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Separator design in petroleum engineering is so important because of its important role in the evaluation of optimum parameters and also to achieve to maximum stock tank liquid. However, no simulator exists that simultaneously and directly optimizes the parameters “pressure”, “temperature”, and so on. On the other hands, Commercial simulators fix one parameter and vary another parameter to achieve the optimum conditions. So, they need long-time simulation. Moreover, gas condensate reservoirs , like another reservoirs , have this problem as well. In present paper, a self-developed simulator applied in the optimized design of gas condensate reservoir’s separators by determining optimized pressure, temperature, and number of separators in order to obtain maximized tank liquid volume and minimized tank liquid density utilizing Matlab software and other commercial simulators such as Aspen-Plus, Aspen-Hysys, and PVTi to do a comparison. Also, each software was separately tested with one, two, and three separators to obtain the optimum number of separators. Additionally, Peng-Robinson equation of state (PR EOS) has been applied in the simulation. For simulation input, a set of field data of gas condensate reservoir has been utilized, as well. The results show a good compatibility of this simulator with other simulators but in so little runtime (this simulator calculates the optimum pressure and temperature in a wide range of pressures and temperatures with the help of a simultaneous optimization algorithm in one stage) and the highest stock tank liquid is calculated with this simulator in comparison to other simulators. Also, with the help of this simulator , we are able to obtain the optimum pressure, temperature, and the number of separators in the gas condensate reservoir’s separators with any desired properties. Finally, this simulator optimizes the temperatures for each separator and obtains very good results despite the other simulators that fix temperatures for all separators in most times.

Gas condensate reservoirs mostly produce gas, with some liquid dropout, frequently occurring in the wellhead separators. The phase diagram shows the retrograde gas must have a temperature higher than the critical temperature. Also, the phase diagram shows the phase changes in the reservoir, while the curve line shows these changes as the fluid cools going up the wellbore and into the separator. In both cases, liquids drop out as the pressure drops below dew point pressure [

Modeling for optimization of the conditions (pressure, temperature, and number of separators) of separators in multistage separators causes to reduce the amount of gas produced with condensate to a minimum [

The separator will be modeled with the help of phase equilibrium calculations. In phase equilibrium calculation, a thermodynamic model and an optimization algorithm must be chosen. A thermodynamic model gives the relation between pressure, molar volume, and temperature for pure components and mixtures. The thermodynamic model is usually nonlinear and nonconvex and therefore, an optimization method must be utilized to find phase equilibrium [

As a result of the optimization technique, the optimization techniques were applied to directly minimize the fluid properties for a specified number of phases [

As mentioned in the previous section, because of the importance of the wellhead separators as well as their parameters optimization due to some problems associated with available commercial simulators, including high cost and time consuming, as well as the lack of a simulator which particularly studies the phase behavior of fluids in gas condensate reservoirs, a new simulator is developed as below.

In this part, we develop a Matlab code to obtain the required optimum parameters with the help of the followed flowchart as

We applied some simulators to optimize the required parameters as mentioned previously to show the ability of these to optimize the separator parameters in gas condensate reservoirs and also to the comparison of these with the developed easy-to-use the simulator to show the ability of this simulator in decreasing time and cost. The existence of an algorithm that simultaneously applies to calculate the temperature and the pressure and gives an optimum temperature and pressure without manual working causes time decreasing. However, existence an algorithm that leads to higher stock tank liquid causes income increasing or cost decreasing especially in a high amount of produced liquid in surface facilities.

With each simulator, the optimum parameters were obtained and important parameters of separators fluids such as liquid and gas density, liquid and gas flow, liquid and gas enthalpy, liquid and gas entropy, and average molecular

weight were observed.

Finally, by applying some rules that liquid volume must be maximum and liquid density must be minimum in separators, we could calculate optimum pressure and temperature with the help of this easy-to-use the simulator.

The simulation occurred with the help of the software below:

a) Aspen Plus b) Aspen Hysys c) PVTi d) Matlab

For analysis, we utilized from a data-set of gas condensate reservoir with 370 k temperature and 250 bar pressure and composition like as

We did calculations in three parts with the Aspen Plus analysis.

Part 1: Simulation with one separator and one stock tank as

Mol percent (−) | Component (−) | No. |
---|---|---|

0.29 | N2 | 1 |

1.72 | CO2 | 2 |

79.14 | C1 | 3 |

7.48 | C2 | 4 |

3.29 | C3 | 5 |

0.51 | IC4 | 6 |

1.25 | NC4 | 7 |

0.36 | IC5 | 8 |

0.55 | NC5 | 9 |

0.61 | C6 | 10 |

4.8 | C7+ | 11 |

analysis results are as

Part 2: Simulation with two separators and one stock tank as

Part 3: Simulation with three separators and one stock tank as

As results, we can see that by increasing in the separators number, the stock tank liquid volume is increased and the stock tank liquid density is decreased as shown in

As shown in

We did calculations in three parts with the Aspen Hysys analysis.

Part 1: Simulation with one separator and one stock tank as

Part 2: Simulation with two separators and one stock tank as

Feed | G1 | G2 | L1 | L2 | ||
---|---|---|---|---|---|---|

C7+ Flow | (kmol/hr) | 4.8 | 3.33E−03 | 8.30E−04 | 4.796675 | 4.795845 |

N2 Flow | (kmol/hr) | 0.29 | 0.285368 | 4.62E−03 | 4.63E−03 | 9.46E−06 |

CO2 Flow | (kmol/hr) | 1.72 | 1.539227 | 0.176727 | 0.180773 | 4.05E−03 |

C1 Flow | (kmol/hr) | 79.14 | 76.17237 | 2.950285 | 2.96763 | 0.017344 |

C2 Flow | (kmol/hr) | 7.48 | 6.47294 | 0.974496 | 1.00706 | 0.032564 |

C3 Flow | (kmol/hr) | 3.29 | 2.31863 | 0.867913 | 0.971371 | 0.103458 |

IC4 Flow | (kmol/hr) | 0.51 | 0.274789 | 0.180572 | 0.235211 | 0.054639 |

NC4 Flow | (kmol/hr) | 1.25 | 0.588138 | 0.463662 | 0.661862 | 0.1982 |

IC5 Flow | (kmol/hr) | 0.36 | 0.111993 | 0.120292 | 0.248008 | 0.127715 |

NC5 Flow | (kmol/hr) | 0.55 | 0.142699 | 0.166146 | 0.407301 | 0.241155 |

C6 Flow | (kmol/hr) | 0.61 | 0.073492 | 0.093216 | 0.536508 | 0.443292 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 87.98297 | 5.998763 | 12.01703 | 6.018266 |

T | (˚C) | 96.85 | 25 | 25 | 25 | 25 |

P | (bar) | 250 | 57 | 1 | 57 | 1 |

Fraction_{VAP}_{.} | (−) | 0.828596 | 1 | 1 | 0 | 0 |

Fraction_{LIQ}_{.} | (−) | 0.171404 | 0 | 0 | 1 | 1 |

Fraction_{SOL}_{.} | (−) | 0 | 0 | 0 | 0 | 0 |

E | (cal/mol) | −22877.4 | −19958.1 | −24034.8 | −50608.3 | −74755.1 |

E | (cal/gm) | −814.732 | −1051.42 | −762.422 | −534.474 | −474.193 |

E | (cal/sec) | −6.35E+05 | −4.88E+05 | −4.00E+04 | −1.69E+05 | −1.25E+05 |

S | (cal/mol-k) | −45.8335 | −30.3582 | −39.2842 | −158.595 | −263.467 |

S | (cal/gm-k) | −1.63227 | −1.59931 | −1.24616 | −1.67492 | −1.67125 |

Ρ | (mol/cc) | 8.81E−03 | 2.73E−03 | 4.07E−05 | 7.04E−03 | 4.90E−03 |

Ρ | (gm/cc) | 0.247364 | 0.051802 | 1.28E−03 | 0.666511 | 0.772773 |

MW_{AV.} | (gm/mol) | 28.07965 | 18.98205 | 31.5243 | 94.68798 | 157.647 |

V_{L} | (cc/min) | 111.8395 | 84.24125 | 7.268958 | 27.59826 | 20.3293 |

Feed | G1 | G2 | G3 | L1 | L2 | L3 | ||
---|---|---|---|---|---|---|---|---|

C7+ Flow | (kmol/hr) | 4.8 | 3.33E−03 | 2.99E−05 | 5.99E−04 | 4.796675 | 4.796645 | 4.796046 |

N2 Flow | (kmol/hr) | 0.29 | 0.285368 | 2.92E−03 | 1.71E−03 | 4.63E−03 | 1.71E−03 | 4.87E−06 |

CO2 Flow | (kmol/hr) | 1.72 | 1.539227 | 0.031015 | 0.145148 | 1.81E−01 | 0.149758 | 4.61E−03 |

C1 Flow | (kmol/hr) | 79.14 | 76.17237 | 1.187863 | 1.765283 | 2.96763 | 1.779767 | 0.014484 |

C2 Flow | (kmol/hr) | 7.48 | 6.47294 | 0.130382 | 0.837625 | 1.00706 | 0.876678 | 0.039054 |

C3 Flow | (kmol/hr) | 3.29 | 2.31863 | 0.046648 | 0.792982 | 0.971371 | 0.924722 | 0.131741 |

IC4 Flow | (kmol/hr) | 0.51 | 0.274789 | 5.28E−03 | 0.161714 | 0.235211 | 0.229926 | 0.068212 |

NC4 Flow | (kmol/hr) | 1.25 | 0.588138 | 0.011132 | 0.407847 | 0.661862 | 0.650731 | 0.242884 |

IC5 Flow | (kmol/hr) | 0.36 | 0.111993 | 1.98E−03 | 0.099258 | 0.248008 | 0.246024 | 0.146766 |

NC5 Flow | (kmol/hr) | 0.55 | 0.142699 | 2.50E−03 | 0.134063 | 0.407301 | 0.404805 | 0.270743 |

C6 Flow | (kmol/hr) | 0.61 | 0.073492 | 1.18E−03 | 0.070246 | 0.536508 | 0.535324 | 0.465077 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 87.98297 | 1.420939 | 4.41647 | 12.01703 | 10.59609 | 6.17962 |

T | (˚C) | 96.85 | 25 | 25 | 25 | 25 | 25 | 25 |

P | (bar) | 250 | 57 | 38 | 1 | 57 | 38 | 1 |

Fraction_{VAP}_{.} | (−) | 0.828596 | 1 | 1 | 1 | 0 | 0 | 0 |

Fraction_{LIQ}_{.} | (−) | 0.171404 | 0 | 0 | 0 | 1 | 1 | 1 |

Fraction_{SOL}_{.} | (−) | 0 | 0 | 0 | 0 | 0 | 0 | 0 |

E | (cal/mol) | −22877.4 | −19958.1 | −20323 | −24992.9 | −50608.3 | −54557.9 | −73795.8 |

E | (cal/gm) | −814.732 | −1051.42 | −1036.32 | −730.942 | −534.474 | −520.81 | −475.531 |

E | (cal/sec) | −6.35E+05 | −4.88E+05 | −8021.61 | −30661.2 | −1.69E+05 | −1.61E+05 | −1.27E+05 |

S | (cal/mol-k) | −45.8335 | −30.3582 | −29.9179 | −43.1607 | −158.595 | −175.176 | −259.43 |

S | (cal/gm-k) | −1.63227 | −1.59931 | −1.52558 | −1.26228 | −1.67492 | −1.67223 | −1.67173 |

Ρ | (mol/cc) | 8.81E−03 | 2.73E−03 | 1.73E−03 | 4.07E−05 | 7.04E−03 | 6.63E−03 | 4.96E−03 |

Ρ | (gm/cc) | 0.247364 | 0.051802 | 0.034017 | 1.39E−03 | 0.666511 | 0.694998 | 0.770258 |

MW_{AV.} | (gm/mol) | 28.07965 | 18.98205 | 19.61078 | 34.19267 | 94.68798 | 104.7559 | 155.1862 |

V_{L} | (cc/min) | 111.8395 | 84.24125 | 1.381344 | 5.600417 | 27.59826 | 26.21692 | 20.6165 |

Feed | G1 | G3 | G4 | L1 | L2 | L3 | L4 | ||
---|---|---|---|---|---|---|---|---|---|

C7+ Flow | (kmol/hr) | 4.8 | 3.33E−03 | 1.15E−04 | 8.35E−05 | 4.796675 | 4.796645 | 4.796529 | 4.796446 |

N2 Flow | (kmol/hr) | 2.90E−01 | 2.85E−01 | 1.68E−03 | 3.07E−05 | 4.63E−03 | 1.71E−03 | 3.14E−05 | 6.41E−07 |

CO2 Flow | (kmol/hr) | 1.72 | 1.539227 | 1.25E−01 | 0.020164 | 1.81E−01 | 0.149758 | 2.48E−02 | 4.61E−03 |

C1 Flow | (kmol/hr) | 79.14 | 76.17237 | 1.689443 | 0.085201 | 2.96763 | 1.779767 | 9.03E−02 | 5.12E−03 |

C2 Flow | (kmol/hr) | 7.48 | 6.47294 | 0.675978 | 0.149642 | 1.00706 | 0.876678 | 0.200701 | 0.051059 |

C3 Flow | (kmol/hr) | 3.29 | 2.31863 | 0.454155 | 0.212735 | 0.971371 | 0.924722 | 0.470568 | 0.257833 |

IC4 Flow | (kmol/hr) | 5.10E−01 | 0.274789 | 0.063909 | 0.040708 | 0.235211 | 0.229926 | 0.166017 | 0.12531 |

NC4 Flow | (kmol/hr) | 1.25 | 0.588138 | 0.140246 | 0.095643 | 0.661862 | 0.650731 | 0.510485 | 0.414842 |

IC5 Flow | (kmol/hr) | 3.60E−01 | 0.111993 | 0.024874 | 0.018816 | 0.248008 | 0.246024 | 0.22115 | 0.202334 |

NC5 Flow | (kmol/hr) | 5.50E−01 | 0.142699 | 0.031085 | 0.023904 | 0.407301 | 0.404805 | 0.37372 | 0.349817 |

C6 Flow | (kmol/hr) | 6.10E−01 | 0.073492 | 0.013367 | 0.010629 | 0.536508 | 0.535324 | 0.521956 | 0.511327 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 87.98297 | 3.219836 | 0.657556 | 12.01703 | 10.59609 | 7.376254 | 6.718698 |

T | (˚C) | 96.85 | 25 | 25 | 25 | 25 | 25 | 25 | 25 |

P | (bar) | 250 | 57 | 4 | 1 | 57 | 38 | 4 | 1 |

Fraction_{VAP}_{.} | (−) | 0.828596 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |

Fraction_{LIQ}_{.} | (−) | 0.171404 | 0 | 0 | 0 | 1 | 1 | 1 | 1 |

Fraction_{SOL}_{.} | (−) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |

E | (cal/mol) | −22877.4 | −19958.1 | −23499.5 | −27201.4 | −50608.3 | −54557.9 | −67255.3 | −70822.1 |

E | (cal/gm) | −814.732 | −1051.42 | −839.969 | −637.115 | −534.474 | −520.81 | −486.402 | −479.743 |

E | (cal/sec) | −6.35E+05 | −4.88E+05 | −21018 | −4968.46 | −1.69E+05 | −1.61E+05 | −1.38E+05 | −1.32E+05 |

S | (cal/mol-k) | −45.8335 | −30.3582 | −36.0418 | −56.9177 | −158.595 | −175.176 | −231.344 | −247.065 |

S | (cal/gm-k) | −1.63227 | −1.59931 | −1.28828 | −1.33313 | −1.67492 | −1.67223 | −1.67312 | −1.6736 |

ρ | (mol/cc) | 8.81E−03 | 2.73E−03 | 1.66E−04 | 4.09E−05 | 7.04E−03 | 6.63E−03 | 5.43E−03 | 5.16E−03 |

ρ | (gm/cc) | 0.247364 | 5.18E−02 | 4.63E−03 | 1.75E−03 | 0.666511 | 0.694998 | 0.751315 | 0.762066 |

MW_{AV.} | (gm/mol) | 28.07965 | 18.98205 | 27.97669 | 42.69463 | 94.68798 | 104.7559 | 138.271 | 147.625 |

V_{L} | (cc/min) | 111.8395 | 84.24125 | 3.715306 | 0.948889 | 27.59826 | 26.21692 | 22.50161 | 21.55272 |

Feed | G1 | L1 | L3 | ||
---|---|---|---|---|---|

Flow fraction_{VAP}_{.} | (−) | 0.863477 | 1 | 0 | 0 |

T | (˚C) | 96.85 | 26.15107 | 26.15107 | 6.440161 |

P | (kpa) | 25000 | 7000 | 7000 | 100 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 88.42481 | 11.57519 | 6.276834 |

Flow_{TOT}_{.} | (kg/hr) | 2807.982 | 1688.545 | 1119.436 | 965.2965 |

V_{L} | (m3/hr) | 6.702509 | 5.085935 | 1.616573 | 1.24514 |

Q | (kj/hr) | 9,783,158 | 7,468,622 | 2,661,763 | 2,143,982 |

Part 3: Simulation with three separators and one stock tank as

As results, we can see that by increasing in the separators number, the stock tank liquid volume is increased and the stock tank liquid density is decreased as shown in

Feed | G1 | G2 | G3 | L1 | L3 | L5 | ||
---|---|---|---|---|---|---|---|---|

Flow fraction_{VAP}_{.} | (−) | 0.863477 | 1 | 1 | 1 | 0 | 0 | 0 |

T | (˚C) | 96.85 | 26.15107 | 24.30809 | 8.421311 | 26.15107 | 24.30809 | 8.421311 |

P | (kpa) | 25000 | 7000 | 4000 | 100 | 7000 | 4000 | 100 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 88.42481 | 1.682519 | 3.453154 | 11.57519 | 9.892669 | 6.439515 |

Flow_{TOT}_{.} | (kg/hr) | 2807.982 | 1688.545 | 33.16979 | 111.4076 | 1119.436 | 1086.267 | 974.859 |

V_{L} | (m^{3}/hr) | 6.702509 | 5.085935 | 9.83E−02 | 0.256468 | 1.616573 | 1.518244 | 1.261776 |

Q | (kj/hr) | −9,783,158 | −7,468,622 | −144,383 | −352,291 | −2,661,763 | −2,517,380 | −2,165,089 |

Feed | G1 | G2 | L1 | L3 | L5 | L7 | ||
---|---|---|---|---|---|---|---|---|

Flow fraction_{VAP}_{.} | (−) | 0.863477 | 1 | 1 | 0 | 0 | 0 | 0 |

T | (˚C) | 96.85 | 26.15107 | 24.30809 | 26.15107 | 24.30809 | 21.45056 | 10.80439 |

P | (kpa) | 25000 | 7000 | 4000 | 7000 | 4000 | 1500 | 100 |

Flow_{TOT}_{.} | (kmol/hr) | 100 | 88.42481 | 1.682519 | 11.57519 | 9.892669 | 8.452935 | 6.673252 |

Flow_{TOT}_{.} | (kg/hr) | 2807.982 | 1688.545 | 33.16979 | 1119.436 | 1086.267 | 1054.275 | 988.1731 |

V_{L} | (m^{3}/hr) | 6.702509 | 5.085935 | 9.83E−02 | 1.616573 | 1.518244 | 1.428958 | 1.285273 |

Q | (kj/hr) | −9783158 | −7468622 | −144383 | −2661763 | −2517380 | −2386674 | −2195199 |

As shown in

We did calculations in one part with the PVTi analysis.

Sep.1 | Sep.2 | Sep.3 | S.T. | ||
---|---|---|---|---|---|

Mol fraction_{VAP}_{.} | (−) | 0.888 | 0.9039 | 0.928 | 0.928 |

Mol fraction_{LIQ}_{.} | (−) | 0.112 | 0.0961 | 0.072 | 0.072 |

V_{V} | (Sm^{3}) | 21.0368 | 21.4149 | 21.9865 | 21.9865 |

V_{L} | (m^{3}) | 0.0158 | 0.0148 | 0.0131 | 0.013 |

GOR | (Sm^{3}/m^{3}) | 1328.286 | 1442.772 | 1677.038 | 1677.038 |

B_{O} | (Rm^{3}/Sm^{3}) | 1.2144 | 1.1382 | 1.0053 | 1.0053 |

ρ_{V} | (kg/m^{3}) | 54.6194 | 34.7169 | 12.375 | 0.8276 |

ρ_{L} | (kg/m^{3}) | 704.8399 | 724.8136 | 757.6122 | 761.6396 |

MW_{AV.V} | (kgm/Kmol) | 19.0365 | 19.148 | 19.54 | 19.54 |

MW_{AV.L} | (kgm/Kmol) | 99.6357 | 111.975 | 138.0461 | 138.0461 |

T | (k) | 298.15 | 298.15 | 298.15 | 288.7056 |

P | (bar) | 60 | 40 | 15 | 1.0132 |

Simulation with three separators and one stock tank was done and the simulation results are as

We did the calculations with the help of the two parameters Peng-Robinson equation of state (PR EOS) as shown in Equations (1) through (8) [

P = R T V − b − a c α V ( V + b ) + b ( V − b ) (1)

a c = 0.457235 R 2 T c 2 P c (2)

b = 0.077796 R T c P c (3)

m = 0.3796 + 1.485 ω − 0.1644 ω 2 + 0.01667 ω 3 (4)

A = a P ( R T ) 2 (5)

B = b P R T (6)

z 3 − ( 1 − B ) z 2 + ( A − 2 B − 3 B 2 ) z − ( A B − B 2 − B 3 ) = 0 (7)

ln ∅ = ( z − 1 ) − ln ( z − B ) + A 2 B 2 ln z + ( 1 − 2 ) B z + ( 1 + 2 ) B (8)

where P, V, T, R, a_{c}, b, α, P_{c}, T_{c}, ω, φ, and z are the pressure, volume, temperature, universal gas constant, real gas correction factor due to the intermolecular forces, real gas correction factor due to the gas molecular size, temperature-dependent parameter, critical pressure, critical temperature, acentric factor, fugacity coefficient and compressibility factor, respectively.

Equilibrium ratio (k_{i}) was calculated with the help of the Wilson Correlation as shown in Equation (9) [

k i = ( P c i P ) exp ( 5.37 ( 1 + ω i ) ( 1 − T c i T ) ) (9)

Subscript “i” is related to i-component in the two-phase solution.

Flash calculations were calculated with the flash calculations equations as shown in Equations ((10) and (12)):

x i = z i 1 + ( k i − 1 ) n v (10)

y i = z i k i 1 + ( k i − 1 ) n v (11)

f ( n v ) = ∑ i = 1 n ( y i − x i ) = ∑ i = 1 n z i ( k i − 1 ) 1 + ( k i − 1 ) n v = 0 (12)

where x_{i}, y_{i}, z_{i}, and n^{v} are the mole percent of i-component in the liquid phase, mole percent of i-component in the gas phase, mole percent of i-component in the two-phase solution, and volume percent of gas (vapor) phase, respectively.

We developed a code that is able to calculate equilibrium calculations for any specific data set and also to obtain the optimum parameters with the help of the algorithms as shown in

Simulation with three separators and one stock tank was done and simulation results are as

Sep.1 | Sep.2 | Sep.3 | S.T. | ||
---|---|---|---|---|---|

Liq. output | (kmol/hr) | 11.69 | 10.47 | 9.13 | 8.72 |

T | (˚C) | 31.85 | 22.85 | 30.85 | 25 |

P | (bar) | 63 | 38 | 13 | 1 |

Sep.1 | Sep.2 | Sep.3 | S.T. | Sep.1 | Sep.2 | Sep.3 | S.T. | ||
---|---|---|---|---|---|---|---|---|---|

Component | z_{i}_{ }(−) | x_{i} (−) | x_{i} (−) | x_{i} (−) | x_{i} (−) | y_{i} (−) | y_{i} (−) | y_{i} (−) | y_{i} (−) |

N2 | 0.29 | 0.02 | 0.01 | 0 | 0 | 0.33 | 0.15 | 0.05 | 0.01 |

CO2 | 1.72 | 1.44 | 1.33 | 0.83 | 0.49 | 1.75 | 2.19 | 4.73 | 2.95 |

C1 | 79.14 | 15.28 | 8.53 | 1.97 | 0.43 | 87.54 | 72.41 | 53.18 | 12.31 |

C2 | 7.48 | 9.2 | 9.01 | 6.71 | 0.466 | 7.23 | 9.73 | 24.59 | 18.29 |

C3 | 3.29 | 11.63 | 12.47 | 12.65 | 11.99 | 2.15 | 3.02 | 10.87 | 11.03 |

IC4 | 0.51 | 2.82 | 3.07 | 3.35 | 3.41 | 0.2 | 0.27 | 1.09 | 1.18 |

NC4 | 1.25 | 7.7 | 8.42 | 9.31 | 9.62 | 0.37 | 0.51 | 2.09 | 2.31 |

IC5 | 0.36 | 2.64 | 2.9 | 3.27 | 3.45 | 0.05 | 0.07 | 0.029 | 0.32 |

NC5 | 0.55 | 4.16 | 4.57 | 5.17 | 5.46 | 0.06 | 0.08 | 0.35 | 0.39 |

C6 | 0.61 | 4.93 | 5.43 | 6.18 | 6.58 | 0.02 | 0.03 | 0.13 | 0.15 |

C7+ | 4.8 | 40.18 | 44.26 | 50.55 | 53.93 | 0 | 0 | 0 | 0 |

gas phases were calculated for each separator stage too as

Code analysis in the optimum parameters calculations shows that output liquid volume and density from the third separator or input liquid volume and density into stock tank calculated from the code is higher and lower than calculated from other simulators that are very important issue in petroleum engineering surface facilities. According to the algorithm, calculations of the third separators in a range of pressures and temperatures shown in

Finally, we concern on the optimum parameters calculated with the different simulators to do a comparison. Optimum pressure, temperature, and liquid output volume calculated from the different simulators are as Figures 12(a)-(c).

The liquid output from the third separator is very important that is maximum in the code calculations in comparison to other simulators as

A computer simulator is written to optimize the pressure, temperature, and the number of separators of gas condensate reservoir’s separators using Matlab software and other commercial simulators such as Aspen-Plus, Aspen-Hysys, and PVTi to do a comparison. This simulator is in good agreement with other

simulators to predict the required parameters.

Also, this simulator is an easy-to-use simulator that the required parameters are directly obtained from it with the help of a simple algorithm.

Additionally, this simulator considers temperature variation with pressure variation simultaneously, and also this simulator is able to show optimum pressure and temperature between any ranges of pressures and temperatures that the user enters into this simulator. So, calculations and optimizations are done without any manual working. Finally, we can see the effect of various parameters on the optimum parameters in a so little runtime.

By considering the effect of both the pressure and the temperature in the optimum parameters (the stock tank liquid volume and the density), this simulator gives the highest amount of liquid volume into the stock tank in comparison to the other commercial simulators.

Also, by considering high amount of produced fluid in the wellhead, if the increased produced liquid volume which is predicted by the simulator is so little, the increased produced liquid volume which is practically predicted is so much in volume, because of the difference in the units. Therefore, it has very economical advantages.

Eventually, this simulator can be coupled with the other simulators to separator analysis with high accuracy.

The acknowledgments are for the Shiraz University for supporting this research.

Ejraei Bakyani, A., Heidari, S., Rasti, A. and Namdarpoor, A. (2018) Developing an Easy-to-Use Simulator to Thermodynamic Design of Gas Condensate Reservoir’s Separators. Modeling and Numerical Simulation of Material Science, 8, 1-19. https://doi.org/10.4236/mnsms.2018.81001

Economic Analysis of the Developed Simulator

Simulator’s feed is calculated as kmol/hr (100 kmol/hr), but field’s feed is calculated as bbl/day (5000 bbl/day for example). So, 100 kmol/hr is equivalent to 5000 bbl/day. If stock tank liquid calculated from various simulators is different (CODE and ASPEN HYSYS) and this difference was 0.68 kmol/hr (9.13 kmol/hr −8.45 kmol/hr), so it is equivalent to a high amount of bbl liquid in several years by applying the appropriate conversion factor.

0.68 kmol / hr × 147.625 kgr / kmol × 1 0.762066 lit / kgr × 1 160 bbl / lit × 24 hr / day ≈ 20 bbl / day

For 5 years:

5 year × 365 day / year × 20 bbl / day ≈ 36500 bbl

Economical view:

36500 bbl × 40 $ / bbl ≈ 1460000 $

T Temperature

P Pressure

Fraction_{VAP}_{.}_{ }Vapor fraction in input flow to separators

Fraction_{LIQ}_{.}_{ }Liquid fraction in input flow to separators

Fraction_{SOL}_{.}_{ }Solid fraction in input flow to separators

E Enthalpy

S Entropy

ρ Average density

ρ_{L}_{ }Liquid density

ρ_{V}_{ }Vapor density

MW_{AV.}_{ }Average molecular weight

MW_{AV.L }Liquid average molecular weight

MW_{AV.V }Vapor average molecular weight

V_{L }Liquid volume

V_{V }Vapor volume

Q Heat rate

GOR Gas oil ratio

B_{o }Oil formation volume factor

z_{i}_{ }Mole percent of i-component in two phase flow

x_{i}_{ }Mole percent of i-component in liquid phase

y_{i}_{ }Mole percent of i-component in vapor phase