TAMU Pemex Offshore Drilling

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TAMU - PemexOffshore Drilling

• Lesson 4
• Blowout Preventers and Their Control

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Lesson 4 - Blowout Preventers and Their Control

• The BOP Stack
• Hydraulic Connectors
• Kill and Choke Valves
• BOP Controls

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Blowout Preventers and Their Control

• Control Pods Shuttle Valves
• Redundancy
• Accumulator Capacity Requirements
• Backup for BOP Controls

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Major Changes in BOP Equipment for Subsea Use

• 1. The size of the BOPs is increased.
• 2. External hydrostatic pressure at the
  ocean floor must be considered.

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Major Changes in BOP Equipment for Subsea Use

• 3. Hydraulics have become more important in
  reaction times, because the longer flow lines
  increase the pressure drop,
• while the larger BOPs require more fluid to
  operate than their land counterparts.

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Major Changes in BOP Equipment for Subsea Use

• 4. To avoid the pressure drop in the return
  lines, the hydraulic fluid is vented to the
  sea. This requires a fluid that is
  non-polluting as well as non-corrosive, yet has
  low viscosity, and is a good lubricant,

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Major Changes in BOP Equipment for Subsea Use

• 4 (contd.) and can mix with water of high
  mineral content.
• 5. The philosophy of stack arrangement,
  especially the location of the kill and choke
  lines has been changed.

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Major Changes in BOP Equipment for Subsea Use

• 6. Pressure drop in the long choke line
  influences well control procedures.

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TELESCOPIC JOINT
CHOKE AND KILL LINES
INTEGRAL MARINE RISER JOINTS
MARINE RISER CONNECTOR
FLEX JOINTS
CONNECTOR
BOP STACK UNITIZATION GUIDE FRAME SYSTEMS
CONNECTOR
WELLHEAD HOUSING
TEMPORARY GUIDE BASE
GUIDE STRUCTURE
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A Subsea Blowout Preventer Stack
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Subsea Blowout Preventer Equipment
Figure 11-1
Failsafe Valve

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Figure 5-1. Cameron U-type ram blowout
preventer.
High pressure, close around pipe, usually for one
size pipe only, hang pipe - 600k
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STEEL FINGERS
RUBBER SEAL
OPENING PORT
ANNULAR PISTON
CLOSING PORT
Annular Blowout Preventer.
Close around pipe of any size, open hole. Used
for stripping and snubbing, often 2 EA
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Annular Blowout Preventers in OperationIllustra
tions and Diagrams
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Annular Element Partly Closed
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Annular Stripping Out
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Annular Stripping In
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Complete Shutoff
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Shaffer spherical BOP with 5 D.P.
Wellbore Pressure, psig
Annular Preventer Closing Pressure, psig
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Figure 5-7
Piston
The GL Hydril Blowout Preventer
The preferred Hydril for subsea. Hydrostatic due
to mud -gt open. Compensate
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Secondary Chamber to Riser
The mud may plug off the opening...
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Secondary Chamber to Open Chamber
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Secondary Chamber to Close Chamber
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Shear Rams
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Dog Cam Piston
Mandril Type Hydraulic Connector
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Collet Finger Cam
Collet Type Hydraulic Connector
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Fail-Safe Kill and Choke Valve
Spring loaded Hydraulic pressure Two in
series Same WP as BOPs
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Figure 5-12 Examples
Configurations of kill/choke line outlets for
conventional four-ram stack
Wellhead Connector
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Schematic of a hydraulic control system.
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Hose Bundle
Hydraulic Subsea BOP Control System
Pod (2 EA)
Accumulators
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Figure 5-15
5/16 Pilot Lines
Power Fluid Line 1
1/4 Pilot Lines
Typical hose bundle for hydraulic system.
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Typical 1. Hydraulic Hose 2.
Multiple-Conductor Electric Cable (faster -
better for deep-water wells)
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Electro-Hydraulic Hose Bundle - contd 3.
Protective Inner Cover 4. Strength
Member 5. Outer Protective Jacket (Optional)

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Pilot Valve - Poppet Type
Vent Opening
Pilot Line Attachment
Power Fluid
To Function
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BOP Control Pod
Pilot valves Pressure regs. Retrievable
Two for Redundancy
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GAS CHARGE PORT
Accumulator - BladderType.
BLADDER
TAPERED VALVE
INLET/OUTLET
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POWER FLUID FROM POD
POWER FLUID TO FUNCTION
Fig. 5-19 Shuttle valve
SEAL
Directs power fluid to function. Isolates
inactive pod. Lines from valve to pod not redund.
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Pilot valves
Shuttle valve
Redundancy between pods on a stack.
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Fig. 5-22
Flow Paths to close rams from drillers panel.
Drillers Handle Air signal to Hydraulic unit
pressurize pilot line pilot valve at pod, power
fluid --gt
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Fig. 5-23
Flow paths to open rams from the drillers panel.
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0.577
1,465
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Example 1,000 ft of water
Precharge pressure is 1,000 psi above ambient
Pc 15 1,000 0.45 water depth 1,465 psia
P 15 3,000 0.45 water depth 3,465 psia
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Friction Losses

• Pressure losses caused by friction in the
  plumbing is a major source of decreased reaction
  times.
• Fluid flow is difficult to define and various
  books have been written on the subject.

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Fanning or Darcy Equation

• A simple approach can be taken by considering
  the friction losses as described by the Fanning
  or Darcy equation that may be expressed as

50 gal in 30 sec gt 100 gal/min 10 gal in
8 sec gt 75 gal/min
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Where
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And Where
D line diameter V fluid velocity r fluid
density m fluid viscosity
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Figure 5-25. BOP Stack Schematic
Connected by clamps. Stresses from Tension,
bending and pressure. Frequent stack testing.
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Figure 5-26. Pressure Differentials Acting on
Preventer.
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See text
Example Calculations
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Allowable Operating Pressure, psig
Tension at the ball joint, kips
For a fixed ball joint angle, the maximum tension
at the ball joint decreases as press. incr.
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Figure 5-29 5-29
Surface Unit- Acoustic backup for BOP
control
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3,200 ft
Example from the GOM
WL
300 ft of 36csg, jet -in
2,300 ft of 20csg, run in 24 hole
ML
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3,200 ft
Jetting-in the 36 Conductor
WL
300 ft of 36csg, jet -in
ML
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Drilling a 24 Hole
WL
3,200 ft
300 ft of 36csg
ML
24 Hole
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Running the 20Casing
WL
2,300 ft of 20 csg.
3,200 ft
ML
24 Hole
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Cementing the 20Casing
WL
Drillpipe
3,200 ft
ML
24 Hole