Mobility control during CO2 EOR in fractured carbonates using foam: Laboratory evaluation and numerical simulations

2015 ◽  
Vol 135 ◽  
pp. 442-451 ◽  
Author(s):  
M.A. Fernø ◽  
Ø. Eide ◽  
M. Steinsbø ◽  
S.A.W. Langlo ◽  
A. Christophersen ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Mobility Control ◽  
Laboratory Evaluation ◽  
Co2 Eor ◽  
Fractured Carbonates

Foam as Mobility Control for Integrated CO2-EOR in Fractured Carbonates

2015 ◽  
Author(s):  
M. Steinsbø ◽  
B. Brattekås ◽  
G. Ersland ◽  
K. Bø ◽  
I.E. Opdal ◽  
...  
Keyword(s):  
Mobility Control ◽  
Co2 Eor ◽  
Fractured Carbonates

CO2 EOR: Nanotechnology for Mobility Control Studied

2012 ◽  
Vol 64 (07) ◽  
pp. 28-31 ◽  
Author(s):  
Sinisha (Jay) Jikich
Keyword(s):  
Mobility Control ◽  
Co2 Eor

Foam Stability Enhanced Technology For Mobility Control Of CO2 EOR

2018 ◽  
Author(s):  
H. Yonebayashi ◽  
K. Takabayashi ◽  
Y. Miyagawa ◽  
T. Watanabe
Keyword(s):  
Foam Stability ◽  
Mobility Control ◽  
Co2 Eor

A New Approach to Model Hysteresis and Its Impact on CO2-EOR Processes with Mobility Control Strategies

2013 ◽  
Author(s):  
Mohammad Reza Beygi ◽  
Mojdeh Delshad ◽  
Venkateswaran Sriram Pudugramam ◽  
Gary Arnold Pope ◽  
Mary F. Wheeler
Keyword(s):  
Control Strategies ◽  
Mobility Control ◽  
New Approach ◽  
Co2 Eor ◽  
Eor Processes

Investigation of the Critical Velocity Required for a Gravity-Stable Surfactant Flood

SPE Journal ◽  
2014 ◽  
Vol 19 (05) ◽  
pp. 931-942 ◽  
Author(s):  
Shayan Tavassoli ◽  
Jun Lu ◽  
Gary A. Pope ◽  
Kamy Sepehrnoori
Keyword(s):  
Numerical Simulations ◽  
Critical Velocity ◽  
Oil Recovery ◽  
Horizontal Wells ◽  
Mobility Control ◽  
Oil Reservoirs ◽  
Three Dimensions ◽  
Analytical Models ◽  
Oil Viscosity ◽  
Fine Grid

Summary Classical stability theory predicts the critical velocity for a miscible fluid to be stabilized by gravity forces. This theory was tested for surfactant floods with ultralow interfacial tension (IFT) and was found to be optimistic compared with both laboratory displacement experiments and fine-grid simulations. The inaccurate prediction of instabilities on the basis of available analytical models is because of the complex physics of surfactant floods. First, we simulated vertical sandpack experiments to validate the numerical model. Then, we performed systematic numerical simulations in two and three dimensions to predict formation of instabilities in surfactant floods and to determine the velocity required to prevent instabilities by taking advantage of buoyancy. The 3D numerical grid was refined until the numerical results converged. A third-order total-variation-diminishing (TVD) finite-difference method was used for these simulations. We investigated the effects of dispersion, heterogeneity, oil viscosity, relative permeability, and microemulsion viscosity. These results indicate that it is possible to design a very efficient surfactant flood without any mobility control if the surfactant solution is injected at a low velocity in horizontal wells at the bottom of the geological zone and the oil is captured in horizontal wells at the top of the zone. This approach is practical only if the vertical permeability of the geological zone is high. These experiments and simulations have provided new insight into how a gravity-stable, low-tension displacement behaves and in particular the importance of the microemulsion phase and its properties, especially its viscosity. Numerical simulations show high oil-recovery efficiencies on the order of 60% of waterflood residual oil saturation (ROS) for gravity-stable surfactant floods by use of horizontal wells. Thus, under favorable reservoir conditions, gravity-stable surfactant floods are very attractive alternatives to surfactant/polymer floods. Some of the world's largest oil reservoirs are deep, high-temperature, high-permeability, light-oil reservoirs, and thus candidates for gravity-stable surfactant floods.

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Clinical features and outcome of acquired haemophilia A

2010 ◽  
Vol 30 (03) ◽  
pp. 156-161 ◽  
Author(s):  
R. Gheisari ◽  
B. Bomke ◽  
T. Hoffmann ◽  
R. E. Scharf
Keyword(s):  
Respiratory Diseases ◽  
Care Center ◽  
Treatment Algorithm ◽  
Early Death ◽  
Underlying Disease ◽  
Pulmonary Sarcoidosis ◽  
Relative Increase ◽  
Laboratory Evaluation ◽  
Haemophilia A ◽  
Acquired Haemophilia

SummaryWe have performed a monocenter study on 29 consecutive patients with acquired haemophilia A who were referred for diagnosis and treatment to the Düsseldorf Haemophilia Comprehensive Care Center between March 2001 and February 2010. Patients, methods: 18 men (age: 44–86 years) and 11 women (age: 20–83 years). For laboratory evaluation, a standardized staged protocol of aPTT, FVIII : C activity and concentration, mixing studies with patient and normal plasma, and quantification of inhibitor titers (Bethesda assay) was used. Diagnostic work-up included elaborate examinations for any underlying disease. Results: In 18 (62%) of the 29 patients with acquired haemophilia A, an underlying disorder was identified, including 9 patients with respiratory diseases (31%), 7 patients with autoimmune disorders (24%), one with malignancy, and one with postpartum state, while in 11 patients (38%) acquired haemophilia A remained idiopathic. Haemotherapy of bleeding, suppression or elimination of the inhibitor, and induction of immunotolerance to endogenous FVIII:C were performed according to a treatment algorithm. Predefined clinical endpoints were control of bleeding, eradication of the inhibitor, complete or partial remission (CR, PR), relapse, or early death (≤30 days). Of the 29 patients in total, 22 individuals achieved CR (76%), three had PR, one relapsed, and three died within 30 days (one of acute myocardial infarction while on anti-haemorrhagic treatment, one of sepsis while on immunosuppression due to active acquired haemophilia A, one of lung bleeding in association with pre-existing pulmonary sarcoidosis). Conclusion: This monocenter study demonstrates that control of life-threatening bleeding, eradication of the inhibitor, and induction of tolerance to endogenous FVIII have significantly improved the clinical outcome of acquired haemophilia A. Our data also suggest a shift in underlying disorders associated with acquired haemophilia A, whereby, in comparison to published studies, a relative increase in the proportion of patients with respiratory diseases is present.

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