Study on the Oil Displacement Effect and Application of Soft Microgel Flooding Technology

Due to the reservoir heterogeneity, there is still a lot of remaining oil that cannot be displaced by water flooding. Therefore, taking the whole injection-production flow field as the research object, the dominant channel is divided into macro and micro channel. Then the corresponding oil displacement system is adopted to realize the continuous flow diversion and effective expansion of swept volume. For micro channels, the soft microgel particle dispersion can be used. It is a novel flooding system developed in recent years. Due to its excellent performance and advanced mechanism, the oil recovery rate can be greatly improved. Soft microgel particle dispersion consists of microgel particles and its carrier fluid. After coming into porous media, its unique phenomenon of particle phase separation appears, which leads to the properties of "plugging large pore and leave the small one open", and the deformation and migration characteristic in the poros media. Therefore, particle phase separation of soft microgel particle dispersion is studied by using the microfluidic technology and numerical simulation. On this basis, by adopting the NMR and 3D Printing technology, the research on its oil displacement mechanism is further carried out. Furthermore, the typical field application cases are analyzed. Results show that, soft microgel particles have good performance and transport ability in porous media. According to the core displacement experiment, this paper presents the matching coefficient between microgels and pore throat under effective plugging modes. Also, the particle phase separation happens when injecting microgels into the core, which makes the particles enter the large pore in the high permeability layer and fluid enters into small pore. Therefore, working in cooperation, this causes no damage to the low permeability layer. On this basis, theoretically guided by biofluid mechanics, the mathematical model of soft microgel particle is established to simulate its concentration distribution, which obtained the quantitative research results. Furthermore, the micro displacement experiment shows that, microgels has unique deformation and migration characteristic in the poros media, which can greatly expand swept volume. The macro displacement experiment shows that, microgels have good oil displacement performance. Finally, the soft microgel particle dispersion flooding technology has been applied in different oilfields since 2007. Results show that these field trials all obtain great oil increasing effect, with the input-output ratio range of 2.33-14.37. And two field application examples are further introduced. Through interdisciplinary innovative research methods, the oil displacement effect and field application of soft microgel particle dispersion is researched, which proves its progressiveness and superiority. The research results play an important role in promoting the application of this technology.

Dynamic generation of aqueous foams and fiber foams in a mixing tank

Mixing tanks are employed in paper and pulp industries to generate aqueous foams and fiber foams. The aim of the present study was to investigate the effect of impeller geometry on dynamic foam generation in a 60 L mixing tank. Three impeller geometries including two radial—Rushton turbine (RT), Bakker turbine (BT6), one axial high solidity pitched blade turbine (HSPBT), and four dual impeller combinations were investigated. Compressed air, water and sodium dodecyl sulphate were used as gas phase, liquid phase and surfactant, respectively, to generate aqueous foam. 1% mass consistency softwood fiber was used to generate fiber foam. The change in aqueous foam density for any given impeller was limited to ± 40 kg/m3 indicating foam density was dictated by impeller type rather than power input. Single impellers generated bubbly liquids whereas dual impellers generated low-density aqueous foams. Besides, stable foam was produced even at low power input compared to single impellers due to increase in impeller swept volume and blade contact area. Addition of fibers increased the foam density by ~ 100–150 kg/m3 and reduced the half-life time by almost threefold for all impellers due to lower air content and higher bubble size. Placement of high shear impeller (BT6) at bottom and down-pumping axial impeller (HSPBT) on top generated fine bubbles.

Design of 3D volumetric display

Stereoscopic, or multi-view, display systems that can give significant visual clues for the human brain to understand three-dimensional (3D) objects, they are regarded as better alternatives to traditional two-dimensional (2D) displays. A device that can render 3D images for viewers without the use of specific headgear or glasses is known as an auto-stereoscopic display. Manipulation of light rays via Light engines is also used to create 3D images in 3D space. We introduce a new auto-stereoscopic swept-volume display (SVD) system based on light-emitting diode (LED) arrays in this research. A display device plus a graphics control sub-system makes up this system. The display device is a 2D revolving panel of LEDs that generates 3D images using “persistence of vision”.

The New Development of Soft Microgel Particle Flooding Technology –From Theoretical Research in Laboratory to Field Trial

Although polymer flooding technology has been widely applied and achieved remarkable effect of increasing oil. Yet the "entry profile inversion" phenomenon occurs inevitably in its later stage, which seriously affects the development effect. In recent years, the soft microgel particle dispersion is a novel developed flooding system. Due to its excellent performance and advanced mechanism, it can slow down the process of profile inversion, and achieve the goal of deep fluid diversion and expanding swept volume. The soft microgel particle dispersion consists of microgel particles and its carrier fluid. After coming into porous media, it shows the properties of "plugging large pore and leave the small one open" and the motion feature of "trapping, deformation, migration". In this paper, reservoir adaptability evaluation, plugging and deformation characteristics of soft microgel particle dispersion in pore throat is explored by using the microfluidic technology and 3D Printing technology. On this basis, by adopting the NMR and CT tomography technology, the research on its oil displacement mechanism is further carried out. Furthermore, the typical field application case is analyzed. Results show that, soft microgel particles have good performance and transport ability in porous media. According to the reservoir adaptability evaluation, the size relationships between particles and core pore throat is obtained, to provide basis for field application scheme design. Through microfluidic experiments, the temporary plugging and deformation characteristics of particles in the pore throat are explored. Also, when injecting soft microgel particle into the core, the particle phase separation happens, which makes the particles enter and plug the large pore in the high permeability layer. Therefore, their carrier fluid displace oil in the small pore, which works in cooperation and causes no damage to the low permeability layer. Furthermore, by using NMR and CT techniques, its micro percolation law in porous media and remaining oil distribution during displacement process is analyzed. During the experiment, microgels presents the motion feature of "migration, trapping, and deformation" in the core pore, which can realize deep fluid diversion and expand swept volume. From 3D macro experiment, microgels can realize the goal of enhance oil recovery. Finally, the soft microgel particle dispersion flooding technology has been applied in different oilfields, such as Oman, Bohai and other oilfields, which all obtained great success. Through interdisciplinary innovative research methods, the oil displacement mechanism and field application of soft microgel particle dispersion is researched, which proves its progressiveness and superiority. The research results provide theoretical basis and technical support for the enhancing oil recovery significantly.

Cold emission optimization of a diesel- and alternative fuel-driven CI engine

This paper deals with the emission optimization of a compression ignition (CI) engine during cold ambient operation. Hence, in the present study, the effect of different injector nozzle geometries and pilot injection strategies, but also the influence of intake swirl, rail pressure, exhaust gas recirculation (EGR) as well as EGR cooling on the emission behavior during cold run are investigated. Therefore, test bed experiments under steady-state cold conditions are conducted on a state-of-the-art CI single cylinder research engine (SCRE) with approximately 0.5 l swept volume representing the typical passenger car (PC) cylinder size. The cold charge air temperature of down to −8 $$^{\circ }\hbox { C}$$ ∘ C and a low engine coolant and lube oil temperature represent a cold run close to reality. For emulating the higher friction of a typical 4-cylinder PC engine during cold run, the indicated mean effective pressure (IMEP) is increased according to a specifically developed equation and the turbocharger main equation is solved permanently to adjust the gas exchange loss. To take account of a potential future tightening of emission legislation, in addition to limited exhaust gas emissions, non-limited emissions such as carbonyls are measured as well. Since alternative fuels are able to make a significant contribution to the defossilisation of transportation, an oxygen-containing fuel, consisting of 100 % renewable blend components (HVO, ethers and alcohols) and fulfilling the EN 590 legislation is investigated under the same cold conditions in addition to the research on conventional diesel fuel.

Effect of Flue Gas on Steam Chamber Expansion in Steamflooding

Summary The expansion of the steam chamber is very important for the recovery performance of steamflooding. In this paper, we discuss 1D and 2D sandpack experiments to performed analyze the effect of flue gas on steam chamber expansion and displacement efficiency in steamflooding. In addition, we examine the effect of flue gas acting on the steam condensation characteristics. The results show that within a certain range of injection rate, flue gas can significantly enlarge the swept volume and oil displacement efficiency of steam. However, when the flue gas injection rate is excessively high (the ratio of gas injection rate to steam injection rate exceeds 4), gas channels may form, resulting in a decline of oil recovery from steamflooding. The results of the 2D visualization experiments reveal that the swept volume of the steam chamber during steamflooding was small, and the remaining oil saturation in the reservoir was high, so the recovery was only 28%. The swept volume of the steam chamber for flue-gas-assisted steamflooding was obviously larger than that of steamflooding, and the recovery of flue-gas-assisted steamflooding in 2D experiments could reach 40.35%. The results of the steam condensation experiment indicate that flue gas could reduce the growth and coalescence rates of steam-condensed droplets on the cooling wall and increase the shedding period of the droplets. Macroscopically, flue gas could reduce the heat exchange rate between the steam and the reservoir and inhibit the rapid condensation and heat exchange of the steam near the injection well. As a result, flue gas could expand the steam chamber into the reservoir for heating and displacing oil.

Work Cycle of Internal Combustion Engine Due to Rightsizing

It is worth still working on the development of the internal combustion engine, because its time was not yet over. This was demonstrated by the author’s review of the literature, indicating at least the perspective of 2050 the universality of the engine as the primary propulsion or support in hybrid transport units. The presented considerations may have a broader perspective, when the thermodynamic problems of a thermal machine such as an internal combustion engine are indicated. This chapter deals with the issues of changing the swept volume known as downsizing/rightsizing. An equivalent swept volume was introduced, defined by the coefficients determining changes in the cylinder diameter and the stroke of the piston. An attempt was made to find the mutual relations to the efficiency of the work cycle and engine operating parameters. The research methodology was proposed as a mix of laboratory tests and theoretical analyses, on the basis of which it was established that while maintaining the same value of the downsizing index, despite the various permissible combinations of cylinder diameter and piston stroke changes, the cycle efficiency remains unchanged. The engine operating parameters are changing, resulting from the use of support systems for rightsizing geometric changes.

The differing physiology of nitrogen and tracer gas multiple-breath washout techniques

BackgroundMultiple-breath washout techniques are increasingly being used to assess lung function. The principal statistic obtained is the lung clearance index (LCI), but values obtained for LCI using the N2-washout technique are higher than those obtained using an exogenous tracer gas such as SF6. This study explored whether the pure O2 used for the N2 washout could underlie these higher values.MethodsA model of a homogenous, reciprocally-ventilated acinus was constructed. Perfusion was kept constant, and ventilation adjusted by varying the swept volume during the breathing cycle. The blood supplying the acinus had a standard mixed-venous composition. CO2 and O2 exchange between the blood and acinar gas proceeded to equilibrium. The model was initialised with either air or air plus tracer gas as the inspirate. Washouts were conducted with pure O2 for the N2 washout or with air for the tracer gas washout.ResultsAt normal ventilation-perfusion (V̇/Q̇) ratios, the rate of washout of N2 and exogenous tracer gas was almost indistinguishable. At low V̇/Q̇, the N2 washout lagged the tracer gas washout. At very low V̇/Q̇, N2 became trapped in the acinus. Under low V̇/Q̇ conditions, breathing pure O2 introduced a marked asymmetry between the inspiratory and expiratory gas flow rates that was not present when breathing air.DiscussionThe use of pure O2 to washout N2 increases O2 uptake in low V̇/Q̇ units. This generates a background gas flow into the acinus that opposes flow out of the acinus during expiration, and so delays the washout of N2.

The Optimal Initiation Timing of Surfactant-Polymer Flooding in a Waterflooded Conglomerate Reservoir

Summary Surfactant-polymer (SP) flooding has been regarded as an efficient technique for enhanced oil recovery in the development of mature oil fields, especially for those with heterogeneous conglomerate reservoirs. However, people are still unclear about the optimal SP flooding initiation timing (OSPT) that is expected to contribute to the maximum ultimate recovery factor in the case with a limited amount of SP solution injection. Accordingly, this study aims to investigate OSPT through conducting a series of experiments, including nuclear magnetic resonance (NMR) online monitoring, full-diameter coreflooding, and microfluidic study. The fractional-flow curve is used to identify OSPT, of which the effect on the oil recovery is analyzed. OSPT is demonstrated to be dependent on the amount of injected SP solution. An earlier-started SP flooding is favorable for achieving higher oil recovery factors under the premise of sufficiently high SP solution injection [more than 1.5 pore volume (PV)]. With the commonly used 0.65 PV of SP solution in the reservoir scale, OSPT is suggested to be at the moment when a water cut of 80 to 90% is reached. The formation of dense emulsions in the early-started SP flooding affects the performance of the post-waterflooding, which eventually decreases the ultimate oil recoveries because of inadequacy of SP solution. An earlier-started SP flooding contributes to a larger swept volume, but the initial efficiency of the SP flooding is lower than that of the waterflooding when the injection pressure is constant. OSPT is proposed through analyzing the fractional-flow curve in the case of 0.65 PV of SP injection, and the determined OSPT is validated by coreflooding experiments and field data. Moreover, OSPT for the conglomerate reservoir is suggested to be earlier than that for the relatively homogenous sandstone reservoir.