scholarly journals Effects of Gas Trapping on Foam Mobility in a Model Fracture

2021 ◽  
Author(s):  
Kai Li ◽  
Karl-Heinz A. A. Wolf ◽  
William R. Rossen
Keyword(s):  
Oil Recovery ◽  
High Speed ◽  
Direct Method ◽  
Viscous Force ◽  
List Type ◽  
Bubble Generation ◽  
Gas Trapping ◽  
Hydraulic Aperture ◽  
Glass Model ◽  
Trapped Gas

Abstract In enhanced oil recovery, foam can effectively mitigate conformance problems and maintain a stable displacement front, by trapping gas and reducing its relative permeability in situ. In this study, to understand gas trapping in fractures and how it affects foam behavior, we report foam experiments in a 1-m-long glass model fracture with a hydraulic aperture of 80 $$\upmu $$ μ m. One wall of the fracture is rough, and the other is smooth. Between the two is a 2D porous medium representing the aperture in a fracture. The fracture model allows direct visualization of foam inside the fracture using a high-speed camera. This study is part of a continuing program to determine how foam behaves as a function of the geometry of the fracture pore space (AlQuaimi and Rossen in Energy & Fuels 33: 68-80, 2018a). We find that local equilibrium of foam (where the rate of bubble generation equals that of bubble destruction) has been achieved within the 1-m model fracture. Foam texture becomes finer, and less gas is trapped as interstitial velocity, and pressure gradient increase. Shear-thinning rheology of foam has also been observed. The fraction of trapped gas is significantly lower in our model (less than 7%) than in 3D geological pore networks. At the extreme, when velocity increases to 7 mm/s, there is no gas trapped inside the fracture. Our experimental results of trapped-gas fraction correlate well with the correlation of AlQuaimi and Rossen (SPE J 23: 788-802, 2018b) for fracture-like porous media. This suggests that the correlation can also be applied to gas trapping in fractures with other geometries. Article Highlights We have made a lab-scale 1-meter-long transparent glass model representing a geological fracture with roughened surface, and we have implemented a direct method of image analysis to quantify the texture of bubbles in the fracture and to link the texture with the strength of the foam; We have successfully created surfactant-stabilized foam flow inside the fracture and examined its stability along the 1-meter-long fracture; We explain the mechanism of gas trapping in fractures and how it affects foam behavior. We also discuss how viscous force and capillary force affect gas trapping in fractures at our experimental conditions. Graphic Abstract

Effects of Gravity on Foam Behavior in Roughened Model Fractures

SPE Journal ◽  
2021 ◽  
pp. 1-14
Author(s):  
K. Li ◽  
K. A. A. Wolf ◽  
W. R. Rossen
Keyword(s):  
High Speed ◽  
Local Equilibrium ◽  
Vertical Flow ◽  
Bubble Generation ◽  
Gravity Segregation ◽  
Foam Generation ◽  
Hydraulic Aperture ◽  
Glass Model ◽  
Flow Experiments

Summary In this study, to investigate how gravity affects foam in open vertical fractures, we report foam experiments in three 1-m-long, 15-cm-wide glass-model fractures. Each fracture has a smooth wall and a roughened wall. Between the two walls is a slit-like channel representing a single geological fracture. Three model fractures (Models A, B, and C) share the same roughness and have different hydraulic apertures of 78, 98, and 128 µm, respectively. We conduct foam experiments by horizontal injection in the three model fractures placed horizontally and sideways (i.e., with the model fractures turned on their long side), and in Model A placed vertically with injection upward or downward. Direct imaging of the foam inside the model fracture is facilitated using a high-speed camera. We find that foam reaches local equilibrium (LE; where the rate of bubble generation equals that of bubble destruction) in horizontal-flow experiments in all three model fractures and in vertical-flow experiments in Model A. In fractures with a larger hydraulic aperture, foam is coarser because of less in-situ foam generation. In the vertical-flow experiments in Model A, we find that the properties of the foam are different in upward and downward flow. Compared with downward flooding, upward flooding creates a finer-texture foam, as sections near the inlet of this experiment are in a wetter state, which benefits in-situ foam generation. Moreover, less gas is trapped during upward flooding, as gravitational potential helps overcome the capillarity and moves bubbles upward. In the sideways-flow experiments, gravity segregation takes place. As a result, drier foam propagates along the top of the fractures and wetter foam along the bottom. The segregation is more significant in fractures with a larger hydraulic aperture. At foam quality 0.8, gas saturation is 27.7% greater at the top than the bottom for Model C, and 19.3% and 10.8% for Models B and A, respectively. Despite the gravity segregation in all three model fractures, water and gas are not completely segregated. All three model fractures thus represent a capillary transition zone, with greater segregation with increasing aperture. Our results suggest that the propagation of foam in vertical natural fractures meters tall and tens of meters long, with an aperture of hundreds of microns or greater, is problematic. Gravity segregation in foam would weaken its capacity in the field to maintain uniform flow and divert gas in a tall fracture over large distances.

Determining Trapped Gas in Foam From Computed-Tomography Images

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 24-34 ◽  
Author(s):  
R.A.. A. Kil ◽  
Q.P.. P. Nguyen ◽  
W.R.. R. Rossen
Keyword(s):  
Computed Tomography ◽  
Oil Recovery ◽  
Ct Images ◽  
Axial Position ◽  
Tracer Concentration ◽  
Computed Tomography Images ◽  
Gas Trapping ◽  
Capacitance Model ◽  
The Difference ◽  
Trapped Gas

Summary Gas trapping by foam is a key mechanism of foam mobility and foam effectiveness in applications such as acid diversion in well stimulation, enhanced oil recovery (EOR), and aquifer remediation. Previous studies have attempted to quantify the extent of gas trapping by injecting a tracer gas within the foam and then fitting the effluent profile to a 1D capacitance model. In this model, at any given axial position along the core, all flowing gas and all trapped gas are each characterized by a single tracer concentration. Computed-tomography (CT) images of experiments using xenon (Xe) tracer show that this characterization is not accurate: Trapped gas near flowing gas comes rapidly to equilibrium with flowing gas long before tracer diffuses into trapped gas farther away. We introduce a method that uses the CT images directly to estimate flowing-gas fraction. In the CT images, tracer advances in many small channels and diffuses outward into surrounding regions of trapped gas a few millimeters in diameter. The difference between the higher tracer concentration at the center of these channels and the lower concentration at the edge can be related to the diffusion coefficient of the tracer and the flowing-gas fraction within the channel. For the CT images of Xe tracer in one experiment, this method gives flowing-gas fractions one or two orders of magnitude smaller than what is estimated using the 1D capacitance model. The model can be used to estimate flowing-gas fraction in different regions of a core in spite of different average gas velocities in the different regions.

scholarly journals Experimental investigation of the displacement flow mechanism and oil recovery in primary polymer flood operations

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Ruissein Mahon ◽  
Gbenga Oluyemi ◽  
Babs Oyeneyin ◽  
Yakubu Balogun
Keyword(s):  
Relative Permeability ◽  
Oil Recovery ◽  
Polymer Flooding ◽  
Mobility Control ◽  
List Type ◽  
Motor Oil ◽  
Flow Mechanism ◽  
Fractional Flow ◽  
Recovery Method ◽  
Polymer Flood

Abstract Polymer flooding is a mature chemical enhanced oil recovery method employed in oilfields at pilot testing and field scales. Although results from these applications empirically demonstrate the higher displacement efficiency of polymer flooding over waterflooding operations, the fact remains that not all the oil will be recovered. Thus, continued research attention is needed to further understand the displacement flow mechanism of the immiscible process and the rock–fluid interaction propagated by the multiphase flow during polymer flooding operations. In this study, displacement sequence experiments were conducted to investigate the viscosifying effect of polymer solutions on oil recovery in sandpack systems. The history matching technique was employed to estimate relative permeability, fractional flow and saturation profile through the implementation of a Corey-type function. Experimental results showed that in the case of the motor oil being the displaced fluid, the XG 2500 ppm polymer achieved a 47.0% increase in oil recovery compared with the waterflood case, while the XG 1000 ppm polymer achieved a 38.6% increase in oil recovery compared with the waterflood case. Testing with the motor oil being the displaced fluid, the viscosity ratio was 136 for the waterflood case, 18 for the polymer flood case with XG 1000 ppm polymer and 9 for the polymer flood case with XG 2500 ppm polymer. Findings also revealed that for the waterflood cases, the porous media exhibited oil-wet characteristics, while the polymer flood cases demonstrated water-wet characteristics. This paper provides theoretical support for the application of polymer to improve oil recovery by providing insights into the mechanism behind oil displacement. Graphic abstract Highlights The difference in shape of relative permeability curves are indicative of the effect of mobility control of each polymer concentration. The water-oil systems exhibited oil-wet characteristics, while the polymer-oil systems demonstrated water-wet characteristics. A large contrast in displacing and displaced fluid viscosities led to viscous fingering and early water breakthrough.

scholarly journals Study on the Effect of Nanoparticle Used in Nano-Fluid Flooding on Droplet–Interface Electro-Coalescence

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1764
Author(s):  
Donghai Yang ◽  
Huayao Sun ◽  
Qing Chang ◽  
Yongxiang Sun ◽  
Limin He
Keyword(s):  
Interfacial Tension ◽  
Oil Recovery ◽  
Liquid Bridge ◽  
High Speed ◽  
Droplet Formation ◽  
Force Balance ◽  
Secondary Droplet ◽  
Droplet Deformation ◽  
Deformation Degree ◽  
Nano Fluid

Nano-fluid flooding is a new method capable of improving oil recovery; however, nanoparticles (NPs) significantly affect electric dehydration, which has rarely been investigated. The effect of silica (SiO2) NPs on the droplet–interface coalescence was investigated using a high-speed digital camera under an electric field. The droplet experienced a fall, coalescence, and secondary droplet formation. The results revealed that the oil–water interfacial tension and water conductivity changed because of the SiO2 NPs. The decrease of interfacial tension facilitated droplet deformation during the falling process. However, with the increase of particle concentration, the formed particle film inhibited the droplet deformation degree. Droplet and interface are connected by a liquid bridge during coalescence, and the NP concentration also resulted in the shape of this liquid bridge changing. The increase of NP concentration inhibited the horizontal contraction of the liquid bridge while promoting vertical collapse. As a result, it did not facilitate secondary droplet formation. Moreover, the droplet falling velocity decreased, while the rising velocity of the secondary droplet increased. Additionally, the inverse calculation of the force balance equation showed that the charge of the secondary droplet also increased. This is attributed to nanoparticle accumulation, which resulted in charge accumulation on the top of the droplet.

scholarly journals The Impact of Lipid Handling and Phase Distribution on the Acoustic Behavior of Microbubbles

Pharmaceutics ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Simone A.G. Langeveld ◽  
Inés Beekers ◽  
Gonzalo Collado-Lara ◽  
Antonius F. W. van der Steen ◽  
Nico de Jong ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Molecular Imaging ◽  
High Speed ◽  
Phase Distribution ◽  
Direct Method ◽  
Ultrasound Contrast Agents ◽  
Lipid Phase ◽  
Acoustic Behavior ◽  
Ultrasound Molecular Imaging ◽  
The Impact

Phospholipid-coated microbubbles are ultrasound contrast agents that can be employed for ultrasound molecular imaging and drug delivery. For safe and effective implementation, microbubbles must respond uniformly and predictably to ultrasound. Therefore, we investigated how lipid handling and phase distribution affected the variability in the acoustic behavior of microbubbles. Cholesterol was used to modify the lateral molecular packing of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)-based microbubbles. To assess the effect of lipid handling, microbubbles were produced by a direct method, i.e., lipids directly dispersed in an aqueous medium or indirect method, i.e., lipids first dissolved in an organic solvent. The lipid phase and ligand distribution in the microbubble coating were investigated using confocal microscopy, and the acoustic response was recorded with the Brandaris 128 ultra-high-speed camera. In microbubbles with 12 mol% cholesterol, the lipids were miscible and all in the same phase, which resulted in more buckle formation, lower shell elasticity and higher shell viscosity. Indirect DSPC microbubbles had a more uniform response to ultrasound than direct DSPC and indirect DSPC-cholesterol microbubbles. The difference in lipid handling between direct and indirect DSPC microbubbles significantly affected the acoustic behavior. Indirect DSPC microbubbles are the most promising candidate for ultrasound molecular imaging and drug delivery applications.

scholarly journals The effect of including the Nordic Hamstring exercise on sprint and jump performance in athletes: protocol of a systematic review and meta-analyses

2020 ◽  
Author(s):  
Kasper Krommes ◽  
Mathias F. Nielsen ◽  
Laura Krohn ◽  
Birk M. Grønfeldt ◽  
Kristian Thorborg ◽  
...  
Keyword(s):  
Systematic Review ◽  
High Speed ◽  
Data Extraction ◽  
Force Production ◽  
List Type ◽  
Jump Performance ◽  
Production Studies ◽  
Hamstring Strain ◽  
Data Extraction Form ◽  
Meta Analyses

AbstractThe Nordic Hamstring exercise reduces hamstring strain injuries in football and other sports, but the exercise is not well adopted in practice. Barriers from practitioners include fear of performance decrements, due to lack of specificity of the exercise with high speed running. However, in theory, increased eccentric hamstring strength could transfer to faster sprinting due to higher horizontal force production. Studies on the effect of the Nordic Hamstring exercise on performance have been conflicting and no synthesis of the evidence exists. We therefore pose the following question: does including the Nordic Hamstring exercise hamper sprint or jump performance in athletes? We will answer this question by performing a systematic review of the literature, critically appraise relevant studies, and GRADE the evidence across key outcomes and perform meta-analyses, meta-regression and subgroup analyses. In this protocol we outline the planned methods and procedures.Progress reportBesides this protocol, our data extraction form and the process of data extraction has been piloted on 3 relevant studies, along with familiarization with the Risk of Bias 2.0 tool. We have also comprised a preliminary search strategy for PubMed.Supplementary filesData Extraction Form (.pdf)Populated PRISMA-P checklist (.pdf)

scholarly journals Diagnosis of primary ciliary dyskinesia: summary of the ERS Task Force report

Breathe ◽  
2017 ◽  
Vol 13 (3) ◽  
pp. 166-178 ◽  
Author(s):  
Claudia E. Kuehni ◽  
Jane S. Lucas
Keyword(s):  
Secondary Care ◽  
Primary Ciliary Dyskinesia ◽  
High Speed ◽  
Task Force ◽  
Diagnostic Testing ◽  
List Type ◽  
European Respiratory Society ◽  
Term Infants ◽  
Task Force Report ◽  
Ciliary Dyskinesia

Key pointsPrimary ciliary dyskinesia (PCD) is a genetically and clinically heterogeneous disease characterised by abnormal motile ciliary function.There is no “gold standard” diagnostic test for PCD.The European Respiratory Society (ERS) Task Force Guidelines for diagnosing PCD recommend that patients should be referred for diagnostic testing if they have several of the following features: persistent wet cough; situs anomalies; congenital cardiac defects; persistent rhinitis; chronic middle ear disease with or without hearing loss; or a history, in term infants, of neonatal upper and lower respiratory symptoms or neonatal intensive care admission.The ERS Task Force recommends that patients should be investigated in a specialist PCD centre with access to a range of complementary tests: nasal nitric oxide, high-speed video microscopy analysis and transmission electron microscopy. Additional tests including immunofluorescence labelling of ciliary proteins and genetic testing may also help determine the diagnosis.Educational aimsThis article is intended for primary and secondary care physicians interested in primary ciliary dyskinesia (PCD), i.e. those who identify patients for testing, and those involved in diagnosing and managing PCD patients. It aims: to inform readers about the new European Respiratory Society Task Force Guidelines for diagnosing patients with PCDto enable primary and secondary care physicians to: identify patients who need diagnostic testing; understand the diagnostic tests that their patients will undergo, the results of the tests and their limitations; and ensure that appropriate care is subsequently delivered.

Air Entrainment and Bubble Generation by a Hydrofoil in a Turbulent Channel Flow

2019 ◽  
Author(s):  
Ichiro Kumagai ◽  
Kakeru Taguchi ◽  
Chiharu Kawakita ◽  
Tatsuya Hamada ◽  
Yuichi Murai
Keyword(s):  
Channel Flow ◽  
Flow Rate ◽  
High Speed ◽  
Air Flow ◽  
Air Entrainment ◽  
Air Bubbles ◽  
Air Flow Rate ◽  
Bubble Generation ◽  
Gas Liquid Flow ◽  
Entrained Air

Abstract Air entrainment and bubble generation by a hydrofoil bubble generator for ship drag reduction have been investigated using a small high-speed channel tunnel with the gap of 20 mm in National Maritime Research Institute (NMRI). A hydrofoil (NACA4412, chord length = 40 mm) was installed in the channel and an air induction pipe was placed above the hydrofoil. The flow rate of the entrained air was quantitatively measured by thermal air flow sensors at the inlet of the air induction pipe. The gas-liquid flow around the hydrofoil was visualized by a backlight method and recorded by a high-speed video camera. As the flow velocity in the channel increased, the negative pressure generated above the suction side of the hydrofoil lowered the hydrostatic pressure in the channel, then the atmospheric air was entrained into the channel flow. The entrained air was broken into small air bubbles by the turbulent flow in the channel. The threshold of air entrainment, the air flow rate, and gas-liquid flow pattern depends on Reynolds number, angle of attack (AOA), and hydrofoil type. We identified at least three modes of air entrainment behavior: intermittent air entrainment, stable air entrainment, and air entrainment with a ventilated cavity. At high flow speed in our experimental condition (9 m/s), a large volume of air bubbles was generated by this hydrofoil system (e.g. air flow rate was 50 l/min for NACA4412 at AOA 16 degrees), which has a high potential to reduce ship drag.

Generation and Transport of Bubbles in a Microfluidic Device

2008 ◽  
Author(s):  
Renqiang Xiong ◽  
Jacob N. Chung
Keyword(s):  
Silicon Wafer ◽  
Microfluidic Device ◽  
High Speed ◽  
Micro Channel ◽  
Bubble Generation ◽  
Air Bubble ◽  
Micro Scale ◽  
Bubble Transport

In this paper we used high speed recording to characterize segmented micro-scale air bubble generation in a T-junction and bubble transport in a serpentine micro-channel fabricated in a standard silicon wafer.

Experimental Study on Cavitation Motion of Underwater Vehicle With Protrusions

2020 ◽  
Author(s):  
Zhaoyu Qu ◽  
Ning Gan ◽  
Yingyu Chen ◽  
Nana Yang
Keyword(s):  
High Speed ◽  
Underwater Vehicle ◽  
Test Method ◽  
Scale Model ◽  
Small Scale ◽  
Reduced Pressure ◽  
Local Flow ◽  
Bubble Generation ◽  
Scale Characteristics ◽  
Motion Characteristics

Abstract For underwater vehicles with protrusions (external structure), the geometric shape of the protrusions is bound to affect the local flow field of the vehicles during the moving process of the vehicles, thus affecting the generation, development and collapse of cavitation around the vehicles. The cavitation may break, fall off and collapse randomly, and other local movements may affect the motion attitude of the underwater vehicle. It is an effective method to study fluid dynamics to simulate prototype cases with small scale models. In this paper, we mainly use the small scale model test method to explore the cavitation motion characteristics of the vehicle in water with protrusions. Through the establishment of a set of vehicle motion test equipment under reduced pressure, a series of experiments were conducted on this basis to explore the motion characteristics of vehicle cavitation under different bump shapes. In this study, two high-speed cameras were used to simultaneously record cavitation generation, development, collapse and other characteristics, to analyze the bubble generation mechanism and scale characteristics caused by the bulge, and then to study the influence of cavitation induced by the bulge on the motion attitude of the vehicle.

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