Gas Well De-Liquification Workshop Adams Mark Hotel, Denver, Colorado March 5 - 7, 2007 Capillary Tubing – Metallurgical Considerations in Application Ben Horn Weatherford International
Corrosion & Metallurgy What metallurgy is appropriate? • Considerations – Partial pressures of H 2 S & CO 2 – Chlorides, temperature, pH – Depth Evaluation applies practice outlined by Schillmoller in “Selection of corrosion-resistant alloy tubulars for offshore applications” Nickel Development Institute,1989 2007 Gas Well De-Liquification Workshop 2 Mar. 5 - 7, 2007 Denver, Colorado
Corrosion & Metallurgy H 2 S & CO 2 Considerations Partial Pressure CO 2 4% CO 2 Est +/- 500 avg pressure in tubulars PP CO 2 = 500psi X 0.040000 = 20 psi Partial Pressure H 2 S 20 ppm H 2 S Est +/- 500 avg pressure in tubulars PP H 2 S = 500psi X 0.000020 = 0.0010 psi 2007 Gas Well De-Liquification Workshop 3 Mar. 5 - 7, 2007 Denver, Colorado
Corrosion & Metallurgy H 2 S & CO 2 Considerations Selection Guide Selection Guide C orrossion R esistant A lloy Tubulars in Gas Wells Corrosion Resistant Alloy Tubulars in Gas Wells 100000 10000 Alloy 625 1000 Duplex 2205 Partial Pressure of CO 2 , psia 100 Super Duplex 2507 10 1 Instructions: 0.1 1. Calculate partial pressures of H 2 S and CO 2 . Alloy 300 series PPCO2 = mole % CO 2 X pressure PPH2s = mole % H 2 S X pressure 0.01 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 0.001 0.001 0.01 0.1 1 10 100 1000 10000 100000 From Schillmoller, 1989 … Selection of Corrosion -Resistant Alloy Tubulars for Offshore Applications Partial Pressure of H 2 S, psia 2007 Gas Well De-Liquification Workshop 4 Mar. 5 - 7, 2007 Denver, Colorado
Corrosion & Metallurgy Chlorides, Temperature and pH Considerations Most Gas Fields are Mild or Moderate Environments… • BHT = 150 - 350°F • Moderate CO 2 , Low H 2 S • Reasonable pHs 2007 Gas Well De-Liquification Workshop 5 Mar. 5 - 7, 2007 Denver, Colorado
Corrosion & Metallurgy Chlorides, Temperature and pH Considerations T<230 o F Region Of Most Oil Field Brines 2007 Gas Well De-Liquification Workshop 6 Mar. 5 - 7, 2007 Denver, Colorado
Corrosion & Metallurgy Chlorides, Temperature and pH Considerations 230 o F<BHT< 390 o F 230 o F<T<390 o F Region Of Most Oil Field Brines 2007 Gas Well De-Liquification Workshop 7 Mar. 5 - 7, 2007 Denver, Colorado
Physical Properties Capillary Coiled Tubing Some Considerations: (1) How much pull can I place on a string before it exceeds yield stength of metallurgy? (2) How deep can I run the string? 2007 Gas Well De-Liquification Workshop 8 Mar. 5 - 7, 2007 Denver, Colorado
Physical Properties Capillary Coiled Tubing Stainless Steel Tubing Stretch Calculator Capillary Technologies Engineered Chemistry TM Data Section Calculations Tubing Data Weight Calculations Tubing Material Tubing Weight Super Duplex 2507 1440 lbs Tubing OD 0.250 in Chemical Weight 198 lbs Tubing WT (wall thichness) Pump Pressure Force 0.035 in 0 lbs Tubing WGHT 80 lbs/1,000 ft Pull Force 0 lbs Total Force to cause 80% Yield Failure 1513 lbs Tubing Set Depth 18,000 ft CAUTION 120 X10 3 psi Total Force to cause Yield Failure 1891 lbs Tubing Tensile Strength OK 80 X10 3 psi Total Force to cause Tensile Failure 2837 lbs Tubing Yield Strength OK 29 X10 6 psi Tubing Modulus of Elasticity Total Tubing "Effective" Weight 1638 lbs Chemical Data Chemical Material WFT 97111W X-Section Calculations Calculations Chemical Dernsity 8.33 lb/gal 0.02364 in 2 Metal X-Section Area Is string full of Chemical? Y Y/N Pump Data 0.02545 in 2 ID X-Section Area psi 0.04909 in 2 Pump Pressure 0 OD X-Section Area Pull Data Elongation Calculations lbs Pull Force 0 Tubing Elongation due to Tbg Weight 37.8 ft Temperature Data o F Tubing Elongation due to Chemical Weight 5.2 ft o F Ambient Temperature Tubing Elongation due to Pump Force 0.0 ft 80 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. 2007 Gas Well De-Liquification Workshop 9 Mar. 5 - 7, 2007 Denver, Colorado
Super-Duplex 2507 Tubing South Texas Application Failed from Pitting Inside out Point of Failure • 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 2007 Gas Well De-Liquification Workshop 10 Mar. 5 - 7, 2007 Denver, Colorado
Physical Properties Capillary Coiled Tubing Conclusion – Rule of Thumb Considerations: Partial Pressures H2S and CO2 • Unless there is extremely high partial pressures of H 2 S most often, Standard Duplex 2205 tubing is sufficient Chlorides and pH • Most often a function of Temperatures. Below 235 o F, normal salinities, Standard Duplex 2205 is sufficient for corrosion stress cracking. • Above 235 o F, 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 2007 Gas Well De-Liquification Workshop 11 Mar. 5 - 7, 2007 Denver, Colorado
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