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Concept of Drill Pipe development for UDD _Ultra Deep Drilling_

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					Concept of Drill Pipe development for UDD
(Ultra Deep Drilling)




                                     5 September 2008
Contents
•Understanding of UDD’s problem
       deep water problem

•Requirements to Drill Pipe
       General requirements
       Opinions in papers
       Concrete specification issued by oil company

•Response from Drill Pipe manufacture
       Investigation of delay fracture
      Sour service performance
      Fatigue resistance

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    Undersatnding to UDD
Difference required in Drill Pipe between ERD and UDD
•     ERD…High torque required but low tension
               TSH wedge type connection will be candidate.
       max. dogleg severity is 6 degree/100feet in rotary drill pipe.


•      UDD… Moderate torque required but high tension and fatigue
    (riser-less drilling)
                  Definition: THD/TVD        0.25
               NK-DSTJ-ST series is candidate.
               Grade: S150
World record 34189 ft (10420m) at KNOTTY HEAD WELL/Gulf of Mexico


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Deep water problems
• Unstable see bed
      Sand base, leaning

• Low temperature at sea bed
      Influence to pipe, device and equipments

• High load to well head
      Design factor, reliability for Engineering

• Operation supports by submarine in sea bed
      Subcontract it to modernized and reliable company

• Difficulty for vertical drilling by current
      Necessity of drilling riser

• Influence of current
      Fatigue of drill pipe vibrated in current.



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 General requirements
• Reduction of Drill Pipe weights

• Low friction factor of hardfacing for Tool Joint

• High torque Tool Joint

• High friction factor dope

• High strength Drill Pipe

• High toughness Drill Pipe
            IMPL(3/4 size     20 ) >59 ft-lbs

• Fartigue resistance Drill Pipe

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  Opinions in papers
Key factors to be solved in UDD


• Maximum capacity of suspending a string at Rig
• Collapse resistance in BOP
• Maximum shearing force in BOP in emergency
• Difficulty of installation of risers to sea bed device and/or
  riser less drilling difficulty by current




 Referenced papers
 SPE 104827 and 105792 indicating difficulty of UDD Oil
 Company specification.

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One specification issued by oil company

High strength Drill Pipe
   Yield strength :                ksi &           ksi
                       range shall be 20 ksi.
   Charpy test
                               4    IMPL (ft-lbs)               Hardness
                                       Each               ve.      HRC
   Sub size of pipe     150 ksi                                     42
                         165 ksi                                    43
    Full size of T/J     135 ksi                                316-375 HB




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One specification issued by oil company

Additionally,      Delay fracture             Fatigue test SSC test
 Condition
             psi balanced with CO2 gas


 Criterion for SSC test
     90% SMYS




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Response from drill pipe manufacture
• Drill Pipe
   Challenge to high strength                 Univ. joint angle
                                              degree
    Delay fracture                                                Current   Nott
    SSC resistance
                                              Univ. joint angle
    toughness at welds                        degree




• Tool Joint
   Influence to external shoulder
  from bending force under high
  tension
   Influence to external shoulder
  from vibration due to fast
  current caused by riser less
  drilling.


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Delay fracture
What we need to consider of in designing of high strength materials
 is delay fracture phenomimum is one of the hydrogen
 brittlement.Hydrogen gas induced by corrosion invade into steel
 material structure and accumulate and pressurize at certain area
 eventually induce fatal cracks. This is called as delay fracture.
It is not managed not to occur by controlling atmosphere, as it
  happen in salt water.
Test method is as follows.
 After sample is prepared as a drawing then created fatigue crack
 by fatigue tester, samples with various values of KI calculated by
 mechanical properties and fatigue crack length are tested to seek
 no failed sample which has the biggest KI value, which is called as
 KISCC value.
Test duration: 500 hr
Test facility: next page




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   1.Delay fracture test
                                       Cell
                                                 Specimen




                                                                             Weight




           Solution circulation pump
              and
           Temperature controller




                                                                          0.15



                                              Test specimen




                                                                                      1.5 1.5
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   2.Test result
                                  Ultimate tensile strength

                                          170ksi
                         450

                         400
                         350
           (kgf/mm3/2)




                         300
                                                           API S135
                         250
                         200
                         150
           KI




                         100
                          50

                           0
                           1000   1100         1200              1300   1400
                                             T.S.(MPa)



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 Condition to use S135 in sour service

• PH<10 in accordance with API spe .7
 But it is difficult to control in Under balanced drilling and High
 PCO2.
                                                                                              Temperature Profiles
                                                                                  DP Circ. Temp.      Annulus Circ Temp    Static Temp

                                                                    0



                                                                  5000




                                 M e a s u r e d D e p th (ft)
                                                                 10000



                                                                 15000



                                                                 20000



                                                                 25000
                                                                         0   50     100        150         200       250      300        350   400
                                                                                                   Temperature (deg F)

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 Product Designing

Grade       pipe: YS 105 ksi,   T/J material: 110 ksi
SSC Criterion
            pipe: 85% SMYS, T/J material: 70% SMYS


 Even though delay fracture test would have been succeeded, it is
 requested that SSC test conditions and the criterion in
 accordance with IRP shall be re-considered due to no realistic
 test method.


 Therefore total coordination for drill pipes considering of
 assorts of full string drill pipes, size, grade and connection.




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Sour service of drill pipe
                                                                           NK C105S         NK C105S
   Pipe Body                   IRP 1.8 SS105              API G105
                                                                             type l          type ll
                                                                                                             G/P XD-105

  Tensile property              Min.         Max.         Min.   Max.      Min.   Max.      Min.   Max.       Min.   Max.
                  YS(Ksi)         105           120       105     135      105        120   105        120    105        120
                  TS(Ksi)         115           140       115      -       115         -    115         -     115         -
                       EL         17%                     as per API       as per API       as per API
  Hardness(HRc)                 Min.         Max.        Not Required Min.        Max.      Min.   Max.       Min.   Max.
           Max. Average          -           28.0                           -     29.0       -     28.0        -     30.0
                 Reading       21.0          29.0                           -       -        -       -         -       -
                             per heat, heat treat lot,
                                                                          per heat, heat treat lot, or
                  freq.      or every 200 tubes.four                                                         Not defined
                                   quadrants.                                 every 200 tubes.
  Toughness
                                  J          ft-lbs        J     ft-lbs     J     ft-lbs     J     ft-lbs      J     ft-lbs
  (3/4size at room temp.)
               Min. Single       80           59          38      28       108        80    120        89
                                                                                                               Not defined
                Min. Ave.         -            -          43      32        -          -     -          -
  SSC
                                       85%               Not Required           80%              85%               70%
  (720h NACE-method A)
                             per heat, heat treat
                  freq.       lot, or every 200                             per heat, heat treat lot         Not defined
                                    tubes.
  Grain size                      6                      Not Required             Not defined                Not Required
                             Special compositons                              J61V.J        J97VBL
  Steel code                    are requested              API
                                                          U26MMM
                                                                          (1.0Cr-0.5Mo) (1.0Cr-0.7Mo)
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Sour service T/J material
                                                                          NK C105S          NK C105S
    Tool Joint                  IRP 1.8 SS105              API G105
                                                                            type l           type ll
                                                                                                            G/P XD-105
   Tensile property              Min.         Max.        Min.     Max.   Min.     Max.     Min.   Max.     Min.   Max.
                  YS(Ksi)          110          125       120       -     110      125      110    125      105    120
                   TS(Ksi)         125          145       140       -     125       -       125     -       115     -
                         EL        15%                    13%             13%               13%             13%
                        RA         35%                    Not defined     Not defined       Not defined     Not defined
   Hardness(HRc)                 Min.         Max.        Min. Max.       Min. Max.         Min. Max.       Min. Max.
              Max. Ave.            -          30.0                  -              30.0            29.0            30.0
                                                         HB 285
                   Reading         -          32.0                  -      -         -       -         -      -      -
                                                         (HRc30)
                               per heat, heat treat        per heat,      per heat, heat treat lot, or
                    freq.      lot, or every 200 T/J     heat treat lot         every 200 T/J
   Suface HA        freq.           every T/J                                     every T/J
   Toughness
                                   J          ft-lbs     Not Required      J       ft-lbs    J     ft-lbs     J    ft-lbs
   (full size at room temp.)
                   Min. Ave.      90           66                         108        80     130        96
                               per heat, heat treat                       per heat, heat treat lot, or      Not defined
                    freq.      lot, or every 200 T/J                            every 200 T/J
   SSC
                                        65%              Not Required          65%               70%        Not Specified
   (720h NACE method A)
                               per heat, heat treat
                    freq.                                                  per heat, heat treat lot
                               lot, or every 200 T/J
   Grain size                            6               Not Required              Not Required             Not Specified
                               Special compositons                                     J97VBL
   Steel code                     are requested            API
                                                            J1235F
                                                                                   (1.0Cr-0.7Mo)
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 Tool Joint fatigue resistance
In general, fatigue failure for drill pipe is considered as follows.
 Failure mode:
  I. circumferential fatal crack occur at 1 to 2m from the ends of tool joints.
  II. root of threads in tool joint due to stress concentration in external shoulder opened.


 Failure process ( internal coated drill pipe):
   I. Pitting corrosion at external surface and/ or slip marks at external surface
    Fatigue crack initiated from a bottom of pits and propagated.
    Fatigue crack reached inside of pipe then leakage started from int.
    to ext. surface.
    Pressure dropped and/or led to spitted.
  II. High fatigue stress from Drill pipes supported by outer casing due to high
    bending and light compression to tool Joint is shifted. Once external shoulder started to
    detach, stress concentrate at a bottom of threads.


Corrective actions:
   I. Cleaning and cleaning drill pipes.
  II. Stress relief groove is applied.


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Fatigue analysis by FEM

                                               Cantilever fatigue tester




                                                                           amplituded
                                                                           force
                                          axial force




  no compression          compression


  Elastic deformation under compression



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Fatigue analysis by FEM




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Fatigue analysis by FEM
Grade                          135    ksi



OD drill pipe                  5.5    inch

NW of drill pipe              23.4    lbs/ft                                    WT     0.316      inch


                                                                                ID            5   inch


                                                                                A           5

A                       B             C                D             E

degree                  lbs           ksi              %             ksi              API         required fatigue resistance                            ksi

                                                       Amplitud
                                                          e
                                      max.                of
                        Bending          surface          vibrat
Dogleg severity            force         stress           ion        FR               grade       E                                   X        G         S

                   3          24324                5        15%            20   F     FR                                         27       29        33         35


                   4          32432                6        20%            27         YS                                         75       95       105       135


                   6          48649            10           30%            41         %                                         36%   31%      31%        26%


                   10         81081            16           50%            68




                                      no tension       of 50%YS


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Others
Reduction of Drill Pipe weights
• FRP,Titan alloy, Alminum alloy
 All industrial products but prices are ten times more expensive
 than low alloy Drill Pipe. And other key issue is strength.
  Alminum alloy :   maximum yield strength                 69 ksi
  Titan alloy:      maximum yield strength 120 ksi
  Low alloy:        maximum yield strength 150 ksi
  If 160ksi material in low alloy exists, the same string weight
  would be achieved.


• Under investigation of influence of heavy load of string
  Based on a result of FEM, it shall be reflected to a modification of
  T/J design.




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