02 Well Cementing - Day 2.pdf

Quartz School for Well Site Supervisors Module – 7 Well Cementing Ops.

1

Schlumberger Private

Section – 2 Well Cementing – II

Day 2

2

Schlumberger Private

Well Cementing

Agenda • Review Day 1 and Homework

• Mud removal • Cementing Job Design

3

Schlumberger Private

• Squeeze cementing

4

Schlumberger Private

Squeeze Cementing

Balanced Cement Plugs A balanced cement plug can be used to:

5

Abandon a well at a prescribed depth. Create a hard medium to start kicking off for a sidetrack. Seal off unwanted perforations. (Squeeze) Seal off Lost Circulation zones. Plug back an unwanted section of open hole. Carry out final abandonment at surface. Cement in place, junk, a fish or lost logging tools.

Schlumberger Private

• • • • • • •

Balanced Cement Plugs

A correctly placed balanced plug leaves the required amount (usually height) of cement slurry in the hole after the pipe is removed: Schlumberger Private

Planned Plug 6

Plug in place with pipe

Drill Pipe removed

Squeeze Cementing packer

•

Injection of Cement Slurry

•

Perforations, Casing Leak,

tubing FORMATION

•

Channels

•

Below or above fracture pressure

DEHYDRATED CEMENT

cement slurry

cement nodes

PRIMARY CEMENT CHANNEL BEHIND CASING

7

Schlumberger Private

casing

Basic Concept • Filtration Process

8

FORMATION PRIMARY CEMENT DEHYDRATED CEMENT

cement nodes

Schlumberger Private

– Differential pressure applied – Porous medium – Filter cake deposition

casing

Effect of Fluid Loss Control Completely bridged casing

Completely filled perforations Partially filled perforations

9

Schlumberger Private

Partially bridged casing

Squeeze Cementing - Definition packer

10

tubing FORMATION casing DEHYDRATED CEMENT

cement slurry

cement nodes

PRIMARY CEMENT CHANNEL BEHIND CASING

Schlumberger Private

• Injection of Cement Slurry into the voids behind the casing • Dehydration of cement requires: fluid-loss, porous (permeable) matrix, differential pressure, time. • Injection below or above fracture pressure

Effect of Fluid Loss Control Node buildbuild-up after 45 min, slurries with different fluidfluid-loss, dP=1000psi dP=1000psi

Completely bridged casing 150 ml/30min

Partially bridged casing

50 ml/30min

Completely filled perforations

15 ml/30min

Partially filled perforations

11

Schlumberger Private

800 ml/30min

Squeeze Cementing - Applications

12

Primary cement job repair Unwanted Water Production High Gas-Oil Ratio (GOR) Casing Splits or Leaks Nonproductive or Depleted Zones

Schlumberger Private

• • • • •

Squeeze Cementing - Applications

– In water injection wells

• Block Squeeze – Above and below the production zone

• Liner-Top Leaks

13

Schlumberger Private

• Formation Losses • Top of Cement Column • Alter Injection Profiles

Squeeze Cementing - Methods • Pumping technique Hesitation Running

• Placement technique • •

High pressure - above formation frac pressure Low pressure - below formation frac pressure

• Tools • •

Packer/Retainer Bradenhead

• Coiled tubing 14

Schlumberger Private

• •

Low Pressure Squeeze Squeeze pressure below fracture pressure Best way to squeeze the pay zone Use small volume of slurry Applicable for : • • • •

15

Multiple zones Long intervals Low BHP wells Naturally fractured formations

Schlumberger Private

• • • •

High Pressure Squeeze

• shoe • liner top • block squeeze

• Wash or acid ahead to minimize pump rates required to initiate fracture 16

Schlumberger Private

• Fracturing is necessary to place cement in the void • Requires placement of large volumes of slurry • Applicable for

Running Squeeze Continuous pumping until final squeeze pressure is attained Clean fluid in the hole Large slurry volumes without fluid loss control Low or high pressure squeeze Applications – – – – – – – 17

Water flow Abandon perforations Increase cement top Casing shoes Liner tops Block squeeze Lost circulation zones

Schlumberger Private

• • • • •

Running Squeeze

Pressure ( psi )

Schlumberger Private

Time (min)

Time (min..)

• Usually a large volume of slurry is pumped with this technique 18

Hesitation Squeeze

19

Intermittent pumping Low pump rates Small slurry volumes Long job times Applications – Channel repair – Long perforated interval – Long splits in casing – Lost circulation – Natural, man-made, caused during breakdown fractured situations

Schlumberger Private

• • • • •

Hesitation Squeeze Pressure (psi)

A

• 10-20 min. intervals

B

C

A

Time (min) 20

D

D

Schlumberger Private

Pressure (psi)

• Rate of 0.25 - 0.5 bpm

Planning the Squeeze Job

21

• •

• • • •

Fluid in the well Well conditions (pre-squeeze clean-up, if necessary) – Formation lithology – Formation permeability – Squeeze temperature Type of squeeze Slurry design and amount Pressure limitations – Pore and frac Plan the injection test

Schlumberger Private

• Problem determination – Temperature log – CBL/CET/USI – Noise log – Water-flow log – Tracer survey • Select tools and location – Casing integrity – Type of squeeze – Volume of the slurry

Injection Test • Perforations are open and ready to accept fluid • • • • •

22

Estimate of the proper cement slurry injection rate Estimate the pressure during squeeze Estimate the amount of slurry to be used Ensure that the perforations are open Could pump an acid treatment ahead

Schlumberger Private

– Water or brine or wash

Washes and Spacers

– water-based mud – mud filter cake – carbonate scale

• During placement slurry needs to be isolated ahead and behind – 5 to 10 bbls of chemical wash or water – 50 - 100 gal/ft of perforations 23

Schlumberger Private

• Perforations, surrounding voids, and formation face clean-out to ensure complete fill-up and dehydration • Clean-up us a separate stage with chemical wash or hydrochloric acid to remove

Slurry properties Fluid loss Filter cake development Viscosity Gel strength Free water Thickening time – Squeeze temperature and pressure

• Compressive strength – not a primary concern 24

Schlumberger Private

• • • • • •

Special Systems

– Acid resistant

• Micro-fine cement – SqueezeCRETE*

25

* Mark of Schlumberger

Schlumberger Private

• Thixotropic • Expanding • GASBLOK*

Slurry Volumes

26

Length of the interval and number of perforations to be squeezed Placement technique to be used
Low pressure Injection rate
Low volume Slurry volume to be left in the wellbore
Low rate Excess
High pressure Local experience Rules of thumb
High volume – Do not exceed capacity of the work string
High or Low rate – Two sacks of cement per ft. of perforations – Should not be greater then could be reversed – Minimum 100 sks if 2 bpm after breakdown, 50 sks otherwise – Volume limited to ensure reverse circulation is possible

Schlumberger Private

• • • • • • •

Bradenhead Squeeze

27

BOP

50'

CEMENT 10' Sand BRIDGE PLUG

Schlumberger Private

• Done through tubing or drill pipe without packer • Advantages – No tool are used (simplicity) – Cost • Disadvantages – Casing and wellhead are exposed to pressure – Old casing

Packer with Tailpipe Squeeze

28

Packer Tail Pipe

CEMENT

Schlumberger Private

• Downhole Isolation tool • Casing and wellhead protection • Tailpipe for placement or setting a bridge plug • Long intervals • Multiple setting of packer

Cement Retainer Squeeze

CEMENT RETAINER CEMENT 10' Sand BRIDGE PLUG

29

Schlumberger Private

• Drillable Isolation Tool • Similar to packer without tailpipe • Applications • Squeeze pressure trapped – Internal control valve • Job Procedure

Squeeze with Cement Retainer (or Packer without tailpipe) Determine the following:
Volume of cement slurry and water ahead/behind


Sacks of cement, mix water and additives




Maximum displacement volume





Displacement, Hydrostatic Pressure and M.A.S.P. at: 

Cement slurry 1bbl to end of tubing (or by-pass)



Cement slurry arrives at C.R. (or packer)



All slurry out of C.R. (or packer)



1bbl slurry above Top of Perforations (end of squeeze)

Chart of Surface Pressure versus Squeeze Volume


30

Depth to set C.R. (or Packer), when to Sting-In (or close by-pass)

Internal yield and collapse pressure of tubular

Schlumberger Private




Squeeze with Cement Retainer (Cont.) Data:

(or Packer without tailpipe) Results:

9”5/8 – 47#/ft Casing

•

Casing damaged at 8000ft

•

Cement Retainer @ 7500ft

•

3”1/2 – 12.95 #/ft Tubing

•

15.8ppg Slurry volume = 250 ft3

•

Water ahead = 5bbl

•

Water behind = 5bbl

•

Brine weight = 9.5 ppg

•

Frac. Gradient = 0.8 psi/ft

31


Do necessary calculations
Draw pressure chart
Job Procedure

Schlumberger Private

•

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

• 1 Tubing and Casing data

CTb CCs AnCsxTb

32

bbl/ft

Schlumberger Private

ft3/ft

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe) 2. Slurry and fluids Unit

Slurry Volume

bbl

Amount of Cement

Sks

Mix Water

bbl

Additive

33

lb or gal

Water ahead

bbl

Water behind

bbl

Calculations Schlumberger Private

Step

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

• 3a. Depth to set Cement Retainer Schlumberger Private

• 3b. When to Sting-Into the Cement Retainer (or close the by-pass) • 4. Maximum Squeeze Volume

Sting-In 34

End Squeeze

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

5a. Hydrostatic pressure: Beginning of squeeze Fluid

Density

Volume

Length

Pressure

ppg

bbl

ft

psi Schlumberger Private

Brine Water Slurry Water Brine Total Start Squeeze 35

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

5b. Water ahead out of the stinger (packer) Fluid

Density

Volume

Length

Pressure

ppg

bbl

ft

psi Schlumberger Private

Brine Water Slurry Water Brine Total 36

Water ahead out

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

5c. All Slurry out of Stinger (packer) Density

Volume

Length

Pressure

ppg

bbl

ft

psi

Schlumberger Private

Fluid Brine Water Slurry Total

Slurry Out 37

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

5d. Water behind out of Stinger (packer) Density

Volume

Length

Pressure

ppg

bbl

ft

psi

Schlumberger Private

Fluid Brine Water Slurry Total

Water behind out 38

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

5e. End of Squeeze (1bbl slurry above perfs.) Density

Volume

Length

Pressure

ppg

bbl

ft

psi

Schlumberger Private

Fluid Brine Brine Water Slurry Total

Water behind out 39

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

6. Maximum Allowable Surface Pressure

a. Start Squeeze b. Water ahead Out c. Cement Slurry Out d. Water behind Out e. End of Squeeze

40

P. Frac. (psi)

P. Hyd. (psi)

P. Safety (psi)

M.A.S.P. (psi)

Schlumberger Private

Stage

Vol. of Brine Pumped (bbl)

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe) 7. M.A.S.P. Chart

Surface Pressure (psi)

re u s

M

es e in r r P u rg s e es Ma fac r r P ty u . e S ac Saf r le F i b a s w p 0 lo SAFE AREA 50 Al m u im x a

Initial Surface Pressure Volume of Brine pumped (bbl) 41

Schlumberger Private

Final Surface Pressure

M.S.V.

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

8. Yield and Collapse Pressure

42

∆P (psi)

Pty (psi)

Ptc (psi)

Pcy (psi)

Pcc (psi)

Schlumberger Private

P Annular P. Squeeze (psi) Maxi (psi)

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe) 9. Job Procedure

43

RIH with Cement Retainer to setting depth of 7500ft; Set Cement Retainer; Sting into Retainer; Perform injection test; Sting out of Retainer; Pump:  5bbl of water ahead;  44.5bbl of Cement Slurry;  5bbl of water behind;  4.6bbl of brine;

Schlumberger Private

• • • • • •

Squeeze with Cement Retainer (Cont.) (or Packer without tailpipe)

9. Job Procedure

 “hesitating” if necessary (if no pressure build up)  Max. pressures shown on chart  Maximum cumulative volume of 85.7 bbl of brine;

• Sting out of Retainer; • Reverse out to clean tubing and stinger (55.1 bbl); • W.O.C

44

Schlumberger Private

• Sting into Retainer; • Inject slurry into zone:

45

Schlumberger Private

Mud Removal

Mud Removal • One of the most important aspect of cement job

• Hole cleaning • Conditioning the drilling fluid • Displace the drilling fluid from the annulus

46

Schlumberger Private

• A 3-step process before cementing

Mud Removal (Cont.) •

Hole Cleaning

•

Conditioning Mud • • • •

•

47

Controlled & optimized mud properties Wiper trips > 95% Total hole volume in circulation Caliper log Break gel strength Lower ty + pv Drill solids < 6% Determine minimum rate to have flow all-around casing

Displace Mud from Annulus • Optimized slurry placement ---> CemCADE • Casing centralization optimized (STO > 75%) • Casing movement

Schlumberger Private

• • • •

Criteria for Effective Mud Removal • Centralize casing • Scratchers • Wiper plugs • Washes and spacers • Flow regime selection

48

Schlumberger Private

• Casing movement

The Ideal Wellbore Casing BHST at top of cement >BHCT at TD

Annular gap

Minimum: 3/4” Ideal: 1 1/2”

No sloughing

Gauge diameter

Uniform as possible ( no washouts or restrictions)

NO LOSSES

NO FLOW

Casing centered in borehole Thin, impermeable mud filter cake (not gelled or unconsolidated) 49

Accurate BHST and BHCT

Schlumberger Private

Properly conditioned hole and mud

Casing Centralization • Relative Variation of flow rate ratio as a function of eccentricity 18

RH

14

RC

12 10 W

8 6

% Stand-off =

4

w RH - RC

X 100

2 0

0

50

20

40 60 API % STAND-OFF

80

100

Schlumberger Private

FLOW RATE RATIO

16

Centralizing the casing • Requires the fitting of centralizers to achieve a minimum stand-off of 67% (API) Schlumberger Private

Ridged Centralizer 51

Spiral & Turbulent Centralizers

Influence of the Casing Stand-Off In Laminar Flow Schlumberger Private

V2 = 4V1 (For 67%) Di Do

In Turbulent Flow V2 = 1.64 V1 (For 67%)

52

Vnar

Vwide

Effects of Standoff on Mud Displacement

Cement

Decreasing StandStand-off 53

Schlumberger Private

Mud

Casing Movement Casing Stationary

ROTATION Gelled Mud

Flowing Cement

Re

s is

t in

Mud almost g

dr a m g fo ud r d i ce c sp la a n ci b ng ec fo om e rc po e

54

removed

sit i ve

Schlumberger Private

Rotation Started

Casing Movement RECIPROCATION

Mud Stand-off 20%% StandStand-off ==20 Cement Slurry

55

StandStand-off = 20 %

Schlumberger Private

StandStand-off = 100 %

Scratchers and Collars Rotating Scratcher

Reciprocal Scratcher Schlumberger Private

Model J10H Stop Collar

56

Model J5H Stop Collar

Plugs • Separate fluids Schlumberger Private

• Wiping casing • Surface indication of placement

Top Plug (Solid)

57

Bottom Plug (Hollow Inside)

Chemical Washes • Low Viscosity Fluids

• Contain Surfactants and mud thinners

58

Schlumberger Private

• Usually Water Based

Chemical Washes (Cont.) • Separate mud and cement • Remove mud from annulus – Turbulence at low pump rate – Erode, dilute and disperse particles

• Leave casing and formation water wet – Function of the Surfactant

• Provide less hydrostatic pressure – Water or oil-based

59

Schlumberger Private

– No incompatibility effect

Spacers • Densified viscous fluid separating mud and slurry

• Compatible with mud and cements • Specified rheology – Low for Turbulent Flow – Adjustable for Effective Laminar Flow

60

Schlumberger Private

• Thorough removal of mud

61

Schlumberger Private

Job Design

Job Design Introduction Stress Analyser Gas Migration Slurry Designer CemCADE – WELLCLEAN II – LabDB

62

Schlumberger Private

• • • • •

Designing a Cement Job • Compute fluid volumes ( Slurry, Wash, Spacer, displacement volumes )

– Hole capacity – Casing capacity – Annular length

• Low cost implies: – Good mixing and economical pumping

63

Schlumberger Private

• based on :

Designing a Cement Job • Check that well security is respected: – Simulate cement pumping process

– – – –

Formation pore pressure Formation fracture pressure Tubular burst pressure Tubular collapse pressure (∆ P)

• Ensure well security when Running In Hole • Check temperature and thickening time 64

Schlumberger Private

to compute hydrostatic and dynamic pressures and compare them to :

Designing a Cement Job • Check for an efficient mud removal to prevent mud channeling and to ensure good zonal isolation – Optimize the pumping rate – Optimize casing centralization

•

Ensure good wall cleaning – Optimize pre-flushes volume, and flow rate

65

Schlumberger Private

– Optimize fluid properties

66

Schlumberger Private

Slurry Designer

Agenda • Why? • What is it?

• How does it work? • What comes next?

67

Schlumberger Private

• The story of making knowledge consistent…

Why SlurryDesigner? Designing properly a slurry right away is complex:

The problem of

affects

Cementing lab technicians and engineers, as well as field and sales engineers

the impact of which is

•Poor new technology introduction •Unnecessary tests done •Time wasted to search suitable additives

68

Schlumberger Private

• many design rules for each slurry system • more than 100 tech memos for additives to be selected

What is it? LabDB or CemCRETE calculator

Slurry Designer

Improves design efficiency by providing all users with a minimum level of expertise rather than just a calculator.

For

All cementing technical community

Who

Are designing slurries on a daily basis

Slurry Designer

Is an engineering application

That

Improves the slurry design efficiency : • ensure better designs right away • support implementation and dissemination of new technology by integrating knowledge into the application

69

Schlumberger Private

Unlike

Towards consistent knowledge Yesterday – InTouch (Case Histories, Best Practices, …) – Tech Memos

– All Tech Memos are consistent with SlurryDesigner -> InTouch and sustaining – Ongoing process, please help!

Tomorrow – Add new functionalities – Keep knowledge base clean – Push updated knowledge everywhere -> SlurryDesigner automatic update mechanism 70

Schlumberger Private

Today

CemCADE

71

Schlumberger Private

Cementing Cem Computer Aided Design & Evaluation Software

CemCADE (Cont.)

• • • • • •

Interactive Graphics Customized Reports Data Exchange Database Load Case Manager Extensive Help 72

• • • • • •

Visualize Problems Printed Reports Reduced Duplication Multiple Data Sets Different Scenarios Optimised in Same Session

Schlumberger Private

Reducing Time to Design and Optimise Cement Jobs

CemCADE - Input Well Type Caliper

73

Schlumberger Private

Tubular Formation Temperature

CemCADE - Output BHCT Placement

Safety Checks

74

Schlumberger Private

U-Tube Well Head Effect Pressure

WELLCLEAN II • A numerical tool that helps the engineer to design a better cement job • It predicts the quality of cement by calculating: Fluid position during and at the end of placement Fluids channeling / bypassing Risk of having mud on the formation and the casing Uses the Herschel Bulkley Model

ItIt is is our our “Down “Down hole hole Eye” Eye” 75

Schlumberger Private

• • • •

WELLCLEAN II (Cont.) OilOil-based

WaterWater-based

Displaced fluid

Formation

Wetting film ““Water Zone WaterWetting WettingZone” Zone” Zone”” The Theoil oilfilm filmisisremoved removed Water wet steel & Water wet steel &formation formation surfaces surfaces

76

Laminar layer on the walls ““Tangential Zone TangentialErosion ErosionZone” Zone” Zone”” The eroded Thelaminar laminarlayer layerisis““eroded” eroded” eroded”” No No“mud-on-the “mud-on-thewall” wall”left left

“Mixing” zone ““Mixing Zone MixingZone” Zone” Zone”” The mixing The““mixing” mixing” efficient mixing””isisefficient i.e. the mud is thinned i.e. the mud is thinnedupon upon mixing (reverse Emulsion) mixing (reverse Emulsion)

Schlumberger Private

Displacing fluid

Casing

WELLCLEAN II (Cont.)

77

Schlumberger Private

• Vertical, inclined and horizontal wells • Laminar and turbulent flow • 3-parameter HerschelBulkley model – Better description at low shear rates

Field Cases • New Orleans

VADN data were used

78

Schlumberger Private

Before Beforeusing usingSimulator Simulator After AfterusiusingngSimulator Simulator Well 55 33 WellNumbers Numbers Wells 33 00 WellsSqueezed Squeezed Squeeze 600600 00 SqueezeCost Cost($K)($K)

WELLCLEAN II Simulator Results

Schlumberger Private

79

Field Cases • Norway Before using WELLCLEAN II Simulator: 5 ½” Liner at 52 deg deviation Schlumberger Private

After using WELLCLEAN II: (LiteCRETE HP) 7” Liner at 90 deg deviation

80

81

Schlumberger Private

End of Day 2