Edge Of Chamber Research Articles

Effects of external parameters on plasma characteristics and uniformity in a dual cylindrical inductively coupled plasma

The dual cylindrical inductively coupled plasma source, compared to the conventional structure of inductively coupled plasma source, can significantly improve the uniformity of plasma. It has an enhanced potential for application in processes, such as etching and ashing. A uniform plasma can be obtained by allowing the remote plasma from the upper chamber modulate the main plasma generated in the lower chamber. In this study, a fluid model was employed to investigate a dual cylindrical inductively coupled Ar/O2 discharge. The effects of external parameters on electron density, electron temperature, O atomic density, and plasma uniformity in the main chamber were studied, and the reasons were analyzed. The results of this study show that remote power can control the plasma uniformity and increase the plasma density in the main chamber. As the remote power increased, plasma uniformity improved initially and then deteriorated. The main power affected the plasma density at the edge of the main chamber and can modulate the plasma density in the main chamber. The gas pressure affected both the uniformity and density of the plasma. As the gas pressure increased, the plasma uniformity deteriorated, but the free radical density improved.

A dynamic solvent chamber propagation estimation framework using RNN for warm solvent injection in heterogeneous reservoirs

Warm solvent injection (WSI), injecting low-temperature solvent into formations to reduce the viscosity of heavy oil, is a clean technology for heavy oil production through reducing greenhouse gas emissions and water usage. The success of WSI operation depends on the uniform development and propagation of solvent chambers in reservoirs. However, reservoir heterogeneity stemming from shale barriers plays a detrimental role in the conformance of solvent chamber development and oil production rate. In this work, we developed a novel recurrent neural network (RNN)-based framework with the capability of efficiently tracking and estimating the solvent chamber positions in heterogeneous reservoirs based on only production time-series data. The developed estimation model utilizes the “sequence-to-sequence" mapping methodology to correlate observed production time-series sequence and solvent chamber edge sequence via a long short-term memory (LSTM) algorithm. The trained RNN models exhibit high accuracy, evidenced by the predicted dynamic solvent chamber locations match the corresponding true locations from numerical simulation, with a high coefficient of determination (R2) and a low mean squared error. Specifically, the achieved R2 values exceed 0.98 on both the training and testing data. The developed RNN-based workflow was tested via several cases from both regularly- and irregularly-shaped shale barriers, and the results were promising. The predicted solvent chambers showed strong agreement with those obtained from numerical simulations. The major benefits of this workflow include reducing computational time and saving overall monitoring and tracking costs for conventional techniques. The present work would provide a good demonstration of the capability of practical integration of machine learning methods in solving engineering problems.

REFINING THE EMPIRICAL MODEL OF THE HEAT TRANSFER BOUNDARY CONDITIONS OF THE PISTON OF A HIGH-SPEED DIESEL ENGINE

The level of temperature of ICE pistons is a factor that greatly affects their reliability. Therefore, the need to simulate the temperature state of pistons with sufficient accuracy and minimal allocation of resources and time exists in research and during design. Primary approaches for determining the boundary conditions of the problem of thermal conduction of the piston on the basis of criterion equations, high-level mathematical models, and empirical models are considered. The latter ones have become widespread by virtue of simplicity and ease of use in practice; their usability is limited to a certain set of operating modes of one engine or a few ones of a similar design. On the basis of data from four series of experimental tests for a well-studied diesel engine 4ChN12/14 the existing empirical models of boundary conditions, suitable for identifying the temperature state of the piston only within the respective separate series separately, are refined in the paper. Processing of the data set on the measured temperatures in the control zones of the piston was performed, and linear function approximations were found that satisfactorily describe the effect of diesel power on the specified temperatures. The model of boundary conditions for a set of eighteen separate regions on the surfaces of the piston was proposed, which takes into account the dependence of the piston temperature state on the brake power of the ICE, the crank angle of the start of fuel injection, and the conditions of cooling the piston with oil. The influence of the heat insulation layer on the piston crown surface on the heat transfer was accounted for by introducing an additional thermal resistance term into the boundary condition equations. The model made obtaining the temperature field of the piston possible in simulation that is consistent with the results of all series of experiments in the control zones of the piston periphery, the edge of the combustion chamber, the vicinity of the groove of the first piston ring, the cooled surface opposite to the combustion chamber, and the piston skirt. The importance of a gradual change in the temperature of the oil and coolant during the transition of the internal combustion engine from one mode of operation to another regarding the temperature state of the piston is demonstrated. Taking the temperatures of oil from previous modes of operation into account is recommended during the analysis of engine transient processes.

Upgrade of the Lyman-alpha diagnostic system on DIII-D for main chamber edge neutral studies.

The LLAMA (Lyman Alpha Measurement Apparatus) pinhole camera diagnostic had previously been deployed on DIII-D to measure radial profiles of the Lyman-α (Ly-α) deuterium neutral line brightness across the plasma boundary in the lower chamber to infer neutral deuterium density and ionization rate profiles. This system has recently been upgraded with a new diagnostic head, named ALPACA, that also encloses two pinhole cameras and duplicates the LLAMA views in the upper chamber. Similar to LLAMA, ALPACA provides two times 20 lines of sight, viewing the plasma edge on the inboard and outboard sides with a radial resolution of ∼2.5 cm (FWHM) and an effective time resolution of ∼1 ms that allows for the investigation of inter-ELM dynamics. The extended Ly-α system provides better coverage to study neutrals in experiments with various plasma shapes utilizing both the upper and lower divertors. Furthermore, post-campaign calibration of the LLAMA diagnostic has successfully been demonstrated for the first time. This was facilitated by various upgrades to the calibration set-up and detailed measurements of the emissivity distribution of the Ly-α calibration source using a pinhole collimator. It was found that the sensitivity of the inboard LLAMA pinhole camera was reduced by a factor of 2.0 ± 0.2 over the course of six months of plasma operation in 2021. The upgraded Ly-α system, equipped with improved absolute calibration, will provide key input for neutral fueling and pedestal particle transport studies and for 2D edge transport code validation on the DIII-D tokamak.

Reuse of Smoulder in Laser Powder-Bed Fusion of AlSi10Mg—Powder Characterization and Sample Analysis

Metal additive manufacturing technologies, such as Laser Powder-Bed Fusion, often rate as sustainable due to their high material efficiency. However, there are several drawbacks that reduce the overall sustainability and offer potential for improvement. One such drawback is waste emerging from the process. These smoulder particles form when the laser hits the powder-bed surface, are blown away from the part by the shielding gas stream and accumulate on the edge of the build chamber. Usually, smoulder does not contribute to the circular reuse of powder that was part of the powder-bed but was not integrated into a part. Instead, it marks an end-of-life state of powder. Significant amounts of smoulder accumulate depending on the irradiated area or the build volume in one job, respectively. This results in the waste of powder that was produced with low energy efficiency. This study investigates the question of whether smoulder can transform from waste to resource via common powder characterization methods and first build jobs using processed smoulder. The investigation of process-relevant powder properties like apparent density and flowability showed no significant difference between virgin powder and smoulder. Sample characterization indicated that neither porosity, surface quality nor mechanical properties deteriorate when samples contain about 50% smoulder. This allows for the reuse of smoulder in terms of powder characterization and part quality.

A new pressure control scheme on steam‐assisted gravity drainage for heavy oil production

AbstractAs one the most important recovery mechanisms of steam‐assisted gravity drainage (SAGD), gravity drainage is largely dependent on the inclination angle of the steam chamber edge. The existence of solution‐gas causes an ellipsoid‐shaped chamber that has small inclination angle at the bottom, which leads to inefficient gravity drainage and slows down oil production. To address this problem, this study proposes a new scheme, variable‐pressure SAGD (VP‐SAGD). It is basically a SAGD process, at certain stages of which pressure surge is induced by controlling the operating conditions so that the shape of steam chamber can be altered. This leads to a larger slip angle in the steam chamber at the bottom and more efficient heat transport between hot steam and crude oil. Results show that VP‐SAGD is able to increase oil recovery by up to 20% and decrease cumulative steam–oil ratio (cSOR) by up to 7%. Its special oil extraction mechanisms include swabbing effect, enlarged inclination angle of steam chamber boundary at the bottom, and enhanced heat transfer. Particularly, the inclination angle is increased by up to 40%. In addition, a lower producer bottom‐hole pressure (BHP) during pressure drawdown leads to a better production incremental in later stages. The optimal timing for pressure surge is the middle stage of steam chamber growth. The lower the producer BHP decrease, the better the yield increase. Moreover, The VP‐SAGD strategy works better in heavy oil reservoirs with a permeability of k = 0.5–10 Darcy or solution gas content of greater than 2%.

Numerical analysis of gas-liquid-solid erosion characteristics of the oil and gas multiphase pump

In the process of oil and natural gas production, solid particle erosion is an important reason affecting the safe operation of oil and gas multiphase pumps. To reduce equipment failure rates, it is urgent to predict positions that are vulnerable to erosion damage. However, the erosion regularities of oil and gas multiphase pumps have rarely been studied in the past. In this paper, the Euler-Lagrange method is used to analyze the gas-liquid-solid flow phenomena in oil and gas multiphase pumps under different operating conditions, combined with the Oka model for erosion prediction. The validity of the erosion prediction method is verified using numerical simulation results of erosion at 90° elbows. To explore the erosion mechanism between fluid and entrained particle flow behavior, the relationship between particle parameters and erosion position and regularities is emphatically studied. The research results indicate that in a certain range, the maximum erosion rate of the oil and gas multiphase pump decreases with the increase of particle density, but increases linearly with the fluid velocity and is also affected by gas volume fraction and other particle parameters. In addition, the erosion usually occurs on the inlet, outlet wall, and the leading edge of the pump chamber, due to the different particle parameters, the erosion range will be slightly different. According to the particle trajectory, it is found that the leading edge of the pump chamber is the most erodible region due to the high frequency and intensity of particle impact. These results provide a reference for optimizing the structural design of the oil and gas multiphase pumps and help to predict their performance against wear.

Trajectories and Forces in Four-Electrode Chambers Operated in Object-Shift, Dielectrophoresis and Field-Cage Modes-Considerations from the System's Point of View.

In two previous papers, we calculated the dielectrophoresis (DEP) force and corresponding trajectories of high- and low-conductance 200-µm 2D spheres in a square 1 × 1-mm chamber with plane-versus-pointed, plane-versus-plane and pointed-versus-pointed electrode configurations by applying the law of maximum entropy production (LMEP) to the system. Here, we complete these considerations for configurations with four-pointed electrodes centered on the chamber edges. The four electrodes were operated in either object-shift mode (two adjacent electrodes opposite the other two adjacent electrodes), DEP mode (one electrode versus the other three electrodes), or field-cage mode (two electrodes on opposite edges versus the two electrodes on the other two opposite edges). As in previous work, we have assumed DC properties for the object and the external media for simplicity. Nevertheless, every possible polarization ratio of the two media can be modeled this way. The trajectories of the spherical centers and the corresponding DEP forces were calculated from the gradients of the system's total energy dissipation, described by numerically-derived conductance fields. In each of the three drive modes, very high attractive and repulsive forces were found in front of pointed electrodes for the high and low-conductance spheres, respectively. The conductance fields predict bifurcation points, watersheds, and trajectories with multiple endpoints. The high and low-conductance spheres usually follow similar trajectories, albeit with reversed orientations. In DEP drive mode, the four-point electrode chamber provides a similar area for DEP measurements as the classical plane-versus-pointed electrode chamber.

Numerical Study on Particle Movement and Crushing Characteristics in Vibromill

In order to optimize the eccentric vibromill to reduce the energy-depleted area and improve the grinding efficiency, the present paper employed the software EDEM to investigate the characteristics of movement and breakup of the grinding materials in an eccentric vibromill under different vibration frequencies and amplitude. The results indicate that the cylinder vibrates continuously at a high frequency under harmonic excitation force. A prominent dynamic rotating center is formed in the dielectric grinding chamber, which changes with the vibration frequency and amplitude. During the mixing process of grinding media and materials, the mixing speed of materials increases with amplitude. However, when the amplitude is too large, some materials are thrown to the edge of the grinding chamber, which reduces the mixing uniformity.

ESTIMATION OF THE THERMALLY STRESSED STATE OF INTERNAL COMBUSTION ENGINE PISTONS, TAKING INTO ACCOUNT THE CREEP THRESHOLD OF THEIR SIDE SURFACE

When creating new engine designs, they are subject to ever more stringent requirements for specific power and reliability indicators while ensuring a combination of other performance indicators. The use of new design solutions or the transition to a different piston material can significantly increase the possible level of engine power. This requires a mandatory analysis of the thermal stress state of the structure. It is this analysis that can show whether one or another competing solution will be effective. This study shows the possible effectiveness of certain constructive measures. The diesel piston 4ChN12/14 was taken as the object of the research. Power levels corresponded to 20-30 kW/l. The analysis of the temperature and heat-stress states of the piston in two designs and for two materials - AL25 and AK4 alloys was carried out. The level of thermal stresses of the structure is set in an elastic setting. The obtained data allow to analyze the condition of the pistons and draw conclusions based on the concept of guaranteed reliability. In the analysis, we used the creep limits of materials that we previously determined. The analysis of the temperature state in the zone of the edge of the combustion chamber of the piston and in the zone of the groove for the first piston ring, where the reliability falling of the piston design is possible, has been analyzed. The creep threshold of materials by the side surface of the piston is estimated. The facts of the appearance of rubbing on pistons in the initial period of their loads are explained on the basis of exceeding the creep threshold of an unhardened material. It is shown that the creep threshold of the non-hardened piston material can be exceeded when, according to the criteria of the temperature state of the combustion chamber edge and the zone of the first compression ring, the design is operable. Based on the results of the analysis, conclusions were drawn about the performance of piston structures during power increasing using two options for oil cooling of the piston and during the transition from aluminum alloy AL25 to alloy AK4.

A systematic comparison of solvents and their concentrations in bitumen gravity drainage under controlled thermodynamic conditions

Solvent-assisted SAGD (SA-SAGD) has been studied as an alternative to improve the efficiency of SAGD. This paper reports a new set of experimental data for SA-SAGD and analyzes the characteristics of bitumen-solvent mixing in the experiments using history-matched numerical models. The dimensions of the sand pack were 3 in. in diameter and 15 in. in length, and the sand pack was contained in a 25-L cylindrical pressure vessel. An annular void space surrounded the sand pack with a gap thickness of 1 in., within which a steady state flow of the injected vapor phase maintained the controlled pressure, temperature, and composition. Therefore, the gravity drainage in the sand pack occurred at a set of specified thermodynamic conditions for the surrounding annular steam chamber, unlike transient conditions near the edge of a steam chamber in larger-scale steam injection processes. In addition to SAGD as the base case, five sets of SA-SAGD were performed: 20 mol% C4, 40 mol% C4, 10 mol% C8, 20 mol% C8, and 10 mol% condensate coinjected with steam at 3500 kPa.The peak oil production rate was 9.84 cm3/min with SAGD, 14.61 cm3/min with 20 mol% C4-SAGD, 16.34 cm3/min with 40 mol% C4-SAGD, 31.33 cm3/min with 10 mol% C8-SAGD, 12.36 cm3/min with 20 mol% C8-SAGD, and 12.33 cm3/min with 10 mol% condensate-SAGD. SAGD was the least effective in bitumen gravity drainage, while the 10 mol% C8-SAGD was the most effective. Increasing the C4 molar concentration from 20 to 40 mol% slightly increased the peak rate; however, the peak rate in C8-SAGD significantly was decreased by increasing the C8 concentration from 10 to 20 mol%. This counter-intuitive result was reported in a few simulation studies with heavy solvents (e.g., C7 and C12) in the literature, but had not been experimentally confirmed before this research.Although the condensate contained 93 mol% C7-like pseudo component (C7, eq), the peak rate of 10 mol% condensate-SAGD was much smaller than that of 10 mol% C8-SAGD. These experimental observations highlight the practical importance of understanding the sensitivity of bitumen gravity drainage to heavy-solvent concentrations near the edge of a steam chamber in SA-SAGD.

The System’s Point of View Applied to Dielectrophoresis in Plate Capacitor and Pointed-versus-Pointed Electrode Chambers

The DEP force is usually calculated from the object's point of view using the interaction of the object's induced dipole moment with the inducing field. Recently, we described the DEP behavior of high- and low-conductive 200-µm 2D spheres in a square 1 × 1-mm chamber with a plane-versus-pointed electrode configuration from the system's point of view. Here we extend our previous considerations to the plane-versus-plane and pointed-versus-pointed electrode configurations. The trajectories of the sphere center and the corresponding DEP forces were calculated from the gradient of the system's overall energy dissipation for given starting points. The dissipation's dependence on the sphere's position in the chamber is described by the numerical "conductance field", which is the DC equivalent of the capacitive charge-work field. While the plane-versus-plane electrode configuration is field-gradient free without an object, the presence of the highly or low-conductive spheres generates structures in the conductance fields, which result in very similar DEP trajectories. For both electrode configurations, the model describes trajectories with multiple endpoints, watersheds, and saddle points, very high attractive and repulsive forces in front of pointed electrodes, and the effect of mirror charges. Because the model accounts for inhomogeneous objectpolarization by inhomogeneous external fields, the approach allows the modeling of the complicated interplay of attractive and repulsive forces near electrode surfaces and chamber edges. Non-reversible DEP forces or asymmetric magnitudes for the highly and low-conductive spheres in large areas of the chamber indicate the presence of higher-order moments, mirror charges, etc.

Modeling the durability of diesel pistons with a crack on the edge of the combustion chamber

BACKGROUND: During periodic long-term tests of tractor diesel engines D-240T with a combustion chamber of the CNIDI after 4000 m-hour, a deterioration in the indicators of the working process was observed. After disassembling the diesels, it turned out that the reason for this is the development of cracks on the edge of the combustion chamber (CC), and the deterioration of indicators is detected when the crack has reached a critical length.
 AIMS: The aim of study is concerned investigation of a methodology for predicting of a tractor diesel piston durability with the crack on the CC edge and development of a method for calculating the crack evolution to before the transition to the improper state.
 METHODS: Both experimental and computational methods were used in the research. Experimental pistons was manufactured with some design changes: the radius of the edge rounding changed, which changed the thickness of the side wall of the CC.
 RESULTS: Motor studies of diesel engines have shown that with a certain piston design, a crack either does not appear at all, or appears after a large number of cycles. Additional computational studies have shown that the crack development depends on the stress intensity coefficient at the crack tip. Using the data of experimental studies, a method has been developed for estimating the critical crack length in the edge of the CC, at which the intensity of stresses in the vicinity of its vertex exceeds the limits accepted for this material from which the piston is made.
 CONCLUSIONS: A method for calculating the durability of the piston during the development of a crack on the edge of the combustion chamber is proposed. Verification of the calculated data obtained during the numerical implementation of the piston evaluation method using the example of the diesel piston D-240 showed that for a range of crack lengths up to 1 mm and operating time over 7000 m-hour, the calculation error com-pared to the operational test data does not exceed 11%.

Processing of experimental data describing internal deflagration explosions

This article is devoted to issues related to experimental studies of internal deflagration explosions or emergency explosions occurring inside buildings and premises. In internal emergency explosions, the main role in reducing the explosive pressure to a safe level is played by discharge openings blocked by safety structures (SS). As discharge openings, windows are often used, covered with glazed window blocks, or opened explosion venting structures (EVS). The article deals with processing experimental data obtained in the study of deflagration explosions occurring inside buildings and premises. The main features and difficulties that arise while analyzing experimental materials are described. The article considers the general methodology for processing experimental data to study deflagration explosions inside buildings and premises. Examples of processing materials from experiments performed in chambers equipped with a transparent edge allow high-speed filming of the explosive combustion process inside the chamber. The article presents a technique that allows, based on data processing on the overpressure in the explosion chamber, to obtain complete characteristics of the loads that occur in the experimental chamber during an internal deflagration explosion. The proposed technique makes it possible to abandon the transparent edge of the explosion chamber and obtain data on the explosion process based on the numerical processing of the excess pressure created in the explosion chamber. An example of processing a full-scale experiment to determine the effectiveness of a real explosion venting structure (EVS) is given.

Experimental assessment of the temperature state of tractor diesel pistons

INTRODUCTION: The paper presents the operating conditions of tractor diesel engines that cause the appearance of thermal fatigue cracks on the edges of the piston combustion chamber. The presence of sharp edges of the combustion chamber in the pistons, which are stress concentrators, leads to an increase in the probability of their destruction and thereby limits the engine life of the diesel engine. The main reasons for the formation of cracks in the zone of the edge of the combustion chamber are indicated.
 AIMS: The aim of this study is the assessment of the temperature state of pistons of the D-240 and the D-245 tractor diesel engines, produced by Minsk Motor Plant (MMP).
 METHODS: Temperature gauging was carried out according to the method in order to identify the nature of changing of piston heads temperatures under stationary and nonstationary operation modes of diesel engines. Transfering of thermal electromotive force from thermocouples to measuring devices was carried out by means of an intermittent current collector. Imitaion of nonstationary operation modes was carried out by means of changing the cyclic feed of a high pressure fuel pump, using a reversible electric motor.
 RESULTS: The data of the temperature state of pistons under various stationary and nonstationary operation modes of engines is provided. It is noted that the temperature state of the D-245 diesel pistons has a higher level of heat stress compared to the D-240 diesel pistons. The maximum amplitude of low-frequency temperature fluctuations at the edge of the combustion chamber and their radial differences along the piston bottom are determined, depending on the parameters of thermal loading cycles. It is noted that the most dangerous modes of diesel operation, in terms of the destruction of the edge of the combustion chamber, are sharply changing modes (eg.: theloading unloading mode).
 CONCLUSIONS: It is proposed to increase the fuel injection advance angle in the thermal loading cycle in order to conduct accelerated comparative tests of piston variants for thermal resistance. The developed thermal loading cycle, in which the total duration of the load increase is 180 s and the total duration of the load decrease is 90 s, can be recommended for accelerated motor tests of pistons for thermal cycling resistance. The obtained temperature measurement data is recommended to clarify boundary conditions of the first kind when calculating the piston using the FEM method.

Optimization of the combustion chamber strength of aluminum pistons in diesel engines using the DuralBowl technology

The article focuses on the problem of loading the combustion chamber of diesel engine pistons together with the method of its optimization using the DuralBowl technology. Along with the growing requirements of exhaust emission standards, the increasing competition in the efficiency of internal combustion engines, the load on the combustion pistons increases due to the increase in pressure and temperature of fuel combustion and the tendency to slim the structure. Numerical analyzes and analyzes of damaged pistons in diesel engines have shown that one of the places most exposed to piston damage are the combustion chambers. There is a concentration of thermomechanical stress at the edge of the combustion chamber, which may lead to the destruction of the piston and the necessity to carry out overhaul of the drive unit. One of the technologies that optimizes the strength of this zone is the DuralBowl local remelting process. This process allows for several timesimprovement in the fatigue strength of pistons in internal combustion engines. The article analyzes the thermomechanical load on the combustion chamber along with the impact of this load on the durability of pistons in diesel engines. An analysis of the DuralBowl process was also performed, aimed at eliminating the negative effects of loading the combustion chamber, extending the piston life. The analysis focused on the microstructure of the material before and after the DuralBowl process.

Mixing performance of the induced charge electro-osmosis micromixer with conductive chamber edges for viscoelastic fluid

Enhancing the micro-channel flow mixing is always a difficult problem. In this study, a micromixer based on induced charge electro-osmosis is proposed. A T-shaped micromixer, which has a chamber with conductive surfaces in the channel, is chosen. Due to the electro-osmotic effect of the induced charge, the induced potential is generated on the conductive surface. The Oldroyd-B constitutive model is chosen to characterize the flow characteristics of polyacrylamide solution, and an open-source solver named rheoTool based on the finite-volume method is used. The effect of the chamber shape, the chamber size, the conductive edge numbers in the chamber, and the applied electric intensity on the mixing efficiency are investigated. The results show that the micromixer with conductive edges in the chamber has better mixing effect because of the vortices. At the same time, compared with other shapes, the micromixer with diamond chamber has the best mixing effect, and the mixing efficiency reaches 79.51%. In addition, the mixing efficiency of one conductive edge in the diamond chamber is 4.39% higher than that of the two conductive edges chamber. It is found that increasing the chamber size will improve the mixing efficiency, and the mixing efficiency increased by 12.76% with the increase in chamber size. On the other hand, when increasing the electric field intensity from 100 to 200 V/cm, the mixing efficiency will decrease.

Experiments on Water Gravity Drainage Driven by Steam Injection into Elliptical Steam Chambers

Based on a recently published theoretical model, in this work we experimentally studied the problem of gravity water drainage due to continuous steam injection into an elliptical porous chamber made of glass beads and embedded in a metallic, quasi-2D, massive cold slab. This configuration mimics the process of steam condensation for a given time period during the growth stage of the steam-assisted gravity drainage (SAGD) process, a method used in the recovery of heavy and extra-heavy oil from homogeneous reservoirs. Our experiments validate the prediction of the theoretical model regarding the existence of an optimal injected steam mass flow rate per unit length, ϕopt, to achieve the maximum recovery of a condensate (water). We found that the recovery factor is close to 85% when measured as the percentage of the mass of water recovered with respect to the injected mass. Our results can be extended to actual oil-saturated reservoirs because the model involves the formation of a film of condensates close to the chamber edge that allows for gravity drainage of a water/oil emulsion into the recovery well.

Rich solvent - Steam assisted gravity drainage (RS-SAGD): An option for clean oil sands recovery processes

The impact of steam generation on Steam-Assisted Gravity Drainage (SAGD) process economics and environmental impacts have led to various modifications of SAGD including solvent co-injection with steam. One example is the Expanding Solvent Steam-Assisted Gravity Drainage (ES-SAGD) process where 1–5 vol% solvent is injected with the steam into the reservoir. The solvent travels with the steam to the edge of depletion chamber dissolving into the oil thereby mobilizing the oil more than would have been achieved with heating alone. This means lower steam-to-oil ratio and thus, greater thermal efficiency, lower emissions intensity, and water consumption intensity. However, processes where the majority of the fluid injected is steam are still overly emissive and expensive to operate. There is a need to develop carbon-neutral bitumen production processes. Rich Solvent-SAGD (RS-SAGD) aims at injecting mostly solvent into the reservoir with small amounts of steam to achieve radically lower emissions and water consumption intensities than that of SAGD. Here, a RS-SAGD process is investigated where the solvent content is >60 vol% by using detailed thermal-solvent reservoir simulation in an Athabasca oil sands reservoir. The results reveal that RS-SAGD yields higher oil rate than that of SAGD and the process has significantly higher energy efficiency, up to 96% lower emissions and water consumption intensities than that of SAGD. Given the performance of RS-SAGD processes, oil sands operators should consider such processes for future operations.

Numerical Modeling of the Steam Chamber Ramp-Up Phase in Steam-Assisted Gravity Drainage

Due to the critical nature of the ramp-up phase of an efficient steam-assisted gravity drainage (SAGD) process, it is important to understand the physics of the steam chamber ramp-up phase in order to improve SAGD production performance. In conventional numerical simulation models, the dynamics of the steam chamber ramp-up phase are not fully resolved because of unclear steam–oil–water interactions during the vertical growth of the steam chamber and how its state changes as the reservoir parameters vary. This work provides an efficient approach for the numerical modeling of the steam chamber ramp-up phase in an SAGD operation. The steam chamber ramp-up phase was fully examined through the consideration of the effects of the temperature-dependent oil–water–gas multiphase flow system and the vertical countercurrent flow. The simulation results revealed that for the large temperature gradient of the mobile oil zone at the edge of the steam chamber, a delicate temperature-dependent multiphase flow system was essential for the reliable estimation of the SAGD ramp-up phase. The vertical countercurrent flows of oil–gas and oil–condensate were the dominant mechanisms over cocurrent flow, which significantly impacted the steam chamber ramp-up rate. The numerical model physically predicted the steam chamber ramp-up phase and could be used to efficiently compute a field-scale simulation using a dynamic gridding function that was based on a fine grid model.