Joint industry project on foam

Transcription

1 Joint industry project on foam, E.D. Nennie (TNO Heat Transfer and Fluid Dynamics) F. Vercauteren (TNO Material Sciences)

2 2 Introduction Foamers for gas well deliquification. Lab tests are being used to evaluate different foamers performance. The foamers performance can be altered by various parameters. Current issues No standard method to evaluate foamer behaviour. Current test methods are limited in pressure and temperature or velocities. Knowledge gap between lab tests and field.

3 3 Project Goal Standard methodology to evaluate different foamers Improve the link between selection and field Quantifying the deliquification measure of foamers Universally accepted test method More representative conditions Handling condensates and brines

4 Mass flow controller 4 Suggested desktop setup (recap) Capability of performing: Build-up/collapse Carryover Defoamer Nit rogen Pressure regulator V0 Pressure Reli eve Valve V4 Pressure Reli eve Valve Foam Column Head Defoamer Nit roge n T5 T P2 V5 He ating oil V6 T6 V7 Defoamer Pressure sensor P3 T7 T V10 He ating Coil T2 T T1 Camera He ating oil Light source Min Max Unit P 1 15 [bar] T [ C] U sg [m/s] P1 Heating oil T4 T3 He ating ma ntle Drain V8 Scale T6 Heating oil V9 Water-cut [%] Water salinity 0 30 [%] Foamer concentration [wppm] Drain V2 V1 V3 Clea ning Liquid Defoamer Pump Liquid & Foam mixture Pump 2-way valve elect rical 2-way valve manual chec k valve Cross connector Heating Coil Mass flow controller T Temperature sensor Pressure sensor Pressure Reli eve Valve Bac k pre ssure Valve

5 Foam setup 5

6 Setup GUI 6

7 7 Preparing the sample Gas: Dry Nitrogen Hydrocarbon: Dodecane Salt: Combination of NaCl and CaCl 2 (Ratio 4:1) PH = 4 Foamer: Foamatron CO2 Foamatron + = PH = 4 +

8 8 Min-Max parameter analysis Quantifying the effect of each parameter on foam behaviour. The base case was kept at 1 bar and 25 C. Buildup, collapse and carryover tests were performed, according to the defined test procedure. Base case P[bar] T [C] Water salinity [%] WC [%] Foamer conc. [ppm] Usg [m/s]

9 9 Definitions Buildup rate = Buildup height Buildup time Buildup height is defined based on foam volume of 1 litre. Collapse rate = Collapse height Collapse time Collapse height is defined as the 2/3 of the buildup height.

10 10 Min-Max parameter analysis Gas velocity, watercut and foamer concentrations have the largest effect on the buildup rate. Temperature, salinity and watercut increased the foamer collapse rate (less stable foam).

11 11 Min-Max parameter analysis Liquid carryover was affected mainly by the foamer concentration, temperature and watercut. The combination of different process conditions could lead to a different behaviour Foamer concentration, temperature Foamer concentration, watercut DoE matrix should be performed.

12 12 DoE results Design of Experiment methods were used to create combinations (based on Orthogonal array). Assumption: all the parameters are treated equally and independent. In total 18 experiments were designed to determine the interaction of 5 parameters at 3 levels (at every pressure level). For this part, only the results of buildup rate and carryover will be discussed. P[bar] T [C] salinity [%] WC [%] Foamer [ppm] Usg [m/s]

13 Carryover weight[gr] Carryover weight[gr] Carryover weight[gr] Carryover weight[gr] Carryover weight[gr] 13 Effect of individual parameters All the measurements are plotted as a function of each input parameter P = 5 bar Some trends could be recognized in the plots. DoE analysis were performed for averaged response calculations Temperature [C] Watercut [%] Gas superficial velocity [m/s] Salinity [%] Foamer concentration [wppm]

14 Buildup rate 14 Buildup rate results Results for a fixed pressure (15 bar). Buildup rate is increasing by increasing the watercut foamer concentration SumSq MeanSq F pvalue Temperature Salinity Watercut Foamer U_sg Error Clear dependence on gas velocity (Non-monotonous) No clear dependence present on Salinity Temperature Temperature Salinity Watercut Foamer concentration Gas velocity

15 Carryover 15 Carryover results Carryover is increasing by increasing Watercut foamer concentration SumSq MeanSq F pvalue Temperature Salinity Watercut Foamer U_sg Error Non-monotonous dependence on gas velocity Marginal effect of Salinity Temperature Temperature Salinity Watercut Foamer concentration Gas velocity

16 Buildup rate Carryover 16 Variation of pressure The trends of carryover and buildup rate is similar at both 5 and 15 bars measurements; The effect of pressure is mostly indirect. The results are well repeatable bar Temperature Salinity Watercut Foamer concentration Gas velocity Temperature Salinity Watercut Foamer Gas concentration velocity

17 Buildup rate Carryover 17 Variation of pressure Pressure Temperature Salinity Watercut Foamer U_sg SumSq MeanSq pvalue 9.86E E E E E E E E E E E E E E E E E E-05 SumSq MeanSq pvalue Pressure Temperature Salinity Watercut Foamer U_sg Pressure Temperature Salinity Watercut Foamer Gas velocity concentration Pressure Temperature Salinity Watercut Foamer Gas velocity concentration

18 18 Interpretation of results Surfactant absorption / desorption (concentration) Low Temp, stiffer tail Parameters could affect foamers at different scales (cell, interface, bulk). In general temperature and salt concentrations are important. In case of the selected surfactant the effect of temperature and salt turns out small compared to the other parameters (not their combination). Increased foamer concentration might compensate the hydrocarbon presence (forming micelles). Salt reduces headgroup repulsion Electrostatic repulsion Steric repulsion Micelles for oil emulsification Zwitterionic surfactants Adsorbing oil reduces mobility

19 19 Interpretation of results The gas velocity shows non-monotonous behaviour. Dynamic behaviour of foamers; Type (size of molecule) Concentration of foamer Bubble formation/breakup Perturbing the interface should be compensated by the dynamic of surfactants. Pugh, 1996

20 20 Lessons learned Sparging dry Nitrogen at high temperatures could lead to evaporation (temperature drop) Process conditions for the foam test at high temperature; Pre-saturation of N2 before sparging Uncontrolled process (condensation) Changing the composition of samples Properly choosing the process conditions to reduce the temperature drop. Higher pressure or lower gas flow rates N 2 out (Saturated) N 2 in (dry) N 2 + Liquid

21 21 Summary Experiments showed that the foam behaviour of this specific surfactant at tested conditions is dominated by: Watercut, foamer concentration (foamer amount), gas superficial velocity Water cut and foamer concentration have the largest effect; increasing both, increases the foam buildup rate and carryover. Gas velocity shows a non-monotonous behaviour for buildup and carryover (might be due to the different foam flow regimes). Salinity, temperature and pressure have a marginal effect on this surfactant (low significance). Combination of different parameters could increase/decrease the foamer effectiveness.

22 22 Summary The tests for foamers at more representative conditions could be performed in this current setup. DoE could reduce the number of measurements by giving insights on the importance of parameters and their combinations. Future works Writing standard test methodology and protocols. Possibly test different foamers, with different salt or hydrocarbon samples.

23 23 We would like to acknowledge Daniel Turkenburg and Dushyant Parkhi for helping us in running tests and interpretation of results. Pejman Shoeibi Omrani Fluid Dynamics department TNO, Delft