Joint industry project on foam

Transcription

1 Joint industry project on foam, E.D. Nennie (TNO Fluid dynamics) W. Schiferli (Shell Projects & Technology)

2 2 Introduction Foamers are used for gas well deliquification. Lab tests are being used to evaluate different foamers performance. The foamers performance can be altered by various parameters: not representative lab tests Project Goal Standard methodology to evaluate different foamers Improve the link between selection and field Quantifying the deliquification measure of foamers

3 3 Current Status- Commonly used Foam Selection methods Courtesy of ASTM Current tests are: Blender test Measuring foam height after blending Lab scale test / ambient condition, high shear Column sparge (e.g. ASTM tests) Buildup/collapse test Lab scale test / ambient condition, low velocities Carryover test Measuring the amount of liquid carryover Lab scale test / ambient condition, low velocities

4 4 Other available setups: Elevated P & T Maini & Ma (1986) Dimensions not stated 69 bar, 200 C Procedure: Gas sparge to fill chamber with foam Switch off gas Recorded parameters: Foam volume Liquid draining from foam Advantage: Allows field P, T Disadvantages: Low velocities Limited observation

5 5 Other available setups: Higher velocities TUDelft flow loop 50 mm ID, 12 m height Ambient P, T Procedure: Air/water, usg up to 20 m/s Foamers at different concentration Recorded parameters: Pressure drop Flow visualization Liquid holdup Advantages: Increased velocities Disadvantages: Ambient P, T

6 6 Other available setups: Elevated P & T BJ Services BJ Services: HPHT test setup Built in 2009 ID ~15 mm 40 bar, 200 C Procedure: Gas sparge up to 1 l /min Recorded parameters: Pressure drop Advantage: Allows field P, T Disadvantages: Velocity below 0.3 m/s Limited observation

7 7 Current Issues No standard method to evaluate foamer behaviour. Current test methods are limited in pressure and temperature or velocities. There is a knowledge gap between the lab tests and field trails.

8 8 Why do current lab tests fail? Drainage: Foams will become unstable with time, due to liquid drainage Temperature: Reduces stabilizing effect May increase liquid drainage (due to lower liquid viscosity) May cause foamer to degrade chemically Pressure: Maina & Ma (1986) showed that pressure stabilizes the foam.

9 9 Parameters affecting foam stability Shear: Pressure gradient causes shear Shear could change the bubble size distribution Expansion: Increase in bubble volume: decrease in lamella thickness Increase in velocity: increase in shear Salinity: It is expected that field brines affect the foam stability by dissolving in the hydrocarbons Condensates: Non-polar, break up lamella May affect foam as it travels up the wellbore

10 10 Suggested desktop setup The goal of the new desktop setup A universally accepted test method More representative conditions, elevated temperature and pressure Study of condensates and brines effects Capability of performing the following tests: Build-up/collapse Carryover Defoamer

11 11 Suggested desktop setup Pressure regulator Pressure Rupture Valve Foam Column Head Defoamer T Temp sensor N2 Defoamer Pressure sensor Back pressure regulator Level sensor Mass flow controller Camera Camera Light source Knock out Drum Nitrogen Drain Drain Scale Heating Coil T Drain Cleaning Liquid Defoamer Pump Foam mixture 2-way valve electrical 2-way valve manual T-Joint connector T Temperature sensor Pressure sensor T Pressure Rupture Valve Pump Cross connector Heating Coil Pressure Rupture Valve

12 12 Specification of the foam column Double-walled glass column. Diameter 60 mm (to decrease wall effect). Height of 0.5 m. Handling pressure up to 16.4 bars. Temperature controlled with an oil bath. N2 is sparged from the bottom. Other connections at the bottom flange for; Draining Foamer liquid injection Temperature Connections on top of the foam column for injecting defoamer and cleaning solvent. Drain Pressure Rupture Valve Foam Head Defoamer Cleaning Liquid Nitrogen Temp sensors

13 13 Specification of carryover vessel Double-walled steel vessel. Pressure regulator Temperature controlled. The amount of liquid carryover is Valve Pressure Rupture measured by scale. Sight glasses are used for foam observations. Foam Head Defoamer Temp sensor Level sensor N2 DEfoamer Pressure sensor Back pressure regulator Vessel connected by a flexible hose to the foam column. Mass flow controller The back pressure regulator is Heating Coil Nitrogen connected via a separator to Heating the oil vessel. Camera Drain Defoamer Pump Scale 2-way valve electrical 2-way valve manual Light source T Temperature sensor Gas-liquid Separator Drain Drain T-Joint connector Pressure sensor T Pressure Rupture Valve Temp sensors Cleaning Liquid Pump Cross connector Heating Coil Pressure Rupture Valve

14 14 Test parameters 6 parameters will be varied during the experiments: Min Max Unit P 1 15 [bar] T [ C] U sg [m/s] Water-cut [%] Water salinity 0 30 [%] Foamer concentration [wppm] L1 DoE Extreme point L2 P2 L3 P1 Design of Experiments (DoE), will be used to decrease the number of experimental points systematically.

15 15 Summary and future plans Different operators and vendors assess foamers performance by performing different tests. Most of the current tests are limited to low velocities, temperature and pressures. The parameters affecting the foam behaviour, such as condensates and brines should also be incorporated in the tests. The new setup is designed to extend the range of parameters in the desktop scale tests. Tests will be performed in the new setup. In the later phases of the project scaling (e.g. increasing the flow velocity and setup diameter) and foam modeling will be performed.

16 16 Questions? Pejman Shoeibi Omrani Fluid Dynamics department TNO, Delft