Impact of choke valves on the IOR polymer flooding Lessons learned from large scale tests

Transcription

1 Impact of choke valves on the IOR polymer flooding Lessons learned from large scale tests Amare Mebratu, Halliburton; Arne Stavland and Siv Marie Åsen, IRIS; and Flavien Gathier, SNF

2 Outline Obje?ve Introduc?on Degrada?on tests Lessons learned

3 Objec=ve Polymer flooding is a promissing IOR method IOR poten?al is reduced by polymer degrada?on Will choke valves be compa?ble with polymer flooding?

4 Introduc=on EOR polymers are at lab scale degraded when flooded through capillary tubes Degrada?on mechanism understood by applied shear rate Laminar Hagen- Poiseuille flow Normalized Viscoisity ID =.58 mm ID =.254 mm ID =.127 mm ID = 1.1 mm ID =.76 mm ID =.58 mm E+3 1.E+4 1.E+5 1.E+6 4QR - 3 /π τ w =η γ = ΔP/l R/2 =η 4Q/π R 3 =η 4<v>/R On general form: τ w = f/8 ρ <v> 2 where f=64/re and Re=2<v>R ρ/η

5 Upscaled ID=.1 mm, Q = cm 3 /min to ID= 5 mm, Q = m 3 /min Normalized viscosity E+3 1.E+4 1.E+5 1.E+6 Shear rate = 4<v>/R

6 Upscaled ID=.1 mm, q = cm 3 /min ID= 1 mm, Q = m 3 /min SC Mod Normalized viscosity E+3 1.E+4 1.E+5 1.E+6 1.E+7 Shear rate = τw/η τ w = f/8 ρ <v> 2 where f=a/ Re 1/4, for Re > 2 In turbulent regime γ = γ (v,r,ρ,η)

7 Resistance coefficient, f 1.E+ 1.E- 1 1.E- 2 Re=2<v>R ρ /η Assump=ons 1.E- 3 1.E+2 1.E+3 1.E+4 1.E+5 1.E+6 Reynold number Laminar, f=64/re Blasius f=.3164/re^1/4 Current Prediction 125 ppm PAA (Escudier, 1999) Non- Newtonian polymer lowers f basis for drag reduc?on, DR= f N f P / f N Shear thinning polymer; viscosity decreases by increasing shear rate Viscosity, mpas 1.E+3 1 ppm 1.E+2 2 ppm 1 ppm 1.E+1 1.E+ 1.E- 1 1.E+ 1.E+1 1.E+2 1.E+3 1.E+4 1.E+5 1.E+6 Shear rate, 1/s Here η = 2.5 cp Increasing polymer concentra?on supresses Re, lowering τ w /η and less degrada?on

8 Large scale yard test Test matrix Flow rate 7-6 liter/min 2 different polymers (HMW HPAM 363 and LMW AMPS AN125) 3 concentra?ons (1, 2 and 1 ppm) Differen?al pressure up to 5 bar 5 different choke concepts Fixed brine salinity (.5% NaCl) Iden?fy feasible choking methods at acceptable degrada?on

9 Choke concepts Standard adjustable choke valve (Choke1) Matek choke valve (Choke 2) SNF Linear pressure reducer, LPR, (Choke 3) Fixed choke valve - ID of 2/64 (Choke 4) and 24/64 (Choke 5) Standard adjustable chokes in series

10 Data collec=on

11 Standard adjustable choke (1) The higher the concentra?on the lower the polymer degrada?on AN AN Choke 1 1 ppm Choke 1 2 ppm 1 ppm 1 Degradation before to after choke, % Differential pressure, bar

12 Matek Adjustable choke (2) AN AN125 2 Choke 2 1 ppm Degradation before to after choke, % Differential pressure, bar

13 SNF LPR Choke (3) AN Degradation before to after choke, % Differential pressure, bar

14 Summary single chokes Increase choke length or choked concentra?on improves stability AN AN AN AN AN Choke 1 1 ppm Choke 1 2 ppm Choke 2 1 ppm 1 ppm Degradation before to after choke, % Differential pressure, bar

15 Mul=ple chokes 1 3 serially mounted chokes Degradation, % Differential pressure, bar Single choke Multiple chokes

16 Effect of salinity Large scale test in 5 ppm NaCl revealed liele difference between LMW AMPS and HMW HPAM Capillary tube experiments In salter water (SSW) the difference in degrada?on becomes significant Degrada?on is a combined effect of salt sensi?ve rheology and salt sensi?ve shear stability Normalized viscosity Normalized viscosity Degradation in 1 ppm NaCl AN125 1.E+4 1.E+5 1.E+6 1.E+7 shear rate [s- 1] Degradation in SSW AN E+4 1.E+5 1.E+6 1.E+7 Shea rate [s- 1]

17 Filterability Screen factor Screen factor Screen factor 5 µm filter at 2 Bar Newtonian Model viscosity, mpas

18 Conclusions Choke valves induce differen?al pressure which poten?ally degrade polymers, but degrada?on is not controlled by differen?al pressure Polymer degrada?on at field scale matched experiments at laboratory scale by using applied shear rate as scaling parameter Choke valves are no show stopper for polymer injec?on High concentrated polymer solu?ons are less degraded Low pressure gradient choke systems, such as SNF LPR choke or serially mounted standard chokes reduce degrada?on However, polymer systems need to be carefully evaluated for degrada?on before field implementa?on as success depends on it!

19 Acknowledgement The authors acknowledge the Research Council of Norway and the industry partners; ConocoPhillips Skandinavia AS, BP Norge AS, Det Norske Oljeselskap AS, Eni Norge AS, Maersk Oil Norway AS, DONG Energy A/S, Denmark, Statoil Petroleum AS, ENGIE E&P NORGE AS, Lundin Norway AS, Halliburton AS, Schlumberger Norge AS, Wintershall Norge AS of The Na?onal IOR Centre of Norway for support.