Gas Well De-Liquification Workshop Adams Mark Hotel, Denver, - - PowerPoint PPT Presentation

Gas Well De-Liquification Workshop

Adams Mark Hotel, Denver, Colorado March 5 - 7, 2007

Ben Horn Weatherford International

Capillary Tubing – Metallurgical Considerations in Application

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 2

Corrosion & Metallurgy

• Considerations

– Partial pressures of H2S & CO2 – Chlorides, temperature, pH – Depth

What metallurgy is appropriate?

Evaluation applies practice outlined by Schillmoller in “Selection of corrosion-resistant alloy tubulars for offshore applications” Nickel Development Institute,1989

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 3

Partial Pressure CO2

4% CO2 Est +/- 500 avg pressure in tubulars

PP CO2 = 500psi X 0.040000 = 20 psi

Partial Pressure H2S

20 ppm H2S Est +/- 500 avg pressure in tubulars

PP H2S = 500psi X 0.000020 = 0.0010 psi

H2S & CO2 Considerations

Corrosion & Metallurgy

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 4

Selection Guide

Corrossion Resistant Alloy Tubulars in Gas Wells

0.001 0.01 0.1 1 10 100 1000 10000 100000 0.001 0.01 0.1 1 10 100 1000 10000 100000

Partial Pressure of H2S, psia Partial Pressure of CO2, psia

Alloy 625 Super Duplex 2507 Duplex 2205 Alloy 300 series

Instructions:

• 1. Calculate partial pressures of H2S and CO2.

PPCO2 = mole % CO2 X pressure PPH2s = mole % H2S X pressure

• 2. Enter X and Y axes appropriately
• 3. Select Alloy based on Color Scheme
• 4. Proceed to Chloride Pitting Charts to further delineate

total treatment recommendation

From Schillmoller, 1989 … Selection of Corrosion -Resistant Alloy Tubulars for Offshore Applications

Selection Guide Corrosion Resistant Alloy Tubulars in Gas Wells

Corrosion & Metallurgy

H2S & CO2 Considerations

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 5

Most Gas Fields are Mild or Moderate Environments…

• BHT = 150 - 350°F
• Moderate CO2, Low H2S
• Reasonable pHs

Chlorides, Temperature and pH Considerations

Corrosion & Metallurgy

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 6

Region Of Most Oil Field Brines

T<230oF

Corrosion & Metallurgy

Chlorides, Temperature and pH Considerations

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 7

230oF<BHT< 390oF

Region Of Most Oil Field Brines

230oF<T<390oF

Corrosion & Metallurgy

Chlorides, Temperature and pH Considerations

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 8

Physical Properties Capillary Coiled Tubing

Some Considerations: (1) How much pull can I place on a string before it exceeds yield stength

• f metallurgy?

(2) How deep can I run the string?

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 9

Physical Properties Capillary Coiled Tubing

Data Section Calculations

Tubing Data Weight Calculations

Tubing Material Tubing Weight 1440 lbs Tubing OD 0.250 in Chemical Weight 198 lbs Tubing WT (wall thichness) 0.035 in Pump Pressure Force 0 lbs Tubing WGHT 80 lbs/1,000 ft Pull Force 0 lbs Tubing Set Depth 18,000 ft Total Force to cause 80% Yield Failure

1513 lbs

CAUTION Tubing Tensile Strength 120 X103psi Total Force to cause Yield Failure

1891 lbs

OK Tubing Yield Strength 80 X103psi Total Force to cause Tensile Failure

2837 lbs

OK Tubing Modulus of Elasticity 29 X106psi

Chemical Data

Total Tubing "Effective" Weight 1638 lbs

Chemical Material Chemical Dernsity 8.33 lb/gal

X-Section Calculations Calculations

Is string full of Chemical? Y Y/N Metal X-Section Area 0.02364 in2

Pump Data

psi ID X-Section Area 0.02545 in2 Pump Pressure OD X-Section Area 0.04909 in2

Pull Data

lbs

Elongation Calculations

Pull Force Tubing Elongation due to Tbg Weight 37.8 ft

Temperature Data

• F

Tubing Elongation due to Chemical Weight 5.2 ft Ambient Temperature 80

• F

Tubing Elongation due to Pump Force 0.0 ft Well Temperature 220 Tubing Elongation due to Pull Force 0.0 ft Tubing Elongation due to Temperature Effect 18.1 ft

Total Tubing Elongation 61.2 ft

Note :

(1) All calculations assume tubing is hanging in air with CC1-A valve in place on end of string. (2) External/Negating forces that would reduce stretch are ignored. This is a worse case stretch evaluation. (3) If "CAUTION" Shows up, Effective Weight exceeds 80% Yield Strength of Tubing - Getting close to Tubing Deform (4) If "ALARM" Shows up, Effective Weight exceeds Yield Strength of Tubing - Tubing will permanently Deform. (5) If "FAILURE" Shows up, Effective Weight exceeds Tensile Strength of Tubing - Tubing will part. WFT 97111W

Stainless Steel Tubing Stretch Calculator

Capillary Technologies Engineered ChemistryTM

Super Duplex 2507

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 10

Super-Duplex 2507 Tubing South Texas Application

Point of Failure Failed from Pitting Inside out

• Occasionally, bacteria can pollute the injection chemical system
• Bacteria consumes the organic polymer in the chemical and excretes H2S
• High operating pressures inside the capillary string (by design) create

high partial pressures

• As predictable…Tubing pits and or cracks and fails

• Mar. 5 - 7, 2007

2007 Gas Well De-Liquification Workshop Denver, Colorado 11

Physical Properties Capillary Coiled Tubing

Conclusion – Rule of Thumb Considerations: Partial Pressures H2S and CO2

• Unless there is extremely high partial pressures of H2S most often,

Standard Duplex 2205 tubing is sufficient

Chlorides and pH

• Most often a function of Temperatures. Below 235oF, normal salinities,

Standard Duplex 2205 is sufficient for corrosion stress cracking.

• Above 235oF, normal salinities, Inconel 625 is more appropriate.
• The closer to the line, judgement call of operator. Just need to

understand the risks and consequences

Depth

• Function of Yield strength of material and desired working range in the

event of future remedial work