Annulars Hydril Gk

The 'GK' annular preventer is designed for surface installations and is also used on offshore platforms and subsea. Standard operation requires both opening and closing pressure. Seal off is affected by hydraulic pressure applied to the closing chamber, which raises the piston, forcing the packing unit into a sealing engagement. Main features include:

  • Only two moving parts (piston and packing unit) mean few areas are subjected to wear. The BOP is thus safer and more efficient requiring less maintenance and less downtime.
  • Piston is designed to be well pressure assisted. This ensures a more positive seal off under kick conditions for a higher margin of safety.
  • Field replaceable wear plate in the BOP head serves as an upper non-sealing wear surface for the movement of the packing unit, making field repair fast and economical.
  • Piston stroke measurement provides indication of packing unit life without disassembly.
  • Three choices of packing unit rubber compounds
Hydril Annular Bop
Figure 27 - Type 'GK' Annular Blowout Preventer

1.6.1 Hydril 'GK' Stripping Operations

During well control operations, drill pipe can be rotated and tool joints stripped through a closed packing unit, while maintaining a full seal on the pipe. Longest packing unit life is obtained by adjusting the closing chamber pressure just low enough to maintain a seal without any leakage as the tool joint passes through the packing unit. As a large diameter tool joint passes through the packing unit it expands. A responsive regulator valve must control the hydraulic surge pressure caused by packing unit expansion. Better control may be achieved with the addition of a surge absorber (accumulator) to the closing chamber. Pre-charge the accumulator to half the closing pressure required to effect seal off. Slow stripping speeds will give longest packing unit life.

Average Closing Pressure (psi) To Establish Initial Seal Off In 'GK' Blowout Preventers For Surface Installations

OD (Ins)

7 1/16 3M

7 1/16 5M

7 1/16 10M

7 1/16 15M

7 1/16 20M

9-3M

9-5M

9-10M

11-3M

11-5M

11-10M

13 5/8 3M

13 5/8 5M

13 5 /8 10M

16-2M

16-3M

16 % 5M

18-2M

6 5/8

350

700

600

350

450

500

5

400

350

450

450

500

800

650

700

400

500

550

4 1/2

350

400

350

2100

2200

400

450

380

450

450

500

900

650

700

500

500

600

600

3 1/2

400

450

550

2100

2200

500

600

570

550

525

700

1000

7000

1200

600

600

650

650

2 7/8

400

450

750

2100

220

550

650

760

650

800

800

1100

750

1400

700

700

750

700

2 3/8

500

500

850

2100

2200

650

750

860

750

900

1100

950

1400

800

800

850

740

1 90

600

600

900

750

850

850

920

1000

1500

900

950

950

850

1 66

700

700

1000

850

950

1000

950

1000

1500

1000

1000

1050

950

CSO

1000

1000

1150

1050

1150

1150

1150

1150

1500

1200

1150

2200

1150

1150

1150

1150

The pressure above is a guideline. Maximum packing unit life will be realised by the use of the lowest closing pressure that will maintain a seal. For subsea applications, see the appropriate Operator's Manual for computation of best closing pressure.

Recommended test pipe for maximum packing unit life

The pressure above is a guideline. Maximum packing unit life will be realised by the use of the lowest closing pressure that will maintain a seal. For subsea applications, see the appropriate Operator's Manual for computation of best closing pressure.

Recommended test pipe for maximum packing unit life

* Reference only replaced by 'GX'

Average closing pressures to establishing initial seal off pressure-surface installations.

Average closing pressures to establishing initial seal off pressure-surface installations.

Gasket Subsea Well Section
Figure 28 — Packing Unit Testing

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Responses

  • j
    Who was GK annular preventer named after?
    8 years ago
  • Aaran
    What does CSO mean when using hydril annulars?
    7 years ago
  • Einojuhani Sievinen
    Is hydril gk annular well bore assisted?
    7 years ago
  • fosco
    CAN I CUTTED THE PACKING UNIT HYDRILL?
    5 years ago
  • oskar
    Can you rotate with GK BOP Annular?
    10 months ago
  • Olga
    What is the hydrill annular closing pressure for 7.75" casing?
    7 months ago

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