Halliburton Deepwater Cementing Powerpoint

AADE Chapter Meeting
Deepwater Cementing Consideration

to Prevent Hydrates Destabilization
F. Tahmourpour, Halliburton
On behalf of Dr. Kris Ravi, Halliburton
November 18, 2009
Houston
Overview
• Background
• Challenges
• Solution
• Results
• Summary
Background
• Shallow Water Flow

– Unconsolidated and relatively young geological formations that
are shallow and have the potential for abnormally pressured
saltwater sands, also known as SWF zones. Weak formations
and pressured sands present very narrow margins between the
frac pressure and pore pressure
• Gas Hydrates
– Clathrate compounds, cage-type host structures in which single
or multiple visitor molecules are trapped in the available space.
The host molecule’s crystalline structure determines the
structural design of the cage. This allows a molecule of methane
get trapped inside a water molecule network. (3-D lattice 60 to
180 times expansion)
Surface Casing Schematic – Deepwater
2,775 meters of water

Shallow Water Flow
Cement slurries need to develop

gel strength/ compressive
strength rapidly in cool
deepwater temperatures, in-
situ volume generation, and/or
increased compressibility will
all assist to control the flow.
This may be achieved by
utilizing:
– Specialized conventional slurry

systems
– Foamed (compressible) slurry
systems
Hydrates
• Extremely large deposits of methane hydrates have
been found under sediments on the ocean floors.
• About 6.4 trillion tons of methane gas is trapped in

deposits of methane hydrates.
• Methane hydrate is a solid form of water containing

large amounts of methane within its crystal
structure.
• Methane hydrates are formed by migration of gas

from great depths along geological faults, followed
by precipitation, or crystallization, on contact of the
rising gas stream with cold seawater.
Hydrate Stability
• Pressure, volume, and temperature (PVT)
– When do hydrates become unstable?
– Will cement hydration cause this outcome?
• 1 L methane hydrate downhole ~ 168 L
methane gas
Destabilization Zoneat STP
– Gas release is a challenge for safety and
economics
Known Gas Hydrates Around the World1
1
Kvenvolden, K. 2001. Gas Hydrate Inventory on New Web Site. USGS Science for a Changing World,
February. http://soundwaves.usgs.gov/2001/02/research2.html.
Methane Hydrate Stability2
Methane Hydrate
Stability Curve
Geothermal Gradient
2
Hardage, B., Roberts, H. 2006. Gas Hydrate in
the Gulf of Mexico. What and Where is the
Seismic Target? The Leading Edge. May.
Challenges
• Shallow water flow may occur during or after cement job
• Under water blow out has happened
• Gas flow may occur after a cement job in deepwater

environments that contain major hydrate zones.
• Destabilization of hydrates after the cement job is

confirmed by downhole cameras.
• The gas flow could slow down in hours to days if the de-
stabilization is not severe.
• However, the consequences could be more severe in worse

cases.
Purpose
• Understand the factors contributing to the
hydrates destabilization
• Analyze the effect of cement slurry heat of

hydration on the annulus temperature (SWF
and Hydrate destabilization)
• Design cement slurry to reduce the heat

liberated during hydration while meeting the
other objectives of deepwater cementing.
• Implement the optimized slurry in the field and

monitor the results.
Deepwater Parameters
• Low fracture gradient
• Shallow water and gas-flow potential
• Low temperatures
• Narrow window between pore pressure and

fracture gradient
• High rig cost

Deepwater Well Objectives
• Cement slurry should be placed in the entire
annulus with no losses
• Temperature increase during slurry hydration

should not destabilize hydrates
• There should be no influx of shallow water or gas

into the annulus
• The cement slurry should develop strength in the

shortest time after placement
¾ Conditions in deepwater wells are not
conducive to achieving all of these
objectives simultaneously
Focusing On Hydrates
Cement Hydration Reaction
2C3S + 6H → C3S2H3 + 3 CH; ΔH = -114 KJ/mole
(tricalcium silicate) + (water) → (C-S-H) + (calcium hydroxide)
2C2S + 4H → C3S2H3 + 3 CH; ΔH = -43 KJ/mole
(dicalcium silicate) + (water) → (C-S-H) + (calcium hydroxide)

Experimental Setup
• Insulating test cell

– Imbedded thermocouple
• Test cell surrounded

by insulation
• Near “adiabatic”
conditions
Adiabatic Temperature Rise
Surface Casing Schematic – Deepwater
2,775 meters of water

Simulations for Cement System 1
ΔH=-50 Btu/lb
Simulations for Cement System 2
ΔH=-25 Btu/lb
Static Gel Strength-Cement System 1@14C
Static Gel Strength-Cement System 2@14C
Compressive Strength
• The cement slurry should develop compressive
strength rapidly
• This is particularly important in the deepwater

environment given the associated rig cost.
• At 14°C, Cement System 2 develops compressive

strength (CS) of 350 psi in 10 hours and 800 psi
in 24 hours.
• Cement System 1 develops 368 psi in 10 hours

and 1,014 psi in 24 hours.
• Large size casings can be self supported very
early on during CS development.
Summary 1 of 2
• SWF is a challenge that need to be planned for
when designing slurry systems
• Both energized (foamed) slurries and

conventional specialized slurries have been
utilized successfully
• Destabilization of hydrates during cementing and

production in deepwater environments is a
challenge to the safety and economics
Summary 2 of 2
• Procedures to analyze and design cement slurries to lower
the heat of hydration and help prevent the destabilization
of the hydrates are presented.
• Data shows that optimizing slurry design reduces the

adiabatic temperature rise – an indicator of the heat of
hydration.
• The Cement System 2 with lower heat of hydration has

been successfully implemented in the field and has helped
to prevent destabilization of the hydrates.
n k s
Tha m ents
n s / C om
ue s t i o
Q

Halliburton Deepwater Cementing Powerpoint

Uploaded by

Document Information

Original Description:

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Halliburton Deepwater Cementing Powerpoint

Uploaded by

Copyright:

Available Formats

AADE Chapter Meeting

Deepwater Cementing Consideration

• Shallow Water Flow

2,775 meters of water

Cement slurries need to develop

– Specialized conventional slurry

• About 6.4 trillion tons of methane gas is trapped in

• Methane hydrate is a solid form of water containing

• Methane hydrates are formed by migration of gas

• Shallow water flow may occur during or after cement job

• Under water blow out has happened

• Gas flow may occur after a cement job in deepwater

• Destabilization of hydrates after the cement job is

• However, the consequences could be more severe in worse

• Analyze the effect of cement slurry heat of

• Design cement slurry to reduce the heat

• Implement the optimized slurry in the field and

• Low fracture gradient

• Shallow water and gas-flow potential

• Narrow window between pore pressure and

• High rig cost

• Temperature increase during slurry hydration

• There should be no influx of shallow water or gas

• The cement slurry should develop strength in the

(tricalcium silicate) + (water) → (C-S-H) + (calcium hydroxide)

2C2S + 4H → C3S2H3 + 3 CH; ΔH = -43 KJ/mole

(dicalcium silicate) + (water) → (C-S-H) + (calcium hydroxide)

• Insulating test cell

• Test cell surrounded

2,775 meters of water

• This is particularly important in the deepwater

• At 14°C, Cement System 2 develops compressive

• Cement System 1 develops 368 psi in 10 hours

• Both energized (foamed) slurries and

• Destabilization of hydrates during cementing and

• Data shows that optimizing slurry design reduces the

• The Cement System 2 with lower heat of hydration has

You might also like