A Method of Predicting Revaporization of Retrograde Condensate by Dry-Gas Injection

1969 ◽  
Vol 9 (01) ◽  
pp. 21-27
Author(s):  
James W. Givens
Keyword(s):  
Mathematical Model ◽  
Phase Equilibrium ◽  
Gas Injection ◽  
Dew Point ◽  
Terminal Point ◽  
Injection Volume ◽  
Liquid Saturation ◽  
Total Composition ◽  
Gas Volume ◽  
Mobile Liquid

Abstract This paper presents a mathematical model for predicting the revaporization of retrograde predicting the revaporization of retrograde condensate liquid by dry-gas injection. The primary assumptions in the model are (1) that complete phase equilibrium exists between the gas and phase equilibrium exists between the gas and liquid in the model; (2) the liquid saturation is less than the mobile liquid saturation; and (3) that the dry gas does not bypass any rich gas as it sweeps through the model. The model calculates the phase compositions and saturations for all 10 cells, liquid phase recovery, and produced gas composition as a function of cumulative injection. The predicted results for two synthetic systems were found to agree favorably with the results of laboratory displacement studies. The systems investigated were a methane-normal pentane system and a sour system containing mainly methane, hydrogen sulfide, normal pentane, and normal heptane. Introduction The revaporization of retrograde liquid is a very important factor that must be considered in selecting the optimum operating procedure for a gas condensate reservoir. Some reservoirs may be cycled at pressures below their dew point without a significant loss of liquid recovery. In order to ascertain the revaporization characteristics for a reservoir, the reservoir fluids and available injection gases must be studied at reservoir temperature and the desired pressure levels. This type of laboratory study requires considerable time and expense; therefore, the mathematical model presented here was developed to reduce the time, presented here was developed to reduce the time, expense and laboratory work necessary to evaluate the revaporization process. THE MODEL The model presented and this paper simulates the linear displacement and revaporization for a core initially filled with condensate gas and liquid. The model assumes that the revaporization process occurs (1) at constant temperature and pressure, (2) at liquid saturations below the mobile liquid saturation, (3) at complete equilibrium between the vapor and liquid phases, and(4) at 100-percent sweep efficiency for dry gas displacing the rich gas. It is also assumed that 10 cells are sufficient to simulate the process adequately. The general steps of the calculational procedure are:The liquid and vapor compositions and liquid saturation are calculated for all 10 cells, using the combined composition for the liquid and vapor phases (total composition), which results from a phases (total composition), which results from a differential liberation to the desired temperature and pressure.The incremental injection volume is selected based on the gas saturation of the cell containing liquid that is nearest the injection end of the model. For the example shown in Fig. 1, the gas volume in Cell 2 would be the incremental injection volume. By choosing the injection volume equal to the gas volume of this cell, there will not be any over or under flow of this cell's boundaries and numerical dispersion will be minimized.The injection increment is added to the first cell after moving an equivalent volume of vapor across the boundary between all cells. The vapor removed from the 10th cell is the produced gas. The GPM (gallons of liquid/Mscf) content of the produced gas is calculated from its composition produced gas is calculated from its composition and used to determine the terminal point for a run. SPEJ P. 21

Dynamic Processes During Pulsed Gas Injection Into Liquid Column

2016 ◽  
Author(s):  
P. D. Lobanov ◽  
O. N. Kashinsky ◽  
A. S. Kurdyumov ◽  
N. A. Pribaturin
Keyword(s):  
Liquid Metal ◽  
Gas Phase ◽  
Gas Injection ◽  
High Amplitude ◽  
Metal Alloy ◽  
Dynamic Processes ◽  
Flow Parameters ◽  
Liquid Metal Alloy ◽  
Inner Diameter ◽  
Gas Volume

An experimental study of dynamic processes during pulsed gas injection into quiescent liquids was performed. Both water and low melting temperature metal alloy were used as test liquids. Air and argon were used as gas phase. The test sections were vertical cylindrical columns 25 and 68 mm inner diameter. Measurements of flow parameters during gas injection were performed. Water – air experiments were performed at room temperature, the temperature of liquid metal alloy was 135 deg C. Time records of pressure in the liquid and in gas phase above the liquid were obtained. Measurements of liquid temperature and level of liquid surface were performed. It was shown that at pulse gas injection into liquid metal high amplitude pressure fluctuation may arise. Also the fluctuation variation of the free surface of the liquid may appear which are connected with the oscillations of the gas volume. Experimental data obtained may be used for verification & validation of modern CFD codes.

scholarly journals Optimasi Intermittent Gas lift Pada Sumur AB-1 Lapangan Brownfield

2018 ◽  
Vol 2 (1) ◽  
pp. 32
Author(s):  
Mia Ferian Helmy
Keyword(s):  
Pressure Gradient ◽  
Production Rate ◽  
Flow Rate ◽  
Oil Recovery ◽  
Gas Injection ◽  
Production Method ◽  
Production Flow ◽  
Injection Volume ◽  
Artificial Lift ◽  
Gas Lift

Gas lift is one of the artificial lift method that has mechanism to decrease the flowing pressure gradient in the pipe or relieving the fluid column inside the tubing by injecting amount of gas into the annulus between casing and tubing. The volume of  injected gas was inversely proportional to decreasing of  flowing  pressure gradient, the more volume of gas injected the smaller the pressure gradient. Increasing flowrate is expected by decreasing pressure gradient, but it does not always obtained when the well is in optimum condition. The increasing of flow rate will not occured even though the volume of injected gas is abundant. Therefore, the precisely design of gas lift included amount of cycle, gas injection volume and oil recovery estimation is needed. At the begining well AB-1 using artificial lift method that was continuos gas lift with PI value assumption about 0.5 STB/D/psi. Along with decreasing of production flow rate dan availability of the gas injection in brownfield, so this well must be analyze to determined the appropriate production method under current well condition. There are two types of gas lift method, continuous and intermittent gas lift. Each type of gas lift has different optimal condition to increase the production rate. The optimum conditions of continuous gaslift are high productivity 0.5 STB/D/psi and minimum production rate 100 BFPD. Otherwise, the intermittent gas lift has limitations PI and production rate which is lower than continuous gas lift.The results of the analysis are Well AB-1 has production rate gain amount 20.75 BFPD from 23 BFPD became 43.75 BFPD with injected gas volume 200 MSCFPD and total cycle 13 cycle/day. This intermittent gas lift design affected gas injection volume efficiency amount 32%.

Application of Multiple-Mixing-Cell Method To Improve Speed and Robustness of Compositional Simulation

SPE Journal ◽  
2015 ◽  
Vol 20 (03) ◽  
pp. 565-578 ◽  
Author(s):  
Mohsen Rezaveisi ◽  
Russell T. Johns ◽  
Kamy Sepehrnoori
Keyword(s):  
Phase Equilibrium ◽  
Gas Injection ◽  
Computational Time ◽  
Simulation Methods ◽  
K Value ◽  
Acceptable Accuracy ◽  
Multiple Mixing ◽  
Tie Lines ◽  
Tie Line ◽  
Equilibrium Calculations

Summary Standard equation-of-state-based phase equilibrium modeling in reservoir simulators involves computationally intensive and time-consuming iterative calculations for stability analysis and flash calculations. Therefore, speeding up stability analysis and flash calculations and improving robustness of the calculations are of utmost importance in compositional reservoir simulation. Prior knowledge of the tie-lines traversed by the solution of a gas-injection problem translates into valuable information with significant implications for speed and robustness of reservoir simulators. The solution of actual-gas-injection processes follows a very complex route because of dispersion, pressure variations, and multidimensional flow. The multiple-mixing-cell (MMC) method, originally developed to calculate minimum miscibility pressure of a gas-injection process, accounts for various levels of mixing of the injected gas and initial oil. This observation suggests that the MMC tie-lines developed upon repeated contacts may represent a significant fraction of the actual simulation tie-lines encountered. We investigate this idea and use three tie-line-based K-value-simulation methods for application of MMC tie-lines in reservoir simulation. In two of the tie-line-based K-value-simulation methods, we examine tabulation and interpolation of MMC tie-lines in a framework similar to the compositional-space adaptive-tabulation (CSAT) method. In the third method, we perform K-value simulations based on inverse-distance interpolation of K-values from MMC tie-lines. We demonstrate that for the displacements examined, the MMC tie-lines are sufficiently close to the actual simulation tie-lines and provide excellent coverage of the simulation compositional route. The MMC-based methods are then compared with the computational time by use of other methods of phase-equilibrium calculations, including a modified application of CSAT (an adaptive tie-line-based K-value simulation), a method using only heuristic techniques, and the standard method in an implicit-pressure/explicit-concentration-type reservoir simulator. The results show that tabulation and interpolation of MMC tie-lines significantly improve phase equilibrium and computational time compared with the standard approach, with acceptable accuracy. The results also show that computational performance of the MMC-based methods with only prior tie-line tables is very close to that of CSAT, which requires flash calculations during simulation. The K-value simulations by use of MMC-based tie-line-interpolation methods improve the total computational time up to 51% in the cases studied, with acceptable accuracy. The results suggest that MMC tie-lines represent a significant fraction of the actual tie-lines during simulation and can be used to significantly improve speed and robustness of phase-equilibrium calculations in reservoir simulators.

Case Study of Condensate Dropout Effect in Unconventional Gas/Condensate Reservoirs with Hydraulically Fractured Wells

2022 ◽  
Author(s):  
Ali H. Alsultan ◽  
Josef R. Shaoul ◽  
Jason Park ◽  
Pacelli L. J. Zitha
Keyword(s):  
Gas Production ◽  
Gas Condensate ◽  
Dew Point ◽  
Productivity Index ◽  
Large Reservoir ◽  
Unconventional Gas ◽  
Gas Condensate Reservoirs ◽  
Liquid Saturation ◽  
Reservoir Volume ◽  
Fracture Performance

Abstract Condensate banking is a major issue in the production operations of gas condensate reservoirs. Increase in liquid saturation in the near-wellbore zone due to pressure decline below dew point, decreases well deliverability and the produced condensate-gas ratio (CGR). This paper investigates the effects of condensate banking on the deliverability of hydraulically fractured wells producing from ultralow permeability (0.001 to 0.1 mD) gas condensate reservoirs. Cases where condensate dropout occurs over a large volume of the reservoir, not only near the fracture face, were examined by a detailed numerical reservoir simulation. A commercial compositional simulator with local grid refinement (LGR) around the fracture was used to quantify condensate dropout as a result of reservoir pressure decline and its impact on well productivity index (PI). The effects of gas production rate and reservoir permeability were investigated. Numerical simulation results showed a significant change in fluid compositions and relative permeability to gas over a large reservoir volume due to pressure decline during reservoir depletion. Results further illustrated the complications in understanding the PI evolution of hydraulically fractured wells in "unconventional" gas condensate reservoirs and illustrate how to correctly evaluate fracture performance in such a situation. The findings of our study and novel approach help to more accurately predict post-fracture performance. They provide a better understanding of the hydrocarbon phase change not only near the wellbore and fracture, but also deep in the reservoir, which is critical in unconventional gas condensate reservoirs. The optimization of both fracture spacing in horizontal wells and well spacing for vertical well developments can be achieved by improving the ability of production engineers to generate more realistic predictions of gas and condensate production over time.

scholarly journals Characteristics and quantitative study on gas breakthrough in developing Yaha-2 condensate gas reservoir in Tarim Basin, China

2018 ◽  
Vol 36 (4) ◽  
pp. 787-800
Author(s):  
Jing Xia ◽  
Pengcheng Liu ◽  
Yuwei Jiao ◽  
Mingda Dong ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Tarim Basin ◽  
Prediction Models ◽  
Graphical Representation ◽  
Gas Injection ◽  
Dew Point ◽  
Breakthrough Time ◽  
Sweep Efficiency ◽  
Reservoir Properties ◽  
Gas Reservoir ◽  
Point Pressure

In order to keep the formation pressure be larger than the dew-point pressure to decrease the loss of condensate oil, cyclic gas injection has been widely applied to develop condensate gas reservoir. However, because the heterogeneity and the density difference between gas and liquid are significant, gas breakthrough appears during cyclic gas injection, which apparently impacts the development effects. The gas breakthrough characteristics are affected by many factors, such as geological features, gas reservoir properties, fluid properties, perforation relations between injectors and producers, and operation parameters. In order to clearly understand the gas breakthrough characteristics and the sensitivity to the parameters, Yaha-2 condensate gas reservoir in Tarim Basin was taken as an example. First, the gas breakthrough characteristic of different perforation relations by injecting natural gas was studied, and the optimal relation was achieved by comparing the sweep efficiency. Then, the designs of orthogonal experiments method were employed to study the sensitivity of gas breakthrough to different parameters. Meanwhile, the characteristic parameters, such as gas breakthrough time, dimensionless gas breakthrough time, and sweep volume, were calculated and the prediction models were achieved. Finally, the prediction models were applied to calculate the gas breakthrough time and sweep volume in Yaha-2 condensate gas reservoir in Tarim Basin. The reliability of the model was verified at the same time. Please see the Appendix for the graphical representation of the abstract.

scholarly journals Regelation and the Deformation of Wet Snow

1978 ◽  
Vol 21 (85) ◽  
pp. 639-650 ◽  
Author(s):  
S. C. Colbeck ◽  
N. Parssinen
Keyword(s):  
Particle Size ◽  
Phase Equilibrium ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Liquid Saturation ◽  
Equilibrium Control ◽  
Wet Snow ◽  
Pressure Melting ◽  
Ionic Impurities ◽  
Particle Geometry

AbstractThe thermodynamics of phase equilibrium control the temperature distribution around the ice particles in wet snow. When the snow is stressed, pressure melting occurs at the inter-particle contacts and the snow densifies. Densification is described by a physical model which simulates the heat flow, meltwater flow, and particle geometry. The effects of ionic impurities, liquid saturation, and particle size are demonstrated. Typical values of the temperature difference, inter-particle film size, and density are calculated as functions of time. The calculated rates of compaction are too large, hence, at some later time, the effects of simultaneous grain growth must be added to the model.

scholarly journals ЗБІЛЬШЕННЯ ДІАПАЗОНУ СТІЙКОЇ РОБОТИ СТУПЕНЯ ВІДЦЕНТРОВОГО КОМПРЕСОРА З БЕЗЛОПАТКОВИМ ДИФУЗОРОМ

2019 ◽  
pp. 4-9
Author(s):  
Микола Васильович Калінкевич ◽  
Микола Іванович Радченко
Keyword(s):  
Mathematical Model ◽  
Gas Injection ◽  
Rotating Stall ◽  
Low Flow ◽  
Stable Operation ◽  
Vaneless Diffuser ◽  
Centrifugal Compressors ◽  
Flow Separation Control ◽  
Flow Part ◽  
Vaneless Diffusers

Centrifugal compressors often operate at different capacities, so it is important to ensure their stable operation over a wide flow range. Stages with vaneless diffusers have several advantages compared to stages with other types of diffusers: they are more technologically advanced to manufacture, and more uniform pressure distribution behind the impeller improves the dynamics of the rotor. At low flows, due to the occurrence of a rotating stall and surge, the efficiency of stages with vaneless diffusers rapidly decreases. The occurrence of unstable operating modes of centrifugal compressor stages at low flow rates is associated with the appearance of developed backflows in the flow part. To expand the range of stable operation of the stages, it is necessary to use methods of flow separation control. Separation of the flow can be controlled either by special profiling the flow part channels or by actively influencing the flow, for example, by injecting gas. To solve this problem, a mathematical model of the gas flow in a vaneless diffuser with gas injection is developed. The characteristics and parameters of the flow in the vaneless diffusers with various meridional profiles with and without injecting gas were calculated. A comparison of the calculated and experimental characteristics of the vaneless diffusers and flow parameters in diffusers with different geometries and with different injection modes confirms the adequacy of the mathematical model. Investigations have confirmed the possibility of improving the characteristics of the stages of centrifugal compressors through the use of vaneless diffusers and diffusers with gas injection. Gas injection diffusers extend the stable operation range of the stages. The use of gas injection in a vaneless diffuser allows reducing the power consumption during antisurge control in comparison with the widespread bypass suction system at the entrance to the impeller

Laboratory Investigation on Oil Increment and Water Cut Control of CO2, N2, and Gas Mixture Huff-n-Puff in Edge-Water Fault-Block Reservoirs

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Peng Wang ◽  
Fenglan Zhao ◽  
Shijun Huang ◽  
Meng Zhang ◽  
Hairu Feng ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Production Efficiency ◽  
Gas Injection ◽  
Co2 Injection ◽  
Gas Mixture ◽  
Injection Volume ◽  
Fault Block ◽  
Asphaltene Deposition ◽  
Water Cut ◽  
Injection Ratio

Abstract Excessive water production is a common matter that seriously affects production efficiency during the development of edge-water fault-block reservoirs. Gas huff-n-puff is an effective water shutoff technology that has the characteristics of small injection volume, no interwell connectivity impact, and minor gas channeling. However, gas injection can destroy the stability of the asphaltene to induce asphaltene deposition. In this article, the laboratory experiment had been conducted to investigate the effect of injection ratio and injection sequence on oil increment and water cut control for gas mixture huff-n-puff. Experimental results indicated that the effect of N2 huff-n-puff on water cut control was the most obvious, while CO2 huff-n-puff had the best performance on oil increment. Oil increment and water cut control of gas mixture huff-n-puff with CO2 injected in advance were obviously better than that of N2 injection preferentially. Subsequently, PVTsim Nova was utilized to investigate whether reducing CO2 injection volume can inhibit asphaltene deposition and predict the possibility of asphaltene deposition at reservoir conditions. Simulation results demonstrated that the asphaltenes were easily deposited with CO2 injection while N2 injection will be unlikely to induce asphaltene deposition. Asphaltene deposition pressure envelope can qualitatively analyze the possibility of asphaltene deposition and provide a reference for screening the appropriate gas injection ratio based on giving full play to the synergistic effect of CO2 and N2. In this study, 7:3 is selected as the optimum injection ratio considering the synergistic effect and the possibility of asphaltene deposition.

Equilibrium Revaporization of Retrograde Condensate By Dry Gas Injection

1968 ◽  
Vol 8 (01) ◽  
pp. 87-94 ◽  
Author(s):  
Lowell R. Smith ◽  
Lyman Yarborough
Keyword(s):  
Gas Flow ◽  
Water Saturation ◽  
Gas Injection ◽  
Gas Condensate ◽  
Dew Point ◽  
Reservoir Pressure ◽  
Sweep Efficiency ◽  
Flowing Fluid ◽  
Condensate Reservoir ◽  
Gas Cycling

Abstract This paper presents results of a laboratory study of retrograde condensate recovery by revaporization into dry injection gas. Flow tests were performed in 10.6-ft long sandpacks at 100F and 1,500 psi. In three runs methane revaporized the liquid from a n-heptane-methane mixture in the presence of immobile water. Two of these tests were water-wet, and the third was totally oil-wet. In the three runs n-heptane recovery was complete after 2.5 hydrocarbon PV of injection. There was no significant performance difference between the two wettability extremes. In a fourth experiment, a methane-hydrogen sulfide mixture revaporized a synthetic light, sour condensate. No water saturation was present. Equilibrium compositions and volumetric data were obtained for the four-component condensate. The heavy component, n-heptane, was removed alter 6 PV production. Comparison of the effluent fluid compositions with known equilibrium data shows that the flowing fluid was equilibrium vapor and that the mixing zone between equilibrium vapor and dry injection gas was short. Data indicated that complete recovery of retrograde liquid occurred after it was contacted by a sufficient quantity of dry gas. Introduction When pressure declines below the fluid dew point in a gas condensate reservoir, a liquid phase forms. In this process, referred to as retrograde condensation, the quantity of liquid formed is frequently small enough that the liquid is not a flowing phase. To prevent loss of valuable retrograde liquids, the process of dry gas cycling has been employed for several years as a more or less standard practice. In this procedure the reservoir pressure is maintained above the fluid dew point so that the liquid components may be produced as vapor and then separated at the surface. Although full pressure maintenance by gas cycling seems ideal in terms of preventing liquids loss, several factors can reduce the attractiveness of such an operation. From a study of a condensate reservoir in Alberta, Canada, Havlena et al. concluded that cycling under conditions of declining pressure leads to economic advantages and to a high recovery of hydrocarbon liquids. This study considered effects of volumetric sweep efficiency, retrograde behavior of the original wet gas and revaporization characteristics of the retrograde liquid when contacted by dry gas. The first major work concerning revaporization of liquid in a gas condensate system is that of Standing et al. Calculations based upon the PVT behavior of a recombined gas condensate fluid indicated that all retrograde liquid can be recovered if it is contacted by a sufficient quantity of dry gas. The paper considered the effect of variable permeability upon the recovery of retrograde liquid. Standing et al. concluded that recovery of heavier components in the retrograde liquid is greatest if reservoir pressure is allowed to decline below the dew point prior to dry gas injection. Since the work of Standing et al., several laboratory studies have been reported which show that recovery of hydrocarbon liquids by vaporization into dry injected gas can contribute to increased recovery above that obtained by ordinary production practices. Vaporization from retrograde condensate, conventional oil and volatile oils reservoirs has been considered. There is little work that deals with revaporization recovery from condensate reservoirs. SPEJ P. 87ˆ

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