Cemeting 2 Flashcards
Purpose of Mud while drilling
Cleans Hole
Transports drill cuttings
Supports wall
lubricates bit
PV and YP
YP- Amount of force needed to put a fluid into motion or PV - keep a fluid in motion.
What is the most common flow property in Mud removal
Laminar flow - Turbulent flow is seldom achieved.
What two factors affect the flow rate property?
Velocity and Standoff.
Pre Job circulation rule of thumb
2-4 top to top volumes or/and well conditioned mud returns to the surface.
Although the rig will want a higher YP and PV to help make a filter cake on the walls, What does Halliburton prefer prior to a good cement job
Decrease YP and PV . YP to 2 and PV down to 15.
HPUJ Shoe
Improves mud displacement
excellent filter cake removal
6 up 4 down.
Spacers and Flushes
Helps with fluid comparability fluid separation mud displacement protection of formation suspends solids.
Displacement Factors: CAMPS
Centralization - 70%
Annular Velocity - As fast as the well will allow without breaking ECD limits
Mud Conditioning - 2 hole volumes
Mechanical aids - Pipe movement. 20 RPM’s increases Disp Efficiency by 35%
Spacers - 1000 ft or 10 min contact time. Whichever is greater.
Principle reason for cementing wells
Isolates zones
supports the casing from corrosion, drilling shocks and potential burst or collapse.
CEment additives
Accelerators retarders Fluid Loss LCM Light weight h heavy weight Dispersant Salt Gas migration
Purpose of an accelerator
Increase early strength development and reduce WOC.
Most commonly used accelerator
CaCl - 1-4% BWOC
CaCl reduction of WOC 6 hours - 0% and 2%
100 and 1100 psi in 6 hours
NaCl is an accelerator and retarder from when to when
<12
18-37%
Calseal
LCM/ Expanding agent and thixotropic/ increases visc and high early strength.. Decreases density and tthickening time. Used in Permafrost bc of of low heat hydration
Retarders have different _____
Temp ranges. because some will break down in certain conditions
Lignin Retarders
HR5 most common by product of paper glucose
Light weight Adds
Tie up additional mix water and help suspend so free water does not form. Most common will be silicates and Bentonite
Gilsonite
Natural Hydrocarbon FLuid Loss Add. Helps with light weight as well
Fluid Loss and light weight adds
Poz, Gilsonite, hollow spheres
Foamed Cement
dispersed gas bubbles entrained in the slurry help it become light.
Heavy Weight
displace heavy mud, keep rheo profile and hold formation back.
Heavy weights:
Barite
Sand
SSA2
Hi dense - iron ore
Dispersants do:
decrease visc so you can achieve higher pump rate without increasing friction
Fluid Loss
PRevents premature dehydration: counteracts the tendancy for a slurry to lose water during displacement
Organic Polymers (HALAD)
LCm
Bridges off fractures or unconsolidated formations
Thixotropic cement is effective in sealing off +___
Lost circ zones and displacing viscous fluids.
Salt cements help protect
Clay and shale formations which are susceptible to sloughing.
CEment retrogression
Permeability of cement decreases over time thus rendering the cement susceptible to more decomposition over time.
SSA prevents this -
SSA1
High temps
Transition time
from the time the slurry starts to gel to 500lb/100sq ft.
Super CBL
Generates gas to counteract the weaking pressure of the cement on formation. it keeps the potential for migration back.
Fine Cem / Micr Matrix Cement
Repair gravel packs and casing leaks. 10x smaller particles
Sandwich loading method
bulk/cmt/bulk.cmt/bulk
Cement Job Design : Formation information
Pay ZOne location sensitivity to water fresh water zones gas zones salt zones water flows
In addition to formation info, frac gradients and formation pressure
Drilling fluids
Temps
Silicalite
Expander
comp strength increase
thixotropic
minor Fluid loss
BEst way to increase density
decrease water. This might make it more viscous and less pumpable . careful
Advantages of Foam Cement
high density range
elastic
increased compressability
good strength to density ratio
Job time v pump time v. thickening time
time it takes to pump job including displacement
pump - time fluids are in motion
thickening time - time the slurry will remain pumpable.
SCR -
Non lingosulfate retarder, imparts thixotropy on slurry. Use with HaLad 9. Higher early strength than HRs
Why control fluid loss?
prevent premature dehydration
prevent swelling or sloughing of zones
prevents bridging from excessive filter cake build up.
CFR
friction reducer - dispersant - lower visc
types of liners
drilling
production
stub
tieback
three techniques (liner)
- over the lap - hard to estimate volumes
- 8-10 joints above lap - - easier to drill out than remedial squeeze
3 planned squeeze
adv and disavd of planned squeeze
eliminates risk of potentially sticking drilling string
but leaves a gap where high pressured gas can cause coorosion etc.
reciprocation is difficult in liners
Dp connected during movement and cement above liner can cause serious problems. frac pressures can be exceeded due to swab or surge pressures.
What do we want in our spacer for liner
suspension of heavy weight additives. Flushes should be used in conjunction with a spacer on a liner
Liner Testing
Hydrostatic test
differential test - packer above and removal of fluids and pressures so we would see if fluid in high pressure zones can penetrate and go into the low pressure zone. tests to see if the cement is honeycombed.
nothing is better for liner cementing than»»
good hole conditioning and stability
reason for running a liner
cost
reduced weight on wellhead
derrick weight restrictions
increased flow rate on drilling and cementing
What retarded do we use in liner and or deeper cementing
SCR - natural sugars break down
Considerations when picking liner type
mechanical or hydraulic
liner rotation during cementing
liner through another liner?
most widely used
mechanical - set from surface rotation
hydraulic
if a liner is in well already…
prevents premature setting
pressure required to set slips
Versaflex liner
advantages: Improves cement job better seals Expandable hanger body setting sleeves
Number one cause of poor cement job?
Poor mud removal
Spacer vs flush
spacer is weighted - Spacer is densified
Why do we use spacer or flush
separate incompatable fluids
aid in mud displacement
leave downhole surfaces waterwet.
Spacers must have the ability to:
mixability
pumpability (Without increasing the ECD
compatability (with both fluids it contacts)
stability - enough visc to suspend solids for removal
wettability - leaves the hole waterwet for a solid cmt bond
Flocculation
abundant calcium in cement reacts with chemicals in the mud and forms cottage cheese like mixture
Common preflushes
water kcl seawater brine mudflush
Mudflush
4lb/bbl - simple- low foaming
MCA
Mud cleanout agent - dehydrates clay particles for removal
Spacers
TS CS DS Superflush POZ - Scavenger
Weighting material in TS3
Barite
Superflush really helps with
Lost circulation - reactive and has silicates to clog pores
Must be staged with non reactive fluid because of flash set
RCM
Recirculating Cement Mixer -
Most important factors concerning mixing
Density and mixing energy
Components of the RCM
4x4 6x5 flowmeter 5bbl recirc tub 3 bbl downhole tub agitators
Micromotion F-300
recirc densometer - diversion tube next to . We typically want around 180 gpm running throught the micromotion F300
Name the field equipment:
Bins, 660, body load, batch, tiger, elite
What is foam cement
cement and foaming agents (nitrogen)
Why use foam
zones that cant support the req height and normal density (hydrostatics)
light slurries with relatively high comp strength
Properties of foam cmt
compressable elastic improves bonding high strength to density low permeability
During placement, foam cement has
low density high visc low fluid loss compressability stable at high temps
