3) Primary Cementing Overview

Primary Cementing Overview

Primary Cementing The introduction of a cementacious material into the annulus between casing and open hole to :  Provide zonal isolation  Support axial load of casing strings and strings

to be run later  Provide casing support and protection  Support the borehole 2

Types of Casings  Conductor  Surface  Intermediate  Production  Liner

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Conductor  Purpose 

Prevents washing out under the rig



Provides elevation for flow nipple

 Common sizes and depths:

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

30” - 20” Welded



20” - 16” Threaded



30’ - 200’ (< 100’ common)

Conductor  Other Remarks:  Plugs not used  Careful pumping practices  Large excess required  Thru-drill pipe cementing common  BOP’s not unusually connected  Common Cements 

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Accelerated Neat

Thru-Drill Pipe Cementing  Key Points:  Cement contamination  Channelling  Displacement  Pump until cement to surface

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Outside Cementing  Purpose 

Bring cement to surface

 Macaroni tubing used  Max. depth 250-300 ft  High friction pressures  Non-standard connections

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Tubing moved during job

Surface Purposes:  Protects surface fresh water formations  Cases off unconsolidated or lost circulation areas  Supports subsequent casing strings  Provides primary pressure control (BOP support)  Common sizes and depths:

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

20” - 9 5/8” threaded



100’ - 3000’ (or more)

Surface Cementing  Excess of 100% plus not uncommon  Recommend thru-drill pipe method to save 

Cement



Rig time

 Common cements:

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

Lead light weight slurries with high yields



Neat tail slurries with good compressive strength



Reduce WOC to a minimum with accelerators

BOP Rotary table Rig Floor Mud Outlet Annular Preventor Choke Line

BLIND RAMS SHEAR RAMS PIPE RAMS

Conductor pipe Cement 10

Surface Casing Head Surface Casing

Intermediate (Also called Protection) Purposes:  Separates hole into workable sections 

Lost Circulation



Salt Section



Overpressured Zones



Heaving Shales

 Common sizes and depths:

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

13 3/8”, 10 3/4”, 9 5/8”



3000’ to 10,000’

Intermediate Casings  Cemented to surface or to previous casing shoe  Two stage jobs common  Plugs, casing equipment, casing accessories usual  Good cementing practices are required  Large cement volumes  Common Cements:

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

Typically filler slurries followed by high compressive tail



Specialised (light, heavy, salt - saturated, etc)

Two Stage Cementing Key Points:  Separation and

isolation of zones

2nd Stage

Stage Collar

 Reduces

hydrostatic  Can leave zone in

the annulus uncemented (cement at TD and surface) 13

1st Stage

Production Purposes:  Isolates the pay zone from other formations and the fluids in

them.  Protective housing for production equipment. 

Subsurface artificial lift



Multiple zone completion

 Screens for sand control  Covers worn or damaged intermediate string.  Common sizes: 

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4 1/2”, 5”, 7”, & 9 5/8”

Key Points:

Liners

 Requires less casing  Deeper wells

Drill pipe Wiper Plug

 Small annular clearance  Specialized equipment Running Tool Shear Pin

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Liner Hanger

Liner Wipe Plug

Casing  API Casing Specs 

OD

9 5/8”



Weight 53.5 lbs/ft (determines ID)



Grade C75 (yield point allowable tension)



Burst pressure 7430 PSI



Collapse pressure



Thread Buttress

6380 PSI

 Tapered string used to minimize well cost.  Casing program for well based on :

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

Burst Pressure



Collapse Pressure



Tensile Load

Thread Types  8 Round  

Seals on threads Use of couplings

 Buttress  

Seals on threads Use of couplings

 VAM  

Seals on threads & shoulder Use of couplings

 Hydrill    17

Seals on threads & shoulder Integral 2 sets of threads

Running Casing  Inspection of Casing  Tuboscope  Pipe tally  Hole Preparation Mud condition  Clearance 

 Running  Casing crews  Too fast  Landing Casing  Nippling up 18

Job Procedures  Pre Job:  Check  Rig

calculations with co-man

up  Stem 1 on equipment  Check materials  Safety and organisation meeting  Prepare mix fluids, spacers and washes

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Job Procedures The Job:  Test

lines  Load plugs  Pump Washes / Spacers  Drop bottom plug  Mix and pump cement  Drop top plug  Displace  Bump plug and check returns 20

Job Procedures Post Job:  Wash

up  Rig down  Stem equipment  Paper work

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