scholarly journals Evaluation of black-oil PVT-model applicability for simulation of gas-condensate reservoirs

2020 ◽  
pp. 43-48
Author(s):  
O. V. Burachok ◽  
D. V. Pershyn ◽  
S. V. Matkivskyi ◽  
O. R. Kondrat
Keyword(s):  
Phase Transitions ◽  
Phase Equilibrium ◽  
Phase Behavior ◽  
Oil And Gas ◽  
Gas Condensate ◽  
Potential Yield ◽  
Model Application ◽  
Compositional Model ◽  
Black Oil ◽  
Black Oil Model

Creation of geological and simulation models is the necessary condition for decision making towards current development status, planning of well interventions, field development planning and forecasting. In case of isothermal process, for proper phase behavior and phase transitions two key approaches are used: a) simplified model of non-volatile oil, so called “black oil” model, in which each phase – oil, water and gas, are represented by respective component, and solution to fiow equations is based on finding the saturations and pressures in each numerical cell, and change of reservoir fiuid properties is defined in table form as a function of pressure; b) compositional model, in which based on equation of state, phase equilibrium is calculated for hydrocarbon and non-hydrocarbon components, and during fiow calculations, apart from saturations and pressures, oil and gas mixture is brought to phase equilibrium, and material balance is calculated for each component in gas and liquid phase. To account for components volatility, the classic black oil model was improved by adding to the formulation gas solubility and vaporized oil content. This allows its application for the majority of oil and gas reservoirs, which are far from critical point and in which the phase transitions are insignificant. Due to smaller number of variables, numerical solution is simpler and faster. But, considering the importance and relevance of increasing the production of Ukrainian gas and optimization of gas-condensate fields development, the issue of simplified black oil PVT-model application for phase behavior characterization of gas-condensate reservoirs produced under natural depletion depending on the liquid hydrocarbon’s potential yield. Comparative study results on evaluation of production performance of synthetic reservoir for different synthetically-generated reservoir fiuids with different С5+ potential yield is provided as plots and tables. Based on the results the limit of simplified black oil PVT-model application and the moment of transition to compositional model for more precise results could be defined.

scholarly journals Reservoir Simulation Analysis of Pressure Depletion Performance in Gas-Condensate Reservoirs: Black-Oil and Compositional Approaches

2021 ◽  
pp. 119-137
Author(s):  
Akinsete O. Oluwatoyin ◽  
Anuka A. Agnes
Keyword(s):  
Relative Permeability ◽  
Reservoir Simulation ◽  
Gas Condensate ◽  
Productivity Index ◽  
Liquid Density ◽  
Gas Condensate Reservoirs ◽  
Compositional Model ◽  
Pressure Depletion ◽  
Black Oil ◽  
Black Oil Model

Pressure depletion in gas-condensate reservoirs create two-phase flow. It is pertinent to understand the behavior of gas-condensate reservoirs as pressure decline in order to develop proper producing strategies that would increase gas and condensate productivity. Eclipse 300 was used to simulate gas-condensate reservoirs, a base case model was created using both black-oil and compositional models. The effects of three Equation of States (EOS) incorporated into the models were analysed and condensate dropout effect on relative permeability was studied. Analysis of various case models showed that, gas production was maintained at 500MMSCF/D for about 18 and 12 months for black-oil and compositional models, respectively. However, the compositional model revealed that condensate production began after a period of two months at 50MSTB/D whereas for the black oil model, condensate production began immediately at 32MSTB/D. Comparison of Peng-Robinson EOS, Soave-Redlich-Kwong EOS and Schmidt Wenzel EOS gave total estimates of condensate production as 19MMSTB, 15MMSTB and 9MMSTB and initial values of gas productivity index as 320, 380 and 560, respectively. The results also showed that as condensate saturation increased, the relative permeability of gas decreased from 1 to 0 while the relative permeability of oil increased from 0.15 to 0.85. The reservoir simulation results showed that compositional model is better than black-oil model in modelling for gas-condensate reservoirs. Optimal production was obtained using 3-parameter Peng-Robinson and Soave-Redlich-Kwong EOS which provide a molar volume shift to prevent an underestimation of liquid density and saturations. Phase behaviour and relative permeability affect the behaviour of gas-condensate reservoirs.

Assessment of Non-Equilibrium Phase Behavior Model Parameters for Oil and Gas-Condensate Systems by Laboratory and Field Studies (Russian)

2020 ◽  
Author(s):  
Ilya Mikhailovich Indrupskiy ◽  
Mikhail Yurievich Danko ◽  
Timur Nikolaevich Tsagan-Mandzhiev ◽  
Ayguzel Ilshatovna Aglyamova
Keyword(s):  
Phase Behavior ◽  
Oil And Gas ◽  
Equilibrium Phase ◽  
Field Studies ◽  
Gas Condensate ◽  
Model Parameters ◽  
Behavior Model ◽  
Non Equilibrium

An Equation of State Compositional Model

1980 ◽  
Vol 20 (05) ◽  
pp. 363-376 ◽  
Author(s):  
Keith H. Coats
Keyword(s):  
Equation Of State ◽  
Critical Point ◽  
Oil And Gas ◽  
Numerical Models ◽  
Volatile Oil ◽  
Gas Condensate ◽  
Numerical Dispersion ◽  
Stable Convergence ◽  
Compositional Model ◽  
Miscible Flooding

Abstract This paper describes an implicit, three-dimensional formulation for simulating compositional-type reservoir problems. The model treats three-phase flow in Cartesian (x-y-z) or cylindrical (r-theta-z) geometries. Applicability ranges from depletion or cycling of volatile oil and gas condensate to miscible flooding operations involving either outright or multicontact-miscibility.The formulation uses an equation of state for phase equilibrium and property calculations. The equation of state provides consistency and smoothness as gas- and oil-phase compositions and properties converge near a critical point. This avoids computational problems near a critical point associated with use of different correlations for K values as opposed to phase densities. Computational testing with example multicontact-miscibility (MCM) problems indicates stable convergence of this formulation as phase properties converge at a critical point. Results for these MCM problems show significant numerical dispersion, primarily affecting the calculated velocity of the miscible-front advance. Our continuing effort is directed toward reduction of this numerical disperson and comparison of model results with laboratory experiments for both MCM and outright-miscibility cases.We feel that the implicit nature of the model enhances efficiency as well as reliability for most compositional-type problems. However, while we report detailed problem results and associated computing times, we lack similar reported times to compare the overall efficiency of an implicit compositional formulation with that of a semi-implicit formulation. Introduction Many papers have treated increasingly sophisticated or efficient methods for numerical modeling of black-oil reservoir performance. That type of reservoir allows an assumption that reservoir gas and oil have different but fixed compositions, with the solubility of gas in oil being dependent on pressure alone.A smaller number of papers have presented numerical models for simulating isothermal "compositional" reservoirs, where oil and gas equilibrium compositions vary considerably with spatial position and time. With some simplification, the reservoir problems requiring compositional treatment can be divided into two types. The first type is depletion and/or cycling of volatile oil and gas condensate reservoirs. The second type is miscible flooding with MCM generated in situ.A distinction between these types is that the first usually involves phase compositions removed from the critical point, while the second type generally requires calculation of phase compositions and properties converging at the critical point. A compositional model should be capable of treating the additional problem of outright miscibility where the original oil and injected fluid are miscible on first contact.A difficulty in modeling the MCM process is achievement of consistent, stable convergence of gas-and oil-phase compositions, densities, and viscosities as the critical point is approached. A number of studies have reported models that use different correlations for equilibrium K-values as opposed to phase densities. Use of an equation of state offers the advantage of a single, consistent source of calculated K-values, phase densities, and their densities near a critical point. SPEJ P. 363＾

A Case History for an Integrated Asset Model with Fluid Delumping for a Complex Gas Condensate Field

2021 ◽  
Author(s):  
Mohamed Ibrahim Mohamed ◽  
Ahmed Mahmoud El-Menoufi ◽  
Eman Abed Ezz El-Regal ◽  
Ahmed Mohamed Ali ◽  
Khaled Mohamed Mansour ◽  
...  
Keyword(s):  
Development Planning ◽  
Production Optimization ◽  
Operating Conditions ◽  
Gas Condensate ◽  
Western Desert ◽  
Design Parameters ◽  
Compositional Model ◽  
Compositional Approach ◽  
Process Plant ◽  
Black Oil

Abstract Field development planning of gas condensate fields using numerical simulation has many aspects to consider that may lead to a significant impact on production optimization. An important aspect is to account for the effects of network constraints and process plant operating conditions through an integrated asset model. This model should honor proper representation of the fluid within the reservoir, through the wells and up to the network and facility. Obaiyed is one of the biggest onshore gas field in Egypt, it is a highly heterogeneous gas condensate field located in the western desert of Egypt with more than 100 wells. Three initial condensate gas ratios are existing based on early PVT samples and production testing. The initial CGR values are as following;160, 115 and 42 STB/MMSCF. With continuous pressure depletion, the produced hydrocarbon composition stream changes, causing a deviation between the design parameters and the operating parameters of the equipment within the process plant, resulting in a decrease in the recovery of liquid condensate. Therefore, the facility engineers demand a dynamic update of a detailed composition stream to optimize the system and achieve greater economic value. The best way to obtain this compositional stream is by using a fully compositional integrated asset model. Utilizing a fully compositional model in Obaiyed is challenging, computationally expensive, and impractical, especially during the history match of the reservoir numerical model. In this paper, a case study for Obaiyed field is presented in which we used an alternative integrated asset modeling approach comprising a modified black-oil (MBO) that results in significant timesaving in the full-field reservoir simulation model. We then used a proper de-lumping scheme to convert the modified black oil tables into as many components as required by the surface network and process plant facility. The results of proposed approach are compared with a fully compositional approach for validity check. The results clearly identified the system bottlenecks. The model enables the facility engineers to keep the conditions of the surface facility within the optimized operating envelope throughout the field's lifetime and will be used to propose new locations and optimize the tie-in location of future wells in addition to providing flow assurance indications throughout the field's life and under different network configurations.

scholarly journals Evaluating the Challenges in Pressure – Volume – Temperature (PVT) Analysis of Gas Condensate Reservoirs

2020 ◽  
pp. 13-18
Author(s):  
Aniedi B. Usungedo ◽  
Julius U. Akpabio
Keyword(s):  
Gas Condensate ◽  
Production Performance ◽  
Prediction Algorithm ◽  
Pvt Properties ◽  
Volume Depletion ◽  
Volume Factor ◽  
Gas Condensate Reservoirs ◽  
Compositional Model ◽  
Compositional Modeling ◽  
Black Oil

Aims: The variations in production performances of the Black oil and compositional simulation models can be evaluated by simulating oil formation volume factor (Bo), gas formation volume factor (Bg), gas-oil ratio (Rs) and volatilized oil-gas ratio (Rv). The accuracy of these two models could be assessed. Methodology: To achieve this objective some basic parameters were keyed into matrix laboratory (MATLAB) using the symbolic mathematical toolbox to obtain accurate Pressure Volume Temperature (PVT) properties which were used in a production and systems analysis software to generate the production performance and hydrocarbon recovery estimation. Standard black oil PVT properties for a gas condensate reservoir was simulated by performing a series of flash calculations based on compositional modeling of the gas condensate fluid at the prescribed conditions through a constant volume depletion (CVD) path. These series of calculations will be carried out using the symbolic math toolbox. PVT property values obtained from both compositional modeling and black oil PVT prediction algorithm are incorporated to determine the production performance of each method for comparison. Results: The absolute open flow for the black oil PVT algorithm and the compositional model for the Rs value of 500 SCF/STB and Rs value of 720SCF/STB were 130,461 stb/d and 146,028 stb/d respectively showing a 10.66% incremental flow rate. Conclusion: In analyzing PVT properties for complex systems such as gas condensate reservoirs, the use of compositional modeling should be practiced. This will ensure accurate prediction of the reservoir fluid properties.

APPLICATION OF THE BLACK OIL PVT REPRESENTATION TO SIMULATION OF GAS CONDENSATE RESERVOIR PERFORMANCE

1987 ◽  
Vol 27 (1) ◽  
pp. 370
Author(s):  
W.H. Goldthorpe ◽  
J.K. Drohm
Keyword(s):  
Oil And Gas ◽  
Volatile Oil ◽  
Gas Condensate ◽  
Phase Behaviour ◽  
Dew Point ◽  
Pressure Drops ◽  
Gas Condensate Reservoirs ◽  
Reservoir Performance ◽  
Black Oil ◽  
Condensate Reservoir

Special attention must be paid to the generation of PVT parameters when applying conventional black oil reservoir simulators to the modelling of volatile oil and gas-condensate reservoirs. In such reservoirs phase behaviour is an important phenomenon and common approaches to approximating this, via the black oil PVT representation, introduce errors that may result in prediction of incorrect recoveries of surface gas and condensate. Further, determination of production tubing pressure drops for use in such simulators is also prone to errors. These affect the estimation of well potentials and reservoir abandonment pressures.Calculation of black oil PVT parameters by the method of Coats (1985) is shown to be preferred over conventional approaches, although the PVT parameters themselves lose direct physical meaning. It is essential that a properly tuned equation of state be available for use in conjunction with experimental data.Production forecasting based on simulation output requires further processing in order to translate the black oil surface phase fluxes into products such as sales gas, LPG and condensate. For gas-condensate reservoirs, such post-processing of results from the simulation of depletion or cycling above the dew point is valid. In principle it is invalid for cycling below the dew point but in practice it can still provide useful information.

Compositional Simulation of Gas Condensate Wells from Tintea � ASTRA Field

2001 ◽  
Vol 71 (3) ◽  
pp. 466-479
Author(s):  
Ayham Mhanna ◽  
Florinel Dinu ◽  
Lazar Avram ◽  
Mohamed Halafawi
Keyword(s):  
Liquid Phase ◽  
Simulation Model ◽  
Phase Behavior ◽  
Productivity Loss ◽  
Fluid Phase ◽  
Gas Condensate ◽  
Compositional Simulation ◽  
Compositional Model

The main aim of this article is to simulate the performance of gas condensate wells utilizing compositional model. Compositional simulation model is done for available data of three drilled wells A, B, and C of this field. P-T diagrams of wells A, B, and C of various critical pressures and temperatures, and various cricondentherm, and cricondenbar are constructed. Results show that composition varies significantly as a function of fluid phase behavior and producing sequence; condensate recovery can be improved with proper producing strategy, and productivity loss can be reduced by changing the producing sequence. Additionally, well A yields the liquid phase (gasoline with condensation traces) due to the present of C7 + C8 components in the mixture starting with the exit of the gases from the choke and up to the separator. However, wells B and C do not yield the liquid phase along the entire tubing path traveled by the extracted gases from the producing zone to the heater of the wells B and C.

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