Slotted Liner

Slotted Liner

A slotted liner is a common sand control screen used in long horizontal completions in wells with limited productivity. In comparison to other sand control devices, slotted liners are widely employed in SAGD wells and other thermal applications due to their higher structural capabilities to handle installation and operation loads.

Base pipes are manufactured to API casing or tubing specifications and range in diameter from 1.5 to 18 inches. CNC-controlled slotting machines or laser machines are used to make precision slotted liners. According to API standards, all slots are deburred, cleaned, and drift tested. Pipes of any diameter are available in any length. Slot widths are frequently expressed in gauge terms. The gauge for a slot or screen is just the opening’s width in inches multiplied by 1,000.

SLOTTED LINER PRODUCT FEATURES

Slot Size of Slotted Liner

The slot size of the slotted liner, which includes the width and length of the slot, is customized to the customer’s specifications. The minimum slot width for straight or keystone slots is 0.012 inches, and the maximum slot width is 0.25 inches.

1.5 inch long

2.0 to 2.5 inch long

2.5 inch long

0.012 inch wide

0.024 inch wide

0.078 inch wide

0.015 inch wide

0.025 inch wide

0.125 inch wide

0.016 inch wide

0.038 inch wide

0.250 inch wide

0.018 inch wide

0.048 inch wide

0.058 inch wide

Slotting Patterns of Slotted Liner

Three distinct slot layouts have been created to accommodate distinct traits (shown below). In comparison to staggered and straight slot patterns, the gang slot design significantly improves the liner’s resistance to lateral buckling and collapse stresses.

shows the slotting pattern of Staggered Slotted Liner

Staggered Slotted Liner

Staggered slots are evenly distributed around the circumference with an offset.

shows the slotting pattern of Gang Slotted Liner

Gang Slotted Liner

Gang slots are made up of many slots that are dispersed around the perimeter.

shows the slotting pattern of Straight Slotted Liner

Straight Slotted Liner

Straight slotted liner features slot columns spaced evenly around the circumference without offset.

Slot Types of Slotted Liner

TUSPIPE can laser-cut slots to customer specifications, either straight or keystone.

- Straight Slots

This slot type is cut perpendicular to the liner and has the same diameter from the inside to the outside of the wall. While straight slots are less expensive to build, they are less effective in containing sand than keystone slots.

- Keystone Slots

Keystone slots, or tapered slots, are cut at a little angle and are larger on the inside than on the outside, ensuring that any particle entering the slot can pass freely without clogging it.

While keystone slots are more expensive to manufacture than straight slots, they eliminate the danger of production losses caused by filled liner slots.

shows the cut slot of Straight Slots
shows the cut slot of Keystone Slots

Slot density

The slot density of a pipe is defined as the number of slots per foot of pipe. It is determined by the pipe’s outer surface’s open area. The open region of a slotted liner has a significant role in diminishing its sand control capacity. In general, open land is between 2% and 4% of the total area.

After determining the open area, slot width, and liner diameter, the slot density per foot can be estimated using the following formula:

N = (12*π*D*C) / (100*W*L)

N stands for slot density or the number of slots per foot
D stands for the outside diameter of the liner in inch
C stands for open area, percentage
W stands for slot width in inch
L stand for the length of the slot in inch

For example, if the open area of a 4.5″ slotted liner is 3%, the slot width is 0.02 inches, and the slot length is 1.5′, what is the slot count per foot?

The required number of slots is shown below using the calculation above:

N = (12*π *4.5*3) / (100*0.020*1.5) = 172

Note: This is a straightforward calculation for a straight slot or a seamed keystone slot.

Dimensions and Sizes of Slotted Liner

- Specification & Size of Tubing Slotted Liner

DN

O. D.

Weight

W. T.

End Processing

Non-upset coupling-thread

Upset coupling-thread

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 Slotted Liner

DN

O. D.

Weight

W. T.

 

End Machining Form

 

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

Features of Slotted Liner

The slotted liner (slotted casing) is classified into two types: oil liner pipe and water collecting liner pipe, each of which is built of a different steel grade. It complies with API Spec 5CT. Slotted screens are made up of a series of longitudinal or spiral straight-line slots of a specified size that are cut into oil casings or tubing in a variety of methods. It is constructed from ultra-thin cutting components and is beam cut. Its slit width is (0.2-0.4)mm (client specified), and the seam length can exceed 20mm (can be determined according to user needs). The slit section is rectangular and trapezoidal, and the slit arrangement can be customized to meet user requirements. The product is sand-proof, non-clogging, and increases the quality of oil recovery. It is frequently utilized in horizontal and side walls, as well as branch wells. Over 90% of comparable good completion procedures used in other countries include oil slotted screens, which is the chosen special pipe for the present special oil recovery process.

This product is constructed with high-quality, high-performance casings and may also be imported to meet the user’s specifications (the raw materials are designated by the customer, the designated grade). And by the necessary design and processing specifications. It features a high penetration rate, a consistent width, a high strength, and a low price. This product features a sophisticated manufacturing method, a high technology content, a stable process, high performance, and high precision.

Applications of Slotted Liner

A laser liner pipe is a unique pipe body that is inserted at the bottom of seamless or welded steel well pipes, such as those used in oil wells, water wells, geothermal wells, and brine wells, to separate the mined liquid from the stratum’s sand. Due to the fundamental structural properties of the formations involved, the variation in particle size of the contact sand, and the difference in viscosity of the produced fluid, the specifications and designs of the slits required by the screens also vary. With the rapid development of China’s petroleum and geo-mineral industries in recent years, oil well drilling technology in the desert area has matured, oilfield development in the middle and late stages has increased, offshore oil production has increased, and geothermal wells, brine wells, and deep wells have exploded in popularity. As technology advances, the demand for laser liner screens increases.

Laser liner pipes (slotted casing) are commonly used in petroleum exploration for regenerating existing wells, drilling new oil wells and exploration (test) wells, offshore oil production wells, and oil suction pipes for horizontal wells, side drilling, radial branching wells, and open-hole gravel packing. The screen is completed, and a small amount of sand control is performed. Geothermal wells, saltwater wells, drought-resistant wells, and residential water wells are all tested for limited sand control daily. In general, the vertical shaft is equipped with a circular slot (hole) screen rather than a blasting perforation, which eliminates several issues associated with the ejection hole. To guarantee that the sand does not become caulked, the inner surface of the tube must be wider than the outer surface. Due to the dramatic increase in international oil prices, miners must raise the oil recovery rate of each well to reduce land occupation, save pipe bodies, reduce drilling expenses, and reduce oil production costs to maximize profits. The initial horizontal wells processed rectangular screens mechanically, laser-based, and in other ways. Due to the permeability issue, mechanical slits and screen screens have been used to compensate for lasers’ inadequacies for a lengthy period.

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