Stimulation of Sandstone and Carbonate Reservoirs Using Chelating Agents
Amin Ameri [email protected] October, 2016
Introduction StimWell™ References Conclusions
Chelates ▬ StimWell Portfolio
Dissolvine StimWell is a chelate based product series
– Dissolvine StimWell HTF (pH 3.8): • CaCO3 • Iron scales
– Dissolvine StimWell DGH (pH 11.5): • CaSO4
– Dissolvine StimWell DDH (pH 14): • BaSO4 • SrSO4
Introduction StimWell™ References Conclusions
Summary
GLDA ASDA EDG MGDA HEDTA MSA HCl Solubility pH<4 ++ + - - +/- ++ ++
Calcite dissolution + +/- - - + ++ ++
Carbonate (300°F, 2cc/min)
++ + - - + -* -*
Sandstone ++ +/- - - + n.d. -
Thermal stability + - ++ ++ + ++ ++
Corrosion L-80 + +/- +/- +/- +/- - -
Corrosion Cr-13 ++ + + + +/- - -
Health ++ ++ ++ ++ ++ - -
Biodegradability (OECD 301D)
++ ++ ++ ++ - ++ n.a.
Solubility in 15% HCl
++ - + +/- ++ n.d. n.a.
Iron control + + ++ +/- ++ n.a. n.a.
* Dependent on T and flow rate conditions
Introduction StimWell™ References Conclusions
0.0009 0.0011
0.0318 0.0900
0.5253
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
20wt% GLDA
10wt% Citric acid
10wt% Acetic acid
20wt% MGDA
20wt% HEDTA
10wt% Formic acid
15wt% HCl
6-ho
urs
met
al lo
ss (l
bs/s
q.ft)
• Cr-13 • 300°F • N2 head space • 6 hour metal loss at
temperature
Coupons fully dissolved GLDA HEDTA
Low corrosion profile
Introduction StimWell™ References Conclusions
• L-80 carbon steel • 300°F • N2 head space • 6 hour metal loss at
temperature
0.1956
0.0394
0
0.2
0.4
0.6
0.8
1
1.2
GLDA 20wt% HEDTA 20wt% MGDA 20wt% Acetic acid 10wt% Citric acid 10wt% Formic acid 10wt% HCl 15wt%
6-ho
ur m
etal
loss
(lbs
/sq.
ft.)
No CI
0.001v% CI
Coupons fully dissolved
GLDA Acetic
Low corrosion profile
Introduction StimWell™ References Conclusions
• Acids are used to create wormholes to connect the formation to the wellbore
• Success depends on how deep this acid will penetrate into the formation creating uniform wormholes
Stimulation in carbonate reservoirs
Introduction StimWell™ References Conclusions
• Acids are used to dissolve the soluble materials
• Solubility tests in the lab (samples from TU Delft - W-1)
– 100°C for 6 hours
Stimulation in sandstone formations
Solvent Dissolved [%] SW HTF 50% 9.87 SW DDH 50% 7.55 HCl 15% 14.34
Introduction StimWell™ References Conclusions
Stimulation in sandstone formations
Bandera core (10% illite)
• Coreflood tests with Bandera cores
Introduction StimWell™ References Conclusions
Case Histories - Overview
Formation
Geometry Temperature
Stimulation
Descaling
Pickling
Applications
150
200
250
300
Chalk
Calcite
Sandstone Dolomite
Materials
Carbon steel
Ni-Cr Cr
ESP 0
50 100 150 200 250 300 350 400
°F
400
Introduction StimWell™ References Conclusions
Field application I: Tight, sour gas well
Post treatment
target
Pre-treatment
5.25
4.2
3.15
0
Prod
uctio
n R
ate
(M
MSC
FD)
2.1
1.05
Expected fracturing
result
+110%
2.1
3.4
4.4
5
GLDA treatment
SPE 163332
• 325°F • 20% H2S • 9% CO2 • Carbonate (calcite
and dolomite) • Porosity: 11.5% • Permeability: 4 mD • CRA and carbon
steel • 20wt% GLDA at
pH=3.4
Introduction StimWell™ References Conclusions
Field application I: Tight, sour gas well
No after treatment required
0
10
20
30
40
50
0 5 10 15 20
Con
cen
trat
ion
(p
pm
)
Sample nr
Fe in stimulation fluid Mn Fe Cr
0
2000
4000
6000
8000
10000
0 5 10 15 20
Con
cen
trat
ion
(p
pm
)
Sample nr
Ca
Mg
All flowback samples pH>6
Effective dissolution of calcite and dolomite
No corrosion SPE 163332
• 325°F • 20% H2S • 9% CO2 • Calcite and
dolomite • Porosity: 11.5% • Permeability: 4 mD • CRA and carbon
steel • 20wt% GLDA at
pH=3.4
Introduction StimWell™ References Conclusions
Field application II: Horizontal well
• 271°F • 200 ppm H2S • 6mol% CO2 • Permeability: 50
mD • L-80 tubular • >4500 feet
horizontal section completed within 4 hydraulic sliding sleeves
• 20wt% GLDA at pH=3.4 at 0.25 bbl/ft
Effective residual filtercake removal and stimulation from heel to toe due to slow reaction rate
Before stimulation After stimulation
Liquid rate (bbl/day)
PI (bbl/day/psi)
Liquid rate (bbl/day)
PI (bbl/day/psi)
Well 1
680 0.8 1215 1.8
Well 2
350 0.4 900 1.6
Introduction StimWell™ References Conclusions
Field application III: Descaling ESP
• 160°F • FeCO3 and
CaCO3 around ESP
• 20wt% GLDA at pH=3.4
The oil production increased from 400 to 512 STB/day and the PI improvement sustained for 6 months SPE 166335
Introduction StimWell™ References Conclusions
Field application III: Descaling ESP
Analysis of flowback samples proved dissolution of the scales, without any adverse impact on the ESP or well tubular
SPE 166335
0
500
1000
1500
2000
2500
0 10 20 30 40 50 60
Con
cent
ratio
n (p
pm)
Sample nr
Ca
Fe
Mn
Zn
• 160°F • FeCO3 and
CaCO3 around ESP
• 20wt% GLDA at pH=3.4
Introduction StimWell™ References Conclusions
Subject Reference Year
Field applications SPE 163332: SPE P&O (2013) 28-3, pp277-285 SPE 166335 SPE 168163: J. of Can. Pet. Tech., 54-5, pp289-297 SPE 173774
2012 2013 2014 2015
Carbonate coreflood SPE 127923: SPEJ (2011), 16-3, pp559-574 SPE 133497: SPEJ (2011), 16-4, pp968-980 SPE 140149
2010 2010 2011
Sandstone coreflood SPE 139815 SPE 143301 SPE 147395: SPE P&O (2015), 30-1, pp43-51
2011 2011 2011
Corrosion SPE 152716 SPE 160849
2012 2012
HSE SPE 157467 SPE 168145
2012 2014
Reaction rates SPE 139816 SPE 164480
2011 2013
Filtercake removal SPE 155426 2012
References
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