PCB 3043
DRILLING AND PRODUCTION TECHNOLOGY
WELLBORE COMPLETION CONCEPTS
COURSE CONTENT
Bottom hole completion techniques
Completion string Components
Bottom hole completion techniques
Bottom hole completion must satisfy the following
objectives:
Provision of optimum production/injection performance.
Ensure safety.
Maximize the integrity and reliability of the completion
over the envisaged life of the completed well.
Minimize the total costs per unit volume of fluid
produced or injected, i.e. minimize the costs of initial
completion, maintaining production and remedial
measures.
Can also fulfill specific objective, i.e. sand control, etc.
Bottom hole completion techniques
After drilling engineers have drilled the borehole to the
zone of interest, the communication between reservoir
and borehole has to be initiated. Therefore, bottom
hole completion need to be accomplished before the
completion of the drilling operations.
Bottom hole completion techniques
There are 3 approaches for the completion of the
reservoir zone:
OPEN HOLE COMPLETION
SCREEN OR PRE-SLOTTED LINER COMPLETIONS
CEMENTED AND PERFORATED CASING/ LINER
COMPLETIONS
Bottom hole completion techniques
OPEN HOLE COMPLETION
Bottom hole completion techniques
OPEN HOLE COMPLETION
The simplest approach is to leave the entire drilled reservoir section
open after drilling.
Sometimes referred to as barefoot completions and the
technique is widely applied.
No equipment requires to be installed, savings in both costs and
time.
The entire interval is open to production and provides no real
selective control over fluid production or injection.
Not recommended for wells where distinctive variations in layeral
permeability.
This lack of zonal control for production or injection is a major
limitation on the application of this technique.
Bottom hole completion techniques
OPEN HOLE COMPLETION
Open hole completions should only be applied in
consolidated formations
Currently open hole completions are applied in a
range of environments:
a)
Low cost / multi well developments
b)
Deep wells, consolidated with depletion drive
c)
Naturally fractured reservoirs
d)
Some horizontal and multi lateral wells
Bottom hole completion techniques
SCREEN OR PRE-SLOTTED LINER COMPLETIONS
Bottom hole completion techniques
SCREEN OR PRE-SLOTTED LINER COMPLETIONS
Once the drilling through completed reservoir section has
been completed, a wire-wrapped screen or steel pipe which
has slots or alternative sand control screen.
The principal purpose of the screen or liner is to prevent
any produced sand from migrating with the produced fluids
The success of the completion in controlling sand
production is dependent upon the screen or slot sizes and
the sand particle sizes.
Slots may quickly become plugged and impede flow
resulting in a loss in productivity.
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Bottom hole completion techniques
SCREEN OR PRE-SLOTTED LINER COMPLETIONS
This system is sometimes used in inclined/high angle angles to
prevent major borehole collapse or facilitate the passage of
logging tools.
This technique also suffers from the same inability for zonal
control and may only effectively control sand.
Low cost technique since the cost of a screen to cover the
reservoir interval is much less than the cost of a casing,
cementing and perforating.
An alternative to the open hole completion in situations where
the reservoir rock consists of relatively large and homogenous
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sand grains.
Bottom hole completion techniques
CEMENTED AND PERFORATED CASING/ LINER COMPLETIONS
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Bottom hole completion techniques
CEMENTED AND PERFORATED CASING/ LINER COMPLETIONS
The final choice is to install either a casing string which
extends back to surface or a liner which extends back into
the shoe of the previous casing string, which would then be
cemented in place by the displacement of a cement slurry
into the annular space between the outside wall of the
casing and the borehole wall.
To provide flow paths for fluid to enter the wellbore from
the formation, or vice versa, the casing and cement sheath
will be perforated at selected locations using explosive
charges contained in a perforating gun.
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Bottom hole completion techniques
CEMENTED AND PERFORATED CASING/ LINER COMPLETIONS
The integrity and selectivity of the completion depends to a
great extent on an effective hydraulic seal being located in
the casing-formation annulus by the cement.
Greater costs and time than the previous options. (cost of
casings, cost of perforating, cementing and the additional
time necessary to complete the borehole)
Ability to control zones efficiently!!, thus will enhance
reservoir management capabilities.
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Bottom hole completion techniques
CASING STRINGS
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Bottom hole completion techniques
CASING STRINGS
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Completion string Components
GENERAL WELL COMPLETION STRING
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Completion string Components
Basic Completion String Components:
X-mas tree
Wellhead
SSSV
Side Pocket Mandrel
Sliding Side Door
Packer
Seal Assembly
Packer
Nipple
Perforated join
Wireline entry guide
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Completion string Components
X-MAS TREE and WELLHEAD
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Completion string Components
WELLHEAD
The wellhead provides the basis for the mechanical construction
of the well at surface or the sea-bed, such as:
Suspension of all individual casing and tubular, concentrically
in the well
Ability to install a surface closure/flow control device on top of
the well namely:
A blow out preventer stack whilst drilling
A Xmas tree for production or injection
Hydraulic access to the annuli between casing to allow cement
placement and between the production casing and tubing for
well circulation
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Completion string Components
X-MAS TREE
The purpose of the Xmas tree is to provide valve
control of the fluids produced from or injected into
the well.
The Xmas tree is normally flanged up to the
wellhead system after running the production
tubing.
All outlets have valves which are manually operated.
In the isolated case, the valve may be controlled
hydraulically.
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Completion string Components
PACKERS
Mechanically set
Hydraulically set
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Completion string Components
Packers can provide annular seal or pack-off in production
wells was necessary for one of the following reasons:
To improve flow stability and production control
Protection of the outer containment system/equipment
such as the production casing and the wellhead.
To provide the facility to select or isolate various zones
during stimulation or production, e.g. to isolate two
producing zones having different fluid properties, GOR,
pressure or permeability (especially relevant for injection)
or to stimulate or pressure maintenance.
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Completion string Components
Packer has three requirements:
1. It should be connected to the tubing.
2. Its OD (outer diameter) should be sufficiently
less than the ID (inner diameter) of the casing to
provide clearance for running in the hole.
3. It must be designed so that when it is in the
proper position, some surface control can be
used to cause it to seal off the annulus between
the tubing and casing.
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Completion string Components
PACKERS
The pack-off is accomplished by
expanding or extending the elastomer
element outwards from the packer
body until it contacts the casing wall.
Two Types:
Retrievable Packer which, can be
easily retrieved after installation.
Permanent Packer which, as its
name indicates, cannot be easily
retrieved. To retrieve the packer it
is necessary to mill away the
packer internal sleeves to allow the
rubber element to collapse.
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Completion string Components
SSSV
Their function is to provide
remote sub-surface
isolation in the event of a
catastrophic failure of the
Xmas tree or as a failsafe
shutdown system
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Completion string Components
SIDE POCKET MANDREL
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Completion string Components
SLIDING SIDE DOORS
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Completion string Components
NIPPLE
Special joint of tubing used near the bottom of the tubing
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SELECTION OF THE FLOW CONDUIT
In
the selection of the method, a range of
considerations may influence the choice
including:
Cost
Flow stability
Ability to control flow and
Ensure well safety or isolation; ensuring that
the integrity of the well will not be
compromised by corrosion or erosion.
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SELECTION OF THE FLOW CONDUIT
For a single zone completion, the following
alternatives exist:
1.
2.
3.
Tubingless casing flow
Casing and tubing flow
Tubing flow with/without annular
isolation
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SELECTION OF THE FLOW CONDUIT
Figures showing different Completions
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Tubingless casing flow.
Advantages:
Fast, simple and minimizes costs
Disadvantages:
Flow area is so large that the fluid superficial velocities
are low enough for phase separation and slippage to
occur,
Only applicable for high rate wells.
The fluid is in direct contact with the casing and this could
result in any of the following:
Casing corrosion, if H2S or CO2 are present in produced
fluids.
Casing erosion, if sand is being produced.
Potential burst on the casing at the wellhead if the well
changed from oil to gas production.
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Casing and tubing flow
Advantages:
Good for highly productive wells
providing a circulation capability deep
in the well where reservoir fluids can
be displaced to surface
removes the necessity for re-injection
into the reservoir
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Tubing flow with annular isolation
Advantages:
Good for all types of wells
The most widely used
Offers maximum well security and control
Disadvantages:
Does not provide a circulation capability
because of packer
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Completion string facilities
BASIC WELL SCHEMATIC
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Completion string facilities
These are the essential attribute of completion string
installations:
The ability to contain anticipated flowing pressure and
any hydraulic pressures which may be employed in
well operations and conduct fluid to surface
(production) or the reservoir (injection wells) with
minimal flowing pressure loss and optimal flow
stability.
The ability to isolate the annulus between the casing
and the production tubing if flow instability is likely or
it is desirable to minimize reservoir fluid contact with
the production casing.
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Completion string facilities
In the event that isolation at surface is not
possible, the ability is needed to shut-in
down-hole either by remote control or directly
activated by changing well flowing conditions.
A means to communicate or circulate
(selectively when required) between the
annulus and the tubing.
A provision for physical isolation of the tubing
by the installation of a plug to allow routine
isolation e.g. for pressure testing of the
tubing.
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Multiple Zone completions
Concepts
Multiple zone completions are employed on
reservoirs where more than one distinct
reservoir layer is to be produced by a single
well and for which the requirement is to
produce these layers separately.
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Multiple Zone completions
Multiple zone completions is categorized as
follows:
1. Co-mingled Flow (Flow from various zone)
More than one zone flows into the tubing
string
2. Segregated-Multiple Zone Flow
Use multiple production conduit within the
same well-bore; requires one tubing for one
production zone
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Multiple Zone completions
1.
Co-mingled Flow (Flow from various zone)
Advantages
Low capital investment needed as more than one zone produced from
one tubing string
Drilling cost is minimized
Disadvantages
Mixing of produced fluids in the wellbore can be disadvantageous if one or
more fluid have any of the following characteristics
-Corrosive material, e.g. acids, H2S, CO2
-When one of the zone is producing sand.
-When fluids have been different hydrocarbon compositions
-Different WOR and GOR as this would influence vertical lift performance
Injection of stimulation fluid cannot be diverted easily into individual layer
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Multiple Zone completions
2.
Segregated-Multiple Zone Flow
Advantages
Production rate from each zone can be independently control
Changes in production characteristics of one zone will not affect other
zone
Stimulation can be applied to each zone
Disadvantages
Since each zone needs a tubing string and other completion
equipment, additional expenditure and installation time is needed
The possibility of component failure is increased with the amount of
completion equipment.
Using of two small tubing sizes to fit in production casing string may
reduce total flow capacity of the well
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Multiple Zone completions
Configurations
Dual Zone Completion
Casing/Tubing Flow
Dual Tubing Flow
Single String Selected Producer
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Multiple Zone completions
Casing/Tubing Flow
Single tubing string is run with a
single packer installed to
provide isolation between
zones.
One zone will produce up the
tubing, while other will produce
up the casing tubing annulus.
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Multiple Zone completions
Casing/Tubing Flow
This configuration needs
one tubing string, two
packers and a crossover tool
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Multiple Zone completions
Dual Tubing Flow
In this type of completion, a separate tubing string for
each zone is to be installed with two packers; one to
isolate between zones and the other to upper zone
from the upper casing annulus
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Multiple Zone completions
Single String Selected Producer
In this type of completion, the well is
completed over two zones, utilizing
one tubing string designed to
selectively allow the production of
either zone.
The completion requires two
packers; one to isolate between
zones and the other to isolate the
annulus.
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Multiple Zone completions
Triple Zone Completion
Utilizing separate zonal flow into one of three tubing
strings (having three packers for isolation)
Two string completion whereby flow from two zones
is co-mingled into one of the tubing strings
Single zone annular flow and two tubing strings
producing separately from two zones
Single string, triple zone selected completion
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Multiple Zone completions
Four or More Producing Zones
Single string selective producer
Dual string selective producer
Triple string with annular production
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Multiple Zone completions
Equipment
Equipment requirements for multiple completions are largely
based on the equipment available for single string completions
with the following exceptions:
1. Tubing hanger systems
2. Tubing packer systems
3. Special installation equipment
The number of tubing strings will affect the completion
procedure
Sizes of tubing and other ancillary equipment are limited by
casing inside diameter, tensile load and torque capabilities
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Multiple Zone completions
Dual Completion Split Hanger
Dual tubing hanger integral
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Multiple Zone completions
Packers; dual and triple configuration
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COMPLETION NO.1
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COMPLETION NO.2
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COMPLETION NO.3
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COMPLETION NO.4
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COMPLETION NO.5
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COMPLETION NO.6
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COMPLETION NO.7
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COMPLETION NO.8
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COMPLETION NO.9
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COMPLETION NO.10
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