Upload
driller22
View
139
Download
4
Tags:
Embed Size (px)
Citation preview
1
TAMU - PemexOffshore Drilling
Lesson 4Blowout Preventers
and Their Control
2
Lesson 4 - Blowout Preventers and Their Control
The BOP Stack Hydraulic Connectors Kill and Choke Valves BOP Controls
3
Blowout Preventers and Their Control
Control Pods & Shuttle Valves Redundancy Accumulator Capacity
Requirements Backup for BOP Controls
4
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.
5
Major Changes in BOP Equipment for Subsea Use:
3. Hydraulics have become more important in reaction times, because the longer flow lines increase thepressure drop,
while the larger BOPs require more fluid to operate than their land counterparts.
6
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,
7
Major Changes in BOP Equipment for Subsea Use:
4 (cont’d.) 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.
8
Major Changes in BOP Equipment for Subsea Use:
6. Pressure drop in the long choke line influences well control procedures.
9
10
11
CHOKE AND KILL LINES
MARINE RISER CONNECTOR
INTEGRAL MARINE RISER JOINTS
TELESCOPIC JOINT
CONNECTOR
BOP STACK UNITIZATION GUIDE FRAME SYSTEMS
FLEX JOINTS
TEMPORARY GUIDE BASE
CONNECTOR
WELLHEAD HOUSING
GUIDE STRUCTURE
12
A Subsea Blowout
Preventer Stack
13
Subsea Blowout
PreventerEquipment
Failsafe Valve
Figure 11-1
14
Figure 5-1. Cameron U-type ram blowout preventer.
High pressure, close around pipe, usually for one size pipe only, hang pipe - 600k
15
Annular Blowout Preventer.
STEEL FINGERS
CLOSING PORT
OPENING PORT
RUBBER SEAL
ANNULAR PISTON
Close around pipe of any size, open hole. Used for stripping and snubbing, often 2 EA
16
Annular Blowout Preventers in Operation
Illustrations and Diagrams
17
Annular: Element Partly Closed
18
Annular: Stripping Out
19
Annular: Stripping In
20
Complete Shutoff
21
Annular Preventer Closing Pressure, psig
Wel
lbo
re P
ress
ure
, p
sig Shaffer
spherical BOP with 5” D.P.
22
The GL Hydril
Blowout Preventer
Figure 5-7
Piston
The preferred Hydril for subsea. Hydrostatic due to mud -> open. Compensate
23
Secondary Chamber to RiserThe mud may plug off the opening...
24
Secondary Chamber to Open Chamber
25
Secondary Chamber to Close Chamber
26
Shear Rams
27
Mandril Type
Hydraulic Connector
Dog
Cam
Piston
28
Collet Type Hydraulic Connector
Collet Finger
Cam
29
Fail-Safe Kill and Choke Valve
* Spring loaded
* Hydraulic pressure
* Two in series
* Same WP as BOPs
30
Configurations of kill/choke
line outlets for conventional
four-ram stack
Figure 5-12Examples
Wellhead Connector
31
Schematic of a
hydraulic control system.
32
Hydraulic Subsea BOP
Control System
Hose Bundle
Pod (2 EA)
Accumulators
33
Typical hose bundle for hydraulic system.
5/16” Pilot Lines
1/4” Pilot Lines
Figure 5-15
Power Fluid Line 1”+
34
Typical
1. Hydraulic Hose
2. Multiple-Conductor Electric Cable
(faster - better for deep-water wells)
35
Electro-Hydraulic Hose Bundle - cont’d
3. Protective Inner Cover 4. Strength Member5. Outer Protective Jacket (Optional)
36
Pilot Line Attachment
Power Fluid
To Function
Pilot Valve- Poppet Type Vent
Opening
37
BOP Control
Pod
* Pilot valves* Pressure regs.* Retrievable* Two for Redundancy
38
Accumulator
- BladderType.
BLADDER
TAPERED VALVE
GAS CHARGE PORT
INLET/OUTLET
39
Fig. 5-19 Shuttle valve
POWER FLUID TO FUNCTION
POWER FLUID FROM POD
SEAL
Directs power fluid to function. Isolates inactive pod. Lines from valve to pod not redund.
40
Redundancy between pods on a stack.
Shuttle valve
Pilot valves
41
Flow Paths to close rams from driller’s panel.
Fig. 5-22
Driller’s Handle; Air signal to Hydraulic unit; pressurize pilot line; pilot valve at pod, power fluid -->
42
Flow paths to open rams from the driller’s panel.
Fig. 5-23
43
44
1,465
0.577
45
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
577.0P
P1.F.V C
46
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.
47
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:
5
2
D
q L fKF
50 gal in 30 sec => 100 gal/min 10 gal in 8 sec => 75 gal/min
48
Where:
conversionunit for constant Kdiameter lineDrate flowq
length lineLline in the lossfriction F
Re offunction factor,friction f
5
2
D
q L fKF
49
And Where:
Dv
number sReynold'Re
D = line diameterV = fluid velocity = fluid density = fluid viscosity
50
Figure 5-25. BOP Stack SchematicConnected by clamps. Stresses from Tension, bending and pressure. Frequent stack testing.
51
Figure 5-26. Pressure
Differentials Acting on Preventer.
52
See text
Example Calculations
53
Tension at the ball joint, kips
All
ow
able
Op
erat
ing
Pr e
ssu
re,
psi
g
For a fixed ball joint angle, the maximum tension at the ball joint decreases as press. incr.
54
Surface Unit- Acoustic backup for BOP control
Figure5-295-29
55
Example from the GOM
3,200 ft
300 ft of 36”csg, jet -in
2,300 ft of 20”csg, run in 24” hole
WL
ML
56
3,200 ft300 ft of 36”csg, jet -in
WL
ML
Jetting-in the 36” Conductor
57
Drilling a 24” Hole
3,200 ft300 ft of 36”csg
WL
ML
24” Hole
58
Running the 20”Casing
3,200 ft
2,300 ft of 20” csg.
WL
ML
24” Hole
59
Cementing the 20”Casing
3,200 ft
Drillpipe
WL
ML
24” Hole