PVT module coupled with ANSYS – CFD

Basic Ideas:

• In order to perform realistic CFD simulations for the Oil & Gas industry, it is important to know:

What kind of fluid are we dealing with? Heavy Oil. Light Oil. Gas – Condensate.

How many phases will be present for a given process? Liquid – Vapor. Liquid – Liquid. Liquid – Liquid – Vapor. Fluid – Solid.

What are the physical properties for each phase? Density. Viscosity… at least.

Basic Ideas:

• PVT information for a specific fluid come from a Lab report – “PVT Report”

• Information:

Composition. Saturation pressure (s) Amount of gas and liquid. Properties such as density and viscosity as pressure and

temperature functions.

Basic Ideas:

• As far as we know, there isn’t any tool or application to help the user to directly charge the information contained in the PVT report into CFX or Fluent.

• So, there is a User’s need to incorporate real properties into CFD.

Basic Ideas:

• The lab information contained in a PVT report can be modeled in what in the Oil & Gas Industry is known as “PVT Module”.

• PVT Module: A program developed to simulate the lab information and tune an Equation-of-State based model.

Represent the experimental data. Predict properties where there is no experimental data

available.

Basic Ideas:

To help users of ANSYS – CFD to deal with complex fluids such as reservoir fluids, an easy connection between a PVT module and ANSYS – CFD is needed. Which module? Grupo SSC is developing an “In-House” PVT module, we

are not using PVTSim, Multiflash, PVTPro or any other commercial PVT, we are using ours.

In this presentation, we would like to show the connection

between a PVT module and ANSYS CFX.

Outline:

• Characterize a reservoir fluid using an “In-House” developed PVT Module. Cubic Equation of State based Software. PVT calculations: Bubble points. Dew points. Flash at constant T and P.

• Generate physical properties for EVERY possible phase present for a given process.

• Generate intput data file for a Compiled Library (Fortran or C). (PVT – ANSYS connection)

• Read CCL file to use the Library. • Perform CFD simulation using the calculated properties.

Characterize a reservoir fluid: “In-House” developed PVT Module

Composition of the reservoir fluid

Characterization Options for the Heavy Fraction.

Characterization Options for the Heavy Fraction.

PVT experiments that can be simulated:

• Phase Envelope • CCE • DLE • CVD • MMP • Swelling Tests

Phase Envelope

Calculation Progress

Phase Envelope

Differential Liberation Expansion – DLE

Calculation Progress

DLE

ANSYS – CFX connection

GSSC PVT Module and ANSYS CFX connection

Generate a properties file for the operating Pressure – Temperature intervals.

Use a set of Fortran based routines to read the Properties File and, for a given Temperature and Pressure, relate all the properties with the Material Properties in CFX.

Properties DATA file in library path

ANSYS configuration after CCL file has been imported

Simulation Results Example:

Flashing of a Volatile Oil flowing through a butterfly valve

41 0API Oil GOR: 67.40

Pressure Field

Velocity Field

Gas Volume Fraction

Simulation Results:

Real properties for the 2 phases (gas and oil)

Equilibrium line crossing implies a

phase change. (Flashing)

A previous version of this module was used along with

ANSYS – CFX in the following project:

Hydrodynamic Description of a 140 km crude oil transport line.

Fluid Properties:

35 oAPI RGA: 8

14%Vol. Water Content

Fluid Characterization and Properties:

Componente % mol PM (g/mol) Tc (K) Pc (bar) ω

N2 0.00061 28.01 CO2 0.00087 44.01 H2S 0.00346 34.08 C1 0.01231 16.04 C2 0.01267 30.07 C3 0.02299 44.10 iC4 0.00692 58.12 nC4 0.02829 58.12 iC5 0.01654 72.15 nC5 0.02953 72.15 C6 0.05455 84.00

Pseudo1 0.14158 102.54 557.43 33.93 0.31074 Pseudo2 0.24920 147.65 626.71 29.02 0.40041 Pseudo3 0.23146 233.29 737.83 19.60 0.63706 Pseudo4 0.13852 370.19 840.28 13.59 0.92242 Pseudo5 0.05050 588.11 938.69 9.63 1.25656

0

5

10

15

20

25

30

35

40

45

50

100 200 300 400 500 600 700 800

Temperatura (K)

Pres

ión

(bar

)

Complete Line – Pressure Drop

Complete Line – Phase Change

Complete Line – Water Bed

Predicted Oil volume loss due to evaporation

Stabilization Platform at

Marine Terminal at Dos Bocas, Tabasco.

PEMEX

Gas recovery system – TMDB

Project Status:

PVT Module that can handle most of the fluids found in the Oil & Gas industry.

Rigorous 2 phase calculations. Rigorous 3 phase calculations. Special processes like EOR can be modeled.

Coupling of this PVT module (Grupo SSC) with ANSYS – CFX

and ANSYS – Fluent. Completed and under test. Currently working on generating SPT-Group OLGA properties

tables. 2 phases – Completed 3 phases – 75% complete.

Project Status: SPT-Group OLGA properties tables.

P-T Phase Envelope: 2 Phases.

Project Status: SPT-Group OLGA properties tables.

P-T Phase Envelope: 3 Phases. Reserv. Fluid + 10%vol Water

We are participating as PEMEX consultants in the OVIP project.

(OLGA Verification and Improvement

Program)

Last meeting: Paris, 2 months ago.

L-5

• Complex pipeline network distribution

• Offshore

Datos API RGA (m3/m3) Psat (Kg/cm2) @ 186.9 C

Experimental 41.00 910.39 417.26

PVTSim 41.05 907.13 418.8

Multiflash 41.16 900.19 418.9

Diferencia PVTSim 0.05 -3.26 1.54

Error (%) PVTSim 0.12 0.36 0.37

Diferencia Mflash 0.16 -10.20 1.64

Error (%) Mflash 0.40 1.12 0.39

Models for evolutive maintenance (PVT) Light Crude Oil: PVTSIM vs Multiflash

Models for evolutive maintenance (PVT) Heavy Crude Oil: Phase Envelope

Heavy Oil

0

5

10

15

20

25

30

35

40

45

50

-200 -100 0 100 200 300 400 500 600 700 800

Temperature (ºC)

Pres

sure

(kg/

cm2)

HYSYSMultiFlashPVT_GSSCPVT_GSSCEXP