drilling and completions_3
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Faculty of Chemical Engineering
Drilling and Completions
Drilling techniques
Verticaldrilling straight down into reservoir (in early days)
Horizontaldrilling horizontally to reach the target zone e.g.
drill to penetrate the reservoir at a very shallow angle or toexpose more of low permeability reservoir to the wellbore so
that production rate is increased
Directional drillingthe process of directing a wellbore along
some trajectory to a predetermined target
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Faculty of Chemical Engineering
Drilling and Completions
Drilling techniquesWellhead
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Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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8/10/2019 Drilling and Completions_3
7/33Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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8/33Faculty of Chemical Engineering
Drilling and Completions
Application of directional drilling
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Drilling and Completions
Application of directional drilling
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Drilling and Completions
Drilling techniques
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Drilling and Completions
Casing and cementing
What is casing?
Large-diameter steel pipe lowered into a borehole and
cemented in place
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Drilling and Completions
Casing and cementing
Purpose of casing:
To prevent contamination of fresh water sands
To enhanced the probability of drilling to total depth (TD) To sealoff weak, fractured and unconsolidated
formations
To control pressure during drilling
To meet production requirements
To confine production to the wellbore
To protect the hole from the mud
To prevent water migration(from mud) to producing
formation e.g. shale tends to draw water out of the
mud causing them to swell
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Drilling and Completions
Casing and cementing
Casing program
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Drilling and Completions
Casing and cementing
Casing program
Surface casing
Drilling operation begins by drilling the large-diametersurface hole to penetrate unconsolidated
formation(near to surface) and any potable water
zones
Normally a few hundred feet deep (3005000ft)
depending on local conditions encountered
Surface casing is usually cemented to the surface
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Drilling and Completions
Casing and cementing
Casing program
Function of surface casing
Prevent fresh-water aquifer from being contaminatedwith drilling mud, gas, oil or salt water
State and federal regulations for the protection of
underground fresh-waters reservoirs are usually quite
specific about the setting depth of surface casing
Maintain hole integrity by preventing cave-in and
washout of loose formations
Minimize lost circulation into shallow, permeable zone
Provide a mean for attaching the BOPs
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Drilling and Completions
Casing and cementing
Casing program
Function of Intermediate casing
Main application of intermediate casing is to case offthe troublesome formations that prevent the well from
being drilled to the target depth e.g. shallower weak
zones (rupture, lost circulation or stuck pipe)
Occasionally, intermediate casing is used to isolate salt
or anhydrite (calcium sulphate)formations, which may
cause drilling fluid contamination, or perhaps leak out
to such an extent as to cause pipe sticking
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Drilling and Completions
Casing and cementing
Casing program
Production casingthis string is set at a depth slight above
midway through or below the pay zone Functionisolate the producing zone from other
formations
Protect the tubing and other equipment used in the well
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Drilling and Completions
Casing and cementing
Cementingobjective of cementing is to create sheath
cement of hard cement completely filling the annular space
between the outside of the casing and the hole, therebyblocking fluid movement and pressure up or down the annulus
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Drilling and Completions
Casing and cementing
Cementing
When bottom plugs lands on
the float valvethin rubberdisc ruptures
Pumping continues as the
cement is pumped around the
shoe and up the annulus
When the last of the cement
has been pumped, a solid
rubber (no rupture disc) follow
plug is inserted into the casing
and mud is pumped in behind it
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Drilling and Completions
Casing and cementing
Scratcher
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TYPICAL CASING CONFIGURATION
Conductor (20 30 OD)
Surface Casing
(13- 3/8 20 OD)
Intermediate Casing
(9-5/8 16 OD)
Production Casing
(4-1/2 9-5/8 OD)
Liner
4-1 2 13-3 8 OD
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TYPICAL HOLE & CASING SIZE
HOLE SIZE CASING SIZE DESCRIPTION
36 30 Conductor
26 20 or 18-5/8 Surface Casing
17 13-3/8 IntermediateCasing
12 9-5/8 ProductionCasing
8 7 Liner
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TYPICAL CASING FUNCTIONS & SETTING DEPTH
RANGES
CasingType
Functions Setting Depths(from seabed)
Conductor To seal off unconsolidated
formationsto prevent erosion
Enables circulation of drillingfluid
150600 ft
Surface
Casing
Seal off any fresh water sands
Support the wellhead and BOPequipment
Prevent lost circulation
10005000 ft
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Casing Type Functions Setting Depths(from seabed)
IntermediateCasing
Isolate troublesomeformations between surfaceand production casing
Normally set in the transitionbetween normal andabnormal zone
Depends on the number ofproblems encountered
1,00010,000 ft
ProductionCasing
Separate producing zonesfrom other formations
Conduit for production andtestin tubin
Set across orabove pay
zone
TYPICAL CASING FUNCTIONS & SETTINGDEPTH RANGES
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Casing Type Functions Setting Depths(from seabed)
Liner
(less than 5000ft casing string
which issuspended
from a linerhanger)
Replace intermediate
casing for deeper drillingeconomic
Separate producing zones
As required
TYPICAL CASING FUNCTIONS & SETTINGDEPTH RANGES
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