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Presented by: JB - AG
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DRILLING ACTIVITIES: cementing
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DRILLING ACTIVITIES: cementing
Different types / function
of casings
Very unconsolidated rocks
Conductor pipe
Surface casing
(BOP support)
cement
Fresh water
Weak / thief zone
Heaving shale
Pressurized zone
Intermediate casing
Drilling liner
Tubing string
RESERVOIR
Production casing
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DRILLING ACTIVITIES: cementing
PURPOSES OF OIL WELL CEMENTING
Oil well cementing falls into three main categories: primary cement jobs on casing strings / squeeze
cementing / cement plugs.
Primary casing job: among the main objectives
- to provide a solid “anchoring” of the casing string on the formation,
- to provide a seal in the annulus casing x formation annulus or casing x casing annulus
- to provide isolation of formation to each other behind the casing
Squeeze cementing: major applications are as follows
- supplement a faulty primary casing cement job; repair casing leaks
- isolation ….: to reduce water-oil, water-gas or gas-oil ratio; abandon a productive zone
- isolate a zone before perforations for production (block squeeze) or before fracturing
- stop losses; bring a well under control
Plugs major applications are: when recompletion above a depleted producing zone is necessary, when a solid seat is
necessary (set a whipstock, side-tracks, …), plug lost circulation zones, at the time of well P&A operations.
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DRILLING ACTIVITIES: cementing
Isolation of troublesome zones
behind the casing from deeper
formations to be drilled
Loss circulation zone
Heaving shale
Casing &
cement
Open hole
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DRILLING ACTIVITIES: cementing
Isolation of weaker shallower
zones behind the casing from
higher pressures below the casing
Shallower
weaker zone
Increase of mud weight
required to control pressures
High
pressure
zone
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DRILLING ACTIVITIES: cementing
Isolation of producing zones
from water bearing sands
cement
casing
water sand zone
Oil sand zone
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DRILLING ACTIVITIES: cementing
PURPOSES OF OIL WELL CEMENTING
Oil well cementing falls into three main categories: primary cement jobs on casing strings / squeeze
cementing / cement plugs.
Primary casing job: among the main objectives
- to provide a solid “anchoring” of the casing string on the formation,
- to provide a seal in the annulus casing x formation or casing x casing
- to provide isolation of formation to each other behind the casing
Squeeze cementing: major applications are as follows
- supplement a faulty primary casing cement job; repair casing leaks
- isolation ….: to reduce water-oil, water-gas or gas-oil ratio; abandon a productive zone
- isolate a zone before perforations for production (block squeeze) or before fracturing
- stop losses; bring a well under control
Plugs major applications are: when recompletion above a depleted producing zone is necessary, when a solid seat is
necessary (set a whipstock, side-tracks, …), plug lost circulation zones, at the time of well P&A operations.
Total Professeurs Associés
Presented by: JB - AG
8
DRILLING ACTIVITIES: cementing
PURPOSES OF OIL WELL CEMENTING
Oil well cementing falls into three main categories: primary cement jobs on casing strings / squeeze
cementing / cement plugs.
Primary casing job: among the main objectives
- to provide a solid “anchoring” of the casing string on the formation,
- to provide a seal in the annulus casing x formation or casing x casing
- to provide isolation of formation to each other behind the casing
Squeeze cementing: major applications are as follows
- supplement a faulty primary casing cement job; repair casing leaks
- isolation ….: to reduce water-oil, water-gas or gas-oil ratio; abandon a productive zone
- isolate a zone before perforations for production (block squeeze) or before fracturing
- stop losses; bring a well under control
Plugs: major applications are: when recompletion above a depleted producing zone is
necessary, when a solid seat is necessary (set a whipstock, side-tracks, …), plug lost
circulation zones, at the time of well P&A operations.
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Presented by: JB - AG
9
DRILLING ACTIVITIES: cementing
WELL CEMENTING:
how to plan a cementing program
Cement planning usually consists of:
- assessment of hole geometry (sizes)
- assessment of downhole conditions of temperatures and pressures
- evaluation of mud properties
- design of the slurries (including setting time)
- design of placement techniques
- casing string equipment selection, …
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cement characteristics
The cement slurry pumped into wells includes cement, special additives and water.
The additives are used to control characteristics such as thickening time, density and
compressive strengths;
Since water and cement qualities vary, slurry must be tested before performing the
actual cement job.
Cementing material: Portland cement is the material used for about 99% of primary
cementing operations. Several types of cement are manufactured for oil well use.
The common types of API cements are: API Class A, Class C, Class G and Class H.
Class G is the cement used in most part of the world;
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
slurry features
Slurry features: the design of the slurry includes
- slurry yield: is the volume of space that will be occupied when the slurry is mixed;
(V in liters = 68.3 / (dsg – 1) ; approx figure ranges 1.05 to 1.35 cu.ft/sack)
(Rule of thumb = > 1 sack of cement (94 lbs, 1 cu ft) + 5 gal water == > slurry d= 1.90
- density: an important design criteria (lost circulation or kicks, ….): density of the “lead”
slurry is (approx.) 13.5 lbs/gal, for the “tail” slurry” (approx.) 16.0 lbs/gal.
- thickening time: most critical property in the displacement process (approx figure
range 1.5 to 2.5 hrs)
- compressive strength: to secure casing in hole and withstand pressure differentials
across the cement (approx figure ranges 3000 to 4000 psi).
- fluid loss: is the water lost from the slurry to the formation during slurry placement.
Spacers
- are pumped ahead of the slurries to prevent/minimize contamination of mud-cement, to
make easier and complete mud displacement.
Practically d mud < d spacer < d slurry
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Slurry design
Main additives:
- accelerators: to shorten the set time of slurries (reduce the WOC period)
- retarders: to decrease the set time of slurries, to slow the rate of strength development.
- fluid-loss additives: reduce the rate at which water from cement is forced into
permeable formations when a positive differential pressure exists
- dispersants: to reduce the viscosity of slurries
- anti-gas migration agents: to modify gel strength process of slurries
- weighting agents: to be used when high density slurries are required (iron oxyde,
barite)
- anti-foam agents: to alter surface tension (for easier mixing)
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cementing techniques
Some comments, notes …
- Experience shows that displacement of the mud in the annulus is better achieved when
cement-slurry is pumped under a turbulent flow.
- The density and rheology of the slurry and the spacer have to be adjusted following
mud characteristics.
- Spacers: (practically)
===>
d mud < d spacer < d slurry
- Thickening time is an important parameter to be evaluated in a lab. before cementing
operation starts.
- Additives rely heavily on pilot testing. Service Companies handbooks provide
sufficient data to make reliable estimates of slurry design.
Cement specialists,
working with Service Companies will provide their expertise and assistance to the
well planner.
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cementing operations
- Primary cementing operations are usually conducted in single or multiple stages
- Liner cementing: achieving an effective cement job is a difficult task (small annulus)
- Squeeze cementing: remedial operations at casing shoe, liner top/overlap, perforation, plug
section(s) of producing zone, seal lost circulation problems
- plugs: to be set in open hole or casing; Common applications include plug back, abandonment, lost
circulation
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DRILLING ACTIVITIES
Running casing operations
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DRILLING ACTIVITIES: cementing
Cementing head
Primary cementing job
M
and cementing equipment
Top plug
M
C
cement displacement in progress
cement
Bottom plug
M
Casing cement collar
(part of casing string)
mud
M
Casing cementing shoe
(part of casing string)
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M
Presented by: JB - AG
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DRILLING ACTIVITIES: cementing
Cementing head
Primary cementing job
and cementing equipment
M
M
end of cement displacement
mud
Top plug
Top cement
Bottom plug
Casing cement collar
(part of casing string)
C
cement
Casing cementing shoe
(part of casing string)
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C
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DRILLING ACTIVITIES: cementing
400 m
Example of multistage cementing
due to lost circulation zone
Second stage
cementing with
light slurry
flowing zone *
600 m
cementing stage
collar
drilling mud
100 m
weak zone
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First stage cementing
heavy slurry
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cementing equipment
Cement planning involves evaluating and selecting equipment to be used with the
cementing process.
The downhole equipment includes parts (e.g. shoes and collars) that are run as integral
sections of the casing string and in addition, many parts attached to the exterior of the
pipes (e.g. centralizers, scratchers, …).
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DRILLING ACTIVITIES: cementing
Cementing head
Some cementing
equipment
Cement top plug
Cement bottom plug
Cement float collar
centralizer
Cement guide shoe
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DRILLING ACTIVITIES: cementing
Some cementing
Equipment (contd.)
Casing cementing shoe, or
cement guide shoe/collar
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DRILLING ACTIVITIES: cementing
Centralizer
Some cementing
Equipment (contd.)
Cementing float collar
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DRILLING ACTIVITIES: cementing
Some cementing
Equipment (contd.)
Centralizer
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cementing operations
- Primary cementing operations are usually conducted in single or multiple stages
- Liner cementing: achieving an effective cement job is a difficult task (small
annulus)
- Squeeze cementing: remedial operations at casing shoe, liner top/overlap, perforation, plug
section(s) of producing zone, seal lost circulation problems
- plugs: to be set in open hole or casing; Common applications include plug back, abandonment, lost
circulation
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DRILLING ACTIVITIES: cementing
Equipment typically used to install
and cement a drilling liner
Source: Drilling Engineering – Penn Well / NJ Adams
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Cementing operations
- Primary cementing operations are usually conducted in single or multiple stages
- Liner cementing: achieving an effective cement job is a difficult task (small annulus)
- Squeeze cementing: remedial operations at casing shoe, liner top/overlap,
perforation, plug section(s) of producing zone, seal lost circulation problems
- plugs: to be set in open hole or casing; Common applications include plug back, abandonment, lost
circulation
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DRILLING ACTIVITIES: cementing
Typical surface-pressure response for hesitation squeeze
Source: Petroleum Well Construction – Wiley / Economides / Watters / Dunn-Norman
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DRILLING ACTIVITIES: cementing
WELL CEMENTING: Cementing operations
- Primary cementing operations are usually conducted in single or multiple stages
- Liner cementing: achieving an effective cement job is a difficult task (small annulus)
- Squeeze cementing: remedial operations at casing shoe, liner top/overlap, perforation, plug
section(s) of producing zone, seal lost circulation problems
- plugs: to be set in open hole or casing; Common applications include plug back,
abandonment, lost circulation
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DRILLING ACTIVITIES: cementing
Reverse
circulate
POOH
of DP
M
M
M
M
M
M
M
M
M
S
M
M
M
M
M
M
M
M
M
M
M
M
S
S
S
S
S
S
C
C
M
M
C
C
C
C
M
M
( M = mud
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C = cement
S = spacer )
Presented by: JB - AG
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DRILLING ACTIVITIES: cementing
WELL CEMENTING:
Special cementing problems
Gas-through-cement flows / kicks:
because the cement column begins to support itself and stops exerting hydrostatic
pressure on the reservoir but does not have enough compressive strength to prevent fluid
migration
preventive measures,
additives should be used to prevent cement volume shrinkage and to reduce fluid loss as
low as practical.
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DRILLING ACTIVITIES: cementing
The four stages in setting cement
Hydratation
pressure
Fully liquid
Early gelation
(cement setting)
Set cement
Hydrostatic
pressure
Critical hydration
period
Pore pressure
Cement set
No gas can invade
After this point
gas can invade
time
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DRILLING ACTIVITIES: cementing
WELL CEMENTING: Special cementing problems
formation
Gas migration
casing
through cement
Channels in
The drilling
fluid
Gas zone
casing
cement
cement
Gas migration
poor mud displacement
Gas zone
Source / illustrations: Petroleum Well Construction – J Willey & Sons
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DRILLING ACTIVITIES: cementing
Truck mounted cementing
unit
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Slides were prepared for presentation and information to Students of Schools and Universities only.
References
Slides presented were prepared with illustrations from the following referenced documents:
- API Standards and Recommended Practices,
- Neal J. Adams, Drilling Engineering , PennWell Books, Tulsa, Oklahoma, 1985,
- (Halliburton) - Petroleum Well Construction – J Willey & Sons
- Miscellaneous books from “Chambre Syndicale de la Recherche et de la Production du Pétrole et du gaz naturel”
- IFP Drilling data handbook
- Miscellaneous documentation from TOTAL Drilling Division
- Halliburton Completion Services
- Miscellaneous books from IFP
- Leading Edge Advantage Ltd (Under Balance Drilling).
- Miscellaneous documentation from web-sites: O&GJ, World Oil, SPE
- Transocean, Saipem, Pride Drilling Contractors
- Baker Hughes, Schlumberger, Weatherford, Wild Well Control Service Companies
- Cameron, Hydril, Companies.
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