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In order to analyse the effect of the injection point size of the CBM (Coalbed Methane) well level monitor on the amplitude and frequency of pressure pulsations in the wellhead manifold, numerical simulations and experiments were carried out to investigate the effect of different injection point sizes on the amplitude and frequency of pressure pulsations downstream of the sudden expansion structure. Using compressed air as the fluid and the size of the injection point as the variable, the amplitude and frequency of pressure pulsations at different locations downstream of the sudden expansion structure were tested. The results show that the pressure pulsation amplitude is affected by the size of the injection point, and the larger the injection point is, the larger the pressure pulsation amplitude is; the size of the injection point has less influence on the pressure pulsation frequency downstream of the protruding and expanding structure, and the pressure pulsation frequency at 0.5 m and 1 m downstream of the protruding and expanding structure is in the vicinity of 76 Hz. Therefore, the echo signal processing should be filtered around this frequency to obtain accurate liquid level echo signals, so as to improve the accuracy of liquid level monitoring and realise the efficient development of coalbed methane wells. [ABSTRACT FROM AUTHOR]

The Triassic massive sandstone reservoir in the Tahe oilfield has a strong bottom-water drive and is characterized by great burial depth, high temperature and salinity, a thin pay zone, and strong heterogeneity. At present, the water-cut is high in each block within the reservoir; some wells are at an ultrahigh water-cut stage. A lack of effective measures to control water-cut rise and stabilize oil production have necessitated the application of enhanced oil recovery (EOR) technology. This paper investigates the development and technological advances for oil reservoirs with strong edge/bottom-water drive globally, and compares their application to reservoirs with characteristics similar to the Tahe oilfield. Among the technological advances, gas injection from the top and along the direction of structural dip has been used to optimize the flow field in a typical bottom-water drive reservoir. Bottom-water coning is restrained by gas injection-assisted water control. In addition, increasing the lateral driving pressure differential improves the plane sweep efficiency which enhances oil recovery in turn. Gas injection technology in combination with technological measures like channeling prevention and blocking, and water plugging and profile control, can achieve better results in reservoir development. Gas flooding tests in the Tahe oilfield are of great significance to identifying which EOR technology is the most effective and has the potential of large-scale application for improving development of deep reservoirs with a strong bottomwater drive. [ABSTRACT FROM AUTHOR]

The injected fluid can chemically react with reservoir rocks and fluids, which changes the properties of petroleum and rocks. Consequently, oil recovery rates are subject to change during the EOR process. Therefore, the study of chemical reactions during EOR process is important. During the CO2 injection, the deposition of asphaltene, and the change of minerals, dissolution and deposition can occur at the same time. Dissolution of rock minerals can increase permeability and effective porosity, but precipitation of asphalt and deposition of these minerals can have the opposite effect. This study investigates the CO2 flooding process in heavy oil reservoirs containing highly permeable sandstone and assesses the effect of orientation on oil recovery and rock-fluid interactions. The results show that due to the gravitational stability in the vertical configuration, there is more oil recovery, mineral solution, and asphaltene sedimentation in the vertical configuration compared to the horizontal configuration. The percentage of asphaltene in the sandpacket model was 1.92 weight percent vertically and 1.18 weight percent horizontally. The increase in porosity for vertical was 2.6% and 1.1% for horizontal infusion. From this it can be concluded that the dissolution of minerals is higher with vertical injection than with horizontal injection. [ABSTRACT FROM AUTHOR]

This study is in line with two previous studies by the same authors on gas injection in yield stress fluids. Gas is injected toward the bottom wall of a prismatic tank containing a yield stress fluid. When rising toward the free surface, trains of bubbles generate fluid recirculation in the tank. Two experimental colorimetric methods are introduced and validated in order to quantify the recirculation liquid flow rate as well as the time evolution of the extent and shape of the mixed volume. The influences of the injection flow rate, fluid rheology, and reactor size have been quantified. Correlations based on the characteristic nondimensional numbers of the flow have been developed to predict the downward liquid flow rate as well as the mixed volume. A model for estimating the mixing time is also developed and compared to experimental results. [ABSTRACT FROM AUTHOR]

We investigate unsteady, two-dimensional laminar fluid flow around cylinders, focusing on understanding the impact of injecting methane gas through two diametrically opposite arcs on the cylinder in the crossflow of the second fluid. This study encompasses applications in mixing and dispersion, which are crucial in various technological and natural processes. Our analysis addresses velocity field's contribution to the spatiotemporal distribution of transported quantities. We observed that mixing induces a transition from laminar to turbulent flow. Depending on the injected-to-crossflow velocity ratios, the wake vortices downstream of cylinder arrays separate from or connect to the injected gas. This phenomenon significantly impacts mixing efficiency caused by asymmetric vortical flow structures and their interactions. In this study, the effective Reynolds number was computed at the outlet to account for the increase of momentum due to the gas injection, and it showed a monotonic rise with increasing injected gas velocity. Particularly, we observed a linear increase in the effective Reynolds number with increasing ϵ (velocity ratio parameter) for the single cylinder case, however, it exhibits a non-linear behavior for the multiple cylinders case due to complex flow interactions and enhanced mixing. We further analyzed flow disturbance using a participation number, a statistical characterization of the system's spatial distribution of kinetic energy. Surprisingly, the participation number decreases with the increase in ϵ. This decrease indicates a highly localized and inhomogeneous distribution of kinetic energy in the system, increased tortuosity, and possibly the first sign of the inertial to turbulent transition in the system. • Enhance mixing and asymmetry of the flow for gas injection case. • Linear growth and non linear growth of the R e e f f with the intensity of the gas injection. • Non symmetric pressure distribution on obstacle-s arcs for the fluid flow with injections. • Decreasing behavior of the energy localization for high R e case. [ABSTRACT FROM AUTHOR]

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of offshore heavy oil is sensitive and complex, which is limited by factors such as platform space, economy, pollution and security, so conventional thermal recovery techniques such as cyclic steam stimulation and steam flooding have difficulty in achieving favorable development effect for offshore heavy oil reservoirs. Horizontal-well multi-thermal fluid stimulation (HW-MTFS) process is a relatively new thermal recovery technique, which combines the multiple advantages of gas injection, horizontal well and thermal recovery process. In this paper, the HW-MTFS physical model was firstly designed. Thereafter, the influences of different factors on steam absorption along horizontal wellbore were studied by sand-packed model experiments. Finally, the development performance of horizontal-well cyclic steam stimulation (HW-CSS) process and horizontal-well multi-thermal fluid stimulation process was compared by two groups of physical experiments. The results indicate that different injection factors significantly influenced the steam absorption along horizontal wellbore. Compared with steam injection, the multi-thermal fluid injection could effectively improve the steam absorption along horizontal wellbore. The HW-MTFS process had a higher oil rate and production, and the recovery of HW-MTFS process was 42% higher than that of HW-CSS in three cycles. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the main problems that affects Ruhrstahl-Heraeus (RH) degasser circulation rate is the obstruction of the gas-injection nozzles. This study aims to elucidate the effects of obstructions in quantity and location using a physical model that depicts 16 injection nozzles on the up-leg distributed symmetrically in 2 rings (8 nozzles/ring). We simulated six, symmetric and nonsymmetric, obstruction conditions to gas flow. The gas-flow rate was varied from 30 to 130 NL/min. The results for symmetric obstructions when the gas-flow rate is kept constant, indicates that the circulation rate in the equipment does not significantly change. However, when these obstructions are non-symmetric, the circulation rate varies drastically, even when the gas-flow rate is kept constant. The analysis of the experimental data generated from this study allowed to determine an equation for the circulation rate that takes into consideration the number and distribution of blocked nozzles. [ABSTRACT FROM AUTHOR]

An experimental study on the multiphase flow of heavy oil gas lift was conducted on 18.25 m high vertical tube. Based on the experimental results and the wellbore heat transfer mechanism, a coupling model of wellbore pressure-temperature gradients was presented for the gas lift with light oil injected from the annulus. Moreover, the solution of coupling annulus flow with tubing flow was also established through cyclic iteration. Experimental results showed that gas injection enables heavy oil and light oil to mix rapidly and completely. Evaluation of pressure drop models shows that the error of the Ansari model is approximately 12.12%, by comparison it is the least. A novel method of gas lift assisted with light oil from the annulus was proposed to solve the actual situation wherein heavy oil cannot be easily lifted from the wellbore at Tuyuke Block in Tuha Oilfield. An instance design based on the sensitivity analysis of the gas injection rate and diluting rate was also completed. The instance design shows that the productivity of heavy oil well can be significantly improved using gas lift and blending diluting oil technology. In order to verify the feasibility and effect of gas lift assisted with light oil in heavy oil well, a pilot test was implemented in Tahe Oilfield, Xinjiang, China. The results of pilot test show clearly that the daily production rate increased from 11.6 to 38 t/day, and the ratio of light oil with heavy oil decreased from 11:1 to 4:1. From the above, gas injection can significantly reduce the usage of light oil needed, and gas lift assisted with light oil injected from the bottom hole can significantly enhance the productivity of heavy oil wells. [ABSTRACT FROM AUTHOR]

Ar-circulated hydrogen engine replaces atmospheric nitrogen with Ar so as to increase engine efficiency and avoid NOx forming. Due to the differences in gas molecular weight of injection gas and ambient gas, two injection strategies were proposed for this engine. This study aims at measuring the characteristics of non-reactive H 2 and O 2 jets in Ar atmosphere by Schlieren method. The experimental results demonstrate that the increase of injection pressure or the decrease of ambient pressure leads to an increase of penetration. Jet penetration length of O 2 is slightly lower than H 2 by 0–6%. The dispersion angle of gas jet increases slightly with the increase of injection pressure and ambient pressure. Under all the experimental pressure boundary conditions, the dispersion angles of H 2 jets are between 31° and 36° and the dispersion angles of O 2 jets are between 22° and 28°. The entrainment rate of gas jet increases with the increase of injection pressure, ambient pressure and injection time. Jet entrainment rate of O 2 is 2.43–2.98 times that of H 2 jet because of the lower volume flow rate of O 2 jet. H 2 jet entrains more total argon volume for its higher penetration and dispersion angle. The actual engine prefers to use the hydrogen injection strategy. [ABSTRACT FROM AUTHOR]

Miscible gas injection is one of the most effective enhanced oil recovery techniques. There are several challenges in accurately modeling this process, which occurs in the near-miscible region. The adjustment of relative permeability for near-miscible processes is the main focus of this work. The dependence of relative permeability on phase identification can lead to significant complications while simulating near-miscible displacements. We present an analysis of how existing methods incorporate compositional dependence in relative permeability functions. The sensitivity of the different methods to the choice of reference points is presented with guidelines to limit the modification of the relative permeabilities to physically reasonable values. We distinguish between the two objectives of reflecting near-miscible behavior and ensuring smooth transitions across phase changes. We highlight an important link that combines the two objectives in a more general framework. We make use of Gibbs free energy as a compositional indicator in the generalized framework. The new approach was implemented in an automatic differentiation general purpose research simulator and tested on a set of near-miscible gas-injection problems. We show that including compositional dependencies in the relative permeability near the critical point impacts the simulation results with significant improvements in nonlinear convergence. [ABSTRACT FROM AUTHOR]

As engine stability is a crucial issue for engine performance and toxic emissions, an experimental research has been conducted to analyze the effects of hydrogen direct injection on engine stability. The experiments have been divided into two parts. The first set is aimed to analyze different parameter characteristics with and without hydrogen direct injection, and the second set tries to find optimal control regions. Excess air ratios, spark timings, engine speeds and engine loads are chosen as primary parameters in the study. The results show hydrogen addition can increase brake thermal efficiency by a range from 6% to 13%, enhancing the lean burn performance. Combustion duration has been shortened to about 80% by adding 10% hydrogen mixture into gasoline. Besides, Hydrogen addition makes the mixture further insensitive to ignition timings, and narrows the optimal regions with higher excess air ratios. Under medium engine speeds, the highest CoV IMEP locates in the low load region for pure gasoline, while this maximum value appears in the medium load region for 10% hydrogen mixture. In addition, the specific value of CoV IMEP with 10% hydrogen is rather small compared to pure gasoline. Thus, hydrogen direct injection can significantly improve engine stability and reduce controlling difficulties. [ABSTRACT FROM AUTHOR]

We present an analytical and experimental study of the formation of bubbles from a submerged vertical needle under mixed injection conditions, where neither the gas flow rate nor the feeding pressure remain constant during the process. In particular, we focus on the temporal evolution of the pressure inside the gas injection chamber during the bubble formation process, p ( t ), modeling it and analyzing the bubble size and shape as functions of the volume of the chamber, V c , and the mean gas flow rate, Q i , for a given needle radius, a . Under this configuration, it has been shown that the water column penetrating inside the injection needle plays an important role on the bubble formation process. Consequently, an analytical model that includes the description of the time evolution of the liquid column penetrating inside the needle after the separation of a bubble, and the subsequent pressurization of the gas chamber, has been proposed. The results given by the model agree well with the experimental measurements. [ABSTRACT FROM AUTHOR]

Minimum miscibility pressure (MMP) is one of the key parameters that affects the microscopic and macroscopic effectiveness (displacement performance) of gas injection for enhanced oil recovery. Numerous research efforts have been made to measure and predict the MMP, including experimental, analytical, numerical, and empirical methodologies. Despite these efforts, a comprehensive, user-friendly, and accurate model does not exist yet. In this study, we introduce “Gene Expression Programming (GEP)” as a novel connectionist tool to determine the MMP parameter. This new model is developed and tested using a large databank available in the literature for the MMP measurements. The accuracy of the proposed model is validated and compared with the outcomes from the commercial simulators. The performance of the proposed model is also examined through a systematic parametric sensitivity analysis where various input variables such as temperature and volatile-to-intermediate ratio are considered. The new GEP model outperforms all the published correlations in term of accuracy and reliability. [ABSTRACT FROM AUTHOR]

• A flow simulation model was created to investigate gas injection of a four-well pad for temporary gas storage and to assess the possibility of incremental oil production. • The effect of the injected gas on adjacent wells is an important consideration regarding regulatory and ownership constraints. The modeling results enable analysis of adjacent wells and the impact to neighboring multi-pads. • Economic evaluation to assess the feasibility of gas re-injection in the Bakken Formation. • A comprehensive study of upstream gas flaring situation in North Dakota, USA. The flaring of associated gas from oil wells and the excess gas from gas-processing units and oil refineries is one of the most prominent producers of greenhouse gas emissions and is an extraordinary waste of economic value given the huge volumes of flared gas. In light of the increasing awareness of its negative impact, the industry is investigating economical means to reduce the anthropogenic release of greenhouse gases into the atmosphere. Oil production from the Bakken and Three Forks formations has significantly increased over the last ten years without commensurate augmentation of gas capture infrastructure, which consequently resulted in increased flaring of the associated gas. The North Dakota Industrial Commission (NDIC) has set rigorous regulations to reduce flaring. However, operating companies are experiencing challenges to meet NDIC gas capturing limit of 95%, which leads to oil production being curtailed. The project's main objectives are to evaluate technically and economically the feasibility of deploying gas re-injection in the Bakken Formation as a means to increase oil recovery, reduce flaring and meet North Dakota Industrial Commission requirements. The techno-economic assessment utilizes reservoir simulation inputs and outputs such as production rate, fluid composition, injection fluid rate and composition, and bottom hole flowing pressure to provide a detailed costs and revenue estimation of injection and production. Different gas injection schemes are investigated, surface equipment and gas injection network are modeled and optimized. It is substantiated that gas re-injection can increase oil recovery by 34%. The results of this effort suggest that gas re-injection to mitigate flaring in the Bakken can be economically achievable. [ABSTRACT FROM AUTHOR]

Enhanced oil recovery methods are the future of maximizing oil recoveries. Any incremental oil recovery can support the world economy by producing more oil at a minimum price. The surfactants are the major constituent of the injection fluids for EOR applications. Addition of foam-generated surfactants in water alternating gas injection is one of the potential solutions for reducing the gas mobility and improving sweep efficiency, but the major challenge of surfactants used with water alternating gas injection is its stability in presence of formation water and crude oil at reservoir conditions. The objective of this study is to investigate the stable surfactant as a foaming agent to improve the efficiency of residual oil and reduce the gas mobility. To achieve this main objective, individual and new surfactant blended formulations were evaluated with injection water and crude oil in the porous media at 96 °C and 1400 psi. Experimental result showed that generated foam in presence of crude oil has reduced gas mobility which provides good indication of CO mobility control and improves sweep efficiency. Oil recovery based on original oil-in-place by surfactant blend of 0.6 wt% AOS + 0.6 wt% TX 100, 0.6 wt% AOS + 0.6 wt% LMDO and individual surfactant of 0.6 wt% AOS were recorded as 91.9, 83.7 and 72.66%, respectively. Foam stability in presence of crude oil, reduction in gas mobility and increase in oil recovery indicated that these surfactant blends are good foaming agents as compared to individual surfactant in enhanced oil recovery applications. [ABSTRACT FROM AUTHOR]

This paper presents a CFD-DEM study of gas-solid flow in the raceway region in an ironmaking blast furnace (BF). In the simulation, 120,000 spherical particles are packed into a full-scale 2D slot BF geometry. Gas is injected into the geometry via tuyeres, generating raceways in different sizes and shapes under different conditions. It is observed that the raceway characteristics are much more complex under the full-scale BF than those observed under the laboratory scale in the literature. Three kinds of raceways can be identified: anti-clockwise circulating raceway, clockwise circulating raceway, and plumelike raceway. The results are analysed in terms of solid flow patterns, and flow and force structures of particles. The simulation has a good agreement with the observed in physical experiments in terms of two contrary circulating gas vortexes located upon and below tuyeres during raceway formation. Moreover, it is also indicated that operational variables have significant effect on one of the gas vortexes, which becomes the main circulating gas flow stream and determines the gas circulating direction. [ABSTRACT FROM AUTHOR]

This paper examines the potential of huff 'n' puff gas-injection method to recover condensate in shale gas-condensate reservoirs by conducting experiments on a shale core. Numerical models were developed to verify experiment results. Our laboratory study shows that condensate recovery was increased to 25% by applying huff 'n' puff gas injection on a shale core. Also, we compared the efficiency of huff 'n' puff gas injection with that of gasflooding. At the end of same flooding with time that is the same as the time for five huff 'n' puff cycles, the condensate recovery is 19%. From the experimental results, we found that huff 'n' puff was more effective than gasflooding. During the experiment, condensate accumulated near the production-end region. In the huff 'n' puff process, because the location for injection in the core was the same as that for production, the pressure in the condensate region built up faster than pressure in the flooding experiment. Also, because of the ultralow permeability, the pressure propagation was much slower in the shale core than in a conventional reservoir core, and the efficiency of gasflooding is much lower than that of the huff 'n' puff. This study indicates that huff 'n' puff has the potential to effectively enhance condensate recovery in shale gas- condensate reservoirs. [ABSTRACT FROM AUTHOR]

Particle size distribution (PSD) is an important factor that determines how asphaltene instability can damage porous media during natural depletion and enhanced oil recovery processes. In this work, aggregate size distribution under natural depletion and miscible nitrogen injection processes are determined via image analysis techniques and the results are modelled by population balance equation. Unimodal distribution curves in natural depletion show the dominance of particle-particle aggregation mechanism and the clustering is detected only around crude oil bubble point pressure. It is also observed that miscible nitrogen injection considerably increases the number and size of asphaltene flocs and directs the agglomeration process towards cluster-cluster aggregation (i.e. bimodal distribution curves) which can severely damage porous media. Results of population balance modeling characterize dominant aggregation mechanisms providing one optimum collision factor for unimodal curves and two optimum collision factors for bimodal distributions which confirms the alteration of aggregation mechanism due to miscible gas injection. [ABSTRACT FROM AUTHOR]

The injected fluids in secondary processes supplement the natural energy present in the reservoir to displace oil. The recovery efficiency mainly depends on the mechanism of pressure maintenance. However, the injected fluids in tertiary or enhanced oil recovery (EOR) processes interact with the reservoir rock/oil system. Thus, EOR techniques are receiving substantial attention worldwide as the available oil resources are declining. However, some challenges, such as low sweep efficiency, high costs and potential formation damage, still hinder the further application of these EOR technologies. Current studies on nanoparticles are seen as potential solutions to most of the challenges associated with these traditional EOR techniques. This paper provides an overview of the latest studies about the use of nanoparticles to enhance oil recovery and paves the way for researchers who are interested in the integration of these progresses. The first part of this paper addresses studies about the major EOR mechanisms of nanoparticles used in the forms of nanofluids, nanoemulsions and nanocatalysts, including disjoining pressure, viscosity increase of injection fluids, preventing asphaltene precipitation, wettability alteration and interfacial tension reduction. This part is followed by a review of the most important research regarding various novel nano-assisted EOR methods where nanoparticles are used to target various existing thermal, chemical and gas methods. Finally, this review identifies the challenges and opportunities for future study regarding application of nanoparticles in EOR processes. [ABSTRACT FROM AUTHOR]

In the present study a mathematical model is developed to examine the effect of dual gas injection system on the distribution of process variables and energy consumption in the Midrex shaft furnace. The developed model was constructed by considering the major chemical reactions and physical structures within the furnace and describes a counter-current moving bed reactor in which hematite pellets are reduced to sponge iron by pure hydrogen gas. Governing equations containing overall continuity, momentum, energy and mass equations are developed for both gas and solid phases in cylindrical coordinate system. Unreacted shrinking core model is implemented to simulate gas–solid reactions in the reactor. The complicated equations are solved by applying finite volume technique. The model is applied to simulate multiphase flow inside the reactor when it is equipped with one and two hydrogen gas intake ports to examine the impact of gas injection arrangement on the process variables. The radial and axial distributions of operational parameters including gas and solid temperature, fractional reduction of iron oxides and hydrogen and water vapor concentration are obtained for both cases. The results indicate that reduction degree and energy consumption are improved by utilizing dual gas injection system. [ABSTRACT FROM AUTHOR]

When the energy of confined runaway electrons approaches several tens of MeV, the runaway electrons can emit synchrotron radiation in the range of infrared wavelength. An infrared camera working in the wavelength of 3-5 μm has been developed to study the runaway electrons in the Joint Texas Experimental Tokamak (J-TEXT). The camera is located in the equatorial plane looking tangentially into the direction of electron approach. The runaway electron beam inside the plasma has been observed at the flattop phase. With a fast acquisition of the camera, the behavior of runaway electron beam has been observed directly during the runaway current plateau following the massive gas injection triggered disruptions. [ABSTRACT FROM AUTHOR]