10 completion fluids

8/12/2019 10 Completion Fluids

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BASIC FLUIDS TRAINING

1Agip KCOWell Area Operations

Drilling Supervisors Training CourseDrilling Muds RPW2021A

COMPLETION FLUIDSCOMPLETION FLUIDS




RPW2021A 2Agip KCOWell Area Operations

Drilling Supervisor Training CourseDrilling Muds

COURSE CONTENTS

• Applications with completion fluids

• Functions & Properties

• Formulations

• Compositions

• Program






HISTORY

• Crude Oil

• Drilling fluid (‘40’s)

• Controlled Filtrate(‘50/’60’s)

•

Completion brines ( 70 ’s)

• Heavy brines (‘80’s)

• Clear fluids (‘90’s)

Completion / coring fluidNo control of properties

Water base muds

Cellulosic polymers

Brines systems

Formation compatibilty

Environmental






INTRODUCTION






INTRODUCTION

• Completion operations :

The phases in well construction can be subdivided into :

• a drilling phase,• a completion phase,

• an optional stimulation phase






• Completion operations

The completion process prepares the well to the production

The fluids used at this stage are called completions fluids

INTRODUCTION






• What is a complet ion f luid ?

A completion fluid is a bridge between the traditionnal

classifications of drilling fluids and stimulation fluids

INTRODUCTION






1 - APPLICATION






• The Completion Fluid can be used :

To help to prepare the well for production

To drill the pay zone

For the completion operations For work over operations

For an abandon well

APPLICATION






• Completion practises

Consists to displace the drilling fluid with a completion

brine after cementing operations

The completion brines are frequently used as perforatingor gravel -pack fluids

APPLICATION






• The Drilling Fluid displacement

Conventionnal drilling fluids contains

• clay• baryte

• drill solids

The solids from drilling fluid will damage the perforation and the pay zone

Clear brine completion fluids are frequently used to displace the drilling fluid from

the reservoir interval before the well is perforated

For this reason

APPLICATION






The Drilling Fluid displacement

Important decision in the completion process

To ensure that clear fluid is opposite the interval to be

perforated, it is necessary to use :

The full - displacement method

APPLICATION







A spacer with a polymer viscosifier will be used to push the drilling

fluid

Several spacers , including surfactants may be used in the process

APPLICATION






«SPACERS»

Chemical wash:

- Cleaning wellbore

Spacer: Separation

Mud

Completion

Fluid

APPLICATION







A better displacement is to reverse circulate : the completion fluid ispumped down the annulus and the returns are through the tubing or drill-pipe

This reverse circulation process prevents solids settling in the annulus of the

well where flow velocities are slower compare inside tubing or drill pipe

APPLICATION







Sweep pills will help to displace drilling fluids.

High viscosity pills are used as spacers in displacements

The elevate low-shear rate rheology available with

biopolymers are exellent components of sweep pills

APPLICATION






Water base mud

or oi l base mud

pit

Spacers

and

Chemicals wash

Completion

fluid

Drilling fluid

pit

Sweep spacer :

polymers

Completion

fluid

APPLICATION







Cleanup fluids are sometimes used to help clean up drilling fluids.

• Surfactants-based fluids will be used to clean and suspend dirt and solids and

to aid in the displacement.

APPLICATION






• Chemicals components

Two groups solubles in water and in oil

Defined by a ratio hydro-lipophile balance (HLB)

• 0 < HLB < 10: lipophile

• 10 < HLB < 20:hydrophile

THE SURFACTANTS






Oil phase

Group

soluble in water

Water

droplet

Group

soluble in oil

The water droplet and the oil are attached

with surfactant :it is an emulsion

THE SURFACTANTS







Enzyme based fluids to break and degrade polymers.

Cosolvent fluids to clean up oil-based mud and breakthe the water in oil-emulsion in these fluids

APPLICATION







After the drilling fluid displacement a common practise is

to circulate and fi lter the completion brine for clarity

APPLICATION






• The Completion Fluid design

The design of these Fluids will depend of Reservoirs andProduction techniques

Completions Fluids may be formulated with water, foams, brines,

oils or emulsions

Low and high density completions brines are available on the

market

APPLICATION






• The Fluid design

The constraints for a Completion Fluid formulation willdepend of reservoir characteristics as :

• Rock character

• Pore cross section

• Pore pressure

• Hydrostatic pressure

• Temperature

APPLICATION






• Perforated completions

Perforated completions offer an excellent isolation zona

for stimulation and production.

The well will be perforated with a conventional clear

completion fluid.

For depleted zones, pressures are low, foam-based

completion fluids will be sometimes used.

APPLICATION






• Open Hole and Liner completions

Wells completed with slotted liners will be completed with a

special drill-in fluid.

This fluid is only used to drill the reservoir interval and will

have many of the characteristics of a completion fluid.

APPLICATION






• Open Hole and Liner completions

These special drill-in fluids contain : brines, polymerics

additives, and size-salt or calcium carbonate for filter cake

solids.

APPLICATION






WHAT IS A DRILL-IN FLUID ?

• Drill-in fluid definition

A fluid that possesses the desirable properties of a good

drilling fluid but will also provide the necessary attributes of a

completion fluid

Its primary attribute is the development of a filter cake which

prevents formation damage and is easily removed






WHAT IS A DRILL-IN FLUID ?






A DRILL-IN FLUID

• The Challenge

The challenge is for an horizontal well which is to perform

satisfactorily both as a drilling fluid and a completion fluid

Important considerations in selection of the drill-in fluid are thereservoir rock type and the matrix permeability.

G G






2 - ENGINEERING






• THE PROPERTIES

ENGINEERING

Completion Fluid

Corrosion Rheology

Compatibilty Filtration

Crystallization Density






• DENSITY requirements.

The primary performance requirement for a completion fluid is

pressure control.

The density must be sufficient to produce a hydrostatic pressure

in the wellbore to control formations pressures.

An over balance of 200 of 300 psi above bottom hole reservoir

pressure is used for well control.

ENGINEERING







The brine density decreases with increasing temperatures

because of thermal expansion, and increases with pressure

because of compressibility.

The temperature effects dominate the pressure effects as thedepth of the well increases.

ENGINEERING







Temperature and pressure corrections are generally needed for

deep wells to control pressure and avoid excessive overbalance

pressures.

Expansibility and compressibility factors for weighted brines will be

used.

The factors can be found in API recommended practice 13 J (march

1996)

ENGINEERING


ENGINEERING






• DENSITY and temperature correction.

The brine density at 70 °F will be related to the density at bottom holetemperature with schimdt equation :

Density ( 70 F ) = density + ( T avg - 70 ) * E f.

Ef = expansibilty factor.

T avg = average well temperature.

T avg = (surface temp + bottom hole temp) / 2.

ENGINEERING


ENGINEERING







Example : temperature correction.

Density : 9.62.

The bottom hole temperature is 230 ° F.

Temp avg: ( 70 + 230 ) / 2 = 150.

The required density at 7O ° F wil l be :

Density (70°F) = 9.62 + (150 - 70) * 0.0024 = 9.81

ENGINEERING


ENGINEERING






• CRYSTALLIZATION requirements.

The crystallization temperature is the second most important

selection criterion for a completion brine.

The crystallisation temperarure is the temperature at which

the brine is saturated, the least-soluble salt becomes

insoluble and precipitates.

ENGINEERING


ENGINEERING






• CRYSTALLIZATION requirements.

The crystallization point is the equilibrium temperature

when the crystals forms.

The crystals can be either solids or freshwater ice.

ENGINEERING


ENGINEERING






CRYSTALLIZATION requirements.

Time,

min

10

20

30

40

10 20 30 40 50

ZnBr 2 / CaBr 2 curve ( 19.2 ppg )° F

LCTD

FCTA

TCTTCT

FCTA

HeatingCooling

ENGINEERING


ENGINEERING






CRYSTALLIZATION requirements.

Time, min

10

20

30

40

10 20 30 40 50

ZnBr 2 / CaBr 2 curve ( 19.2 ppg )° F

Last crystal todissolve

True crystallisationTemperature

First crystal to

appear

ENGINEERING


ENGINEERING






• Crystallization.

Crystals and precipitations can lead a number rigs problems :

• The density may be too low , the crystals salts settle in

the pits.

• Brine viscosity increases with salt crystals, brine appears

to be frozen solids.

• Lines are plugged.

• Lost rig time and expense.

ENGINEERING


ENGINEERING






•

FORMATION compatibili ty requirements. The third selection criterion is the completion brine wil be

chemically compatible with the formation rock, water and

hydrocarbons.

Incompatibilities cause formation damage, blocking poreopenings and pore-throat plugging.

ENGINEERING


ENGINEERING






• COMPATIBILITY with formation clays.

The main concern is with formation clay compatibility.

The contact with reservoir rock will cause swelling and / or deflocculating

of formation clay.

To prevent clay swelling, a completion fluid must meet a minimum

salinity requirement.

( 3% NH4CL or 2 % KCL ).

ENGINEERING


ENGINEERING






• COMPATIBILITY with formation waters.

The incompatibilty with formation water is :

• The formation of scales.

Scales are deposit of inorganics materials.

ENGINEERING


ENGINEERING






• COMPATIBILITY with formation waters.

The scales found in formation water are :

Calcium

Iron carbonates

Sulfates

Silicates

ENGINEERING


ENGINEERING






•

COMPATIBILITY with formation waters.

Scales can be formed by mixing incompatible waters, when

solubility change with pressure and temperature, and

water evaporation.

ENGINEERING


ENGINEERING






• COMPATIBILITY with formation crude and gas.

The main concern is :

formation of oil-water emulsion and / or sludge which will block

pores and cause formation damage.

ENGINEERING


ENGINEERING






• COMPATIBILITY with formation crude and gas.

Incorporation of surfactants or solvents will be necessary.

Natural gas as CO2 will cause calcium carbonate precipitation.

ENGINEERING


3 . TESTING






3 . TESTING


TESTING





• Filtration.• Rheology.

• Fluid Loss control.

• Weighting.

•

Corrosion.


ENGINEERING

TESTING





• Filtration.

The fluid that contacts the formation must be a particle -

free.


ENGINEERING

TESTING





• Filtration.

Sources of particles in fluids for completion.

• Solids from mud incorprated during displacement.

• Scales in pits and storage.

• Insolubles impurities in salts or other components.

• Solids and fines in suspension with waters.


TESTING





• FILTRATION process.

Mixing plant filtration use two stage process :

• Fluid is passed through a 10-micron filter cartridge.

• Then fluid is filtered with a 2-micron pleated paper cartridge.


TESTING





• FILTRATION process.

The quality control of filtration is the degree of clarity.

Turbidity, particle size distribution and gravimetric measurements of total

solids will be conducted.


TESTING





• RHEOLOGY measurement.

Rheology is tested with the rotating fann V-G meter commonly used in the

drilling fluid industry.

This rotating - cylinder viscommeter measured shear rate vs shear stress.


TESTING





•

RHEOLOGY measurement.

A brookfield viscometer is used to measure a very low shear rates viscosity

to enhance suspension properties of the fluid.


TESTING





•

FLUID LOSS control.

The completion fluid must be designed for minimum

invasion in the formation in static and dynamic conditions.


TESTING





• FLUID LOSS control.

The completion fluid must be designed for minimum spurt-loss by adding the

proper amount of sized solids.

Minimizing the spurt loss and exposure.

The fluid must have minimum high temperature and high pressure static

filtration.

Fluid-loss contol materials will be used.


TESTING





Pore Throat

Pore blocking

agents from lowfiltrate fluid

systems.

Fluid phasepasses through at

rates dependent

on permeabilities

and properties

of skin and

dynamic zone

FLUID LOSS

schematic


TESTING





• Weighting.

The density of a completion fluid will need adjustment.

• Weighting up with solids salts or heavy brines.

• Weighting down will be done by dilution with fresh water or a

lower-density brine.

• Sea water will never be used , introducing bacterias or undesirable

ions.


TESTING





• Corrosion.

The electrically conductive nature of fluid ( brine ) provides corrosion of

metals.

Corrosion rates is important if the fluid has a low PH or contains

dissolved oxygen.


TESTING





• Corrosion

The solubility of oxygen decreases in brines basedcompletion fluids as saturation of salts is approached.


TESTING





• Corrosion.

Injection of oxygen scavenger (amonium bisulfite) is needed.

Corrosion inhibitors , filming, amine type, brine soluble may be used incompletion brines.


TESTING





• Corrosion

Thioconate chemicals as corrosion inibitors will form a film on

the surface of steel or iron in zinc based brine environment.


4 . TECHNOLOGY FORMULATIONS & COMPOSITIONS






FORMULATIONS





•

Clear fluids• Low density

Foams

Emulsions

• High density

Brines


FORMULATIONS





Clear Fluids

Solutions

Foams

Invert emulsions

Clear fluids

Brines, foams or oil base fluids


FORMULATIONS





Foams : 0.1SG( 0.83 ppg) - 0.5 ( 4.1ppg )

Air / gas / nitrogen

Foaming agents Polymers

Low density


FORMULATIONS





Oil base fluids : 0. 5 SG( 5 ppg) - 1. 00 ( 8.3ppg )

Oil or invert emulsion

Oil and microsphères

Organophilic clay

( *) Microspheres : Shell-shaped glass marble

Acid soluble in regular acid

20- 128 Microns

• Low density


FORMULATIONS





Brines : 1.00 ( 8.3 ppg) - 2.3 ( 19.0 ppg )

POTASSIUM Chloride -( K Cl ) d : 1.16- ( 9.6 )

SODIUM Chloride- ( NaCl ) d : 1.20- ( 9.9 )

MAGNESIUM Chloride- ( Mg Cl 2 ) d : 1.30- (10.8 )

CALCIUM Chloride- ( Ca Cl 2 ) d : 1.40- (11.6 )

SODIUM Bromide- ( Na Br ) d : 1.51- (12.5 )

CALCIUM Bromide- ( Ca Br 2 ) d : 1.80- (14.9 )

ZINC Bromide- ( Zn Br 2 ) d : 2.30- (19.0 )

• Low density


FORMULATIONS





Density Fresh Water NaCL CL NaCL Crystallization

ppg bbl lb mg/l %wt Point °F

8. 33 1. 000 0. 0

8. 6 0. 986 16. 2 26643 4. 5 27

9. 0 0. 961 41. 5 72267 10. 9 19 9. 8 0. 903 95. 4 166334 23. 2 - 5

10. 0 0. 887 109. 1 189048 26. 0 - 25

Materials required to prepare one final barrel of NaCL at 60 °F

• Mixing chart


FORMULATIONS





• High density

Brines mixtures will be used for économical reasons

Compositions will use tables of crystallisation points


FORMULATIONS





Brines mixtures* : 1. 00 ( 8.3 ppg) - 2.3 ( 19.0 ppg )

Economical formulations

- Nacl +Cacl 2 d = 1.20 - 1.40 ( 9.9 - 11.6 ppg )

- Nacl +Na 2CO3 d = 1.20 - 1.27 ( 9.9 - 10.5 ppg )

- Nacl +Nabr d = 1.20 - 1.51 ( 9.9 - 12.5 ppg )

- Ca cl2+Cabr2 d = 1.40 - 1.80 (11.6 - 14.9 ppg )

- Cabr2+Zn br2 d = 1.80 - 2.30 (14.9 - 19 ppg )

* Crystallisation points / Tables

• High density


FORMULATIONS





• High density : > 1.00 ( 8.3 ppg) - 2.3 ( 19.0ppg)

Mixtures

CaBr2 brine d = 1.70 d=1.50

715 liters CaBr2 + 285 lit water = 1 m3 (d=1.5 )

355 liters CaBr2 + 645 lit CaCl 2 (d : 1.39) = 1 m3 (d=1.5)

268 liters CaBr2 +CaCl2 97%+ 732lit CaCl2 = 1 m3 (d=1.5)

( 268 li t d = 1.80 ) + (732li t d=1.39)


FORMULATIONS





High density : > 1.00 ( 8.3 ppg) - 2.3 ( 19.0ppg)

Mixtures

CaBr2 brine d = 1.70 d = 1.50

1 m3 ( d =1.5 ) price : 10.000 FF / 1500 USD

1 m3 ( d=1.5) price : 6800 FF / 970 USD

1 m3 ( d=1.5) price : 5000 FF / 750 USD


FORMULATIONS





• High density : > 1.00 ( 8.3 ppg) - 2.3 ( 19.0ppg)

POLYBRINE :

Formulation of polymers and carbonates used as a viscosifier and seepage losscontrol agent in completion brines.

Prevent excessive filtrate invasion

Formation protection from solids blocking

Acid soluble


COMPOSITIONS





15

25

20

10

5

0 1 1.5 2 3 4 6 8 12 16 24 32 48 64 96

Particle Size, microns

Particle Size Distribution of Carbonate

%


COMPOSITIONS





• PRODUCTS

Other acid soluble products used

• XC Polymer if suspension is required

• Blends of polymers, calcium lignosulfonate and NaCl

particulate


COMPOSITIONS





• PRODUCTS

Other acid soluble products used

• Used as bridging, viscosifier and suspension agent

• The sealing ability may be enhanced with the addition of

supplemental bridging agent


PROGRAM





•

Procedures

A program to ensure that pits , tanks and lines are clean is an

essential part of any completion operation

Procedures wil be necessary




CONCLUSION





• Drilling fluids # Drill-in Fluid

• Completion and Production

technology

• Chemicals and propertiesadapted to Reservoir

• Laboratory evaluations

• API specifications

• Environmental concepts

10 completion fluids

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