SPE-190844-MS Sulphate In Original Reservoir Chalk Rocks: Release - - PowerPoint PPT Presentation

▶
spe 190844 ms
SMART_READER_LITE
LIVE PREVIEW

SPE-190844-MS Sulphate In Original Reservoir Chalk Rocks: Release - - PowerPoint PPT Presentation

Aug 22, 2023 214 likes •450 views

Slide 1 SPE-190844-MS Sulphate In Original Reservoir Chalk Rocks: Release Of Sulphate By Desulphated Sea Water And Effects On Wettability Ingebret Fjelde IRIS, University of Stavanger, National IOR Center of Norway Slide 2 Sea water (SW)

slide-1
SLIDE 1

SPE-190844-MS Sulphate In Original Reservoir Chalk Rocks: Release Of Sulphate By Desulphated Sea Water And Effects On Wettability

Ingebret Fjelde

IRIS, University of Stavanger, National IOR Center of Norway

Slide 1

slide-2
SLIDE 2

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Sea water (SW) injection in chalk reservoirs

  • Pressure support and good recovery, but SW can cause
  • Reservoir souring
  • Scale deposition
  • Weakening of chalks
  • Desulphated sea water (D-SW)
  • Lower sulphate concentration and may reduce problems
  • Also Ca2+ and Mg2+ reduced and Ca2+/Mg2+-ratio increased

Slide 2

slide-3
SLIDE 3

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Objectives

  • Investigate formation damage potential and release of sulphate when

injection water changed from SW to D-SW in reservoir chalk

  • Effects of low sulphate concentration as in real FW, on spontaneous

imbibition and viscous flooding of reservoir chalk

Slide 3

slide-4
SLIDE 4

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Injection brines to reservoir chalk

Slide 4

Element/ion FW (mmol/l) SW (mmol/l) D-SW (mmol/l) SRPW (mmol/l) Al

  • <0.002

Ba

  • 0.0004

Na+ 996.1 457.2 414.1

  • K+

5.29 10.00 8.72 9.21 Ca2+ 28.94 10.55 0.85 4.24 Mg2+ 7.78 53.36 1.77 10.29 Ca2+/Mg2+ 3.72 0.19 0.48 0.41 S

  • 0.212

Si

  • 0.024

Sr

  • 0.029

SO4

2-

0.510 22.955 0.177 0.198 Cl- 1064.5 546.8 426.3

  • HCO3
  • 9.26

2.33 1.38

  • D-SW prepared based on recipe from a sulphate removal plant

SRPW sample received from a sulphate removal plant

slide-5
SLIDE 5

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Injection of brines to reservoir chalk

  • Reservoir plugs cleaned by toluene/methanol and dried with N2-gas
  • Brine injection
  • Differential pressure (dP)
  • Effluent analyzed for sulphate, pH and elements

Slide 5

slide-6
SLIDE 6

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW/SRPW (CP1)

  • FW → D-SW, i.e. injection of D-SW where SW not injected

Slide 6

No formation damage dP

slide-7
SLIDE 7

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW/SRPW (CP1) Sulphate release

Slide 7

  • FW sulphate release
  • D-SW first step → sulphate peak
  • SRPW after aging, small sulphate peak
  • SRPW low pH (pH=5.6) as injected

Sulphate Injection FW without sulphate (Fjelde 2008)

340mg/l = 3.54mmol/l

slide-8
SLIDE 8

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW/SRPW (CP1) pH

  • D-SW higher than injected
  • SRPW much higher than injected

Slide 8

slide-9
SLIDE 9

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW/SRPW (CP1) Elements

Slide 9

Ca-peak and Mg low in same period as sulphate peak Ca and Mg Ba and Sr Ba and Sr produced

slide-10
SLIDE 10

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW (CP2) Sulphate and pH

Slide 10

  • D-SW higher than injected
  • FW peak but stabilized
  • D-SW
  • First D-SW, peak
  • After aging, smaller peak
  • Similar as plug CP1

Sulphate pH

slide-11
SLIDE 11

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

FW/D-SW (CP2) Elements

Ca peak and low Mg when sulphate peak

Slide 11

Ca and Mg Ba and Sr Interactions similar in CP2 and CP1 Sr and Ba high

slide-12
SLIDE 12

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

SW/D-SW (CP3)

Slide 12

  • From SW to D-SW, i.e. injection of D-SW where SW has been injected

No formation damage D-SW high pH dP pH

slide-13
SLIDE 13

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

SW/D-SW (CP3) Elements

Ca and Mg close to injected

Slide 13

Ca and Mg Ba and Sr Ba and Sr low, but higher than injected

slide-14
SLIDE 14

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

D-SW/SW (CP4)

  • Injection SW when D-SW not necessary because brine will not reach producers

Slide 14

dP No formation damage

slide-15
SLIDE 15

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

D-SW/SW (CP4) Sulphate and pH

Sulphate peaks during D-SW

Slide 15

slide-16
SLIDE 16

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

D-SW/SW (CP4) Elements

Ca-peak in same period as sulphate peaks

Slide 16

Ca and Mg Ba and Sr

Ba and Sr higher than injected

slide-17
SLIDE 17

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Effect of initial sulphate on oil recovery

  • Reservoir chalk plugs (Field 2) prepared with and without sulphate in FW
  • Spontaneous imbibition (SI) experiments earlier reported (Fjelde & Asen, 2015)
  • Viscous flooding experiments with SW after SI

Slide 17

slide-18
SLIDE 18

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Effect of initial sulphate on recovery / Spontaneous imbibition

  • Earlier reported (Fjelde and Asen, 2015)

Slide 18

  • SI higher when initial sulphate present than without initial sulphate
  • i.e. more water-wet in presence of initial sulphate than without initial sulphate

So vs time

slide-19
SLIDE 19

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Effect of initial sulphate on recovery / Viscous flooding

Slide 19

  • More water-wet when initial sulphate
  • Spontaneous imbibition
  • Viscous flooding
  • After SI
  • Without initial sulphate
  • Slow production and So low
  • Extra oil when rate increased
  • With initial sulphate
  • Production ended earlier
  • Minor extra oil when rate increased
slide-20
SLIDE 20

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Brine compositions

  • Composition SRPW can vary
  • Important to evaluate formation damage and sulphate release within expected range
  • Brine composition important for oil recovery in chalk
  • SW improved spontaneous imbibition in reservoir chalks without initial sulphate

(e.g. Fjelde and Asen, 2009; Webb et al., 2005)

  • Even though SRPW instead of SW can reduce problems, it is important that oil

recovery is not reduced

  • Reservoir chalk preparation important
  • FW with low sulphate as in real FW, gave more water-wet reservoir chalk than FW

without sulphate

  • Important to prepare core plugs with the correct amount of initial sulphate

Slide 20

slide-21
SLIDE 21

SPE-190844-MS • Sulphate in Original Chalk Rocks …. • Ingebret Fjelde

Conclusions

  • Injection of SRPW to reservoir chalk
  • No formation damage (FW → D-SW/SRPW, D-SW → SW, and SW → D-SW)
  • Sulphate released during D-SW/SRPW injection
  • Effluent pH increased during SRPW injection
  • When sulphate peaks D-SW/SRPW injection, Ca-, Ba- and Sr- peaks while Mg low
  • Initial sulphate gave more water-wet reservoir chalk than without initial sulphate
  • Spontaneous imbibition of SW higher with than without initial sulphate
  • Viscous flooding production profile
  • Even though SRPW can reduce problems as reservoir souring, sulphate scaling and chalk

weakening, it is important that recovery is not reduced

  • Important to prepare reservoir chalk with correct concentration of initial sulphate

Slide 21

slide-22
SLIDE 22

Acknowledgements

Slide 5

Ingebret.fjelde@norceresearch.no Ingebret.Fjelde@uis.no