PROBLEMS RELATED TO DRILLING FLUIDS

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Feb 22, 2014 (3 years and 7 months ago)

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PROBLEMS RELATED TO DRILLING FLUIDS

钻井液相关问题

Chapter 8

Principles
of Drilling Fluids

钻井液工艺原理

Prof. Dr.
Xiuhua

Zheng

E
-
mail:
Xiuhuazh@cugb.edu.cn

Exploration
Dept. School of Engineering and Technology, China University of Geosciences(Beijing)

中国地质大学
(
北京
)
工程技术学院勘查教研室

Test for
§
7

1.
Water base
muds

2.
Subsurface formation pressures

3.
suspending agent

4.
weighting materials

5.
Thinners

6.
Fluid loss control

7.
Dispersed

8.
Non
-
Inhibited

9.
Inhibited

10.
Non
-
dispersed

1.
水基钻井液


地层压力


悬浮剂

4.
加重剂

5.
稀释剂


滤失控制


分散

8.
非抑制

9.
抑制

㄰1
不分散


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
3

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

Glossary of
§
8

1.
Diagenesis

2.
Water sensitive

3.
Sloughing/collapse

4.
Cation

Exchange Capacity

5.
Encapsulator

6.
Lubricants

7.
Penetration rate

8.
Loss Circulation

9.
Sticking

10.
Borehole stability

1.
成岩作用

2.
水敏性

3.
坍塌

4.
阳离子交换容量

5.
包被剂

6.
润滑剂

7.
机械钻速

8.
井漏

9.
卡钻

10.
井壁稳定


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
4

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

Contents


1.
Borehole stability
井壁稳定

2.

Loss Circulation
井漏

3.
Drilling String Sticking

卡钻



Drilling Fluids

2010
中国
地质大学
(
北京
)
page
5

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.

Borehole stability


Borehole

instability

is

a

result

of

complexity

of

actions

of

varied

factors
.

Unstable

formations

are

predominately

shale

formations

therefore

the

problem

of

borehole

instability

is

essentially

the

problem

of

shale
.


1.1 Cause of Borehole Instability

1.1.1 Inherent Mechanical Instable Formations


Some

formations

themselves

are

mechanically

instable

formations

because

the

characteristics

of

diagenesis
(
成岩
作用
)

a n d

g e o l o g i c a l
-
s t r u c t u r a l

m o v e m e n t s

in

their

sedimentation

process

manifest

as

sloughing,

falling,

collapsing

and

creeping

when

they

are

exposed

in

drilling

process
.

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
6

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.1.2
Water Sensitive Chemical
-
Physical Instable Formations (
理化敏感
†††
地层
)

† ††††††


Water

sensitive

chemical
-
physical

instable

formations

are

basically

shale

formations
.

The

instability

of

these

formations

derives

from

hydration

and

followed

swelling,

dispersion

and

disintegration

of

shale

when

it

is

in

contact

with

water
.

five

categories

of

shale

are

classified

as

shown

in

the

following

Table

(Table

1
-
1
)
.

Table

1
-
1

Classification

of

Shale










1.

Borehole stability

Type

Hard
-

ness

MBT

Meq/

100g

Water

Clay content, %

Type

%

(w)

%

(w)

Clay type

ρ

g/cm
3

Character

S

I

S
-
I

C

1

S

20
-
40

F&B

25
-
70

20
-
30

40.4

5.5

1.2
-
1.5

H.D

2

H

10
-
20

B

15
-
25

20
-
30

25.4

42.0

0.7

1.5
-
2.2

L.H.D

3

VH

3
-
10

B

5
-
15

20
-
30

38.3

13.0

2.2
-
2.5

M.D,T.O.S

4

EH

10
-
20

B

2
-
10

20
-
30

18.1

8.3

2.3
-
2.7

E.H.&B,T.O.D&C

5

B*

0
-
3

B

2
-
5

5
-
30

35.0

15.0

15.0

2.5
-
2.7

H,L.D,T.O.S

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
7

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1. Borehole stability


Where:


Clay type

S
-

Smectite
, I
-
Illite
, S
-
I
-

Smectite
, I
-
Illite
, C
-
Clorite


Hardness: S
-
Soft, H
-
Hard, VH
-
very hard, EX
-
Extreme hard, B
*
-
Brittle


Water type: F&B
-
Free & Bounded, B
-
Bounded


Character: H.D.
-
High
dispersable
, L.H.D
-
Less high
dispersable
,
M.D
-
Medium
disperable
, T.O.S
-
Tendency of sloughing, E.H.B
-
Extreme hard & brittle, T.O.D&C
-
Tendency of dispersion &collapse,
L.D
-
Less
disperable


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
8

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.1.3 Mechanically Induced Borehole
Instability(
力学原因诱发的井壁不稳定
)



Improper

drilling

technical
-
engineering

measures

very

often

provoke

borehole

instability

such

as
:



A
.

Lower

than

required

mud

density

can

not

create

an

adequate

hydrostatic

pressure

to

hold

varied

down
-
hole

pressures

in

balance

as

before

the

formations

are

not

drilled

out
.



B
.

Reduction

of

mud

column

height

by

pipe

pulling

out
.


C
.

Surge

or

swab

resulted

from

excessively

fast

pulling

or

lowering

of

drill

string

may

fracture

or

break

down

formations

and

result

in

loss

of

circulation

and

collapse
.


D
.

Collapse

as

consequences

of

uncontrolled

loss

of

circulation,

kicks

or

blowout
.



Drilling Fluids

2010
中国
地质大学
(
北京
)
page
9

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.1.3 Mechanically Induced Borehole
Instability(
力学原因诱发的井壁不稳定
)



E
.

Washout

and

erosion

of

borehole

wall

caused

by

turbulent

flow

or

long

time

circulation

against

an

interval

of

formations
.


F
.

Collapse

caused

by

collision

of

drill

pipe

on

"dog

leg"

or

on

segments

of

formations

with

sudden

change

of

inclination

or

orientation
.



Drilling Fluids

2010
中国
地质大学
(
北京
)
page
10

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.2 Indications and
Judgement

of
Borehold



Instability
(井壁不稳定的显示和判断
)

A.
Excessive cuttings on shale shakers and
detritus
(碎石)
† †
of
sloughing
or caving shale.

B.
Borehole packing
-
off and bottom filled up and abnormal
amount of cuttings, pump burst at starting or failure of pump
start after a trip in.

C.
Build
-
up of massive cutting beds manifested by trip lags
in defined intervals, difficulty, abnormal pressure or pump
burst at pump starting or sudden drill pipe reversion in drill
pipe running or reaming operations.

D.
Stuffed lower portion of dill collars and bit nuzzles by
cuttings.

E.
Excessively enlarged hole determined by caliper log.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
11

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.3 Obtaining stabilized Borehole and
Prevention of Instability


1.3.1 Get Knowledge on Instable Formations(
认识不稳定地层
)


Collect shale samples of varied intervals and conduct the
following tests:


X
-
ray diffraction for
petrographical
(
岩石
) and mineralogical analysis.


Cation

Exchange Capacity
test.


Water content.


Expansion test.


Dispersion and recovery test.


3
-
dimentional stress test(
三轴应力测试
).


Capillary Suction Time
(CST) test
(毛细管吸入时间测试)
.


Shale Stability Index or SSI test.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
12

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.3.2 Properly Determine and Adjust Mud
Density(
确定和调整钻井液密度
)




According

to

a

field

statistics,

80
-
90
%

of

cases

of

borehole

instability

were

provoked

directly

by

loss

of

mechanical

balance

of

borehole

pressures
.

so

do

not

raise

mud

density

too

fast

and

over

the

formation

fracturing

limit

in

order

to

avoid

irritation

of

loss

of

circulation

and

formation

break

down
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
13

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.3.3 Selection of Inhibitive Mud System and
Addition of Shale Inhibitive Agents

1.3.3.1 Shale inhibitive agents(
页岩稳定剂
)


†††
There

are
:

Polymer

encapsulator
(
包被剂
)

Inorganic

无机盐


inhibitors

or

electrolytes

Asphaltic

products

Cationic

polymers

and

so

on
.

1.3.3.2 Inhibitive drilling fluid systems(
抑制性钻井液体系
)


Calcium

base

mud

(lime

mud,

gypsum

mud)
.


Salt

water

mud
.


KC
1
-
PHPA

mud
.


Silicate

mud

or

organosilicon

mud
.


Glycol
-
polyglycol

mud

聚合醇钻井液

.



Formate

甲酸盐

mud
.


Oil

base

mud

and

W/O

invert

emulsion

drilling

fluid
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
14

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.3.3 Selection of Inhibitive Mud System and
Addition of Shale Inhibitive Agents

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
15

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.3.4 Proper Drilling Engineering Measures


适的钻井工艺)

1.
Control

drill

pipe

pulling

and

running

speed

to

avoid

excessive

surge

and

swab

caused

by

pipe

movement
.

2.
Apply

adequate

pump

rate

and

adjust

mud

rheological

properties

to

ensure

laminar

or

transitional

flow

pattern

过渡流型

and

reduce

borehole

mechanical

erosion
.

3.
Maintain

a

proper

gel

strength

and

start

pump

gently

to

avoid

excessive

surge

and

swab

pressures
.

4.
Control

pipe

rotation

speed

to

reduce

drill

pipe

collision

onto

borehole

wall
.

5.
Keep

a

full

borehole

by

pumping

mud

in

annulus

during

drill

pipe

pulling

process
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
16

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

1.4 Borehole Instability Remedial Procedure
(
井塌事故的处理
)



1.4.1 Un
-
aggravated Cases of Borehole Instability
(一般井塌
)

†††
Abnormal

amount

of

sloughing

and

caving

shale

on

shakers

excessive

torque

and

drag

on

trips

or

connections
.

1
.
4
.
2

Severe

Cases

of

Borehole

Instability

严重井塌



When

severe

cases

of

borehole

instability

occur,

the

phenomena

as

aggravated

torque

and

drag

or

sudden

reverse

on

connections

and

trips,

abnormal

difficulty

of

pump

starting

or

pump

burst,

no

progress

of

reaming,

stuffing

of

bit

nozzles

or

lower

portion

of

drill

collars

by

cuttings,

sudden

abnormal

pressure

build

up

or

sudden

stuck

drill

pipe

may

be

encountered
.

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
17

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2. Loss Circulation
(井漏)


2.1 Causes and Types of Loss of Circulation(
井漏的原因和类型
)


T
here

are
:

Seepage

Loss

渗透性漏失



Natural

Fissure

裂缝

and

Cavern

Loss

空洞性漏失



Induced

Fracture

Loss


2.1.1 Seepage Loss
(渗透性漏失)


A

Causes
:

Seepage

loss

occurs

naturally

under

normal

drilling

conditions

in

formations

with

permeability

higher

than

14

D

such

as

unconsolidated

sands,

massive

coarse

sandstones,

gravels

or

reef

deposits

礁石沉积层



B

indications
:

Seepage

loss

appears

generally

as

repeated

or

successive

losses

with

a

relatively

low

rate

in

range

of

tens

of

barrels

per

hour

and

in

most

cases

no

evident

pump

pressure

drop

shows
.















Drilling Fluids

2010
中国
地质大学
(
北京
)
page
18

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.1 Causes and Types of Loss of
Circulation(
井漏的原因和类型
)


2.1.2 Natural
Fissure
(裂缝)
and
Cavern Loss
(空洞性漏失)




A

Causes
:

This

kind

of

loss

of

circulation

occurs

in

carbonate

石灰


,

dolomite

and

chalk


白云岩

formations

with

fissures

and

caverns,

faulted

formations,

discordant

formation

faces,

shatter

belts,

fractured

zones

and

eruptive

cavernous

and

vugular

formations
.




B

Indications
:

Sudden

and

severe

loss

of

circulation

without

return

and

loss

rate

may

reach

couple

to

hundreds

of

barrels

per

hour

very

often

accompanied

by

sudden

erratic

rates

of

penetration

or

drilling

break
.



Drilling Fluids

2010
中国
地质大学
(
北京
)
page
19

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.1 Causes and Types of Loss of
Circulation(
井漏的原因和类型
)

2.1.3 Induced Fracture Loss


A
.

Causes
:

This

kind

of

loss

of

circulation

occurs

when

formations

are

fractured

by

improper

engineering

operations

such

as

overweighted

mud

introduction,

excessively

fast

lowering

of

drill

string

or

brute

pump

starting
.



B
.

Indications
:

Depending

on

the

magnitude

of

fracture

induction

pressure

and

strength

of

formations,

the

rate

of

loss

is

quite

different

and

some

time,

loss

rate

can

be

hundreds

of

barrels

per

hour

or

even

greater
.


C
.

When

pressure

in

the

borehole

is

raised

to

a

certain

value,

it

may

cause

the

formation

to

be

fractured

and

begin

to

absorb

a

great

mass

of

drilling

fluid

from

well

bore
.

The

hydrostatic

pressure

in

borehole

of

this

case

is

right

equal

to

the

formation

fracture

pressure
.

The

procedure

is

as

follows

fig

2
-
1


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
20

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.1 Causes and Types of Loss of
Circulation(
井漏的原因和类型
)

Fig. 2
-
1. Fracturing test of curve

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
21

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.1 Causes and Types of Loss of
Circulation(
井漏的原因和类型
)

2.1.4 Hydrostatic Pressure of Drilling Fluid Column


The

hydrostatic

pressure

of

drilling

fluid

is

the

pressure

of

drilling

fluid

column

in

static

state

exerted

on

the

bottom

of

the

well
.




2
-
1




Where

:



P

--
Hydrostatic

pressure,

psi,


--
Drilling

fluid

density

in

well

bore,

lb/gal,


H
--
True

vertical

depth

of

the

well,

ft
.








052
.
0

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
22

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.2 Prevention of Loss of Circulation
(
井漏的预防
)


The

following

measures

can

be

taken

for

prevention

of

loss

of

circulation
:


1
.
Carefully

collect

and

analyze

the

regional

geological

information

and

properly

design

casing

program

and

mud

density

in

different

intervals

of

a

well
;



2
.
Reduce

surge

and

swab

pressures
;


3
.

Lower

and

pull

drill

string

in

a

gentle

way,

and

so

on
.


4
.
Add

a

certain

amount

and

proper

type

of

LCM

according

to

the

formation

nature

and

mud

properties
.


5
.

Weight

mud

to

the

required

density

in

several

circulating

circles

and

conduct

pressure

control

procedure

as

required

right

away

when

abnormal

pressure

formations

are

encountered
.

And

so

on





Drilling Fluids

2010
中国
地质大学
(
北京
)
page
23

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3 Remedial Measures for Loss of
Circulation
(井漏的处理)


2.3.1 Seepage Loss


If

pump

pressure

decreases,

and

reduced

flow

rate

in

flow
-
line

and

drop

of

level

in

mud

tanks

are

observed

during

drilling

process,

it

means

seepage

loss

of

circulation

occurs
.

We

must

take

measure

as

follows
:


1
.

Stop

pump

for

observation


2
.

Add

some

viscosifiers

such

as

lime,

CMC,

PAC,

MMH,

XC,

and

so

on
.


3
.

reduced

pump

rate

and

lowered

penetration

rate

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
24

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3.2 Partial Loss


One

of

the

following

measures

can

be

taken

based

on

the

specific

conditions
:


1
.

Add

some

viscosifiers

and

LCM

of

different

shapes

and

sizes
.


2
.

Pump

a

pill

of

thick

mud

mixed

with

30
-
40

lb/bbl

LCM

of

varied

shapes

and

sizes

against

the

loss

interval
.


3
.

Squeeze

a

high

filtration

barite
-
diatomite

slurry

into

the

loss

zone

at

a

lowered

rate
.

The

formulation

of

barite
-
diatomite

slurry

is

shown

in

the

following

table

(Table

2
-
2
)
.






Drilling Fluids

2010
中国
地质大学
(
北京
)
page
25

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3.2 Partial Loss






Table 2
-
2 Formulation of P reparation of 1 bbl
Bentonite
-
Diatomite Slurry




Drilling Fluids

2010
中国
地质大学
(
北京
)
page
26

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3.3 Loss of Circulation without Return



A
.

Squeeze

and

set

cement

or

soft

plug

slurries
.


Extensively

used

plug

slurries

are

quick

setting

bentonite
-
cement,

diesel
-
bentonite
,

lime
-
bentonite

plug

and

quick

setting

cement

slurries(
纯水泥浆
)
.



Table

2
-
3

Formulation

of

Quick

Setting

Bentonite
-
Cement

Slurry







Drilling Fluids

2010
中国
地质大学
(
北京
)
page
27

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3.3 Loss of Circulation without Return


Table 2
-
4 Formulation of Diesel
-
Bentonite

Slurry







Table 2
-
5 Formulation of Diesel
-
Bentonite

Slurry





Drilling Fluids

2010
中国
地质大学
(
北京
)
page
28

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

2.3.3 Loss of Circulation without Return





B
.

Drill

blind

without

return

and

attempt

to

cure

the

loss

by

plugging

effect

of

cuttings
.




C
.

Change

to

drilling

with

foam,

mist

or

air
.




D
.

Introduce

casing

to

seal

the

loss

zone,

this

is

the

most

safe

and

certain

measure
.

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
29

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3. Drilling String Sticking
(卡钻
)



Drill

string

sticking

can

be

divided

into

the

following

types
:

differential

pressure

sticking,

cutting

precipitation

sticking,

cutting

bridge

sticking,

formation

collapse

sticking,

tight

hole

sticking,

key
-
seat

sticking

and

falling

object

sticking
.


3
.
1

Differential

Pressure

Sticking


When

a

section

of

drill

string

stays

in

contact

with

borehole

wall

of

a

permeable

formation

for

a

interval

of

time,

the

string

may

be

pressed

tightly

into

the

wall

and

the

driving

power

on

the

string

can

not

overcome

the

friction

and

adhesion

of

the

string

on

the

wall

surface

and

the

string

can't

be

moved

(pulled

up,

lowered

down

or

rotated)

under

the

differential

pressure

between

the

mud

hydrostatic

pressure

and

the

formation

pressure
--
a

differential

pressure

sticking

occurs


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
30

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

Fig 3
-
1

Differential pressure
sticking mechanism

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
31

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.1.2 Prevention Measures



1. Apply a reasonably lower mud density.



2. Select adequate drilling fluid system.



3
.

Move

drill

string

accordingly

in

process

of

mud

circulation

and

equipment

repairs




4
.

Add

some

mud

lubricants

to

improve

lubrication

character

of

mud

and

mud

cake
.

The

lubricity

of

different

lubricants

and

drilling

fluid

systems

are

listed

in

the

following

tables

(Table

3
-
2
,

Table

3
-
3
)
.




Drilling Fluids

2010
中国
地质大学
(
北京
)
page
32

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.1.2 Prevention Measures

Table 3
-
2 Comparison of Various Mud Lubricants


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
33

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.1.2 Prevention Measures

Table 3
-
3 Lubrication Coefficient of Different Types of Drilling
Fluids

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
34

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.1.3 Spotting for Stuck Pipe Release



The

effective

procedure

for

releasing

the

stuck

pipe

is

submersing

the

stuck

interval

of

the

drill

string

by

spotting

fluid
.

Formulation

of

oil

base

spotting

fluid

can

be

seen

in

the

following

table

(Table

3
-
4
)


Table 3
-
4 Formulations of Oil Bade Spotting Fluids




Drilling Fluids

2010
中国
地质大学
(
北京
)
page
35

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.2 Cutting Precipitation Sticking and Cutting
Bridge Sticking(
沉砂卡钻和砂桥卡钻
)

3.2.1 Causes and Indications


1.
Cutting precipitation sticking


Precipitation

of

abundance

of

cuttings

onto

bottom

may

cause

stuck

pipe

when

pump

is

suddenly

stopped

since

low

mud

viscosity

and

gel

strength

and

severe

accumulation

of

cuttings

in

annulus

resulted

from

excessively

high

penetration

rate

and

poor

mud

suspension

capacity
.

On

the

other

hand,

the

bit

may

intrude

into

cuttings

precipitated

on

bottom

and

stuck

pipe

may

occur

at

pipe

connections
.


2.
Cutting bridge sticking


Cutting

bridge

may

be

built

up

in

borehole

steps

formed

by

presence

of

a

series

of

alternations

of

soft

swelling

shale

formations

overlapped

by

sloughing

shale

formations
.

If

pipe

lowering

is

too

fast,

the

bit

may

intrude

into

the

cutting

bridge

and

it

results

in

cutting

bridge

sticking
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
36

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.2.2 Prevention Measures



1.

Maintain good mud
rheological

properties


2. Control penetration rate in soft formations,


3. Remove drill cuttings on time and maintain borehole
and bottom clean by application of proper annular
hydraulics

and running solid control equipment.


4. Gently lower the drill string while vigilantly watch pump
pressure gauge and weight indicator.


5. Avoid long
-
term circulation with bit unmoved against
an interval of hole in order to eliminate borehole erosion.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
37

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.3 Formation Collapse Sticking(
缩径卡钻
)



3.3.1 Causes and Indications


Formation

collapse

sticking

is

caused

mainly

by

sudden

formation

collapses

that

result

from

surge

or

swab

provoked

by

rude

pipe

pulling,

lowering

or

collision

of

drill

string

on

borehole

wall

or

improper

starting

of

pump
.


3.3.2 Prevention and Remedy


The

principal

manners

for

prevention

of

formation

collapse

sticking

are

enhancing

borehole

stability

by

raising

mud

inhibition

and

avoiding

surge

and

swab

caused

by

pump

starting

and

pipe

movement
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
38

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.4 Salt Creeping and Tight Hole Sticking
(岩盐层塑性蠕动缩径卡钻)



3.4.1 Causes and Indications


When

a

rock

salt

formation

is

drilled

out,

it

will

expand

or

creep

continuously

into

borehole

as

a

plastic

object

under

the

over
-
burden

pressure

of

the

formations

above

and

cause

trip

difficulty,

or

even

worse,

it

may

result

in

sticking



3.4.2 Prevention and Remedy


The

creeping

of

rock

salt

and

the

related

down

hole

troubles

can

be

resolved

only

by

raising

mud

density

and

borehole

hydrostatic

pressure

to

balance

the

overburden

pressure,

usually

the

mud

density

must

reach

2
.
40

g/cm
3

or

more
.

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
39

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.5 Key Seating Sticking
(键槽卡钻)





The

key

seating

sticking

is

originated

from

inserting

of

drill

string

into

a

key

seat

in

an

interval

of

formation
.

It

is

not

related

to

drilling

fluid

and

is

characterized

by

sudden

occurrence

with

normal

circulation

pressure

as

before

and

without

an

abnormal

amount

of

sloughed

or

collapsed

shale

on

shakers
.

Drilling Fluids

2010
中国
地质大学
(
北京
)
page
40

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

3.6 Falling Object Sticking(
落物卡钻
)






Failing

object

sticking

is

provoked

by

falling

objects

such

as

bit

cones

or

some

pieces

of

manual

tools

or

other

equipment

into

borehole

and

it

is

characterized

by

no

observation

of

rising

of

pump

pressure

and

absence

of

excessive

cuttings

on

shakers
.


Drilling Fluids

2010
中国
地质大学
(
北京
)
page
41

China
University of Geosciences (Beijing)



§
8

Problems related to the drilling fluids

Discussion


The concepts of hole stability, lost
circulation, Sticking pipe and the
Effects of drilling fluids them.