Water-gas Mixture Research Articles

Application of machine learning in on-line calibration of flow measurement errors

With the vigorous construction of an intelligent pipe network, an automatic flowmeter was the key to realize online flow measurement of oil and gas. Ensuring the accuracy of flow measurement was very important to achieve real-time feedback on oil–gas production status for adjusting the oil recovery technology. However, due to the changing flow state of the oil–gas in the pipe and the error of the flow-meter itself, there were some errors during flow measurement. Therefore, based on the machine learning method, this paper corrected the errors caused by the pulsating flow and the flowmeter itself in data drift. The results showed that the toy–LSTM model can measure the pulsating flow accurately. When the number of toy–LSTM model neurons was ranged between 10 and 50, both RMSE and R2 showed good performance. The average of multiple predicted results presented higher accuracy than that of single predicted results, and furthermore, the drop rate can significantly increase the robustness of the toy–LSTM model. It should be noted that the optimal case proposed in this paper was based on a specific condition in the field. In the actual application, it was necessary to comprehensively consider the number of branch pipes, the change in oil well production, the characteristics of the oil–gas–water mixture, and other factors to determine the specific values of the number of neurons, the drop rate, and other parameters. Aiming at the distortion caused by the data drift of the flowmeter itself, the program was designed and data were collected from the software platform, information collector, and base station. The data acquisition of temperature–pressure integrated sensor and flowmeter was carried out in the field. In 20 groups of experiments, the online corrected program based on the Mexican Hat wavelet transform can realize accurate identification and automatic corrected responses, and the corrected time was within 5 min.

Numerical investigation of unsteady shedding behaviors of a reentrant jet supercavity

To investigate the unsteady shedding characteristics of a reentrant jet supercavity with a low Froude number, a high-fidelity numerical model based on the inhomogeneous multiphase model is developed to predict the complex supercavitation flow that occurs during supercavity development. The developed solver is validated quantitatively against experimental results in terms of supercavity geometry and closure mode. This study focuses on the initial generation and development process of a reentrant jet supercavity, revealing three distinct stages: foam cavity, transparent supercavity with rapid growth in dimensions, and fully developed supercavity exhibiting significant deformation. Owing to reverse flow of the gas–water mixture, interfacial instabilities arise from the unsteady cavity shedding, leading to fluctuations in supercavity shape. The types of large-scale cavity shedding observed in this work—wing-like and cloud-like—are caused by the concave deformation resulting from the reentrant jet. As the gas entrainment coefficient increases, the unsteady characteristics of pressure oscillation weaken, and the instance of wing-like cavities decreases. When the gas entrainment coefficient reaches a critical value, the twin-vortex closure mode occurs, resulting in a more stable flow behavior. In sum, we propose a theoretical model that elucidates the strength of the reentrant jet and reveals its unsteady shedding behavior during supercavity development.

Decarbonization of simulated biogas with microchannel mixer by pressurized water scrubbing

Pressurized water scrubbing is an environmentally friendly technology for the decarbonization of biogas. However, the key bottlenecks such as low efficiency, high cost of water consumption and secondary CO2 emission by water absorption and desorption in the process of decarbonization are still necessary to be solved. This study focused on improve the mass transfer effect by introduce finger-crossed microchannel in the process of simulated biogas decarbonization using pressurized water scrubbing. The simulated biogas was mixed with pressurized water in the finger-crossed microchannel, and the gas-water mixture was continuously separated in the gas-water separation tank. The effects of pressure (26–30 bar), temperature (5–30 °C), gas-water ratio (5:1–12:1), liquid volumetric flowrate (5–10 mL/min), and other factors on the decarbonization were investigated. The overall mass transfer coefficient based on the liquid phase and the CO2 flux were also calculated and analyzed. The decarbonization parameters were optimized using the response surface methodology as follows: temperature 20 °C, pressure 29/27 bar, gas-water ratio 10:1, liquid volumetric flowrate 5 mL/min. The process remained stable, achieving 98 % removal of CO2 under optimal conditions. Furthermore, the CO2 concentration in the purified gas was maintained below 3 %. Additionally, a significant number of micro-nano bubbles were observed in the absorption water obtained through this mixer, and the releasing of CO2 from the water lasted 5 days. These results indicated the excellent decarbonization performance of the finger-crossed microchannel in pressurized water scrubbing and potential application value of new ways of CO2 absorption water without desorption.

Molecular Insights into the Wettability and Adsorption of Acid Gas-Water Mixture.

Sequestration of acid gas in geological formations is a disposal method with potential economic and environmental benefits. The process is governed by variables such as gas-water interfacial tension, wetting transition, and gas adsorption into water, among other things. However, the influence of the pressure and temperature on these parameters is poorly understood. This study investigates these parameters using coarse-grained molecular dynamics (CG-MD) simulations and density gradient theory (DGT). Simulations were carried out at 313.15 K and a pressure range of 0-15 MPa. A comparison was made against H2S-water systems to clarify the effects of adsorption on interfacial tension due to vapor-liquid-liquid equilibrium. The predicted H2S-water interfacial tension and phase densities by CG-MD and DGT matched the experimental values well. The adsorption can be quantified via the Gibbs Adsorption function Γ12, which correlated well with the three-phase transition. On the one hand, pressure increments below the three-phase transition revealed a significant adsorption of H2S. On the other hand, above the three-phase transition, the Gibbs Adsorption capacity remained constant, which indicated a saturation of H2S at the water surface due to liquid-liquid equilibrium. Finally, H2S behaves markedly differently in wetting transition, rather than the involved for CO2 to different molecular layers beneath the surface of aqueous solutions. In this respect, H2S is represented by a first-order wetting transition while CO2 presents a critical wetting. Finally, it has also been found that the preferential adsorption of H2S over the H2O interface is greater if compared to that of CO2, due to its strong interaction with water. In fact, we have also demonstrated that CO2 under triphasic conditions strongly influences the wetting of the ternary system.

Experimental Assessment of Oil Displacement Efficiency by Flue Gases for a Developed Reservoir in Carbonnate Formation of Urals-Volga Region

The paper presents the results of experimental evaluation of oil displacement efficiency by flue gas of a thermal power plant, compared to water, for a carbonate reservoir in the Ural-Volga region. The experiments were performed under two different injection schemes using an original laboratory complex for coreflood studies, with recombined reservoir oil, model of formation water, reservoir core material, and under reservoir thermobaric conditions. It has been confirmed that due to the prevailing nitrogen content and low values of reservoir pressure and temperature, flue gas is ineffective as an independent displacement agent either for injection from the beginning of reservoir development or as a tertiary method after waterflooding. Taking into account the relevance of synergy between increasing oil recovery and sequestration of industrial emissions, evaluation of flue gas injection as part of water-gas mixtures (SWAG) is recommended.

Analysis of wave propagation in non-isothermal poroelastic solids saturated by two-phase fluids

SUMMARY This work presents a model to characterize the behaviour of waves propagating in non-isothermal poroelastic solids saturated by two-phase fluids. The dynamic differential equations include the poroelasticity and heat equations with the solid, fluid and thermal fields combined using coupling terms. A plane wave analysis shows that five waves can propagate, three compressional, one fast (P1) and two slow (P2, P3), a shear fast (S) and a thermal slow (T). P2, P3 and T are diffusive waves at low frequencies, while P1 and S behave as propagating waves. The T wave is coupled with the compressional waves and uncoupled with the S wave. The plane wave analysis applied to a real sandstone saturated with gas–water mixtures compares phase velocities and attenuation factors for two-phase and effective single-phase fluids, considering or neglecting the coupling terms. It is observed that P1 and P2 waves have higher velocities for coupled cases, while P3 and T waves exhibit the opposite behaviour. Furthermore the plane wave analysis is performed in the coupled case for oil–water and gas–water two-phase fluids, with compressional waves exhibiting higher velocities for gas–water than for oil–water mixtures. The propagation of waves in a 1-D thermo-poroelastic medium saturated by a gas–water mixture is presented and analysed using a finite element procedure. Considering temperature may become important in high-pressure high-temperature hydrocarbon and geothermal reservoirs.

Computer Vision Algorithm for Characterization of a Turbulent Gas–Liquid Jet

A computer vision algorithm to determine the parameters of a two-phase turbulent jet of a water-gas mixture traveling at a velocity in the range of 5–10 m/s was developed in order to evaluate the hydrodynamic efficiency of mass exchange apparatuses in real time, as well as to predict the gas exchange rate. The algorithm is based on threshold segmentation, the active contours method, the regression of principal components method, and the comparison of feature overlays, which allows the stable determination of jet boundaries and is a more efficient method when working with low-quality data than traditional implementations of the Canny method. Based on high-speed video recordings of jets, the proposed algorithm allows the calculation of key characteristics of jets: the velocity, angle of incidence, structural density, etc. Both the algorithm’s description and a test application based on video recordings of a real jet created on an experimental prototype of a jet bioreactor are discussed. The results are compared with computational fluid dynamics modeling and theoretical predictions, and good agreement is demonstrated. The presented algorithm itself represents the basis for a real-time control system for aerator operation in jet bioreactors, as well as being used in laboratory jet stream installations for the accumulation of big data on the structure and dynamic properties of jets.

Prospects for the implementation of SWAG-technology to enhance oil recovery at the Rechitskoe field using flue and flare gases

This article proposes the introduction of SWAG-technology at the Rechitskoe oil field of RUE Belorusneft. An analysis of previously conducted research on the implementation of technology at the selected facility revealed a number of technological factors that reduced the effectiveness of the method. It is proposed to use pump-ejector systems –devices that will allow obtaining and pumping a water-gas mixture with the required pressure. To ensure rational gas content, it is advisable to add flare and flue gases to the water, which will reduce the carbon footprint. The addition of foaming surfactants helps to improve the characteristics developed by the booster pump, suppress the coalescence of gas bubbles and increase the efficiency of injection of the water-gas mixture.

Approaches to the effective implementation of SWAG-technology and technology for intrastratal carbon dioxide generating

This article provides an overview of the results of studies of water-gas methods and carbon dioxide generation in reservoir conditions as methods for increasing oil recovery. It is shown that the efficiency of technology implementation is influenced by the choice of technical device and the composition of the selected agents selected for injection into the reservoir. The effectiveness of the implementation of these methods is directly influenced by reservoir conditions (pressure and temperature), as well as the mineralization composition of the liquid phase (injected in the form of a water-gas mixture or formation water). It turned out that in the case of an optimal mineralization composition of the liquid, the technological efficiency of the methods increases. In other cases, it is necessary the composition and concentration of surfactants are given. Recommendations on the composition and concentration of surfactants are given. To implement methods in a specific field, it is recommended to conduct laboratory studies to determine the optimal composition of the agent acting on hydrocarbon-saturated rock.

”Increasing oil recovery by injecting an air composition of the surface active substance (SAS) in the irrigated layers”

The introduction of a water-gas mixture into the reservoir necessitates gas production along with oil in the field. This creates difficulties in the old fields of Azerbaijan. Therefore, unlike the water-gas mixture injected into the layers, the use of a solution of surfactant (SAS) in water instead of air water instead of gas guarantees that the process is both cheap and effective. During the injection of the mixture, the air, being a non-wet phase, will enter the small permeable pores of the layer, helping to displace the oil from it, as well as prevent the formation of water tongues in the layer. The solution from the SAS reagent to be added to the water will not only increase the oil-washing capacity, but also relieve the surface tension at the border with the oil, causing weakening of the capillary forces. Thus, the impact coverage of the reservoir will increase, which will ensure the rise of the oil recovery of the reservoir. By replacing the injection of water with the injection of a solution-air composition through an injector to remove residual oil from the irrigated reservoir, the oil yield coefficient increased by 27%. The injection of the solution-air composition through the reservoir injector increased the oil recovery and also led to a decrease in the volume of the outgoing water.

Some aspects of thermochemical method of bottom-hole zones processing application in the «White Tiger» oil field

The article describes the scope of the thermochemical method of bottom-hole formation zones treatment, the thermal methods classification and their effectiveness, various types of formation thermal treatment (heat-steam heating, hot water, water vapor, gas-water mixtures, various chemical compositions injection, etc.). The physicochemical essence of thermochemical action for the purpose of the bottom-hole formation zone treating by a thermochemical composition based on magnesium metal powder, hydrochloric acid, and other auxiliary materials to increase the productivity of the «White Tiger» deposit wells is considered in detail. Keywords: bottomhole formation zones treatment; sand collector; thermal effect; exothermic reaction; dewaxing; productive zone; bottomhole formation zone.

Experimental studies on the effect of mixing chamber length on the characteristics of a liquid-gas ejector during the injection of exhaust gases to achieve a water-gas impact on formation

Experimental measurements were conducted to determine the effect of mixing chamber length on liquid-gas ejector performance. The tests were performed on a laboratory bench designed for physically modeling the process of creating a water-gas mixture using exhaust gases. For the first time in this study, liquid-gas ejector parameters were measured during the injection of exhaust gases from a real source. The study investigated how the ratios of displacement chamber diameters, chamber length, and working nozzle affect the liquid-gas ejector's characteristics under various operating modes. The results obtained enable optimal parameter selection of the ejector and reveal the potential for utilizing exhaust gases to produce a water-gas mixture for injection into reservoirs to enhance oil recovery. Keywords: pump-ejector system; exhaust gases; liquid-gas ejector; water-gas impact; pressure-energy characteristics of the ejector.

Waterflooding, water-gas method and generation of carbon dioxide in the reservoir – methods of enhanced oil recovery and technology development

This article discusses reservoir pressure maintenance methods: flooding and SWAG technology. The accumulated experience of waterflooding technology introduction described in literature sources is analyzed. Identified such disadvantages of waterflooding as reservoir watering due to significantly low viscosity compared to the viscosity of reservoir oils and low oil recovery factor. A method for detecting and preventing the instability of the front of displacement of residual reserves by injected water is indicated. Particular attention is paid to the innovative method of reservoir stimulation, which consists in the generation of carbon dioxide in reservoir conditions. The essence of the technology, method of implementation, advantages compared to gas injection through injection wells are described. Water-gas methods are investigated. The advantage of SWAG technology with the use of pump-ejector systems in comparison with other modifications is proved and the results of the latest research are presented, which cover data on the characteristics of pump-ejector systems, the topical issue of the technology for obtaining water-gas mixtures and the processes of interaction of gas bubbles when pumping mixtures through wells into the reservoir, as well as ways to implement the technology, taking into account the geological and field conditions of potential targets for implementation. This analysis will allow you to correctly choose the method of stimulation of the reservoir and operate the facilities as efficiently as possible. It should be noted that the considered gas and water-gas methods involve the injection of carbon dioxide, associated, exhaust, flue gases into the reservoir, which makes these technologies the most attractive from an environmental point of view.

THE RESULTS OF A COMPARATİVE ANALYSİS OF OPERATİONAL FACİLİTİES OF THE BALAKHANİ SUITE (THE CASE OF THE BİBİEIBAT FİELD)

The article is devoted to ways of efficient development of the formations of the long-exploited Bibiheybat deposit located on the Absheron Peninsula. At the same time, the issues of oil and gas content, lithology, and collector properties were also investigated according to the development plan of the exploitation facilities. Despite the fact that this field has been exploited for a long time, there are still enough residual reserves. The amount of residual resources in these deposits creates the basis for obtaining a high level of production from them in the future. Here, the issues of applying new methods to increase the oil yield of the formations are reflected. Development curves were drawn up to systematize the actual data obtained for a fundamental analysis of development. To identify the relationship between production wells and annual oil production for given horizons the graphs were built up. The possibility of increasing the final oil recovery factor through the use of new methods of enhanced oil recovery was studied and it was found that when using the water-gas mixture method for the horizon “XIV suite”, the final oil recovery can be increased by 5-6% and an additional 201-241 thousand tons of oil, while using the micellar method we get 8-15% of the effect from additional production. As for the technological reasons for the difference in current oil recovery factors for reservoir objects, this is primarily due to the number of drilled production wells, which is 3 times more in the first horizon than in the second. Due to geological reasons, the reservoir properties of the first horizon are better than those of the second horizon, as well as the energy of the gas dissolved in oil during the development of the “XIV suite” horizon, the movement of the waters of the outer contour (elastic-water-pressure mode) was stronger compared to the “XV layer” horizon ". In general, the difference between current oil production rates is a factor due to geological reasons, as well as technological reasons during development. Keywords: development, suite, horizon, residual reserves, development curves, oil and gas field.

HOW THE LOWERING OF PRESSURE OR THE FORMATION OF ICE AFFECT THE FORMATION AND DISSOCIATION OF METHANE HYDRATES: VARIATIONS IN TERMS OF METASTABLE PHASE AND ANOMALOUS SELF-PRESERVATION

This research proposes the multiple and consecutive formation of methane hydrates with the same gas-water mixture and in a small-scale reactor. The scope consisted of better exploring how the variation of the initial pressure of the system modified the formation and dissociation processes. One of the most promising solutions for gas hydrates exploitation consists in the replacement of methane with carbon dioxide. This process inevitably requires the formation of CO<sub>2</sub> hydrates; thus, more details and analyses on the driving forces of the formation process are required in order to improve the overall replacement efficiency. Also, the competition with ice was analyzed. Nine tests were carried out in order to consider all these parameters. Each test was characterized thermodynamically and the time required to complete each specific phase of the process was measured. The tests were carried out at two different initial pressures: 60 and 50 bar, respectively. It was found that the main effect, associated with a lower initial pressure and/or with the presence of ice, is the stretching of the so-called metastable phase; since the local conditions became suitable for the formation of hydrates, the system required more time to begin in these latter cases. In the tests made at 60 bar, the delay in hydrate formation related to the metastable phase was equal to 0.73-1.04 h, while it ranged from 7.29 to 15.16 h in the tests made at 50 bar. Moreover, the results proved that the presence of ice hindered the formation process by reducing the heat transfer rate and by lowering the volume available for the process. Conversely, the begin of the dissociation phase was similar in all the experiments: the anomalous self-preservation, or the capability of the system to preserve itself even outside the hydrate stability zone was not observed, proving again that these limiting factors (lower initial pressure and ice formation) mainly affected the process during the formation phase.

On reducing the carbon footprint through the rational use of petroleum gas

This study is devoted to the problems of irrational combustion of petroleum gas. The problems of introducing APG application methods are indicated, the methods of using gas in the fields are analyzed. The analysis of the data made it possible to establish that the harmful effect can be reduced by injecting oil gas into the reservoir with water in the form of a water-gas mixture (SWAG-technology). Exhaust or flue gases can also be used. Flue gases emitted during the flaring of associated petroleum gas can also be captured and injected as a water-gas mixture. Pump-ejector systems are proposed as a technical solution.

Improving the SWAG-technology with the use of pump-ejector systems

A set of technical solutions for improving the SWAG-technology using pump-ejector systems is proposed. To effectively influence the reservoir, it is necessary to implement the injection of a water-gas mixture into wells that open reservoir sections with the largest residual reserves (into wells with maximum reserves – a mixture with the highest gas content from the range of rational values). In this case, associated gas, nitrogen, can be used as a source of the gas phase. A description of the pump-ejector system for the use of associated gas from the annulus of production wells is also given. For the efficient operation of the system, it is necessary to select the elements of the system that will be operated with maximum efficiency under field conditions. The results of experimental studies of ejectors are presented: the efficiency of the ejector is directly related to the mineralization of the working fluid, as well as the inlet pressure.

Investigation of gas bubble coalescence suppression and its effect on the operation of a booster pump as part of a pump-ejector system when pumping water-gas mixtures

Article presents an overview of studies of the gas bubbles interaction processes in the composition of water-gas mixtures. Data are given on theories that indirectly indicate the nature of the phenomenon of coalescence, or its suppression. It has been established that there are rational ranges of parameter values at which coalescence suppression is observed, however, when some critical values of these parameters are exceeded, the coalescence suppression regime breaks down. The experimental studies of the gas flow rate effect, passed in the bubbles flow form through a column with liquid, at various pressures and salinity of the liquid showed that an increase in the maximum gas flow rate with suppressed coalescence is observed in a certain range of salinity (with increasing pressure). However, further with an increase in salinity, the maximum the gas flow rate remains constant, after which the regime breaks. The addition of foaming surfactants increases the maximum gas flow rate. At the same time, a study of multistage centrifugal pump characteristics showed that the addition of surfactants improves the performance of the pump up to a certain concentration, with an increase in this concentration, the performance improves slightly. A further direction of studying the technology of creating stable water-gas mixtures is also formulated. Keywords: carbon footprint reduction; SWAG technology; pump-ejector systems; water-gas mixture; coalescence of gas bubbles.

Study of the influence of foaming surfactants on the operation of a multistage centrifugal pump when pumping water-gas mixtures created by an ejector

When implementing the SWAG technology, the degree of stability of the water-gas mixture plays a key role. A many factors of various nature is known to the suppression of the coalescence of gas bubbles is facilitated. This article presents the results of studies of the effect of surfactants of various compositions and concentrations on the operation of a multistage centrifugal pump when pumping water-gas mixtures. The foaming agent disolvan 4411 is determined to the degree of negative influence of free gas on the characteristics of the pump is significantly reduced. The reagent Neftenol VVD provides operating parameters very close to the characteristics of the pump when using disolvan 4411. The concentration of Neftenol VVD, recommended for addition to the water-gas mixture, has been determined. The expediency of choosing this surfactant is also due to the fact that the use of this reagent improves the injection capacity of wells. Keywords: multistage centrifugal pump; ejector; water-gas mixture; foaming surfactants.

Investigation of the ejector`s characteristics for the system of injection of water-gas mixtures into the reservoir

Implementation of SWAG injection by means of injection of a water-gas mixture is a promising method for increasing oil recovery. The use of associated petroleum gas as gas components in the water-gas mixture allows a multiple reduction in the amount of irrationally consumed gas and a reduction in the carbon footprint. This article uses the technology of multi-stage ejector reproduction to obtain and pump a water-gas mixture in plastic. The right choice of equipment allows you to operate the system with maximum efficiency. The article presents a schematic diagram of the SWAG installation. The effect of the working pressure on the efficiency of the ejector has been studied. Dependences of pressure-energy characteristics are obtained. Keywords: water-gas mixture; pumping-ejector system; SWAG technology; liquid-gas ejector; pressure-energy characteristics of ejectors.