Transcript SubSea MudLift Drilling Basic Technology

Dual Gradient Drilling
Basic Technology
Lesson 2
Key Success Factors in DGD
Jerome J. Schubert
Hans C. Juvkam-Wold
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 1 of 42
Introduction
Success Factors in Equipment
 Success Factors in Drilling Operations
 Success Factors in Well Control

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 2 of 42
Success Factors in Equipment
Riser
 Return line
 Achieving dual density
 Cuttings processing unit
 Isolation of mud from seawater
 Managing the u-tube

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 3 of 42
Riser
No Riser
 Conventional Riser
 Other

–
–
–
–
–
11/06/00
Phantom riser
Super straw
Cork/Snapper
Holy riser
Top drum/tulip
Confidential to Subsea Mudlift Drilling JIP
DGD Template 4 of 42
Return line
Riser
 Free standing
 Choke & Kill line
 Boost line
 Separate return line

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 5 of 42
Achieving dual density
Gas lift
 Glass beads
 Water-jet pump
 Centrifugal pump
 Positive displacement pump

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 6 of 42
Positive displacement pumps
Progressive cavity pumps
 Reciprocating Piston or Plunger pumps
 Diaphragm pumps

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 7 of 42
Diaphragm pumps
Constant discharge rate
 High efficiency
 Large volume displacement
 Good HP rating
 Low pressure surges
 Can handle mud, gas, and solids

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 8 of 42
Pump Design Criteria
Maximum output GPM
 Maximum output HP
 Maximum pressure
 Maximum mud density

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 9 of 42
Pump Controls
Match subsea pump rate with surface pump
rate
 Automatic pump operation vs. manual
controls
 Reaction time for start, stop, change in rate
 Subsea seawater pressure sensor
 Subsea mud reservoir level sensor

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 10 of 42
Pump Redundancy

11/06/00
What can be done if one or more of the pump
chambers fails?
Confidential to Subsea Mudlift Drilling JIP
DGD Template 11 of 42
Pump power

Hydraulic power
– Electric motors to run hydraulic pumps
– Hydraulic fluid pumped from the surface
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 12 of 42
Solids processing unit
System must handle solids in some way
 Pump ok
 How about plugging choke/kill and return
lines?

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 13 of 42
Isolation of mud from seawater
How do we separate mud in the annulus from
the seawater either in the riser or open
ocean?
 SRD
 Pressure rating
 Active for tripping, running casing, logging,
etc.

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 14 of 42
Managing the u-tube
How will we handle the u-tube?
 Write all procedures compensate for the
active u-tube?
 Build a DSV to manage it?

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 15 of 42
DSV design factors
How is it going to open and close?
 Will it have an adjustable opening pressure?
 Will it pass MWD signals and LCM?
 What will it do to circulating pressures?
 Are the opening and circulating pressure
repeatable?
 Where will it be located in the drillstring?

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 16 of 42
Success Factors in
Drilling Operations
Lower riser loads
 Lower deck loads
 Lower deck space requirements
 Drill to TD with fewer casing strings

11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 17 of 42
Success Factors in
Drilling Operations






Balanced Cement Plug
Running Casing
Cementing
Check for
Underbalance
Circulation
Connections







11/06/00
Dual to Single Density
Conversion
Routine Drilling
Start-Stop Circulation
Tripping
Unplanned Shutdown
Fishing
Logging
Confidential to Subsea Mudlift Drilling JIP
DGD Template 18 of 42
What a Dual Gradient Drilling System Must
Be Able To Do For Effective Well Control
TM
A
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 19 of 42
Outline
 Understanding DGD Well Control - what is
different ?
 How can we educate ourselves and
develop a detailed understanding?
 What must an effective DGD well control
system be able to accomplish?
 What must an effective DGD system contain?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 20 of 42
Understanding WC in DGD
 Accept that DGD Well Control is not a simple
task - it is different - and it is frequently
neither intuitive nor obvious
 for example U-tubing
- how does it affect kick detection?
- how can we ensure that a constant bottomhole pressure is being maintained?
- what if power fails during WC operations?
 More details later . . .
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 21 of 42
U-Tubing in DGD
FLOATER
~SEAWATER
HYDROSTATIC
PRESSURE
BOP
STATIC
FLUID
LEVEL
PUMP
Even with a DSV there is
still a potential U-tube
TM
A
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 22 of 42
Outline
How can we educate ourselves and
develop a detailed understanding?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 23 of 42
How can we Educate Ourselves?
 We have found that detailed hydraulics
modeling is essential to understanding DGD
 Study each aspect of the process in detail:
- Four PhD and seven MS studies have been
completed or are in progress at Texas A&M!
 Detailed procedures had to be developed to
cover all essential drilling and WC operations
 Procedures are critically peer reviewed and
tested against the hydraulics model
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 24 of 42
Outline
What must an effective DGD well control
system be able to accomplish?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 25 of 42
WC System must be able to:
 Avoid kicks - as far as possible
 Detect Kicks early - to minimize their size
 Determine kick size and Intensity
 Measure new formation pressure (“SI-BHP”)
 Safely remove kick from hole
 Maintain constant BHP
 Detect equipment failures during WC operations
 Provide contingencies for all potential failures
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 26 of 42
Avoiding Kicks
 Recognize the signs of increasing pore
pressure? How?
 Allow the recovery of cuttings of sufficient
size to evaluate their characteristic
shape and other properties?
 Allow you to maintain satisfactory BHP
during connections? While tripping?
When cementing? When power fails?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 27 of 42
Detecting Kicks Early
 Can you perform a conventional flow check?
 How accurate is your pit gain indicator?
 What other kick detection methods are
available?
 What is the smallest kick that can detect?
 How quickly can you stop the influx? How?
 How do you handle the U-tube to ensure that
its effects are not confused with kick
indicators?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 28 of 42
Dual Gradient Drilling System
FLOATER
Surface Pump
Seafloor Pump
SEAFLOOR
~SEAWATER
HYDROSTATIC
PRESSURE
BOP
PUMP
How are you
going to handle
this kick?
KICK
TM
A
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 29 of 42
Determining Kick Size
 What is the initial size of the kick when its
presence is first confirmed?
 What is the size of the kick when influx stops?
 How can you measure kick volume and
intensity?
 How can you maintain constant BHP
- while circulating the kick out of the hole?
- if you can’t circulate and kick is migrating?
 What is the Expected Kick Fluid Behavior?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 30 of 42
Gas Kick Behavior
 As the gas kick moves up the hole the pressure
generally decreases so we would expect the
gas volume to expand - but how fast?
 At the seafloor pump there is an increase in
pressure - how does the volume behave?
 Can we continue to assume that PV = const?
 Or should we use PV = ZnRT?
 We will take a closer look!
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 31 of 42
Outline
 What must an effective DGD system
contain? - Essential Equipment?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 32 of 42
Which DGD System?
There are basically two different methods we can use to
Reduce annulus pressure at seafloor:
 Install pump at seafloor
 Inject a low density fluid in the return line
 Gas (e.g. air or nitrogen)
 Low density particles (e.g. hollow spheres)
Can we maintain safe well control
with all of these methods?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 33 of 42
Dual Gradient Drilling System
FLOATER
Surface Pump
Trip Tank(s)
Mud Tanks, etc
SEAFLOOR
~SEAWATER
HYDROSTATIC
PRESSURE
BOP
Seafloor Pump
- Power Transmission
- Sensors
- Controls
TM
Seafloor Pump
Seafloor Choke?
- Backup?
Coordination
between the pumps?
- Instrumentation
KICK
A
11/06/00
Or gas or
bead
injector
Confidential to Subsea Mudlift Drilling JIP
DGD Template 34 of 42
In Summary ...
 What are the Key Factors that will
ensure safe and efficient DGD
Drilling and Well Control?
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 35 of 42
Key Success Factors
for Well Control in DGD?
 Kick Detection
 Kick Containment (stop flow into well)
 Kick Removal (circulate kick out of hole?)
 Determine New Pore Pressure (after kick)
 Increase Mud Weight in hole (if necessary)
 Perform Leak-off Test
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 36 of 42
Key Success Factors - cont’d
 Manage the “U-tube”
 Detect and Manage Trapped Pressure
 Use Driller’s Method
 Perform Volumetric Well Control
 Manage Kick Expansion
(pump very slowly)
 Manage Loss of Pumping Capability
 Understand the Behavior of Gas Kicks
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 37 of 42
Additional Success Factors
 Tripping
 Logging
 Running Casing
 Cementing Casing
 Setting Cement Plugs, etc.
 Handle Non-water Based Drilling Fluids…
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 38 of 42
The End
Jerome J. Schubert
Hans C. Juvkam-Wold
Key Success Factors in DGD
11/06/00
Confidential to Subsea Mudlift Drilling JIP
DGD Template 39 of 42