Acido2.ppt

Completion Fluid Damage Treatment Options.

Damage Mechanism

Solids invasion

Clay swelling Clay mobilisation

Water block

Emulsion block

Wettability damage

Precipitation of solids

Treatment Options

HCl:mud acid Solids dependent

HCl:mud acid

HCl:mud acid

Surface Tension Reduction

Dependent on emulsion external phase.

Mutual Solvents and or Surfactants

Solids dependent

Formation Damage Treatment Options

for Different Drive Mechanisms.Formation Damage Mechanism

Water Drive

Accelerated water production after acidizing.

Asphaltene damage

Water production

Scale formation

Gas Drive

Water block

Paraffin damage

Treatment

Selective acidizing

Paravan/Solvent soaks

Aquatrol 1,2 or 3, Direxit

Depends on composition

Reduce surface tension

Paravan/Sovent soaks

Formation Damage Mechanism

Solution Drive

Water block

Inadequate formation pressure

Organic formation damage

Combination Drive

Treatment

Reduce surface tension

Carbon Dioxide or Nitrogen

Paravan/Sovent soaks

All of the above

Formation Damage Treatment Options for Different Drive Mechanisms.

Temperature Considerations

150°F

L

L

U

L

L

L

L

U

L

L

165°F

L

L

U

L

L

L

L

U

L

L

170°F

M

M

U

M2

L

L

L

U

L

M

180°F

M

M

U

M2

L

M

M

U

L

M

185°F

M

M

U

M2

L

M

M

U

L

M

200°F

U

M

M

U

L

M

M

M3

M

U

240°F

U

U

L

U

L

U

U

M3

M

U

Situation

Emulsion Blocks

Organic Deposition

Asphaltene Coking

Bacteria

CaCO3 Scale

BaSO4 Scale

CaSO4 Scale

Chlorination of Mutual Solvents

Rigid Emulsion Film

Are Retarded HFSystems Economical

Temperatures

Treatment Options for Formation Damage Caused by Indigenous Minerals

Siderite,Hematite

Iron HydroxidePrecipitation

Acidize - Standard HCl/HCl:HF withproperly evaluated sequesterants

Pyrite Iron HydroxidePrecipitate.Asphaltene

Sludging

Mobile FinesFormationFines

(Feldspars,Quartz, Etc)

High Flow Rates Preflush - 7.5% HClAcidize - 7.5:1.5 HCl:HF + BoricAcid (Volume as required).Overflush - as required.

Calcite,Dolomite

>18% - HCl Only.<18% - Standard HCl/HCl:HF

CalciumFluoride

Precipitation

Contact ofcalcium ion with

HF Acid.

Oxygen RichSystems

Oxygen RichSystems

Preflush - 25 Gal/ft Xylene + 10%AceticAcidize - Standard HCl/HCl:HF withproperly evaluated sequesterants

Mineral PotentialProblems

Treatment OptionsWhat ToAvoid



Kaolinite Mobile Fines Rate Control.<5%-Acidize - Standard HCL/HCL:HF>5% - Evaluate for Stress Pack

High Flow Rates

Illite Mushing Permeability > 120 Md Acidize -Standard HCl/HCl:HFPermeability < 120 md reducesurface tension to 30 Dynes/Cm2

Fresh WaterSystems

Swelling Acidize - Standard HCl/HCl:HFPerform Immersion Tests to see ifalcohol/acid blends or otheradditives are necessary to preventswelling

(Montmoril-Smectite

lonite)

Fresh WaterSystems

Chlorite Iron HydroxidePrecipitate,

Hydrous SilicatesAmorphous

Alumino Silicate

Acidize - Standard HCl/HCl:HF withproperly evaluated sequesteringagents, boric acid volume asrequired. Overflush as required

Oxygen RichSystems: Ph>2.8

InadequateSequesterant.

Buffered Acids


Chamosite Iron HydroxidePrecipitate Oxygen Rich

Systems: Ph>2.8 Acidize - Standard HCl/HCl:HF withproperly evaluated sequesterants



Swelling Acidize - Standard Hcl/Hcl:HfMixed LayerIllite/ Smectite

Fresh WaterSystems

Feldspars SilicaPrecipitation

> 20%- 7.5% HCl, 7.5:1.5 HCl:HF< 20%- Standard HCl/HCl:HF

High % of HF Acid


Acid Treating Volumes Based on Permeability

Average Permeability w/o Damage

Ku (md).

< 0.1 md

0.1 - 1.0 md

1.0 - 10 md

10- 50 md

> 50 md

Normal HClRange Gal/ft

(L/M)

15-25(185-310)

25-50 (310-620)

35-75(430-930)

50-100(620-1240)

50-100(620-1240)

Normal HCl:HF Range Gal/ft

(L/M)

Not Recommended

35-50(430-620)

75-100(930-1240)

100-150(1240-1865)

100-200(1240-2480)

Recommended Treating Volume of HCl:HF in

Gallons Per Square Foot of Pay

GALLONS PER FOOT OF TREATED INTERVAL

TR

EA

TIN

G R

AD

IUS

(F

t)

0 100 200 300 400 500 600 700 800 900 0

1

2

3

4

5

6

7 20 gallonsper sq.ft

15 gallonsper sq.ft

10 gallonsper sq.ft

5 gallons per sq.ft

Volume of 12:3 HCl:HF Required to Treat a 3.0 Inch Damage Zone -

Gallons Per Foot of Pay. Temperature

100° F

Gal/ft

70

50

50

50

50

50

50

150° F

Gal/ft

80

65

55

50

50

50

50

200° F

Gal/ft

100

75

65

55

50

50

50

250° F

Gal/ft

120

80

75

65

50

50

50

Pump Rate

BPM/ft

0.001

0.005

0.010

0.025

0.050

0.100

0.200

Volume of 12:3 HCl:HF Required to Treat a 6.0 Inch Damage Zone - Gallons Per

Foot of Pay. Temperature

100° F

Gal/ft

350

275

225

175

140

130

150° F

Gal/ft

350

350

300

250

200

160

200° F

Gal/ft

350

350

350

325

260

210

250° F

Gal/ft

350

350

350

350

320

260

Pump Rate

BPM/ft

0.005

0.010

0.025

0.050

0.100

0.200

Gallons Per Foot of Treating Fluid for

Differing Porosities.

BA

RR

EL

S P

ER

FO

OT

OF

SA

ND

TH

ICK

NE

SS

0 1 2 3 4 5 6 7 0

20

40

60

80

100

120

140

160

180

200 220

240

260

280

300

320

340

360

380

400

35 % Porosity

100 %Porosity

RADIUS DISTANCE IN FEET FROM WALL OF 7 INCH WELLBORE

GA

LL

ON

S P

ER

FO

OT

OF

SA

ND

TH

ICK

NE

SS

9

8

7

6

5

4

3

2

1

0

5.0 % Porosity

15 % Porosity

25 % Porosity

Acid Selection Based On %Carbonate & Temperature.

Temp°F (°C)

< 200(93)

200-250(93-121)

250-350(121-177)

>350(177)

Temp °F (°C)

< 250(121)

250-350(121-177)

>350(177)

5.0 to 15%

75 gal/ft(930 L/M)15% HCl

followed byHCl: HF

50 gal/ft(620 L/M)7.5% HCl

followed byHCl: HF

35 gal/ft(430 L/M)

7.5% HCl +10% Formicfollowed byFormic:HF

35 gal/ft(430 L/M)

10% Formicfollowed byFormic:HF

10 to 15%

75 gal/ft(930 L/M)15% HCl

then washperforations

withHCl: HF

50 gal/ft(620 L/M)

7.5% HCl +10% Formic

35 gal/ft(430 L/M)

10% Formic

> 15%

100 gal/ft(1240 L/M)15% HCl

50 gal/ft(620 L/M)

7.5% HCl +10% Formic

35 gal/ft(430 L/M)

10% Formic

Percentage of Carbonate in the Formation

< 5.0%

50 gal/ft(620 L/M)

15% HCl followed by HCl: HF

35 gal/ft(430 L/M)7.5% HCl

followed byHCl: HF

35 gal/ft(430 L/M)

10% Formic Formic:HCl

or Formic:HF

35 gal/ft(430 L/M)

10% Formicor Formic:HF

HCl Acid Strength Based on Formation Solubility

Formation Solubility(Percentage)

0 -10

10 - 20

20 - 40

Greater than 40

Acid Strength(Percentage)

3 - 5

5 - 7.5

7.5 - 10

10 - 28

Flow Improvement Ratio of Various Treating Solutions

in Berea Sandstones

Treating Volume : Gallons Per Square Foot

Flo

w I

mp

rove

men

t R

atio

K

20.00.0 2.5 5.0 7.5 10.0 12.5 15.0 17.51.0

1.5

2.0

2.5

3.0

7.5% HCl - 4% HF

15% HCl - 4% HF

15% HCl - 3% HF

15% HCl

15% HCl - 7% HF

15% HCl - 2% HF

Recommended Preflush Volume in Gallons of 15%

HCl Per Foot of Pay for Various Radii.

GA

LL

ON

S O

F 1

5 %

HC

l P

ER

FO

OT

OF

PA

Y

0 1 2 3 4 5 6

TREATING RADIUS (FEET)

1

10

100

1000

1.0 % HCl Solubility

5.0 % HCl Solubility

10 % HCl Solubility

Selective Acidizing Treatment Options

Situation

Oil Well - Non Gravel Packed

Oil Well - Gravel Packed

Gas Well

Treatment

SAF Mark II

SAF

65 Quality Foam Preflush

Relative Retarding Action of Different Systems

RegularAcid

HCl Acid

HCl:HF

Mixture ofHCl + Organic

Super-Sol (EQH) Acids

ChemicallyRetarded Acid

Sta-Live Acid Systems

Retarded Mud Sol Systems. (HCl:HF)

SGMA

PhysicallyRetarded Acid

Gelled Acids and Crosslinked Acid.

SRA-3 Emulsified Acid.

Sandstone Acid

Least MostRetardation

Carbon Dioxide and Nitrogen Guidelines.

Reservoir Type

Gas.

Low Pressure Gas.

Oil, (Above the Bubble Point).

Oil, (Below the Bubble Point).

Water Injection or Disposal Well.

Nitrogen

Yes

Yes

(3, 4)

Yes

(3, 4)

Carbon Dioxide

Yes (1)

(2)

Yes

Yes

(3, 4)

Injection Rates (Non-Fracturing) into Permeable Formations at

Various Differential Pressures.

0 100 200 300 400 500 600 700 800 900 1000

P=2000 PSI

P=2500 PSI

P=1500 PSI

P=1000 PSI

P= 500 PSI

P= 200 PSI

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

0

10

20

30

40

50

FORMATION CAPACITY, kh - md.ft.

INJE

CT

ION

RA

TE

Q -

BA

RR

EL

S P

ER

MIN

UT

E

0

1

2

3

4

5 DARCEY'S EQUATION FOR RADIAL FLOW

Drainage Radius = 5.0 ftInjected Fluid Viscosity = 1.0 cpDifferential Pressure ( P)

Treating Pressure (+ Plus)Hydrostatic Column (- Minus)Reservoir Pressure = psi

Formation Capacity (kh)Average Effective Permeabilityx Thickness of Sand Body = md. ft.

( For small volume treatments in partially saturated reservoirs)

Recommended Acid Strengths at Different Temperatures.

Temperature

Up to 180° F (82° C)

180° F to 220° F(82° C to 104 °C)

Above 220° F (104° C)

MaximumHCl Strength

15%

10%

7.5%

MaximumHCl:HF Strength

12:3%

9:3%

7.5:1.5%

Common Strengths Of HCl: HF MIxtures% HCl

6.07.5121515

% HF

0.51.53.03.04.0

Reaction of Acids on Limestone at Various Concentrations.

Acid

HCl *

Acetic

Formic

Concentration%

15*2025

15*2025

15*2025

Calcium CarbonateDissolvedPer Gallon.

Pounds

1.842.503.22

1.081.431.80

1.421.902.40

Carbon DioxideFormed

Per Gallon.cu.ft.

6.999.47

12.20

4.095.416.82

5.387.209.09

Calcium SaltFormed

Per Gallon.Pounds

2.042.753.57

1.712.252.84

1.842.473.12

Amount of Limestone Dissolved by 1000 Gallons of

HCl Acid

STRENGTH OF HYDROCHLORIC ACID %

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

10.011.012.013.014.015.016.017.018.019.020.021.0

0

500

1000

1500

2000

2500

3000

3500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Ft3

OF

LIM

ES

TO

NE

DIS

SO

LV

ED

BY

10

00

GA

LL

ON

S O

F H

Cl

AC

ID

Relative Reaction Rates of 15% HCl with

Limestone Formations at 75° F.

0 5 10 15 20 25 30 350

10

20

30

40

50

60

70

80

90

100

* Atmospheric pressure at sea level

Curve

ABCD

Pressurepsi

14.7 *400800

1200

To

tal

Rea

ctio

n,

%

Minutes

D

C

A

B


Limestone Formations at 140° F.

Minutes

0 5 10 15 20 25 30 350

10

20

30

40

50

60

70

80

90

100 T

ota

l R

eact

ion

, %

Curve

ABCD

Pressurepsi

14.7 *40012002000


A

B

D

C


Dolomite Formations at 75° F.

Minutes

0 20 40 60 80 100 120 140 0

10

20

30

40

50

60

70

80

90

100

To

tal

Rea

ctio

n,

%


Curve

AB

Pressurepsi

14.7 *2000

A B


Dolomite Formations at 140° F.

0 10 20 30 40 50 60 700

10

20

30

40

50

60

70

80

90

100

To

tal

Rea

ctio

n,

%

Minutes

A

B

C D


Curve

ABCD

Pressurepsi

14.7 *400

12002000

Acido2.ppt

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