther regions. However, there is little change in temperature in the central region of the steam chamber. The condensed steam/solvent mixture drains outside the chamber, leading to the formation of a mobile liquid stream (drainage region) where heated oil, condensed solvent, and water flow together to the production well. The condensed solvent mixes with the heated oil and further reduces its viscosity. The additional reduction in viscosity by solvent more than offsets the effect of reduced temperature near the chamber boundary. As the steam chamber expands laterally because of continued injection and as temperature in the hitherto drainage region increases, a part of the condensed solvent mixed with oil evaporates. This lowers the residual oil saturation (ROS) in the steam chamber. Therefore, ultimate oil recovery with the steam/solvent-coinjection process is higher than that in steam-only injection. The higher the solvent concentration in oil at a location, the greater is the reduction in the ROS there. Our explanation is corroborated by the experimental results reported in the literature, which show smaller ROS in the steam chamber after a steam/solvent-coinjection process. A lighter solvent has a lower viscosity, a higher volatility, and a higher molar concentration of solvent in the drainage region. Thus, a lighter solvent causes a greater reduction in the viscosity of the heated oil and also leads to a lower ROS. Therefore, the lightest condensable solvent (butane, under the conditions investigated) provides the most favorable results in terms of enhancements in oil rate and oil recovery. This is different from the prior claims in the literature.

Modeling Study on Reviving Abandoned Oil Reservoirs by In Situ Combustion Without CO2 Production While Recovering Both Oil and Heat

2021 ◽  
Vol 143 (8) ◽  
Author(s):  
Yun Han ◽  
Kewen Li ◽  
Lin Jia
Keyword(s):  
Numerical Simulation ◽  
Oil Recovery ◽  
Oil And Gas ◽  
Numerical Models ◽  
Oil Reservoirs ◽  
Co2 Production ◽  
Geothermal System ◽  
Residual Oil ◽  
Gas Reservoirs ◽  
Oil And Gas Reservoirs

Abstract A large number of oil wells have been or will be abandoned around the world. Yet, a very large amount of oil and energy is left behind inside the rocks in abandoned reservoirs because of technological and economic limitations. The residual oil saturation is usually more than 40%, and in shale reservoirs it can be more than 90%. There have been many enhanced oil recovery methods developed to tap the residual oil and improve the oil recovery. Interestingly, a concept has been proposed to transfer abandoned oil and gas reservoirs into exceptional enhanced geothermal reservoirs by oxidizing the residual oil with injected air (Li and Zhang, 2008, “Exceptional Enhanced Geothermal Systems From Oil and Gas Reservoirs,” 43rd Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA). This methodology was referred to as an exceptional enhanced geothermal system (EEGS). However, zero CO2 production has not been achieved during the process of EEGS. To this end, numerical models of EEGS in abandoned oil reservoirs configured with vertical wells were established in the present study. Numerical simulations in different well configurations were conducted. The effects of well distance, perforation position, and formation permeability on the CO2 production and the reservoir temperature have been investigated. The numerical simulation results showed that when the depth difference between the production and the injection well perforation positions reaches a specific value, the daily CO2 production rate could be kept at almost zero for over 50 years or even permanently while producing oil and thermal energy continuously. This implies that we realized the concept of EEGS with no CO2 successfully using numerical simulation.

Facile Fabrication of Nanoemulsions through the Efficient Catanionic Surfactants for Spontaneous Imbibition in Tight Oil Reservoirs: Experimental and Numerical Simulation

2021 ◽  
Author(s):  
Bing Wei ◽  
Runxue Mao ◽  
Haoran Tang ◽  
Lele Wang ◽  
Dianlin Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Oil Recovery ◽  
Surfactant Solution ◽  
Spontaneous Imbibition ◽  
Oil Reservoirs ◽  
Wettability Alteration ◽  
Tight Oil ◽  
Catanionic Surfactants ◽  
The Matrix ◽  
Tight Oil Reservoirs

Abstract Spontaneous imbibition (SI) is an essential method for accelerating mass exchange between fracture and matrix in tight oil reservoirs. However, conventional systems such as brine and surfactant solution have limited imbibition effects, so there is still abundant remaining oil in the matrix. Nanoemulsion holds the most promising potential in improving tight oil recovery owing to the favorable surface activity and nanoscale droplets, but it still lacks economic and facile methods to fabricate nanoemulsions. Therefore, in this paper, we prepared a kind of O/W nanoemulsion of catanionic surfactants with a low dosage of surfactant and energy consumption, which was then used to assess spontaneous imbibition performance in Changqing outcrop cores by experimental and numerical simulation. We have fully considered the possible imbibition mechanisms of nanoemulsion including wettability alteration, IFT reduction, solubilization and emulsification, etc., and successfully applied to the nanoemulsion imbibition model. The model and experimental data were found to be in good agreement. The results showed that the imbibition rate and oil recovery factor of the nanoemulsion in the first 100 hours are lower than that of brine. In the late stage, we observed a longer equilibrium time and a faster and higher oil imbibition process in nanoemulsion with ultralow IFT. Finally, we confirmed that solubilization and emulsification is one of the domiant mechanisms for nanoemulsion imbibition by comparing with the modelling without considering solubilization and emulsification.

scholarly journals The Supercritical Multithermal Fluid Flooding Investigation: Experiments and Numerical Simulation for Deep Offshore Heavy Oil Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Xianhong Tan ◽  
Wei Zheng ◽  
Taichao Wang ◽  
Guojin Zhu ◽  
Xiaofei Sun ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Oil Production ◽  
Oil Field ◽  
Oil Reservoirs ◽  
Oil Viscosity ◽  
Steam Flooding ◽  
Heavy Oil Reservoirs

The supercritical multithermal fluids (SCMTF) were developed for deep offshore heavy oil reservoirs. However, its EOR mechanisms are still unclear, and its numerical simulation method is deficient. In this study, a series of sandpack flooding experiments were first performed to investigate the viability of SCMTF flooding. Then, a novel numerical model for SCMTF flooding was developed based on the experimental results to characterize the flooding processes and to study the effects of injection parameters on oil recovery on a lab scale. Finally, the performance of SCMTF flooding in a practical deep offshore oil field was evaluated through simulation. The experiment results show that the SCMTF flooding gave the highest oil recovery of 80.89%, which was 29.60% higher than that of the steam flooding and 11.09% higher than that of SCW flooding. The history matching process illustrated that the average errors of 3.24% in oil recovery and of 4.33% in pressure difference confirm that the developed numerical model can precisely simulate the dynamic of SCMTF flooding. Increases in temperature, pressure, and the mole ratio of scN2 and scCO2 mixture to SCW benefit the heavy oil production. However, too much increase in temperature resulted in formation damage. In addition, an excess of scN2 and scCO2 contributed to an early SCMTF breakthrough. The field-scale simulation indicated that compared to steam flooding, the SCMTF flooding increased cumulative oil production by 27122 m3 due to higher reservoir temperature, expanded heating area, and lower oil viscosity, suggesting that the SCMTF flooding is feasible in enhancing offshore heavy oil recovery.

NUMERICAL SIMULATION OF NON-ISOTHERMAL FLOW IN NATURALLY FRACTURED OIL RESERVOIRS USING A ONE-EQUATION MODEL

2019 ◽  
Author(s):  
Juan Diego dos Santos Heringer ◽  
Paulo de Tarço Honorio Junior ◽  
Grazione de Souza ◽  
Helio Pedro Amaral Souto
Keyword(s):  
Numerical Simulation ◽  
Equation Model ◽  
Isothermal Flow ◽  
Oil Reservoirs ◽  
Naturally Fractured
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