1. FLUIDS & CEMENTING
3rd year bachelor’s degree students
Prepared by: Dr. Ali SeyfeddineGUENAOUI
2022-2023
University of Kasdi Merbah Ouargla
Faculty of Hydrocarbons, Reneweble Energies, Earth and Univers Sciences
Department of Production of Hydrocarbons
3. Introduction
• The drilling operation makes it possible to connect
the layer containing oil or gas to the surface to allow
the exploitation of these sources, but the difficulties
of the ground make it necessary to drill the wells in
successive sections. Each phase is carried out in two
operations:
• A drilling operation,
• A casing and cementing operation to isolate the
formations crossed.
4. Why cementing the well?
Primary cementing is the introduction of cementitious material
into the annulus between casing and open hole to:
• Provide zonal isolation,
• Support axial load of casing stfloat collar and other stfloat
collars to be run later,
• Provide casing protection,
• Support the borehole,
Secondary/or Remedial jobs:
• Squeeze cementing,
• Cement plug.
5. The principle of cementing
Cementing operations can be divided into two broad categories:
• Primary cementing
• Remedial cementing.
Cementing is the process of mixing a slurry of cement and water
and pumping it down through casing to critical points in the
annulus around the casing or in the open hole below the casing
stfloat collar.The two principal functions of the cementing
process are to restrict fluid movement between the formations
and to bond and support the casing.
7. Condition of the well
In order to prepare a cementing, it is necessary to have as much information as
possible about the condition of the well and the drilling history. In particular:
• The lithological section,
• Deviation measurements,
• The geometry of the hole,
• The static well temperature and a good estimate of the circulation temperature,
• The characteristics and type of mud,
• Fracture gradient,
• Pore size and pressure,
8. Condition of the well
Based on this information and the difficulties encountered during drilling, it will be
possible to schedule:
• The control of the hole before casing,
• The descent and the casing of the column,
• Cementing.
9. Well preparation
This phase consists of cleaning the walls of the hole to
ensure good cement adhesion and water tightness.
This is done as follows:
• Ensure that the hole has a sufficient diameter,
• Ream all friction points,
• Preliminary circulation (for 1 or 2 cycles) with the
drilling pumps until the cuttings are completely
evacuated (one to two hours),
• during this circulation, move the column to scrape
the cake with the scrapers,
10. Well preparation
It should be noted that circulation is also done to
check the efficiency of the float collar and shoe valves
and to ensure that nothing is blocking the inside of
the tubes. It is also done to:
• Check the stability of the well (no losses, no gains),
• Eliminate gas plugs,
• Reduce the bottom temperature and stabilize it,
• Homogenize the mud.
11. The casing column
• The lengths are added together in such a
way that during the descent, the depth of
the shoe can be known at any time by the
number of the last tube inserted.
12. Distance between the shoe and the float
collar
• The float collar is always inserted
two to three tubes above the shoe so
that the interior volume of the
column between the shoe and the
float collar serves as a reserve for the
slag polluted by the last scraping of
the upper plug.
13. Centralizers
• The centering of a column is a determining factor in obtaining a good cementing,
the centering devices must be placed :
• In line with the zones to be cemented,
• In line with the doglegs,
• In areas where there is a risk of sticking or loss.
14. The drilling rig
• The preparation of the drilling rig consists of removing some tubular materials,
setting up the pipe handling equipment and checking the components whose
correct functioning conditions the success of the operation.
17. Float Shoe or Guide Shoe
• The cement shoe is screwed to the first length of casing
to be run and acts as a guide.
• Inside is a ported check valve to prevent a back flow of
cement during the cementing operation.
• It can be drilled out with the bit so the next section of
hole can be drilled.
18. Float Shoe or Guide Shoe
• Prevents back flow of cement
• Can be drilled out with the bit
• It is attached to the bottom casing joint,
• It serves as a guide for the casing as it is being run
into the wellbore and acts as a one way valve.
19. Float Collar
• Float collars are set about 20 feet
back from the shoe and allow the
cement to be displaced through
into the annulus by a simple plug
launch system.
• This is set about two-three joints
above the casing shoe, and act as a
one way valve.
• When it is used, the cement plugs
land on top of it.
20. Cementing Basket, Centralizer
• Cementing Basket, to minimize losses in weak zones.
• Centralizer, to center casing in bore hole to promote even distribution of cement
around casing. Centralizers are placed around the outside of the casing in sections
of the hole were this is most likely to occur.They allow the casing sheath to be
equal in thickness all the way around the hole to prevent fluid migrating up the
low side of the hole
21. Scratchers
• to scratch off the mud cake to
improve cement bond,The
scratchers are attached to
scrape away the wall cake to
allow a good bond to the wall of
the well.
22. Wiper Plugs
• The launch plugs are held in place until all the cement has
been pumped.The lower pin is pulled allowing the
bottom plug to be launched inside the casing.Then the
cementer switches over to pumping mud.
• The bottom plug lands out on the float collars and
releases the check valve to allow the cement to pass
through into the annulus.The top plug with the drilling
mud behind it is then pumped.When it lands out on the
bottom plug all the cement will have been displaced into
the annulus.
23. Wiper Plugs
• They both fit inside the cement head. After the cement has be pumped they are
released to ensure the cement is displaced Into the annulus.
• The purpose of the launch plugs is to separate the cement from the mud during
displacement of the cement.
• Wiping the casing clean,
• Surface indication of placement.
24. Cement Head
• Cement heads are fitted to the last length of
casing to allow the cement to be pumped into
the casing and displaced to the annulus with
spacers or cement plugs.
29. Salinity checking
Salinity of mixing water needs to be less than 1000 mg/l
Quantab method, we wait until the orange line becomes black, then we read, result 2.4 which
means 325 mg/l
30. Rheology at surface conditions
• 5 min in the surface conditioning
• Viscosity fann35YP w viscosity
31. Plastic viscosity (VP)
• Plastic viscosity in centipoise (cP) and (pascale per second) is calculated by the
Fann viscometer by the following formula:
• VP = L600 - L300
• Where, L300: Fann reading 300
32. Yield value
• The yield value (expressed in Pa or lb/100ft2) is given by the following relationship:
YP= L300 -VP = (VA -VP).2
The yield value is the initial resistance that must be overcome for the fluid to flow.
It is a measure of the attractive force; these forces are the result of the negative
and positive charges placed on the surface.The yield point therefore measures
these forces under flow conditions.
33. Rheology at BH conditions
• A Conditiometer is used to simulate BH conditions
• In creaseTemperature + Pressure at a specified time
• Than theViscosity andYV are measured usingViscometer Fann35
• YP of cement is always bigger than spacerYP which bigger than theYP of mud
• Cement G (API) is usually used in Algeria
35. Thickening time
• A consistometer is used to Increase Pressure
• IncreaseTemperature
• BC is measured
• Burden consistency (pumpability) (needs to be less than 80 BC)
37. Free fluid
• After finishing cement job a free fluid will be escaped to the top
• Fluid loss additives is optional
• ESCA ultra sonic cement analyzing (pressure of cement) compressive strength
• SGSA static gel strength analysisTransit time from liquid to gel less than 30 min
39. ESCA ultra sonic cement analyzing
• A pressure is applied on cement to measure the compressive strength
• To be able to start the drilling of the new phase the CS needs to be more than 500
psi
• Transit time from liquid to gel less which needs to be less than 30 min
SGSA static gel strength analysis
41. Primary Cementing
• Here we can see in the left-hand
drawing, the bottom plug landed in the
float collar which is an integral part of
the shoe in this case.When the
diaphragm splits due to the pump
pressure at the top of the bottom plug
the cement shown in green is forced
through and up the annulus. In the right
hand drawing we can see the top plug
has landed out on the bottom plug.
This plug is solid rubber so the
cementer can see a pressure build up
and knows that the cement has been
displaced.
42. Conductor Pipe
Purpose
• Prevent cavities under the unit
Standard sizes and depths :
• 30-in. - 20 -in. - 16 -in. Screwed
or welded
• 10 - 100 m
Cementing Procedure:
• Plugs not used,
• Large excess required,
• Thru-drill pipe cementing
common,
• BOP’s not usually connected,
• Common Cements;
Accelerated Neat
43. Conductor Pipe
Thru-Drill Pipe Cementing;
• Key Points:
• Cement Contamination,
• Channeling,
• Displacement,
• Pump Until Slurry is at surface.
45. Surface Casing
Purpose:
• To protect groundwater
• Isolate unconsolidated formations or lossy areas.
• Support the following casings
• Allow well control (BOP)
Typical sizes and depths :
• 20-in. - 9 5/8-in. screwed
• 30 m - 1000 m (or more)
46. Surface Casing
Cementing Procedure:
• Excess of 100%,
• Recommended thru-drill pipe method to save:
• Cement,
• Rig time.
Common Cements:
• Lead light slurry with high yields,
• Neat tail slurries with good compressive strength,
• Reduce WOC to a minimum with accelerators.
52. Intermediate Casing
Purpose
• Separating incompatible areas
• Losses
• Saline horizons
• High pressure
• Reactive clays
Typical sizes and depths:
• 13 3/8-in., 10 ¾-in., 9 5/8-in.
• 1,000 to 3,000 m
53. Intermediate Casing
Cementing Procedure:
• Cemented to surface or to
previous casing shoe,
• Possibly a two stage jobs,
• Plugs, casing equipment and
casing accessories are usual,
• Good cementing practices are
required,
• Large cement volumes.
Common Cements:
• Typically filler slurries followed
by high compressive tail,
• Specialized (light, heavy, salt -
saturated, etc.)
54. Production Casing
Purpose
• Isolate the production area from
others
• Protecting production equipment
• Subsurface artificial lift
• Multiple completion
• Safety barrier
• Protection against defective
intermediate casing
• Mesh for sand control
Standard sizes:
• 4 ½-in., 5-in., 7-in., & 9 5/8-in.
55. Liner cementing
• Run on liner hangers with Drill pipe
• Cemented toTop Of Liner (TOL)
• Drill pipe and liner wiper plug combination used
• Generally small volumes
• Fewer pipes
• Deep well
• Smaller annular space
• Specific equipment
• Less cemented column
63. Two Stages Cementing
Reasons to do:
• Separation and isolation of zones,
• Reduces hydrostatic,
• Can leave zone in the annulus
uncemented (cement atTD and
surface),
• Loss zone.
