Importance of Predicted Cementing Temperatures for Critical HPHT by hzp22842

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									SPE 114928                    2008 SPE ATCE, Denver



   Importance of Predicted
 Cementing Temperatures for
 Critical HPHT Casing Design

             Albert R. McSpadden
                Simon Glover
             (Altus Well Experts, Inc.)
           Overview

• Review basics of thermal loads
• Influence of initial temperatures
• Why not just assume geothermal?
   –Current industry environment
• Case Studies for HPHT wells
• Conclusions & Recommendations
Basics: Wellbore Thermal Loads

Axial Load: FZ = (AE)ε
                  dL
Total Strain: ε =    − εT − εPoisson − εBuck
                  L

Thermal Strain:   εT = CLE ⋅ ΔT
Change in Avg Temp: ΔT = TFinal − TInitial
 Other Thermal Load Effects

• Compressive Axial Loads
 – Helical Buckling = Bending Stress
• Proprietary Connections
 – Reduced axial compression rating?
• APB: Severe Collapse & Burst
 – APB is also a function of ΔT
Basics of Wellbore Thermal Loads
     Initial Conditions
                          Temperature

                      DRILLING




                             UDT
      Depth




                        WOC
Basics of Wellbore Thermal Loads
      Final Conditions
                             Temperature

                          Production




                                UDT
      Depth




              Injection     WOC
What is Average Initial
   Temperature?
                    Temperature

                Average?




                       UDT
   Depth




                  WOC
Cement Boundary Condition
                           Temperature

                       Avg T (WOC)


               Avg T
               (UDT)

              TOC              UDT
      Depth




                         WOC
   Initial Conditions
Determine Load Severity
                   Temperature


                  ΔT?

                  ΔT?


           TOC
   Depth
Current Industry Environment
• Practical costs of modelling
  – Determine assumptions (e.g. drilling)
  – Gather data & parameters
  – Consider contingencies
• Shortage of personnel
  – Complex software requires expertise
• More & more HPHT wells
• Use “rules of thumb” for worst case
   Why not Assume UDT?

• Assuming UDT “seems” worst-case
• Design first using UDT as initial state
  – If no loads critical, then design is OK
  – If critical loads identified, refine with
    models as needed
• An effective design strategy?
• Is UDT always conservative?
Three Case Study Examples

1. Extreme HPHT Tubing Leak
   UDT can be over conservative
2. Marginal HPHT Tubing Leak
    UDT can be non-conservative
3. HPHT Downhole APB
   UDT can be non-conservative
      Case Study #1:
Extreme HPHT Tubing Leak
               • Well TD at 21000 ft
               • Reservoir: 420ºF,
                 18kpsi
               • Gas Condensate
               • 7” Tubing Monobore
               • Production Casing
                  – 10 ¾” 109# P110
                  – 10” 68.8# Q125
               • Hot Tubing Leak
               • 14kpsi SITHP
                                                                                        Case Study #1
Assume Undisturbed Initial Conditions

       Design Limits - 9.998" Production Casing - Section 2 - OD 9.998 - Weight 68.80 - Grade Q-125
                                     20000


                                     16000
                                                        Burst 1.100
                                                                                            Triaxial 1.250
                                                                                                                                 Tension 1.300                   Combined
                                                                                                                                                                 compression,
                                     12000


                                      8000                                                     Hot Tubing Leak
Effective Internal Pressure (psig)




                                      4000
                                                        Compression 1.300
                                                                                                                                                                 buckling and
n Compression 1.300
                                          0
                                                                                                                                                                 burst load
                                      -4000


                                      -8000
                                                                                                                                                                 results in
                                     -12000
                                                                                                                                                                 exceeding
                                     -16000
                                                        Collapse 1.000
                                                                                                                                                                 safety limits.
                                              Note: Limits are approximate
                                     -20000
                                         -2500000   -2000000   -1500000   -1000000   -500000         0        500000   1000000     1500000   2000000   2500000
                                                                                          Effective Tension (lbf)
           Case Study #1
Use ‘As Cemented’ Initial Conditions

                           TUDT = 139 o F
                           TCMT = 169 o F
                           THOT = 349 o F

                           Average T
                           decreases
                           14%
                           Axial load @
                           TOC reduced
                           by 27%
                                                                                     Case Study #1
                                     Optimal Design Basis Achieved

       Design Limits - 9.998" Production Casing - Section 2 - OD 9.998 - Weight 68.80 - Grade Q-125
                                     20000
                                                                                                                                                                 Realistic
                                     16000


                                     12000
                                                        Burst 1.100
                                                                                            Triaxial 1.250
                                                                                                                                 Tension 1.300
                                                                                                                                                                 cementing
                                      8000                                                        Hot Tubing Leak
                                                                                                                                                                 temperatures
Effective Internal Pressure (psig)




                                      4000
                                                        Compression 1.300
                                                                                                                                                                 show that
                                                                                                                                                                 UDT was too
n Compression 1.300
                                          0




                                                                                                                                                                 conservative.
                                      -4000


                                      -8000




                                                                                                                                                                 Design
                                     -12000

                                                        Collapse 1.000
                                     -16000


                                     -20000
                                              Note: Limits are approximate
                                         -2500000   -2000000   -1500000   -1000000   -500000         0        500000   1000000     1500000   2000000   2500000
                                                                                                                                                                 change
                                                                                          Effective Tension (lbf)
                                                                                                                                                                 avoided.
       Case Study #2:
Marginal HPHT Tubing Leak
              • Deviated, TD @12350’
              • Reservoir: 265ºF/
                7kpsi
              • Oil & Gas Producer
              • 12.5 kbpd, 45 MMscfd
              • Production Casing
                 – 10 3/4” 55.5# L80
                 – 9 5/8” 53.5# 95SS
              • Hot Tubing Leak
              • Mud Deterioration
              • 5kpsi SITHP
                                                                                          Case Study #2:
Assume Undisturbed Initial Conditions

       Design Limits - 9 5/8" Production Casing - Section 2
                                       10000                                            Triaxial 1.250
                                                         Burst 1.100                                                   Tension 1.300


                                                                                                                                                                Tubing Leak
                                        8000


                                        6000


                                        4000                                                                                                                    design load is
Effective Internal Pressure (psig)




                                                         Compression 1.300

                                        2000
                                     Connection Compression 1.300
                                                                                                                                                                acceptable.
                                           0


                                       -2000
                                                                                                                                                                Kill load case
                                       -4000


                                       -6000
                                                                                                                                                                marginally
                                       -8000             Collapse 1.000
                                                                                                              Tubing Leak (Deteriorated Mud)
                                                                                                                                                                exceeds limit.
                                               Note: Limits are approximate                                   Tubing Leak - Kill (Deteriorated Mud)
                                      -10000
                                         -1500000 -1250000 -1000000 -750000 -500000 -250000      0     250000 500000   750000 1000000 1250000 1500000 1750000
                                                                                           Effective Tension (lbf)
           Case Study #2
Use ‘As Cemented’ Initial Conditions

                           TUDT = 132 o F
                           TCMT = 107 o F
                           THOT = 254 o F

                           Differential
                           temperature
                           increases 21%
                           Axial load @
                           TOC increases
                           28%
                                                                                      Case Study #2
                                ‘As Cemented’ Temps Worst-Case
       Design Limits - 9 5/8" Production Casing - Section 2
                                     10000                                               Triaxial 1.250
                                                         Burst 1.100                                                          Tension 1.300
                                      8000


                                      6000


                                      4000                                                                                                                    Unacceptable
Effective Internal Pressure (psig)




                                                         Compression 1.300

                                      2000
                                     Connection Compression 1.300
                                                                                                                                                              triaxial & axial
                                                                                                                                                              results occur
                                         0


                                      -2000


                                      -4000
                                                                                                                                                              for both loads
                                      -6000


                                      -8000              Collapse 1.000
                                                                                                             Tubing Leak (Deteriorated Mud)
                                              Note: Limits are approximate                                   Tubing Leak - Kill (Deteriorated Mud)
                                     -10000
                                        -1500000   -1200000   -900000   -600000   -300000         0         300000   600000      900000   1200000   1500000
                                                                                       Effective Tension (lbf)




                                     In this case UDT is not conservative!
   Case Study #3:
HPHT Downhole APB

          • Vertical, TD @15000’
          • Reservoir: 350ºF,
            14kpsi
          • 64 MMscfd & 10 kbpd
          • 7” 35# P-110 Liner
          • Possible 100 ft of mud
            below liner hanger
          • Downhole APB
            collapse?
                                                                                             Case Study #3
Assume Undisturbed Initial Conditions

       Design Limits - 7" Production Liner - Section 1 - OD 7.000 - Weight 35.00 - Grade P-110
                                     15000

                                                                     Burst 1.100                                       Tension 1.600
                                     12000
                                                                                              Triaxial 1.250


                                      9000                                                                                                                            API Collapse
                                      6000
                                                                     Compression 1.600                                                                                load is still
Effective Internal Pressure (psig)




                                                                                                                                                                      significant
                                      3000


                                         0


                                      -3000
                                                                                                                                                                      but within
                                                                                                                                                                      design
                                      -6000


                                      -9000


                                     -12000                                                                                                                           guidelines
                                                                     Collapse 1.000
                                     -15000                                                                                     SS Production APB

                                              Note: Limits are approximate
                                     -18000
                                         -1200000 -1000000 -800000   -600000   -400000   -200000       0      200000   400000     600000   800000   1000000 1200000
                                                                                            Effective Tension (lbf)
           Case Study #3
Use ‘As Cemented’ Initial Conditions
                           TUDT = 278 o F
                           TCMT = 240 o F
                           THOT = 346 o F

                           Differential
                           temperature
                           increases 56%
                           APB increases
                           from 5000 psi
                           to 7200 psi
                           (44%)
                                                                                            Case Study #3
                                     ‘As Cemented’ Temps Worst-Case

       Design Limits - 7" Production Liner - Section 1 - OD 7.000 - Weight 35.00 - Grade P-110
                                     15000


                                     12000
                                                                     Burst 1.100
                                                                                              Triaxial 1.250
                                                                                                                       Tension 1.600                                Now critical
                                      9000                                                                                                                          API collapse
                                      6000
                                                                     Compression 1.600                                                                              result
Effective Internal Pressure (psig)




                                                                                                                                                                    occurs in
                                      3000


                                         0


                                      -3000
                                                                                                                                                                    mud zone.
                                      -6000


                                      -9000
                                                                                                                                                                    Here again
                                                                                                                                                                    UDT is not
                                     -12000

                                                                     Collapse 1.000
                                     -15000                                                                                SS Production APB

                                     -18000
                                              Note: Limits are approximate
                                         -1200000 -1000000 -800000   -600000   -400000   -200000       0      200000
                                                                                            Effective Tension (lbf)
                                                                                                                       400000   600000   800000   1000000 1200000   conservative
            Conclusions:

• Initial temperatures determine
  thermal load severity
• TOC depth affects average ΔT
  – Shallow TOC amplifies heating effect
  – Deep TOC amplifies cooling effect
• Default UDT assumption for initial
  state not always appropriate
• Extreme HPHT: UDT often too
  conservative
       Conclusions (cont.):

• UDT is not always “worst-case”
  – Critical loads may not be identified
• Thermal simulation often required to
  identify worst case
• Initial temperatures and APB
  – Mudline vs. Downhole Annuli
  – UDT non-conservative for deep annuli

								
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