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75 Cards in this Set

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What are the objectives of primary cementing?
Zonal Isolation
Support the Casing
Protect the Casing
Name 7 characteristics of an ideal wellbore.
-Properly conditioned hole and mud
-Gauge diameter
-Centered Casing
-Accurate BHST/BHCT
-Thin, impermeable mud filter cake
-No Losses/No Flow
-Min annular gap: 3/4, ideal 1.5
What is the mud removal process?
- Clean the hole
- Condition the mud
- Displace the drilling fluid from the annulus
How do you prepare the well?
- Drill with good mud properties
- Have an in-gauge hole
- Maintain wellbore stability
- Clean cuttings from hole
Characterisitics of hole cleaning
- Controlled/optimized mud properties
- Wiper trips
- >95% total hole volume in circulation
- Caliper log
Characteristics of mud conditioning
- Lower Ty and Pv
- Solids content <6%
- Determine MPG to find Qmin for all-around flow
- Break gel strength
Characteristics of displacing mud from the annulus
-Optimize slurry placement
-Centralize Casing (STO>75%)
-Casing Movement
Name 3 goals of circulating/conditioning mud
-Circulate a minimum of 1 hole volume
- Lower rheologies as much as possible
- Lower solids content
- Satisfy MPG requirement
What is the purpose of fluid calipers?
To determine circulation efficiency or amount of fluid which is moving in the wellbore
Criteria for effective mud removal?
Centralize Casing
Move Casing
Scratchers
Wiper Plugs
Washes/Spacers
Flow Regime Selection
Name 3 characteristics of the density heirachy
Chemical Washes arent considered
Slurry has priority
Density of displacing fluid is greater than that of the fluid being displaced
Rules of Effective Laminar Flow
Density Heirachy
Friction Pressure Heirachy
MPG
Differential Velocity
Name 3 characteristics of Minimum Pressure Gradient
To have flow, Ty(mud) < WSS
Applies only to fluids with YP
All fluids flow in the well
Name 3 characteristics of the Friction Pressure Heirachy
Nature takes easiest route
Displacing fluid needs to be stronger
Given to be a 20% friction pressure difference between displace and displaced fluid
Name 3 characteristics of Differential Velocity
Fluid has a preference to flow on the west side
Needs to be an upper limit (Qmax)
Function of standoff/density differential
T/F Effective Laminar Rules apply to the fluids in the casing
False
What CWs are for WBMs?
CW7, CW100
What CW's are for OBMs?
CW8, CW101
What CW's are for intermediate casings?
CW7, CW8
What CW's are for production casings?
CW100, CW101
Name 3 required properties of spacers
Compatible with all other fluids
Stability
Controllable Density/Rheology
Good Fluid Loss Control
Environmentally Safe
What's the D code for Mudpush II?
D970 and D971
Name 4 major problems resulting from fluid incompatibility
Poor interfaces
High rheological properties
Changes in Cement Slurry Properties
Reduction of hydraulic bond
How do you do a compatibility tests and what values of R indicate compatibility?
Take rheologies of different concentrations of mud and spacer at ambient and BHCT.
R at 100RPM: <0 Compatible 0<R<40 Compatible (check FP)
Herschel Bulkley better predicts under what conditions?
At low shear rates and when extrapolating at very high shear rates
Name 4 characteristics of reciprocating the casing
1-5 min per cycle
Need scratchers to be effective
Casing may become stuck during movement
Excessive swab/surge pressures may be created
Name 4 characteristics of rotating the casing
Cannot be the only method of mud removal
Scratchers help efficiency
Need special rotary cement head/power swivels
Torque must be closely monitored
Which API standard applies to lab operations?
Spec 10
Name 6 lab tests completed on cement
Thickening time, Fluid Loss, Free Water, Compressive Strength, Free Water, Rheology
Name 4 Slurry Properties
Free Water/ Sedimentation
Density
Pumpability
Fluid Loss
Rheology
Name 4 properties of set cement
Bonding, Sulphate Resistance, Strength Retrogression, Permeability
What volume of sample is mixed for slurry testing in the lab?
600mL
How long and at what speeds are normal slurries prepared
15s @4000RPM
35s @1200RPM
How long and at what speeds are CREETES prepared. Why is it a different procedure?
5 min @ 4000RPM

As to not crush the little spheres (D124)
How many mL of slurry are needed for a free water test. How long does it take?
250mL
2hrs
How is the fluid loss determined if the slurry is dehydrated in less than 30 min?
F = 2 X Filtrate at time X sqrt(30/t)
What speeds are tested during rheologies?
300, 200, 100, 60, 30, 6, 3
What calculation is used to determine Pv and Ty
Pv = (Reading@300 - Reading@100) X 1.5.

Ty = Reading@300 - Pv
What is the reading at 3 and 6 RPM used for. Why not test at 600RPM as well?
3- used for gel strength @10sec and 10min

6 - used for HB rheology (along with 3

600 - creates too much shear stress in the slurry
Name 4 characteristics of Thickening Time
Reported in Bc
Upper API limit - 100Bc
Performed in a pressurized consistometer that simulates T and P
Determines the length of time a slurry remains fluid
Two ways to determine compressive strength
Crush Test
UCA
Define Gas Migration
Invation of formation fluids into the annulus due to a pressure imbalance at the formation face (loss of hydrostatic pressure. i.e Pformation>Phdrostatic)
Name 4 consequences of Gas Migration and an example of each
Blow Out - lost rig/personnel
Environmental Damage - freshwater aquifers
Poor zonal isolation - lost production
Repair Required - casing corrosion
Name 3 pathways for Gas and what they result from
A channel - poor mud removal
Invasion during placement - fluid loss
Set cement failure(microannulus) - due to shrinking/expanding of casing
What are the phases of setting cement?
Fully Liquid
Early Gelation
Hydration
Set Cement
What are the two types of fluid loss, and consequences of each. What fluid loss is recommended
Dynamic - increased rheology
Static - promotes early gelation, loss of overbalance

<50mL/30min
Name 4 causes of set cement failure and a cause of each
Cracks/Debonding due to downhole stresses
Tensile cracks/well bore stress changes - due to cement expansion
Poor interfacial Bonding (Microannulus) - due to casing movement
Debonding at formation interface - due to shrinkage
Name the 5 pieces to the gas migration control puzzle
Slurry Design
Mud Removal
Set Cement Mechanical Properties
Fluid Density Control
Cement Hydration
What are some ideal slurry properties during and after placement
Before: Good rheologies for mud removal, zero free fluid, fluid loss less than 50mL/30min
After:Low fluid loss to avoid early gelation, short transition time from 100-500lb/100ft^2
How do you avoid a pathway for gas in set cement
FlexSTONE - can withstand cyclical stress variation, no shrinkage b/w casing/formation
Prevention methods for gas migration
Optimize slurry
Short transition times
Special Techniques
GASBLOK
Physical solution to gas migration
Annular pressure, multistage cementing, reduced cement column length, increase mud density
Cement solutions to gas flow. Name 4.
Compressible Cements
Thixotropic Cements
RAS Cement
Surfactant Cement
Expansive Cements
Microsilica Cements
Impermeable Cements
Name a concept and disadvantage of compressible slurries
Concept - attempt to maintain cement pore pressure about formation gas pressure

Disadvantage - safety hazard, stability which may cause gas channeling itself, time dependent
Name a concept and disadvantage of thixotropic slurries
Concept - gel strength strongly binds particles before cement sets and gas cannot break the structure

Disadvantage - limited to low gas pressure zones, poor fluid loss control
Name a concept and disadvantage of RAS slurries
Concept - slurry sets to rapidly gas doesnt have a chance to invade

Disadvantage - difficult to accomplish <250 F
Name a concept and disadvantage of surfactant slurries
Concept - formation of a stable foam in slurry if gas enters in annulus. Subsequent impairment of gas flow/migration

Disadvantage - doesnt work on highly permeable zones
Name a concept and disadvantage of expansive slurries
Concept - volumetric expansion of cement close gas channels and improve interfacial seals

Disadvantage - Expansion occurs after gas migration started, can result in unsoundness
Name a concept and disadvantage of microsillica slurries
Concept - extremely small particles pack between larger cement particles preventing gas from entering

Disadvantage - Not efficient under severe conditions
Name a concept and disadvantage of impermeable slurries
Concept - Reduce permeability during liquid-solid transition time

Disadvantage - latex is sensitive to temp, difficult making product for oil industry
How do you optimize a slurry?
Free water, fluid loss control, gelation control, thickening time, hydration kinetics, slurry density
What is GasBLOK?
A complete engineered solution to gas migration. Excellent fluid loss control, impemeable film formed during transition period
GasBLOK works under what conditions?
Density: 2-24ppg
Temp: 32-375F
Depths greater than 20,000ft
Temp/Density range for LT GasBLOK
32-160F
10.5-16.4ppg
Temp/Density range for MT GasBLOK
150-250F
8-23ppg
Temp/Density range for HT GasBLOK
250-375F
8-23ppg
GasBLOK Slurry Design Considerations
<50mL/30min Fluid Loss
Minimize gel strength
Slurry stability
Short transition time
GasBLOK concentration depends on...
BHST
SVF (Solid Volume Fraction)
Additive used to stabilize D700
D701 - replaced D135
Deep Water Cementing Objectives
Competent Hydraulic Seal
Structural Support
Long term Cement Sheath Durability
Short WOC
Special Deep Water Problems
Shallow Water Flow
Gas
Low Temperature
Mud Displacement
Risk of Losses
Where does shallow water flow occur?
Unconsolidated sands/clays
Faults
Over-pressured, high permeability
DeepCRETE application range
Fresh water to 37% salinity
Density 8-13.5ppg
Temperature 40-80F
Pressure: Surface to 5000psi (else burst D124 spheres)
DeepCRETE advantages. What are D185 and D186
Low density (maintains returns)
Short WOC

D185 - Dispersant
D186 - Accelerator
Depths greater than (..blank..) are considered deep water.
1000ft