OCTG

OCTG (Casing and Tubing)

OCTG (Oil Country Tubular Goods) refers to a group of rolled metal products used in the oil and gas industry, including casing and tubing. They are indeed used in the drilling process.

 

Casing is a term that refers to the OCTG that is installed inside a drilled well to protect and support the well stream. The Casing completely surrounds the wellbore, protecting the soil layers and, most importantly, the groundwater from contamination by drilling mud and frac fluids. Additionally, it stabilizes the wellbore, which means that the casing must be able to withstand extremely high loads.

PRODUCT FEATURES

Types of OCTG (Tubing and Casing)

- Lining with Casing

In this type of OCTG, casing refers to the external tubes. Casing completely surrounds the wellbore, protecting the soil layers and, most importantly, the groundwater from contamination by drilling mud and/or frac fluids. Additionally, it stabilizes the wellbore, which means that the casing must be able to withstand extremely high loads. Drilling and casing operations alternate – the drill string is removed at predetermined intervals and the wellbore is lined and cemented with casing. Then the drilling resumes.

- Production with Tubing

In this type of OCTG, tubing is used to carry petroleum from the well’s depths to the surface – this is the third phase of the wellbore. Oil and gas occasionally self-elevate to the surface; however, pumps are typically required to bring the fluids to the surface. Besides the 4 1/2-inch diameter, tubing is normally smaller in diameter than the casing. A casing or tubing with an outer diameter of 114.3 mm (4 1/2 inches) is considered a threshold size. Anything smaller than tubing is referred to as tubing, while anything larger is referred to as casing. The casing shrinks in diameter as it descends from the surface to the bottom of the well – there are various types of casing depending on their purpose and diameter. The “kickoff point” is the gradual transition of the wellbore from vertical to horizontal. Horizontal drilling enables more precise targeting of deposits. After the procedure, the drill string is removed and the production casing is inserted and cemented into the wellbore. After fracturing the well, the tubing is installed inside the production casing.

Production Standards of OCTG

APT 5CT specified that casing and tubing used in OCTG production must be cased with a material that is both strong and functional. The standard establishes requirements for three Product Specification Levels and a variety of grades (API 5CT J55, K55, N80, L80, P110).

Dimensions and Sizes of OCTG (Tubing and Casing)

- Specification & Size of Tubing

DN

O. D.

Weight

W. T.

End Processing

Non-upset

coupling-thread

Upset

coupling-thread

OCTG Steel Grade

in

mm

lb./ft.

lb./ft.

in

mm

H40

J55

L80

N80

C90

T95

P110

2-3/8

2.375

60.32

4.00

0.167

4.24

PU

PN

PN

PN

PN

PN

4.60

4.70

0.190

4.83

PNU

PNU

PNU

PNU

PNU

PNU

PNU

5.80

5.95

0.254

6.45

PNU

PNU

PNU

PNU

PNU

6.60

0.295

7.49

P

P

P

7.35

7.45

0.336

8.53

PU

PU

PU

2-7/8

2.875

73.02

6.40

6.50

0.217

5.51

PNU

PNU

7.80

7.90

0.276

7.01

8.60

8.70

0.308

7.82

PLB

PLB

PLBE

PLB

9.35

9.45

0.340

8.64

PLB

PLB

PLBE

PLB

10.50

0.392

9.96

PLB

PLB

PLB

PLB

11.50

0.440

11.18

PLB

 

3-1/2

3.500

88.90

7.70

0.216

5.49

PN

PN

PN

PN

PN

PN

9.20

9.30

0.254

6.45

PNU

PNU

PNU

PNU

PNU

PNU

PNU

10.20

0.289

7.34

PN

PN

PN

PN

PN

PN

12.70

12.95

0.375

9.52

PNU

PNU

PNU

PNU

PNU

14.30

0.430

10.92

P

P

P

15.50

0.476

12.09

P

P

P

17.00

0.530

13.46

P

P

P

4

4.000

101.60

9.50

0.226

5.74

PN

PN

PN

PN

PN

PN

11.00

0.262

6.65

PU

PU

PU

PU

PU

PU

13.20

0.330

8.38

P

P

P

16.10

0.415

10.54

P

P

P

18.90

0.500

12.70

P

P

P

22.20

0.610

15.49

P

P

P

4-1/2

4.500

114.30

12.60

12.75

0.271

6.88

PNU

PNU

PNU

PNU

PNU

PNU

15.20

0.337

8.56

P

P

P

17.00

0.380

9.65

P

P

P

18.90

0.430

10.92

P

P

P

PLB

21.50

0.500

12.70

P

P

P

PLB

23.70

0.560

14.22

P

P

P

PLB

26.10

0.630

16.00

P

P

P

PLB

P——Plain;N—— Non-upset coupling-thread;U—— Upset coupling-thread; L——Integral

- Specification & Size of Casing Pipe

DN

O. D.

Weight

W. T.

End Machining Form

OCTG Steel Grade

in

mm

lb/ft

kg/m

in

mm

H40

J55

L80

N80

C90

P110

K55

T95

4-1/2

4.500

114.3

9.50

14.14

0.205

5.21

PS

PS

10.50

15.63

0.224

5.69

PSB

11.60

17.26

0.250

6.35

PSLB

PLB

PLB

PLB

PLB

13.50

20.09

0.290

7.37

PLB

PLB

PLB

PLB

15.10

22.47

0.337

9.56

PLB

5

5.000

127

11.50

17.11

0.220

5.59

PS

13.00

19.35

0.253

6.43

PSLB

15.00

22.32

0.296

7.52

PSLB

PLB

PLB

PLBE

PLB

18.00

26.79

0.362

9.19

PLB

PLB

PLBE

PLB

21.40

31.85

0.437

11.10

PLB

PLB

PLB

PLB

23.20

34.53

0.478

12.14

PLB

24.10

35.86

0.500

12.70

PLB

5-1/2

5.500

139.7

14.00

20.83

0.244

6.20

PS

PS

15.50

23.07

0.275

6.98

PSLB

17.00

25.30

0.304

7.72

PSLB

PLB

PLB

PLBE

PLB

20.00

29.76

0.361

9.17

PLB

PLB

PLBE

PLB

23.00

34.23

0.415

10.54

PLB

PLB

PLBE

PLB

26.80

39.88

0.500

12.70

29.70

44.20

0.562

14.27

32.60

48.51

0.625

15.88

35.30

52.53

0.687

17.45

38.00

56.55

0.750

19.05

40.50

60.27

0.812

20.62

43.10

64.14

0.875

22.22

6-5/8

6.625

168.28

20.00

29.76

0.288

7.32

PS

PSLB

24.00

35.72

0.352

8.94

PSLB

PLB

PLB

PLBE

PLB

28.00

41.67

0.417

10.59

PLB

PLB

PLBE

PLB

32.00

47.62

0.475

12.06

PLB

PLB

PLBE

PLB

7

7.000

177.8

17.00

25.30

0.231

5.87

PS

20.00

29.76

0.272

6.91

PS

PS

23.00

34.23

0.317

8.05

PSLB

PLB

PLB

PLBE

26.00

38.69

0.362

9.19

PSLB

PLB

PLB

PLBE

PLB

29.00

43.16

0.408

10.36

PLB

PLB

PLBE

PLB

32.00

47.62

0.453

11.51

PLB

PLB

PLBE

PLB

35.00

52.09

0.498

12.65

PLB

PLB

PLBE

PLB

38.00

56.55

0.540

13.72

PLB

PLB

PLBE

PLB

42.70

63.54

0.625

15.88

46.40

69.05

0.687

17.45

50.10

74.56

0.750

19.05

53.60

79.77

0.812

20.62

57.10

84.97

0.875

22.22

7-5/8

7.625

193.68

24.00

35.72

0.300

7.62

PS

26.40

39.29

0.328

8.33

PSLB

PLB

PLB

PLBE

PLB

29.70

44.20

0.375

9.52

PLB

PLB

PLBE

PLB

33.70

50.15

0.430

10.92

PLB

PLB

PLBE

PLB

39.00

58.05

0.500

12.70

PLB

PLB

PLBE

PLB

42.80

63.69

0.562

14.27

PLB

PLB

PLB

PLB

45.30

67.41

0.595

15.11

PLB

PLB

PLB

PLB

47.10

70.09

0.625

15.88

PLB

PLB

PLB

PLB

51.20

76.19

0.687

17.45

55.30

80.30

0.750

19.05

8-5/8

8.625

219.08

24.00

35.72

0.264

6.71

PS

28.00

41.62

0.304

7.72

PS

32.00

47.62

0.352

8.94

PS

PSLB

36.00

53.57

0.400

10.16

PSLB

PLB

PLB

PLBE

PLB

40.00

59.53

0.450

11.43

PLB

PLB

PLBE

PLB

44.00

65.48

0.500

12.70

PLB

PLB

PLBE

PLB

49.00

72.92

0.557

14.15

PLB

PLB

PLBE

PLB

9-5/8

9.625

244.48

32.30

48.07

0.312

7.92

PS

36.00

53.57

0.352

8.94

PS

PSLB

40.00

59.53

0.395

10.03

PSLB

PLB

PLB

PLBE

43.50

64.73

0.435

11.05

PLB

PLB

PLBE

PLB

47.00

69.94

0.472

11.99

PLB

PLB

PLBE

PLB

53.50

79.62

0.545

13.84

PLB

PLB

PLBE

PLB

58.40

86.91

0.595

15.11

PLB

PLB

PLB

PLB

59.40

88.40

0.609

15.47

64.90

96.58

0.672

17.07

70.30

104.62

0.734

18.64

75.60

112.50

0.797

20.24

10-3/4

10.750

273.05

32.75

48.74

0.279

7.09

PS

40.50

60.27

0.350

8.89

PS

PSB

15.50

67.71

0.400

10.16

PSB

51.00

75.90

0.450

11.43

PSB

PSB

PSB

PSBE

PSB

55.50

82.59

0.495

12.57

PSB

PSB

PSBE

PSB

60.70

90.33

0.545

13.84

PSBE

PSB

65.70

97.77

0.595

15.11

PSB

PSB

73.20

108.93

0.672

17.07

79.20

117.86

0.734

18.64

85.30

126.94

0.797

20.24

11-3/4

11.750

 

42.00

62.50

0.333

8.46

PS

47.00

69.94

0.375

20.24

54.00

80.36

0.435

8.46

60.00

89.29

0.489

9.53

65.00

96.73

0.534

11.05

71.00

105.66

0.582

14.42

13-3/8

13.375

339.73

48.00

71.43

0.330

8.38

PS

54.50

81.10

0.380

9.65

PSB

61.00

90.78

0.430

10.92

PSB

68.00

101.19

0.480

12.19

PSB

PSB

PSB

PSB

PSB

72.00

107.15

0.514

13.06

PSB

PSB

PSB

PSB

16

16.000

406.4

65.00

96.73

0.375

9.53

PS

75.00

111.61

0.438

11.13

PSB

84.00

125.01

0.495

12.57

PSB

109.00

162.21

0.656

16.66

P

P

P

P

18-5/8

18.625

473.08

87.50

130.21

0.435

11.05

PS

PSB

20

20.000

508

94.00

139.89

0.438

11.13

PSL

PSLB

106.50

158.49

0.500

12.70

PSLB

133.00

197.93

0.635

16.13

PSLB

P——Plain;S——Short-thread;L——Long-thread;B——Buttress thread;E——Extreme thread

Chemical Composition of OCTG (Tubing and Casing)

Group

OCTG

Steel

Grade

Type

C

Mn

Mo

Cr

Ni

Cu

P

S

Si

min.

max.

min.

max.

min.

max.

min.

max.

min.

max.

max.

max.

max.

1

H40

0.03

0.03

J55

0.03

0.03

K55

0.03

0.03

N80

1

0.03

0.03

Q

0.03

0.03

2

M65

0.03

0.03

L80

1

0.43

1.9

0.25

0.35

0.03

0.03

0.5

9Cr

0.15

0.3

0.6

0.9

1.1

8

10

0.5

0.25

0.02

0.01

1.0

13Cr

0.15

0.22

0.25

1

12

14

0.5

0.25

0.02

0.01

1.0

C90

1

0.35

1.2

0.25

0.85

1.5

0.99

0.02

0.01

2

0.5

1.9

NL

NL

0.99

0.03

0.01

C95

0.45

1.9

0.03

0.03

0.5

T95

1

0.35

1.2

0.25

0.85

0.4

1.5

0.99

0.02

0.01

2

0.5

1.9

0.99

0.03

0.01

3

P110

0.03

0.03

4

Q125

1

0.35

1.35

0.85

1.5

0.99

0.02

0.01

2

0.35

1

NL

NL

0.99

0.02

0.02

3

0.5

1.9

NL

NL

0.99

0.03

0.01

4

0.5

1.9

NL

NL

0.99

0.03

0.02

a. The carbon content for L80 may be increased up to 0, 50 % maximum if the product is oil-quenched.

b. The molybdenum content for Grade C90 Type 1 has no minimum tolerance if the WT is less than 17, 78 mm.

c. The carbon content for R95 may be increased up to 0, 55 % maximum if the product is oil-quenched.

d. The molybdenum content for T95 Type 1 may be decreased to 0, 15 % minimum if the WT is less than 17, 78 mm.

e. For EW Grade P110, the phosphorus content shall be 0,020 % maximum and the sulfur content 0,010 % maximum

NL = no limit. Elements shown shall be reported in product analysis.

Mechanical Properties of OCTG (Tubing and Casing)

Group

OCTG

Steel

Grade

Type

Total
%

Yield Strength
MPa

Tensile
MPa

Hardness
max

W. T.
mm

Changes in

Hardness

min.

max.

min.

HRC

HBW

1

H40

0.5

276

552

414

J55

379

552

517

K55

379

552

655

N80

1

552

758

689

Q

552

758

689

2

M65

0.5

448

586

586

22

235

L80

1

552

655

655

23

241

9Cr

552

655

655

23

241

13Cr

552

655

655

23

241

C90

1、2

621

724

689

25.4

255

≤ 12.70

3.0

621

724

689

25.4

255

12.71 ~ 19.04

4.0

621

724

689

25.4

255

19.05 ~ 25.39

5.0

621

724

689

25.4

255

≥25.40

6.0

C95

655

758

724

T95

1、2

655

758

724

25.4

255

≤ 12.70

3.0

655

758

724

25.4

255

12.71 ~ 19.04

4.0

655

758

724

25.4

255

19.05 ~ 25.39

5.0

655

758

724

25.4

255

≥25.40

6.0

3

P110

0.6

758

965

862

4

Q125

all

0.65

862

1034

931

≤ 12.70

3.0

862

1034

931

12.71 ~ 19.04

4.0

862

1034

931

≥19.05

5.0

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