Date post: | 19-Jan-2016 |
Category: |
Documents |
Upload: | teresa-wilkinson |
View: | 220 times |
Download: | 0 times |
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 1 of 64
Dual Gradient Drilling Basic Technology
Dual Gradient Drilling Basic Technology
Lesson 1
Introduction to DGD
Jerome J. Schubert
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 2 of 64
IntroductionIntroduction
Current deepwater drilling problems
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 3 of 64
Introduction, con’tIntroduction, con’t
Brief history of DGD– Phase I– Phase II– Phase III
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 4 of 64
Introduction, con’tIntroduction, con’t
Describe the DGD SystemHow can DGD can solve the existing drilling
problems?Equipment overview
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 5 of 64
Current Deepwater Drilling Problems
Current Deepwater Drilling Problems
Deeper water results in longer and heavier drilling risers
High pore pressures and low fracture gradients leads to more casing strings
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 6 of 64
Land Well
2 strings of casing
after 20”
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 7 of 64
Riserless Drilling -AWater Depth = 500 feet
0
5000
10000
15000
20000
25000
30000
35000
400008.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (T
VD
ss)
2 strings of casing
after 20”
500’ Water Depth
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 8 of 64
Riserless Drilling -AWater Depth = 1000 feet
0
5000
10000
15000
20000
25000
30000
35000
400008.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)
1000’ Water Depth
2 strings of casing
after 20”
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 9 of 64
Riserless Drilling -AWater Depth = 5000 feet
0
5000
10000
15000
20000
25000
30000
35000
400008.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)
5000’ Water Depth3 strings of casing
after 20”
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 10 of 64
Riserless Drilling -AWater Depth = 10000 feet
0
5000
10000
15000
20000
25000
30000
35000
400008.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)10,000’ Water Depth
4 strings of casing
after 20”
with no kick or trip margins
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 11 of 64
0.5 ppg Standoff0.5 ppg Standoff0
5000
10000
15000
20000
25000
30000
35000
40000
8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)
30" 26" 20" 16" 13 3/8" 113/4" 9 5/8" 7 5/8"
5 1/2" to TD
6 strings of casing
after 20”
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 12 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
Too many shallow casing points– May not reach TD– No contingency casing available
This leads to larger wellheads, even larger and heavier risers, and finally to bigger and more expensive rigs
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 13 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
Well Control is more difficult - because of the pore pressure/fracture proximity, and long choke lines with high friction pressure drops
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 14 of 64
Kick w/ 750 psi SIP
Pore Pressure
Fracture Pressure
Mud HSP (13.1 ppg)
Mud HSP + 750 psi
Formation has fractured
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 15 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
Very high riser loads (current and weight)Weight of the drilling riser increases with
depth.
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 16 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
In 10,000’ of water– 21-inch riser has an internal capacity of ~4000
bbls! (~$1 million)– Weight of the riser itself is ~ 2million lbs– Weight of 16 ppg mud inside the riser ~ 2.7
million lbs
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 17 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
Water depths beyond rig fleet– New builds and major upgrades
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 18 of 64
Current Deepwater Drilling ProblemsCurrent Deepwater Drilling Problems
Small wellbore at TD precludes large production tubing - limiting production rates
Began 2nd quarter of 2000
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 19 of 64
Drilling’s Major Benefits of DGD
Reduces drilling cost by $5-15 MM per well in young depositional basins (4 casing strings)
Provides contingency casing for SWF’s, sub-salt
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 20 of 64
Drilling’s Major Benefits of DGD
Drilling’s Major Benefits of DGD
Allows room for high rate completions
Expands capacity of existing rig fleet
Mitigates effects of high currents
Improves Well Control margin
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 21 of 64
Describe the DGD SystemDescribe the DGD System
“DGD” Drilling, in the present context, refers to drilling where mud returns DO NOT go through a conventional, large-diameter, drilling riser.
Instead the returns move from the seafloor to the surface through one or more small - diameter pipe(s) separate from the drillpipe.
A Mudlift system is used in the Return Line
A Dual Gradient mud system is achieved.
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 22 of 64
12.4 ppg mud
13.5 ppg mud
Single vs. Dual Gradient ConceptSingle vs. Dual Gradient Concept
Single Gradient Wells– Wellbore contains a
single density fluid– Single pressure
gradient Dual Gradient Well
– Wellbore feels seawater gradient to the seafloor, and mud gradient to bottom
Pressure, psi
Depth
ft
Seafloor @ 10,000’
Seawater HSP
23,880 psi
@ 37,500’
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 23 of 64
Dual Gradient Achieved by:Dual Gradient Achieved by:
Placing SRD on top of the BOP stack and diverting the mud flow from the annulus to the MLP
The MLP then pumps mud back to the rig via the return lines
Suction pressure to the MLP is maintained at Seawater HSP + ~20 to 50 psi
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 24 of 64
Dual Gradient
Heavier Mud w/ Seawater Above
Mudline
Same Bottom Hole
Pressure
SingleMud
Weight
Conventional
Single vs. Dual-Gradient Mud Systems
From the perspective of the well, there is no mud above the mudline in a dual-gradient system!
Figure 3
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 25 of 64
How can DGD can solve the existing drilling problems?How can DGD can solve the existing drilling problems?
By placing the MLP on the seafloor we can reduce the pressure exerted on the shallow weak formations and still maintain the required pressure at the bottom of the hole to control formation pressure
Riser margin is back - emergency disconnect and drive-off will not result in an automatic kick.
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 26 of 64
Pore and Fracture GradientsPore and Fracture Gradients0
5000
10000
15000
20000
25000
30000
35000
40000
8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)
Dual Density: Pore Gradient Fracture Gradient
Conventional: Pore Gradient Fracture Gradient
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 27 of 64
Graphical Casing Seat Selection - Dual Density
Graphical Casing Seat Selection - Dual Density
0
5000
10000
15000
20000
25000
30000
35000
40000
8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0
Pressure Gradient (ppg)
Dep
th (
TV
D s
s)
0.5 ppg trip and kick margin1.0 ppg trip and kick margin
11 3/4"
13 3/8"
16"
20"
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 28 of 64
Dynamic Casing Seat SelectionDynamic Casing Seat Selection
D
e
p
t
h
ft.
Pressure, psi
1.0 ppg kick
0 bbl influx volume
Frac. Press.
Pore Press.
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 29 of 64
Dynamic Casing Seat SelectionDynamic Casing Seat Selection
1.0 ppg kick
50 bbl influx volume
Frac. Press.
Pore Press.
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 30 of 64
1.0 ppg kick, 50 bbl influx
Kick Tolerance is Back
20” @ 12,500’
16” @ 14,000’
13 3/8” @ 17,000’
11 3/4” @ 22,800’
9 5/8” @ TD
DGDConventional
20” @ 12,500’
16” @ 13,000’
13 3/8” @ 14,000’
11 3/4” @ 15,000’
9 5/8” @ 17,500’
7 5/8” @20,000’
5 1/2 “ @ TD
0.5 ppg standoff
no influx
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 31 of 64
Equipment overviewEquipment overview
Marine RiserSRD - SubSea Rotating DiverterDSV - Drillstring ValveMLP - MudLift PumpReturn LinesManifoldingDual Trip Tanks
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 32 of 64
Wellhead and BOP
Return Line
Drillpipe
Rotating Diverter
BHADrill String Valve
Mud Return and Pump
Seawater-Driven MudLift Pump
Seawater Filled Marine Riser
SubSea MudLift ConfigurationSubSea MudLift Configuration
Seawater Power Line,Control Umbilicals
Seawater Pumps(Existing Mud Pumps)
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 33 of 64
Marine RiserMarine Riser
Essentially a conventional riser filled with seawater
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 34 of 64
Wellbore ComponentsWellbore Components
Subsea RotatingDiverter (SRD)
Return Outlets
RiserAdapter
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 35 of 64
Drill String Valve (DSV)Drill String Valve (DSV)
Flow Nozzle
Closing Spring
Seawater Driven MudLift PumpMud Enters the
Diaphragm Pumps
Mud Inlet
Seawater Pumped from the
Rig
Displacing the Mud Back to the
Rig
Mud Outlet
While Seawater Discharged to
Sea
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 37 of 64
Stroke Indicator Sensor (Fixed)
Hydraulic Fluid In/Out
Mud In/Out
Diaphragm
Stroke Indicator Magnet Assembly
Stroke Indicator Tube (Moving)
Connection to Diaphragm
Diaphragm PumpDiaphragm Pump
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 38 of 64
Seawater Driven MudLift SystemSeawater Driven MudLift System
14’ x 17’ x 11’h175,000 lbs
plusSeawater Conduit
MudROV-Style
Cables
B
C K
HSeawater
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 39 of 64
Return LinesManifolding
Seawater Trip TankMud Trip Tank
Return LinesManifolding
Seawater Trip TankMud Trip Tank
Confidential to Subsea Mudlift Drilling JIP11/6/00 DGD Template 40 of 64
The EndThe EndThe EndThe End
Jerome J. Schubert
Introduction to DGD