High-pressure Gas Injection Research Articles

Study on the Oxygen Content of Oxygen-Reducing Air Flooding Based on Anticorrosion Considerations

Abstract Oxygen-reduced air flooding (ORAF) is an important efficient development means for tight and low permeability reservoirs because of its low cost, low risk, and ability to penetrate into voids and substrates. However, the critical value of oxygen-reduced, which can take into account the cost and corrosion protection requirements, is uncertain. Therefore, the corrosion behavior of N80, J55, and 3Cr steels under simulated high pressure (30 MPa) gas injection with different oxygen content (1%–12% vol.) was studied by weight loss method and Ultra-Depth Three-Dimensional Microscope. Under this oxygen content, the corrosion behavior of N80, J55, and 3Cr steels under different total pressure (20–35 MPa), temperature (25℃–70℃), and coexistence of gas and water was further studied. The results show that under the condition of high temperature and high-pressure drying, when the oxygen content in the oxygen-reduced air is reduced to 5%, all three kinds of steels belong to slight corrosion (<0.025 mm/a), and the oxygen-reduced cost can still be kept at a low level. In addition, under the condition of 5% oxygen content, when the corrosion medium of the wellbore is only deoxidized gas, the corrosion is slight, so N80 steel at a lower cost can be used. However, when the wellbore contains liquid, the corrosion is serious, and anticorrosion measures need to be taken. This study can provide certain data support for the selection of oxygen content and the corrosion protection of gas-injection wells shaft in the process of high-pressure gas injection by ORAF.

Experimental Investigation to Assess the Performance Characteristics of a Marine Two-Stroke Dual Fuel Engine under Diesel and Natural Gas Mode

With the aim of CO2 emissions reduction in the maritime sector, dual fuel engines operating on natural gas are the most prominent technical and commercially available solution. A promising variant is the two-stroke high-pressure natural gas injection engine, utilizing diesel pilot fuel injection for ignition of the gaseous fuel while being able to operate in diesel-only mode. In this study, a comparative analysis of the performance and the combustion mechanism of dual fuel and diesel mode for this engine type is conducted using experimental data. Studies based on measurements conducted on actual scale are limited in the literature due to the engines’ sheer size not allowing lab testing. The analysis was conducted using measurements acquired during the factory acceptance tests involving conventional operating data and cylinder pressure data acquired using a piezoelectric sensor. In terms of the mean pressure and temperature, only minor differences were found. The specific fuel consumption was improved under low load operation for the dual fuel mode by 1.8%, while a small increase of 1.2% was found near full load. Differences were found in the combustion process from 25 to 75% load with considerably faster premixed and diffusion combustion for the dual fuel mode leading to a 6–8% decrease in combustion duration. Despite the combustion process differences, the performance under dual fuel operation was overall close to that of conventional diesel with an acceptable 1.5% efficiency reduction on average. This confirms that modern dual fuel marine engines can achieve the performance standards of conventional ones while benefiting from low-carbon fuel use to reduce CO2 emissions.

Supervision and Control System of the Operational Variables of a Cluster in a High-Pressure Gas Injection Plant

The objective of this research was to develop a technological architecture proposal that allows for the supervision and control of the operational parameters of gas injection (flow, temperature, and pressure) in a cluster of a high-pressure gas injection plant. The proposal provides a supervision and control system for the HPGIP I high-pressure gas injection plant that includes instrumentation equipment (transmitters and actuators), a remote terminal unit (RTU) as a control device, and the creation of a control logic as the basis for the development of the SCADA GALBA®, through which the operational variables involved in the process of the gas injection plant can be visualized and controlled, allowing the automatic regulation of the flow of gas that enters the deposits. Automatization of the process allows for the elimination of the average error differential that increases from 2 to 5% when the control valve is opened manually. Currently, the MUC-67 and MUC-68 wells that make up cluster 5 require a control valve opening of 20% and 5%, respectively, and this percentage is directly affected by the average valve opening error when performed manually. In addition, there is a savings of around 40 min in the response time by the operators for the adjustment of the opening or closing parameters of the control valve manually. The proposal allows for the different control actions on the variables or parameters of gas injection present in the clump to be carried out from a control room.

Design and Performance Research of Single Rubber Cylinder for High Pressure Gas Injection Packer

In order to solve the problem of "gas explosion" at the end of common rubber cylinder in the process of high temperature, high pressure and gas drive operation, the rubber cylinder with new structure suitable for 51/2in casing pipe is developed. The "M" type single rubber cylinder structure is adopted in the new structure rubber cylinder, and the "gas explosion" problem of the end gas in the low-pressure side is solved by setting the double-layer staggered slotted steel cover to prevent outburst. The finite element method is used to simulate the setting of the rubber cylinder, and the structural parameters of the new rubber cylinder are obtained by single factor analysis and orthogonal optimization, simulation test and seal test were carried out to verify the sealing performance of the rubber cylinder. According to the actual working condition, the simulation test results and seal test results show that the sealing capacity of the packer reaches 50MPa under the temperature resistance of 120℃, and the end steel cover is fully opened to wrap the rubber cylinder, which meets the operation requirements of high temperature and high pressure gas injection packer.

Study on the ignitability of a high-pressure direct-injected methane jet using a scavenged pre-chamber under a wide range of conditions

Natural gas is a promising alternative fuel for internal combustion engines, it allows for a reduction of engine-out emissions without impairing high engine efficiencies. Although this approach is already utilized from small to large engine classes, it is almost exclusively based on the combustion of a premixed homogeneous charge. For ignition, small engines use standard spark plugs or pre-chambers, while large and lean-operated engines use pre-chambers and pilot injections. Direct high-pressure gas injection is a more recent, alternative way to operate gas engines which offers benefits compared to premixed operation such as high combustion pressures, leaner operation, easier quantity regulation, and higher compression ratios, among others. However, in contrast to diesel injection, the compression temperatures are too low for the auto-ignition of the gas jets. Therefore, an additional ignition system is required, usually a pilot injection system is used. In this study, the usability and performance of a scavenged pre-chamber used for the ignition a high-pressure gas jet has been investigated in an optically accessible test-rig that is able to operate at engine-like conditions. Results show that the turbulent hot jet generated by the pre-chamber was able to ignite the high-pressure gas jet under a wide range of operating conditions. Moreover, it also appears to be a promising ignition strategy for very early direct injection during the compression stroke as well as for port injection. The good performance is attributed to the intense mixing of the main gas jet with the hot jet exiting the pre-chamber.

An Environment-Friendly Rock Excavation Method

Blasting is used as an economical tool for rock excavation in mines. However, part of the explosive energy is converted into elastic waves, resulting in ground vibration and excessive vibration, which may cause damage to nearby buildings. Meanwhile, toxic gases are also produced during the explosion. In this paper, an environment-friendly method for rock excavation is proposed. A series of vibration tests were conducted, and the peak particle velocity was monitored. The results showed that the proposed method can replace the conventional blasting method in mines. Besides that, the vibration caused by the proposed method is much smaller than by the conventional method. By adjusting the direction of the high-pressure gas injection, buildings around the mine can be protected well from vibration. Also, the production of toxic gases during excavation will no longer be a problem. Thus, a milder environmental impact can be achieved. However, the rocks excavated by the proposed method are relatively large, which still need to be broken further. On this issue, further study is required.

Impact research of CH4 replacement with CO2 in hydrous coal under high pressure injection

Purpose. Based on high-pressure gas injection technology that enhances coal seam gas drainage, the effect of CH4 replacement with CO2 in aquiferous coal has been studied. Methods. Using the laboratory experimental method and the self-built high-pressure gas injection experimental device, high-pressure CO2 is injected into coal with different moisture contents to replace CH4 under different adsorption equilibrium pressures. Findings. With an increase in coal moisture content, the adsorption capacity of coal for CH4 and CO2 gradually weakens, the adsorption capacity for CO2 is always greater than that of CH4, and the CH4 replacement rate and the CO2 injection ratio gradually decrease. It is concluded that the CH4 replacement rate and the CO2 injection ratio are negatively correlated with the water content of coal. With an increase of the pre-adsorption equilibrium CH4 pressure (0.5, 0.75, 1.0, 1.3 and 2.0 MPa), the CH4 replacement rate and the CO2 injection ratio first sharply and then slowly increase. The transition point is 1.3 MPa (pre-adsorption equilibrium pressure of CH4). Originality. Based on the adsorption characteristics of coal seam gas injection, the influence of coal water content and gas injection pressure on CH4 replacement rate and CO2 injection ratio is analyzed, and the mechanism is studied. Practical implications. The experimental results have important guiding significance for selecting reasonable gas injection pressure and the source of gas to drive its injection into underground coal seam.

A measurement method for the dual fuel coupling injection characteristics of the high-pressure natural gas and diesel co-direct injection engine

This paper presents an innovative measurement method for a two-phase fuel transient flow rate in the same space–time dimension. Based on the jet momentum measurement, a spray filter is designed to realize the space extraction of the target jet. The optimized jet baffle structure is proposed, which greatly improves the quality of the test signal. Compared with the pressure–time method, this method has higher precision in the gas injection rate shape measurement and the recognition precision of gas injection beginning and ending moment. The coupling effect of two-phase fuel injection and the influence of different ambient pressures on injection performance can be studied by this method. The results show that the pilot diesel injection will cause more than 20% fluctuation of gas injection mass, and the ambient pressure can promote the gas needle opening, which will significantly affect the fuel injection mass of the engine.

Analysis of the effectiveness of the technological system for the development of the XXIII layer of the Goyt-court

The analysis, development of the XXIII reservoir of the Goyt-Kort field, the choice of the field as a priority object for high-pressure gas injection to enhance oil recovery is well substantiated by the geological and production characteristics of the reservoir, technological features of the developed process and economic needs. The relevance of additional development, restoration and arrangement of the field, study of the current state of the reservoir, conducting research of wells, designing technology and techniques for the process of stimulating the reservoir. The reservoir of the XXIII layer of the Goyt-Kort field is characterized by low permeability, significant heterogeneity and clay content. The process of displacement by water in such conditions is very difficult, and therefore attempts to master the injection of water into the XXIII reservoir were unsuccessful. The active mode of injection of compressed hydrocarbon gas into the reservoir has been carried out for more than twelve years and during this time about one and a half billion cubic meters of gas have been injected into the reservoir. The main oil production at the field is currently carried out from the XXIII layer. The field tested and implemented the technology of continuous injection of the inhibitor into the annulus of the well. To remove the clay bridging agent of the pore matrix of high-temperature terrigenous objects, the use of reagents based on boronfluorinehydrogen acid is recommended.

The Effect of High Protein Powder Structure on Hydration, Glass Transition, Water Sorption, and Thermomechanical Properties.

Poor solubility of high protein milk powders can be an issue during the production of nutritional formulations, as well as for end-users. One possible way to improve powder solubility is through the creation of vacuoles and pores in the particle structure using high pressure gas injection during spray drying. The aim of this study was to determine whether changes in particle morphology effect physical properties, such as hydration, water sorption, structural strength, glass transition temperature, and α-relaxation temperatures. Four milk protein concentrate powders (MPC, 80%, w/w, protein) were produced, i.e., regular (R) and agglomerated (A) without nitrogen injection and regular (RN) and agglomerated (AN) with nitrogen injection. Electron microscopy confirmed that nitrogen injection increased powder particles’ sphericity and created fractured structures with pores in both regular and agglomerated systems. Environmental scanning electron microscopy (ESEM) showed that nitrogen injection enhanced the moisture uptake and solubility properties of RN and AN as compared with non-nitrogen-injected powders (R and A). In particular, at the final swelling at over 100% relative humidity (RH), R, A, AN, and RN powders showed an increase in particle size of 25, 20, 40, and 97% respectively. The injection of nitrogen gas (NI) did not influence calorimetric glass transition temperature (Tg), which could be expected as there was no change to the powder composition, however, the agglomeration of powders did effect Tg. Interestingly, the creation of porous powder particles by NI did alter the α-relaxation temperatures (up to ~16 °C difference between R and AN powders at 44% RH) and the structural strength (up to ~11 °C difference between R and AN powders at 44% RH). The results of this study provide an in-depth understanding of the changes in the morphology and physical-mechanical properties of nitrogen gas-injected MPC powders.

Experimental study on the two-phase fuel transient injection characteristics of the high-pressure natural gas and diesel co-direct injection engine

In this paper, an innovative fuel injection rate measurement methodology for the natural gas and diesel co-direct injection injector was designed to study the dual-fuel injection characteristics for a high-pressure natural gas direct injection engine. The results indicate that the injection mass shows two different upward trends as the energizing time (ET) increases, and it appears more sensitive to the length of ET when it is short. The gas injection duration is affected by both the injection pressure and ambient pressure under the same ET, thus any increase in either will significantly increase the injection duration, resulting in a pronounced increase in gas injection mass. The process of diesel pilot injection has a remarkable effect on the gas injection rate. According to the actual engine working condition, provided that the pilot diesel ET is 0.8 ms, the gas injection mass reaches the minimum value when the split time is about 0.8 ms, meanwhile, it reaches the maximum value when the split time is about 0.2 ms or 2 ms. The results of this study can provide an accurate database for the performance of the injector and accurate fuel injection boundary conditions for the combustion process in the engine cylinder.

Study on the ignitability of a high-pressure direct-injected methane jet using a diesel pilot, a glow-plug, and a pre-chamber

Natural gas is a promising alternative fuel for internal combustion engines, it allows for a reduction of engine-out emissions without impairing high engine efficiencies. Although this approach is already utilized from small to large engine classes, it is almost exclusively based on the combustion of a premixed, homogeneous charge. For ignition, small engines use standard spark-plugs or pre-chambers, while large and lean-operated engines use pre-chambers and pilot injections. Direct high-pressure gas injection is a more recent, alternative way to operate gas engines which offers benefits compared to premixed operation such as high compression ratio, high combustion pressures, lean operation, quantity regulation, among others. However, in contrast to diesel direct injection, the compression temperatures are too low for the auto-ignition of the gas jets. Therefore, an additional ignition system is required, usually a pilot injection system is used. In this study, the usability and performance of three ignition strategies for direct injected high-pressure gas jets have been investigated in an optically accessible test-rig that is able to operate at engine-like conditions. The first type of ignition system is a pilot injection with a liquid fuel, the second is a glow-plug located near the main gas jet, and the third system is a pre-chamber with a nozzle hole aimed at the main gas jet. Results show that all three strategies are feasible options under the studied conditions. Ignition by a pilot fuel injection is a safe and reliable way to ignite the main fuel. The glow-plug is less reliable and leads to high cycle-to-cycle variation. The best option in the present study is the pre-chamber, it is very reliable, delivers the highest peak cylinder pressure and exhibits the lowest cyclic variability. The good performance is attributed to the intense mixing of the main gas jet with the hot jet exiting the pre-chamber.

Анализ эффективности технологической системы разработки XXIII пласта месторождения Гойт-Корт

The article presents an analysis of technological schemes for the development of the XXIII layer of the Goyt-Kort field, as a result of which the implementation of measures for high pressure gas injection is proposed. The geological and production characteristics of the reservoir, technological features of the developed process and economic needs justified the choice of the Goyt-Кort field as a priority object for high-pressure gas injection to enhance oil recovery. As a result of the proposed measures, an increase in reservoir pressure was noted in the area of the first row of production wells, an improvement in their performance due to gas injection.The characteristic reasons for the frequent well workovers caused by deposits of asphalt-resin-paraffin substances in equipment, in tubing and flow lines have been identified. Measures are provided to eliminate and combat the listed complications. Thus, the field tested and implemented the technology of constant dosing of the inhibitor into the annulus of the well. Comparative testing of the activity of the reagents was carried out. To remove the clay bridging agent of the pore matrix of high-temperature terrigenous objects, the use of reagents based on boronfluorinehydrogen acid is recommended.

Numerical Simulation of Immiscible CO2-Assisted Gravity Drainage Process to Enhance Oil Recovery

The Gas Assisted Gravity Drainage (GAGD) process has become one of the most important processes to enhance oil recovery in both secondary and tertiary recovery stages and through immiscible and miscible modes. Its advantages came from the ability to provide gravity-stable oil displacement for improving oil recovery, when compared with conventional gas injection methods such as Continuous Gas Injection (CGI) and Water – Alternative Gas (WAG).
 Vertical injectors for CO2 gas were placed at the top of the reservoir to form a gas cap which drives the oil towards the horizontal oil producing wells which are located above the oil-water-contact. The GAGD process was developed and tested in vertical wells to increase oil recovery in reservoirs with bottom water drive and strong water coning tendencies. Many physical and simulation models of GAGD performance were studied at ambient and reservoir conditions to investigate the effects of this method to enhance the recovery of oil and to examine the most effective parameters that control the GAGD process.
 A prototype 2D simulation model based on the scaled physical model was built for CO2-assisted gravity drainage in different statement scenarios. The effects of gas injection rate, gas injection pressure and oil production rate on the performance of immiscible CO2-assisted gravity drainage-enhanced oil recovery were investigated. The results revealed that the ultimate oil recovery increases considerably with increasing oil production rates. Increasing gas injection rate improves the performance of the process while high pressure gas injection leads to less effective gravity mediated recovery.

Synergistic Effect of O2 and H2S on the Corrosion Behavior of N80 Steel in a Simulated High-Pressure Flue Gas Injection System

The aim of this work was to understand the synergistic effect of O2 and H2S on the corrosion behavior of N80 steel in a simulated high-pressure flue gas injection system. Weight loss measurements show that the presence of O2 and an increase in temperature significantly accelerated the general corrosion rate of the N80 steel. We calculated a gray relational grade between different impact factors and the general corrosion rate from the results of an orthogonal experimental corrosion rate. The grade ranking of impact factors was: O2 concentration (0.817) > temperature (0.706) > total pressure (0.689) > H2S concentration (0.665) > CO2 concentration (0.517). Surface characterization of corrosion scales was done using scanning electron microscopy, energy-dispersive spectroscopy, x-ray powder diffraction, and 3D optical microscope analysis. The results show that in the O2-H2S-CO2-H2O coexistence system the products were composed mainly of FeCO3, FeS, Fe2O3, Fe3O4, and elemental sulfur. The results of the corrosion rate test and the characterization show that the presence of O2 greatly accelerated the corrosion process and changed the corrosion mechanism. Elemental sulfur, which was generated by the reaction between the H2S and the O2, participated in the corrosion process of the N80 steel. It could be considered that the synergistic effect of O2 and H2S accelerated the corrosion of the N80 steel. In addition, the porous structures of the corrosion scales and the severe local pits show that the high content of O2 inhibited the formation of FeCO3 and aggravated the corrosion of N80 steel.

Dynamic transport and reaction behaviour of high-pressure gases in high-rank coal

This paper presents the results obtained through continuous and simultaneous measurements of gas flow, temperature and coal deformation during high-pressure gas injection in high-rank coal samples, obtained from the South Wales coalfield (UK). The results demonstrate that CO2 flow rates experience an initial decline due to internal coal swelling, followed by the flow rate recovery and global coal swelling. As the flow of high-pressure CO2 induces measurable temperature drop within the sample related to the Joule-Thomson cooling, the changes induced by the variations in thermal state of the system are associated with abrupt shift in coal response to reactive gas flow. However, subsequent injections of He and N2 show that the changes induced by CO2 sorption on coal permeability to gases are irreversible. This work demonstrates the importance of considering the coupled reactive gas and heat transport, and consequent coal deformation mechanisms while assessing the storage potential of coal seams.

To Depict Oil Extraction Efficiency from Gas Invaded Zone: Simulation Study

Future exploitation scheme of an oil reservoir in each cycle within its production life depends on the profitability of the current extraction scenario compared with predicted recoveries that acquire with applying other available methods. In fractured reservoirs appropriate time to pass from the gas injection process into chemical enhanced oil recovery (EOR) firmly depends on the oil extraction efficiency within the gas invaded zone. Several variables including fluid characteristic, fracture network and matrix units properties, etc., impact gas-oil gravity drainage (GOGD) performance within the gas invaded zone. In this work, CMG GEM and ECLIPSE 300 were used to simulate GOGD mechanism in several 2D cross-sectional models to investigate effects of the matrix height, matrix rock type, fracture network transmissibility, and miscibility conditions on the oil extraction rate, change of average pressure and producing gas-oil ratio (GOR). Results showed that in small heights of the matrix units especially at compacted rock types, GOGD was weak that caused a rapid decrease in oil production rates and early increase in producing GOR. Results also showed that wherever the matrix porosity and permeability values were high, recovery was accelerated and GOR remained constant for longer exploitation times. Furthermore, using high-pressure lean gas injection for miscible GOGD gives higher extraction efficiencies rather than applying rich or enriched gas.

Process design and economic optimization of boil-off-gas re-liquefaction systems for LNG carriers

Recent LNG carriers are equipped with high pressure gas injection engines. However, there has been a lack of research on liquefaction processes for boil-off gas (BOG) on LNG ships driven by high pressure fuel. Thus, this paper investigates the economic feasibility of the additional BOG liquefaction facilities in the high pressure fuel supply system on the vessels. To utilize the existing BOG compressor for fuel production, the liquefaction was conducted by the Joule Thomson (JT) cycle, which can use the pressurized BOG as a working fluid. For the comparison of the fuel supply system and its variations with BOG liquefaction, they are optimized with respect to total annual cost (TAC) as the objective function. With an LNG price of 5 USD/MMBtu, the optimization results show that the use of BOG liquefiers on LNG vessels reduces the TAC by at least 9.4% compared to the high pressure fuel supply system. The use of a liquid turbine in the liquefaction configurations also resulted in 2.4% savings in TAC compared to the JT cycle based process. However, a sensitivity analysis with different LNG prices indicates that the liquefaction systems are not economical compared to the fuel supply system when the LNG price is lower than 4 USD/MMBtu.

Rapid and massive throughput analysis of a constant volume high-pressure gas injection system

Abstract Fusion power shutdown system (FPSS) is a safety system to stop plasma in case of accidents or incidents. The gas injection system for the FPSS presented in this work is designed to research the flow development in a closed system. As the efficiency of the system is a crucial property, plenty of experiments are executed to get optimum parameters. In this system, the flow is driven by the pressure difference between a gas storage tank and a vacuum vessel with a source pressure. The idea is based on a constant volume system without extra source gases to guarantee rapid response and high throughput. Among them, valves and gas species are studied because their properties could influence the velocity of the fluid field. Then source pressures and volumes are emphasized to investigate the volume flow rate of the injection. The source pressure has a considerable effect on the injected volume. From the data, proper parameters are extracted to achieve the best performance of the FPSS. Finally, experimental results are used as a quantitative benchmark for simulations which can add our understanding of the inner gas flow in the pipeline. In generally, there is a good consistency and the obtained correlations will be applied in further study and design for the FPSS.

Analysis of Secondary and Tertiary High-Pressure Gas Injection at Different Miscibility Conditions: Mechanistic Study

Summary In the current survey, the time required to rupture the water film shielding the oil as a result of oil swelling caused by the diffusion of dissolved gas in the water phase and trapped oil behind it has been investigated in porous medium at high pressure and temperature. To study the active mechanisms, the experiments have been conducted with two different types of injectants: carbon dioxide (CO2) and methane (with different solubility in water), under different miscibility conditions at equal reduced pressures. Experimental observations have been interpreted using theoretical studies. Furthermore, the time of water-film rupture has been identified in production data and matched by an analytical model. This time and its monitoring during various gas-injectant types and regimes under reservoir conditions have not been previously addressed. The results show that water film reduces the performance of oil recovery by limiting the interface of oil and gas phases. Under such a condition, the best scenario is miscible gas injection because the gas can effectively swell the oil and rupture the water shield. At miscible and near-miscible conditions, the time required to eliminate the water film increases as the injectant solubility in water decreases; however, there is a negligible difference at the immiscible regime. The trend of oil-recovery curves after rupture of the water film shows that oil swelling is one of the main mechanisms involved in water-trapped oil recovery. These results suggest practical guidelines to better understand the effect of the water-shielding phenomenon in the field of tertiary gas injection. The outcome of this integrated study could effectively increase the knowledge of shielded oil recovery using different gas-injectant types under various miscibility conditions and could prepare the required basis for compositional simulation of waterflooded oil production during tertiary gas injection.