Drilling Operations

(1)

(2)

Drilling operations

a) Overview of drilling plants, equipment, components

b) Overview of drilling fluids: muds, cements & chemicals

c) Outline of drilling techniques. Innovative vs traditional

drilling. On-shore & off-shore drilling

d) Blow –out prevention and control

e) Drilling site organisation

(3)

The main goal is to reach the target!

Original Well Path

Vertical well

Directional well

(4)

Sand

Shale

30" 20" 13 3/8" 9 5/8" 7" 0 m 2000 m 4000 m 6000 m

Sand + shale

Reservoir

dro

ca

rbo

n

(5)

(6)

(7)

(8)

(9)

Land rigs

Floating rigs

Swamp rigs

Stationary platforms

Drilling Rigs

(10)

(11)

(Dynamic positioning)

Drilling ship

Tension legs

(Anchored) drilling

ship

Semi sub rig

Jack up rig

Stationary Platform

100 m

1000 m

200 m

Off-shore Rigs

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

100 m

0 m

Surface Wellhead

Jack up rig

Off-shore Rigs

(27)

(28)

In legs-out position

Jack-up rig

(29)

Subsea Wellhead

Semisub rig

(30)

(31)

(Anchored)

Drilling ship

Subsea Wellhead

(32)

(Dynamic positioning)

Drilling ship

Subsea Wellhead

(33)

(34)

Max Water Depth

3000 + SHELL SHELL SHELL ELF TEXACO PETROBRAS SHELL SHELL EXXON EXXON EXXON HUMBLE OIL PETROBRAS SHELL PETROBRAS SHELL 2500 Expl. Prod. Subsea Tree TLP TotalFinaElf SHELL 2000 1500 500 1000 0 1980 1990 2000 2001

Off-shore Rigs

(35)

(36)

Ground Floor

N

O

A

G

B

C

F

D

E

H

_I

M

L

A) Asta motrice

B) Taglia mobile

C) Gancio

D) Piattaforma del pontista

E) Taglia fissa

F) Water table

G) Argano

H) Baracca del perforatore

I ) Testina d'iniezione

L) Rotary hose

M) Aste di perforazione

N) Tool joint

O) Torre

A) Top Drive

B) Mobile pulley block

C) Hook

D) Derrickman Floor

E) Fixed pulley block

F)

G)

Winch

H)

Driller’s cabin

I )

Injection head

Jacket hose

M)

Drill pipes

O)

Mast

Blow Out Preventer (BOP)

Wellhead

L )

N)

(37)

(38)

Kelly

Section

Bushing

Travelling block

Hook

Injection Head

Rotary

Hose

Drilling line

Kelly

The old rotary system comprises: kelly – kelly bushing – rotary table –

injection head – hook – travelling block

(39)

(40)

Drill Pipes

Heavy Weight (intermediate stiffness pipes)

X-over

Drill Collars (Heavy weight pipes)

Jar (Shock tool to be activated while drilling string stuck)

Drill Collars

Stabilizer (for hole reaming)

Drill Collar

Shock absorber (vibrations damper)

Stabilizer

Drill Collar

Near bit

Drill bit

(41)

9,5 m (31 ft)

3-joint drill

pipe stand

Drill pipe

28,5 m - (94 ft)

Drill pipe

Drilling String

(42)

(43)

PDC BITS

Matrix Body

Steel Body

(44)

NATURAL DIAMOND BITS

Nat. Diamond

Impregnated

(45)

(46)

Coil Tubing

• Coiled tubing can be used in

several

wellbore

operations:

perforating, fluid pumping, bridge

plug setting, etc.

• It allows to carry out operations

in a well while other operations

are performed in a second well

• It can also be used in the drilling

phase

(47)

(48)

Steel for drill pipes

Steels used for drill pipes are alloys of:

– Iron-carbon

– Manganese

– Silicon

– Molibden

– Nickel, etc…in different percentages.

In these alloys impurities must not exceed the following values:

0,060 % of sulphur

(49)

Material of drill pipe

TYPES OF STEEL

Minimum Yield Strength

psi

kg/mm

2

Common steel X_42

42000

29,52

Mud pipes X-52

52000

36,55

Tubular goods are classified according to the Minimum Yield Strength.

(50)

Pipe body and pipe joint

The drill pipes, are composed by :

Drill pipe body

Tool joint

• Drill pipe body

– Hollow cylindrical pipe with

upset at the end.

– Built using different tipes of

steel (E, X, G e S).

• Tool joint

– Box or pin end of the drill pipe:

– Build using 120000 steel type

(51)

Upset

• An upset is done at the two ends of the drill pipe body in order to

have higher thickness in the end part and therefore a gradual

change in section from drill pipe body to tool joint

(52)

Tool Joint

(53)

The connection of a drill pipe body and a

tool joint should be provided by:

FLASH WELDING

FRICTION WELDING

(54)

Types of a drill pipe inspections :

– Visual Inspection

– Magnaflux

– Penetrant Liquids

– Ultrasounds And Gamma Rays

(55)

PENETRANT LIQUIDS:

They enable the identification of discontinuities having an outlet to the surface.

Unlike the MAGNAFLUX method, with penetrant liquids it is possible to survey

discontinuities (cracks) also at high depth only with an outlet on the surface.

ULTRASOUND AND GAMMA RAY:

These nondestructive test methods are very effective. They are able to survey

not only the presence of discontinuities inside the drill pipe, but also its position

and extent. They also enable to verify the thickness and transversal section of

the drill pipe.

(56)

Heavy Weight Drill Pipes

The Heavy Weights are semi heavy drill pipes: something between DP and

DC (drill collar)

They have similar configuration to normal drill pipes. However, the tool

joints are much longer and have an upset in the centre, working as

stabilizer.

Both the tool joints and the centre upset are protected from wear by hard

facing bands.

(57)

Heavy Weights are normally installed between the drill pipes and

the drill collars to connect the flexibility of the drill pipes and the

stiffness of the drill collars, reducing the fatigue stress acting on the

last drill pipes, just above the DC.

HWDP are design to work also in compression: their positioning

above the DC enables the compensation of the shifting of the

neutral point during normal drilling.

Their function is providing weight to the bit, when the well

conditions require fewer drill collars.

In deviated wells characterized by high dip, they can be used

instead of DC.

They must work in tension when used in vertical wells with high

(58)

The drill collars (heavy drill pipes) are manufactured from a

solid bar, externally turned, internally bored and thread at its

ends.

(59)

Drill Collar

(60)

Drill Collar

They are produced in a wide range of dimensions

– Minimum external diameter:

2 7/8”

– Maximum external diameter:

14”

– Minimum internal diameter:

1”

(61)

(62)

• Containing formation fluids by exercising a hydrostatic pressure

at bottom hole

• Consolidating the borehole walls by creating a filter cake

• Cooling and lubricating the drill bit

• Conveying drilling debris from the bottom hole to the surface

• Keeping cuttings in suspension when circulation is halted

• Providing information on drilled formations

(63)

Mud is a two-phase compound:

- LIQUID PHASE

_{- SOLID PHASE}

• Fresh H

₂

O

• Salt H

₂

O

• Low Toxic OIL

• Sintetic OIL

Weigh-down materials

Solids incorporated in mud

(64)

- (inhibiting or non-inhibiting) WATER-BASED MUDS

- (direct or reverse-emulsion) OIL BASED MUDS

- AIR-CUT MUDS (seldom employed)

(65)

Control Formation Pressure: Density

• One of the main functions of drilling fluid is to keep the formation

pressure under control

• The pressure exerted by the mud column in static conditions

(without circulation) is called hydrostatic pressure.

• Hydrostatic pressure is the product of the mud weight and the

True Vertical Depth (TVD) of the well. If the hydrostatic pressure of

the column of drilling mud is equal to or higher than the formation

pressure, formation fluids can’t flow into the wellbore

(66)

Control Formation Pressure: Density

• Formation pressure typically increases with depth

• To compensate for this we increase the density of the mud with

barite

• Mud weight must be limited to the minimum necessary to control

the well, maintain its stability, and still stay below the fracture

gradient

(67)

• Mechanical and hydraulic energy generated by pumping mud to the bit, and

abrasion between the drill string

and the hole, produces a great amount of

heat

• Since the formation is a poor conductor the heat has no where to go

• Circulating fluid helps to dissipate this heat at surface

• Because of the composition of the mud, it has a lubricating effect which also

cuts down on the heat production. Indicators of poor lubrication are high

Circulation of the drilling fluids cools the bit and the drillstring

assembly, to temperatures lower than the bottom-hole

temperature

(68)

• Maximize penetration rate (ROP)

• Remove cuttings from under the bit and up to the surface

• Run downhole motors and other special equipment

• The hydraulic program is based on using the right diameter

nozzles in the bit, the pump’s efficiency, and choosing the

proper circulation pressures and rates for the hole conditions

Hydraulic Power is used to:

(69)

Mud chemicals store

Mixing hopper

Shale shaker

(70)

(71)

(72)

(73)

(74)

Original Well Path Corrected Well Path

Original Well

Sidetrack

Reservoir

(75)

(76)

Reservoir

(77)

(78)

Horizontal well

To increase well productivity

Vertical well

Why use horizontal drilling?

(79)

Long Radius

Medium Radius

Short Radius

Different types of horizontal wells

(80)

(81)

Bent Sub & Motor

Kick Off Sub (KOS)

Motor

Double Kick Off (DKO)

Motor

1/2° - 3°/100ft (30m) Large BOS No Surface Rotation 1/2° - 3°/100ft (30m) Smaller BOS No Surface Rotation ≤ 6°/100ft (30m) Large BOS No Surface Rotation Bent Sub Kick-Off Sub Double Kick-Off Sub

Downhole Motors

(82)

Rotating shaft

Non-rotating sleeve

Movable piston

(83)

AutoTrak Features

AUTOTRAK (for deviated wells)

Rotary Closed-Loop Drilling System

• It can change direction while rotating

• Expandable ribs create a side force on the bit, producing a controlled

closed loop with the MWD tool

(84)

Autotrak

Standard steerable

(85)

(86)

What is a “Casing” ?

• Casing is metallic pipe that is lowered in a

well in order to cover the open hole,

isolating it from the drilled formations.

• Once positioned at the desired depth,

casing is cemented in place by pumping a

slurry inside it. The slurry goes out of the

casing’s bottom, which is called “shoe”,

and rises in the casing/open hole annulus.

(87)

What is the casing function?

• To support the wellhead and the BOPs

• To allow mud circulation to the surface

• To isolate formations having different pore

pressure or fracture gradients

• To exclude formations that can cause

problems to drilling activities on account of

their geological characteristics

(88)

Different Types of Casing

• Conductor pipe

• Surface casing

• Intermediate casing

• Production casing

• Liner (a casing string that does

(89)

(90)

Why a cement should be use?

What is casing cementing?

Casing is cemented in place by pumping slurry in the open hole/casing

annulus. As the slurry solidifies, it acquires the necessary mechanical

resistances.

• To cement casing in place (single-stage or multi-stage operations)

• To run cement plugs (permanent abandonment, plugs to start a

sidetrack, isolation of depleted productive formations)

(91)

Manufacturing Portland Cement

The following reactions take place during the product baking stage:

100º C

evaporation of free water

600º C

dehydroxylation of clay minerals

900º C

crystallization of dehydroxylated clay minerals

900º - 1200º C

reactions between CaCO

₃

and CaCO with the

aluminiumsilicates

1250º - 1280º C start of the liquid phase

above 1280º C

the material becomes Clinker

(92)

The characteristics of a cement slurry can be altered depending on its

use. These characteristics can be summed up as follows:

1. Easy mixing and pumping.

2. Ideal rheological characteristics for the removal of the mud.

3. Rapid development of compressive strength.

4. Capacity to prevent the passage of gas.

5. Maintain a good level of compressive strength over time.

6. Capacity to fix to the surfaces.

7. Elasticity.

8. Capacity to maintain these characteristics at high temperatures.

(93)

Filling the annular space between the wall of an uncased hole and the casing is

the first operation after the bit has been run out of the hole and the casing has

been run in for the following reasons:

a) To support the casing and anchor it to the borehole wall.

b) To prevent the borehole from caving.

c) To protect the casing from corrosion.

d) To protect the casing from crushing or bursting.

e) To isolate adjacent zones of the borehole and prevent the different

formation fluids from mixing.

f) To extend and optimize the life of a well.

(94)

Cement slurries can be used in three types of jobs:

a) Cementing of casing or strings (primary)

b) Remedial or complementary cementing

c) Cement plugs.

(95)

Depending on the order, their position and purpose, casing

can be called:

a) Surface casing

b) Intermediate casing

c) Production casing

d) Liner

Casing Cementing

(96)

The normal dimensions of the casing or liner and in which open hole they are run in are

shown below; the dimensions are given in inches:

casing/ liner dimension

open hole dimension

(inches)

20”

26”

18 5/8”

24”

13 3/8”

17.5”

9 5/8”

12.25”

7”

8.5”

5”

6.5”

(97)

Types of casings



Conductor pipe



Surfaces



Intermediate



Production



Liner

(98)

YIELD

This is an important value on which the calculation of the final volumes, in

bottomhole conditions, depends. There are additives such as Sferelite whose

microsfers

tend to break under pressure and so undergo fluid invasion when

they are in the well, increasing the need for mixing water compared to the 0

pressure conditions on the surface.

It will therefore be the down hole yield, based on the volume of liquid cement

required for the job, which will therefore tell us the quantity of powdered cement

needed.

Yield is expressed in litres of slurry per 100 kg of cement, or in cubic feet per

sack.

For a class “G” cement without additives, these values are around 760 lt / 100

kg, or 1.15 cuft / sk.

(99)

THICKENING TIME

This is perhaps the most significant and closely examined value in a

lab report.

For a very good reason, because the Thickening Time (T.T.) is the

value which allows us to carry out the job in safe conditions.

Underestimating the time can result in disastrous cementing which

can even lead to the well having to be abandoned in the most serious

cases.

(100)

Main characteristics of cement slurry

RHEOLOGY (Fann Reading)

Cement slurry is classified as a “non Newtonian” fluid; i.e. a fluid whose viscosity is not

constant but varies with the speed at which it flows through a pipe.

Rheology measurements on slurry allow the characteristics of its flow to be predicted as well

as its capacity to suspend solids.

The PV (Plastic Viscosity) and YP (Yield Point) values can be obtained on the basis of the

apparent viscosity values, determined for example using a Fann Viscosimeter. These values

tell us to what extent a slurry is fluid and if it is able to transport solids and keep them in

suspension.

Moreover, the Flow Index (n’) and Consistency Index (K’) are obtained and allow us to

estimate the pressure loss caused by friction during the motion of the slurry and its flow type;

that is, if it movement is plug, laminar or turbulent.

(101)

(102)

Operational sequence of casing cementing

M

a

lt

a

M

a

lt

a

F

an

g

o

F

an

g

o

F

an

g

F

an

g

oo

F

an

g

o

F

an

g

o

1)Displacement of cement by a drilling

mud

1)Displacement of cement by a drilling

mud

2)The plugs are in contact and

displacement is completed.

Cement starts to solidify

2)The plugs are in contact and

displacement is completed.

Cement starts to solidify

The time needed the cement to set

at the end of displacement (WOC)

will vary according to the type of

used slurry

The time needed the cement to set

at the end of displacement (WOC)

will vary according to the type of

used slurry

(103)

What is the chemical composition of cement?

• Cement is a complex mixture of silicates and calcium aluminates.

Its grinding fineness determines its hydration capacity.

• A little difference in the chemical composition or in the physical

condition of cement can cause a strong performance variation.

• It is essential to perform lab tests before each operation, using

water, cement and additives samples obtained from the site

where the operation will take place.

(104)

(105)

• PARTIAL LOSSES

Absorption up to a maximum value of about 8 m3/h

• TOTAL LOSSES

Mud doesn’t return to the surface during drilling operations

Absorptions are caused by:

• High-porosity and high-permeability formations

• Fractured formations

• Underpressured formations

• Karst

(106)

(107)

Main stuck pipe causes are:

• Key seats

• Differential pressure (sticking)

• Wedging in (Packing off)

- While the drill string is being lowered

- While the drill string is being pulled out

• A collapse caused by:

- Total circulation loss

- Unstable formations

- Debris accumulation in caved-in boreholes

(108)

(109)

Drill pipes

Sticking Block

(110)

(111)

(112)

(113)

Underground

Blow-out

(114)

Gas

Migration

Charged formation

Underground Blow-out

(115)

Gas

Migration

Shear Rams (open)

(116)

Gas

Migration

Shear Rams (closed)

Fracturing below csg. shoe

(117)

Gas

Migration

Shear Rams (closed)

Initiation of

underground blow out

Underground Blow-out - 3

(118)

Well Capping

Techniques

(119)

Capping

1) Well Flowing

(120)

2) positioning BOP

= Valves Closed

Guide Line

Capping

(121)

3) Set Up Choke & Kill lines

Choke

Kill line

BOP open

= Valves Closed

(122)

4) opening Choke & Kill lines

= Valves Open

Choke line

Kill line

BOP open

(123)

5) Closing BOP

= Valves Open

Choke line

Kill line

BOP

closed

(124)

6) Gradual Closing of Choke e Kill lines (the well is in pressure)

Choke line

Kill line

BOP

closed

= Valves closed

(125)

7) Well Killing by pumping through kill line.

= Choke closed

Choke line

Kill line

BOP

closed

(126)

Bag Preventer

Double rams Preventer

Single ram Preventer

Drilling Spool

Used on land, offshore, jack-up,

tender rigs and stationary platforms

The BOP stack components are:

• Bag BOP

• Ram BOPs

• Drilling spool (optional)

• Choke valves

• Kill valves

They are usually built according to API

16 A standards.

(127)

(128)

(129)

Relief Well

Techniques

(130)

Reservoir

(131)

(132)

.

(133)

(134)

0 LOSS

GAIN

Suction Pit

Pit

Gain

Indicator placed on

the driller’s console

(135)

Drilling in an over

pressurized formation

Drilling in an over

pressurized formation

Gas

Causes of a kick

(136)

Blowout Control Systems

• Blowout control systems can be divided into:

• Primary (active): these are the systems that prevent the

occurrence of a blowout (i.e. hydrostatic load of a mud)

• Secondary (passive): all safety equipment contributes to

close a wellbore when a serious possibility of blowout exists

or when a blowout is already under way

• Blowout control systems can be divided into:

• Primary (active):

these are the systems that prevent the

occurrence of a blowout (i.e. hydrostatic load of a mud)

• Secondary (passive):

all safety equipment contributes to

close a wellbore when a serious possibility of blowout exists

or when a blowout is already under way

(137)

• Road transports

• Sea transports

• Communications

(138)

• This service provides logistical

assistance and transport of

materials in onshore operations

(139)

• The Supply Vessel Service provides logistical

assistance and transport of materials in offshore

operations

• The Helicopter Service provides in – out rig

personnel transport

(140)

The Communications Service allows data

transmission in the rig – operational district –

headquarters loop

(141)

(142)

Drilling Waste

•Drilling fluids

•Wash water

•Exhaust mud

•Drilling Cuttings

•Municipal solid wastes

Management And Cycle Of Drilling Waste

(143)

•Drilling waste from WBM (mud and

cuttings):

non-hazardous

•Drilling waste from OBM (mud and

cuttings):

hazardous

(144)

Operations priorities:

Reduction at source

Recycle – Re-use

Recovery

Treatment

Disposal

Waste

Reduction

Management And Cycle Of Drilling Waste

(145)

Guiding criteria

Waste volume reduction

Re-use of wash water

Storage by type

Use of dedicated corrals

(excluding shallow wells)

(146)

Disposal methods:

On-site treatment

Transport to treatment plant

(147)

(148)

Cuttings

Cuttings can be treated chemically, physically or

mechanically in order to separate or fix contaminants to reach

legal standards

• Consolidation/stabilization

• Thermal treatment

• Biodegradation

(149)

CORRAL

excavator

Consolidation and inertization

Sodium Silicate Cement Mixing conveyer pomp silos

Shale shakers

(150)

Thermal treatment of cuttings

The process consists of heating the cuttings to reach a water-oil

gaseous stage and subsequent condensation

low Temp 250° - 370° (oil recovery)

high Temp >900° (incinerator)

(151)

Biodegradation

A natural process where adapted microorganisms degrade

complex hydrocarbons to a more elementary chain that can be

easily reduced to environmentally acceptable Carbon

compounds

Operationally simple

Does not need special

equipment (farm equipment)

Does not generate a

(152)

Disposal methods:

•On-site treatment

Cuttings

Exhaust mud

Washing water

Dehydration

process

Water

Solid

Depuration

process

Landfill

Re-use

Re-use on rig

Waste water depuration plant

(153)

Dehydration

(154)

Discharge into the sea of

cuttings (OBM/WBM) and muds

(WBM)

Zero-discharge

and consequent

transport to shore of solid and

liquid waste (WBM - OBM)

•Up to 1987 :

•From 1987:

Off-shore disposal methods:

(155)

vibrovagl

Closed Loop System

Cuttings washer

Shale shakers

(156)

Cuttings slurrification and re-injection

Options :

-- Existing well (production well)

-- Drilling and re-injection simultaneously well

-- Dedicated well

(157)

Cuttings re-injection

cuttings

Exhaus drilling fluids

water

(158)

(159)

• Drilling debris

• Exhausted mud

• Washing H2O

• Intervention fluids

• Urban solid waste

(160)

Why to carry out a waste management ?

To reduce the environmental impact with respect to the

regulations in force

To maximize waste recycling (cement, brick and expanded

clay plants, environmental restoration, RSU dump covers)

(161)

How we can manage waste disposal?

ONSHORE :

_{OFFSHORE :}

• Zero discharge: solid and

liquid waste (WBM –

OBM) is transported

onshore

• Rig site treatment

(consolidation and

dehydration)

• Untreated waste disposal

• H2O recycling ( a closed-loop

system allows reduction of

waste volumes to be disposed

of by recovering water from

exhausted mud)