Solids and Relation to Fluids 2000

7/26/2019 Solids and Relation to Fluids 2000

1/63

27 September 2004


2/63

FUNCTIONS OFFUNCTIONS OF

DRILLING FLUIDSDRILLING FLUIDS


3/63

Functions Of Drilling Fluid Introduction

Objective of Drilling Operation drill safely evaluate complete

produce Responsibility

Drilling Fluids are critical for successfully achievingthese objectives

Mud Engineer is responsible for maintaining thedrilling fluid system


4/63

Functions

1. Remove Cuttings From The Well Viscosity

The use of shear-thinning, thixotropic fluids with low

shear rate viscosity... Velocity

Annular velocity is key parameter Density

Pipe Rotation higher rotary speeds also aid hole cleaning


5/63

Functions

2. Controlling Formation Pressure


6/63

Functions

3. Suspend and Release Cuttings

Drilling fluids must suspend and release cuttings for efficienct solids control.


7/63

Functions

4. Seal Permeable Formations


8/63

Functions

5. Maintain Wellbore Stability

Wellbore stability is a complex balance.


9/63

Functions

6. Minimize Formation Damage

Protecting the reservoir from damage is a big concern.


10/63

Functions

7. Cool & Lubricate, Bit, and Support Drilling

Assembly & Casing


11/63

Functions

8. Transmit Hydraulic Energy To Tools and Bit

Hydraulic energy can be used to maximize ROP. Provides power for downhole motors and MWD, LWD tools


12/63

Functions

9. Ensure adequate formation evaluation

accurate formation evaluation is essential for the success cuttings logs coring


13/63

Functions

10. Corrosion Control

Dissolved gases can cause serious corrosion problems


14/63

Functions

11. Facilitate Cementing and Completion

The mud should have a thin, slick filter cake.


15/63

Functions

12. Minimize Impact On The Environment


16/63

Functions

Summary Mud Selection Process Mud Properties vs. Functions Functions and Properties will clash

Drilling fluids engineering almost always requires tradeoffs...


17/63

Mud Check / Properties IntroductionMud Check / Properties Introduction

Solids in a mud system determine fluid density,Solids in a mud system determine fluid density,viscosity, gel strengths, filter- cake quality andviscosity, gel strengths, filter- cake quality and

filtration control.filtration control.

Solids and their volumes also influence such factorsSolids and their volumes also influence such factors

as ROP, hydraulics, dilution rates, surge and swabas ROP, hydraulics, dilution rates, surge and swab

pressures, differential sticking, bit life, pump life..pressures, differential sticking, bit life, pump life..


18/63

Measured in: pounds per gallon

kg/m3

SG lb/ft3

Mud Check / Properties DensityMud Check / Properties Density


19/63

Non-aqueous liquids used to formulate OBM &SBM are compressible Fluids. Density increases with pressure

Density decreases with temperature Due to T & P effects, equivalent downholedensity will be different to surface condition

Effects somewhat counter each other Effects more severe when drilling in hightemperature environments



20/63


R TUAL

HYDRAUL CS

ESD: Equivalent Static Density Profile vs MDUnocal Thailand NPWF

Saraline 200: 2!" l#$%al & '0 (F) T*0+ , " (F) T*TD+ , 2-' (F

2!.00 2!/00 2!"00 2!-00 !000

0

2

1

.

"

0

2

1

.

Equivalent Density *l#$%al+

MeasuredDe2th*

000ft+


21/63


R TUAL

HYDRAUL CS

Density versus Pit Te3eratureUnocal Thailand NPWF

0 '0 00 '0 200 2'0 002!2'

2!'0

2!/'

!00

!2'

!'0

Density*l#$%al+

Pit Te3erature *(F+


22/63

Mud Check / Properties Density

UNOCAL SPECIFICATION: 6-1/8 HOLE SECTION

9.2 - 13.0 ppg

TheMud WeightMud Weight will vary but in most cases will be

in this range


23/63

Definition:Definition:Internal resistance to flow of a fluidInternal resistance to flow of a fluid

Mud Check / Properties ViscosityMud Check / Properties Viscosity


24/63

Marsh Funnel

Classic Viscometer

Timed in sec/qt.

UNOCAL SPEC

40 - 80 sec/qt40 - 80 sec/qt

Will vary with temperature!


25/63

MUD RHEOLOGY

Mud Check / Properties RheologyMud Check / Properties Rheology


26/63

Rheology is the study of

how matter deforms and flows



27/63

Hole cleaning Suspension of solids

Hole stability

Solids control

Equivalent circulating densities

Surge / swab pressures

Factors Influenced by Mud Rheology


28/63

Sleeve

Bob

Dial

Spring

Concentric Cylinder Viscometer

For oilfield viscometers:600 RPM !0"" rec# sec#

$00 RPM %!! rec# sec#

! Dial &nit !#06' lb(!00 s ft


Standard MudStandard MudTesting RheometerTesting Rheometer

Fann Model 35Fann Model 35 VG MeterVG Meter 6 speed6 speed


29/63

Dial Units Shear Stress

RPM Shear Rate

Mud Check / Properties VG MeterMud Check / Properties VG Meter


30/63

Plastic Viscosity

Definition:

A measure of the internal resistance to fluid flowattributable to the amount, type, size and shape

of solids present in a given fluid.


31/63

Plastic Viscosity Increased By:

Drill Solids Clays, Shales

Inert Solids Barite, Sand, Limestone, etc.

Colloidal Matter Organophilic Clay, Fluid Loss Additives


32/63

Plastic Viscosity Increased by:

Particles breaking, thus increasing surface areaand more friction

Weight material to increase density

Water Additions

Tightly emulsified water


33/63

Plastic Viscosity

600 DR - 300 DRPV =PV =

PV = Plastic Viscosity, centipoisePV = Plastic Viscosity, centipoise

Measured at Constant Temperature of 150Measured at Constant Temperature of 150ooFF


34/63

Mud Check / Properties Plastic Viscosity


15 - 35 cps

The above stated range forPlastic ViscosityPlastic Viscosity is

dependent upon mud weights.

Measured At 150oF


35/63

Area Increase by Breaking of Solids

6*inc+ c,be

!*inc+ c,be

!*foot c,be

V-.&M/! c, ft !'" c, in 6*in c,bes !'" c, in!'" !*in c,bes !'" c, in

S&RF1C/ 1R/1! c, ft 62 s) in 6*in c,bes !'" s) in

!'" !*in c,bes !03$6 s) in

!03$6 * 62 4%02 s) in increase


36/63

Plastic Viscosity Decreased by:

Removal of Solids

Shale shaker

Desanders, desilters, and centrifuges Lowering of gel strength allows larger particlesto settle out

Dilution of solids with base fluid or premix


37/63

Yield Point

Definition:

Resistance to initial flow or represents the stress required to start fluid movement.Due to:

dispersion or attraction between solids because of electrical charges located onor near the surfaces of the particles

water phase attraction organophilic clay content


38/63

Yield Point Increased by:

Drilled clay and shale increasing reactive solidscontent

Insufficient treatment with emulsifiers andwetting agents

Adding inert solids (like barite) causing attractiveforces to increase due to crowding of reactivesolids

Addition of gelling agents


39/63

Yield Point Decreased by:

Dilution Solids Removal

Increase in wetting efficiency (sometimes) Emulsifier additions (sometimes)


40/63

Yield Point

300 DR - PVYP =YP =

YP = Yield Point, lb/100 ftYP = Yield Point, lb/100 ft22

Measured at Constant Temperature of 150Measured at Constant Temperature of 150ooFF


41/63

Mud Check / Properties Yield Point


8 - 18 lb/100 ft8 - 18 lb/100 ft22

Yield PointYield Point to be maintained in the abovestated range.

Measured At 150oF


42/63

Gel Strength

Gel structure develops as a result of charged

particles assuming equilibrium positions

(positive to negative) with respect to each other.

Gel strength is a function of time, temperature,

concentration and strength of attractive particles.


43/63

Gel Strength

Assists in decreasing the settling rate ofcuttings when circulation is interrupted


44/63

Ti3e

4els

PR-5R/SSV/

FR15./

Gel Strength


45/63

Problems Attributed to High Viscosity and Gel Strengths

More pump pressure required

Higher ECDs

Lost circulation by pressure surges

Swabbing of formation fluids into wellbore

Slow gas breakout


46/63

Initial GEL (Dial deflection after 10 seconds ofstatic conditions)

10-minute GEL (Dial deflection after 10seconds of static conditions)

Expressed in lb/100 sq ft

Gel Strengths

M dCh k/P G lS h


47/63

Mud Check / Properties Gel Strength


4-8 / 7-12 / 12-22 lb/100 ft2

The10 second10 second and1010& 30& 30minute Gel Strengthminute Gel Strengthss tobe maintained in the above stated range.

Measured At 150oF


48/63

Plastic Viscosity & Yield Point

Both Effected by Temperature & Pressure ChangeBoth Effected by Temperature & Pressure Change


49/63

Plastic Viscosity & Yield Point

Unocal Thailand

15 Drill Pie

MD:

T6D:

7it Si8e:

Date:

.// ft

-0" ft

.!2' in!

.9Se92001

erator:

Well Na3e:

;ocation:

TU?; @AD>?U;==;;=N4 F;U=D

SASTEM D?T?

Saraline 200

P>ESSU>E ;SS *si+

Modified PoCer ;aC

Mud Wei %ht 2!" l#$%al

Test Te3 '0 (F

FloC >ate 2'0 %al$3in

>iser Pu3 0 %al$3in

>P '0 ft$hr

>PM 20 r3

W7 0 l#

No88les 1919191

No88les

Drill Strin%

MWD

7it

7it n$ff?nnulus

Surface Equi

U9Tu#e Press

Total Syste3

.0-

1.-

20

00--

20

.'

"1

ESD ED@ 9 6ersion 2!/

File 9 NPW?!MD7

0 2' '0 /' 00

Pressure ;oss *G +

Drill Strin%

7it

?nnulus

0 0#"% 0#%0 0#'% !#00

@ole


50/63

VG Meter Dial Reading

Direct Reading 600 rpm 300 rpm 200 rpm 100 rpm 6 rpm (Low Shear Rate Rheology) 3 rpm

Indirect Calculation LSYP (Low Shear Yield Point) = 2 x 3 rpm 6 rpm DR


51/63

HTHP Fluid Loss Effected By:

Viscosity of the continuous phase Temperature oil- or synthetic fluid ratio

high ratios require more dedicated FLadditives

tightness of the emulsion water-wetting of solids

solids content amount of fluid loss additive

Mud Check / Properties HTHP Fluid LossMud Check / Properties HTHP Fluid Loss


52/63

Problems With High HTHP FL: Stuck Pipe Formation Damage



53/63

HTHP Fluid Loss Procedure 350oF or Formation Temperature 500 psi differential Testing started after reaching test temperature Time: 30 minutes

Report: Total Filtrate collected times 2 Report Cake Thickness in 32nd inch

Water in Filtrate is Indication of Weak Emulsion


M dCh k/P ti HTHPFlidL


54/63

Mud Check / Properties HTHP Fluid Loss


< 3.0 mls at TD

The HTHP Fluid Loss is measured at 350oF 500 psidifferential pressure


55/63

Heat In Retort (+/- 900oF) Pass Vapor Through Condenser Collect Fluid In Graduated Cylinder Record On Mud Check

SF % by Volume Water % by Volume Solids % by Volume

Calculate SF/W Ratio and

Solids Analysis

Mud Check / Properties Composition AnalysisMud Check / Properties Composition Analysis

Water

Solids

Synthetic Fluid

MudCheck/PropertiesLowGravitySolids


56/63

Mud Check / Properties Low Gravity Solids


40 - 50 ppb

LGS to be maintained by efficient use of thecentrifuges. In most instances, this will require

continuous operation.

MudCheck/PropertiesElectricalStability


57/63

Mud Check / Properties Electrical Stability

The electrical stability is an indication of howtight the water is emulsified in the oil orsynthetic phase

MudCheck/PropertiesElectricalStability(Volts)


58/63

Mud Check / Properties Electrical Stability (Volts)

Oil and SF do not conduct electricity In the electrical stability test, the voltage (electricpotential) is increased across electrodes on a

fixed-width probe until the water dropletsconnect to form a continuous bridge This completes the circuit Record voltage at which the connection is made

M dCh k/P ti EltilStbilit


59/63


Factors Effecting ES Water Content Water-wet solids

Emulsion Strength (larger droplets, lower ES) Temperature (higher temp., lower ES) Salt Content (slight reduction in ES with high salt) Weight Material

MudCheck/PropertiesElectricalStability


60/63


The electricalstability of a oil- orSDF should be usedto indicate trends... UNOCAL SPEC:

> 500 volts


61/63

MudCheck/PropertiesCaClContent


62/63


35% By Wt.35% By Wt.

Mud Check / Properties CaCl2Content

Conclusion


63/63

Conclusion

Solids removal is one of the most importantSolids removal is one of the most importantaspects of mud system control.aspects of mud system control.

Solids and Relation to Fluids 2000

Documents

Transcript of Solids and Relation to Fluids 2000