COSL-CS-001 Introduction to Offshore Oil Industry.pdf

Part 1: Introduction to Offshore Oil Industry
u The proven reserves of offshore oil are about 38 billion tons；
u Offshore accounts for 34% of the world's total oil resources;
u More than 50 countries are exploring Oil & Gas in deepwater.
Introduction
Oil & gas distribution of the world
34%
66%
Offshore Onshore

Introduction
Mexico
56 billion barrel
Brazil
>260 billion barrel
Middle west africa
>58 billion barrel
Norway
3.1 billion barrel
Atlantic
u 44% of offshore oil resources distribute in deepwater areas.
u In recent years, oil and gas discoveries in the deep water areas of the Atlantic region are 70% in
all findings.
Deepwater oil and gas operations are the future of oil development!

Classification
500m(1640 ft) 1,500m(4921 ft)
Shallow Water Deepwater Ultra Deepwater

Characteristics - High Technology Requirements
The Building of Rig Huizhou-21B.
u Compared to onshore drilling, offshore drilling faces subsea challenges, requiring specialized equipment
and more complex technology during the rig building and operation process.
u Underwater construction is characterized by high technical requirements and high cost.
u Subsea equipment, Subsea wellhead, Conductor casings.

Characteristics - Large Investment
HYSY981
u Height: 136m/447ft
u Weight: 30,000tons
u Maximum operation water depth: 3,000m/9,852ft
u Maximum drilling depth: 10,000m/32,841ft
u Total investment：1 billion USD
u Daily rental cost: More than 400 KUSD/day

Characteristics - High Risk
The BP blowout in Gulf of Mexico in April, 2010:
u Rig: Deepwater Horizon (one of the most advanced rigs in
2010)
u Total investment：350 million USD
u Maximum operation water depth: 3000m/9,852ft
u Location of the accident: Bloc MC252 in Macondo, GOM
Disastrous Consequence
u 11 killed, 17 injured；
u 4.9 million barrels’ of oil spilled；
u 2,500 Km2 of water polluted by oil；
u Ecological disaster；
u BP was fined $20.8 billion.

Oil Development Process
u Geophysical Exploration：to locate the oil and gas.
u Drilling Operation: to establish oil and gas production channels.
u Production & Processing: to produce and process oil and gas.
Geophysical Exploration Drilling Operation
stratigraphic section
Cables

Oil Development Process
Production & Processing

Questions
u What is the classifications of shallow water, deepwater or ultra deepwater?
u What is the characteristics of offshore oil drilling?
u What is the basic oil development process?

Questions
u What is the classifications of shallow water, deepwater or ultra deepwater?
l Shallow water: ＜500m(1640 ft)
l Deepwater: 500-1500m(1640 ft-4921ft)
l Ultra deep water: ＞1500m(4921 ft)
u What is the characteristics of offshore oil drilling?
l High Technology Requirements
l Large Investment
l High Risk
u What is the basic oil development process?
l Geophysical Exploration: to locate the oil and gas.
l Drilling Operation: to establish oil and gas production channels.
l Production & Processing: to produce and process oil and gas.

Part 2: Geophysical Exploration
Procedure
1. Send artificial sound
waves underground by
geophysical vessel;
2. Receive and analyze
the reflected waves
from different
formations;
3. Deduce the distribution
of formations;
4. Deduce the distribution
of oil and gas
resources.
Geophysical Exploration
Cymoscope
Hypocenter
Geophysical vessel
Principles of offshore seismic exploration
u Geophysical exploration refers to the research and observation of various geophysical field changes to
detect the formation of lithology, geological structure and other geological conditions.

Geophysical Vessel HYSY 720
12×8000m cables
The most advanced and most capable
geophysical exploration ship in Asia
Sound generator
Buoy
Cable
Seismic ships and long cables towed

Part 3: Drilling Operation
Introduction to Drilling
u Drilling operation is the most important measure in the exploration and
development of oil and gas resources.
u Worldwide, drilling accounts for more than 50% of investment in exploration
and field development.
u Drilling operation technical services generally include
• Drilling (Directional Drilling & Measurement / Logging While Drilling)
• Drilling fluid
• Cementing
• Well completion
• Other operations
u Classification of drilling operations
l By drilling methods: Conventional drilling, special technology drilling
(directional drilling, underbalanced drilling, etc.).
l By drilling purpose: Exploration well, development well.

Drilling Rig
u Drilling rigs are offshore structures
primarily used to drill Wells.
u Rig is equipped with
l Drilling equipment
l Power
l Communication
l Navigation
l Other equipment (safety and life
saving facilities, personnel living
facilities).
u Rig is an indispensable means for
offshore oil and gas exploration and
development.

Drilling rig
Differences between onshore rig and offshore rig
u How to raise the derrick smoothly above the water.
u How to withstand the environment of waves.
u How to link a subsea wellhead at seabed to drilling equipment at rotary table.
Rig onshore Rig offshore
u Subsea equipment
u Subsea wellhead
u Conductor casings
1. Rig 2. Conductor 3-5. BOP

Drilling rig
Drilling rig components

Drilling rig
Semi-submersible drilling rig
Jack-up drilling rig
Fixed drilling rig
Jacket
Drilling
equipment
Classifications of drilling rig in offshore

Drilling rig
Fixed drilling rig
Jacket
Drilling
equipment
Classifications: 1. Fixed drilling rig
u A device that is fixed on the seabed, with the help
of a pipe frame and cannot move freely.
u The deck is laid on the platform for the placement
of drilling equipment.
u The pile legs supporting the fixed platform are
driven directly into the seabed.
u Stability of the drilling platform is good, but the
platform cannot move, lead to a high cost.
u Fixed drilling rig is seldomly used now.

Drilling rig
Jack-up drilling rig
Classifications: 2. Jack-up drilling rig
u Composed of platform, pile leg, lifting mechanism.
u Can rise and fall along the pile leg, but has no self-navigation ability.
u When working,
• Pile legs be lowered into seabed;
• Platform be lifted to a safe working height away from the sea level;
• Pile legs be preloaded to ensure that the platform does not sag during
drilling operations.
u After the completion of the well,
• Platform be lowered to the sea level;
• Pile legs be pulled out and lifted, and platform floats to the surface;
• Platform be towed by the tow wheel to the new well position.
u With the advantages of mobility and reuse, it becomes one of the
most widely used types of drilling rigs.

Drilling rig
u Jack-up drilling rig can not work in deepwater drilling.
Classifications: 2. Jack-up drilling rig
Towage of jack-up drilling platform
HYSY 944
Max. working water depth: 122m

Drilling rig
Semi-submersible drilling rig
Classifications: 3. Semi-submersible drilling rig
u The upper part is work deck, the lower parts are two lower
hulls, connected by support columns.
u When working, the hull is submerged into water, and the
deck is at a safe height on the water.
u Characteristics:
• Small water line area, small wave effect, good stability;
• Strong self-sustaining force with anchors;
• Deepwater.
u Compared with jack-up drilling rig,
• Advantages: deepwater for some rigs, flexible
movement;
• Disadvantages: Large investment, high maintenance
costs, need for a complex set of subsea vehicles.

Drilling rig
NANHAI 2
Max. working water depth:
304m/1,000ft
Prospector
1,500m/4,926ft
HYSY 981
3,000m/9,852ft
Classifications: 3. Semi-submersible drilling rig
u Semi-submersible drilling rig can work in deepwater with depths ＞3,000m/9,852ft.

Drilling rig
Classifications: 4. Drilling Ship
u Drilling ship is a floating drilling platform on which
drilling equipment is mounted.
u Advantages:
• Good mobility;
• Deepwater;
• Strong self-sustaining force;
• Large storage capacity.
Disadvantages:
• Sensitive to waves, poor stability;
• Small deck area;
• Hig cost
WEST AURIGA
u Height: 228m/749ft
u Weight: 60,554tons
u Maximum operation water depth: 3,600m/12,000ft
u Total investment：1.24 billion USD
u Daily rent fees: Mote than 500 KUSD/day

Main Operations - 1. Drilling
u Drilling is to penetrate the formation into a certain depth with a number of different casing strings by
using rigs.

Main Operations - 2. Drilling fluid
u Drilling fluid, also known as mud, is a
circulating fluid that can meet the needs of
drilling operation.
u Its main role is to clean the wellbore, balance
formation pressure, transfer the geological
information of the drilled formation to surface,
and break rock hydraulically, etc.

Main Operations - 2. Drilling fluid
Ø Hole cleaning
Remove the drilled cuttings from the hole & suspend the cuttings when circulation is
stopped.
Ø Pressure Control
Maintain BHP (hydrostatic Bottom Hole Pressure) greater than formation pressure to
prevent formation fluids from entering the wellbore.
Ø Cooling & Lubricating
Cool and lubricate the bit and drill pipe.
Ø Borehole stability
Improve the borehole stability, prevent the walls of the hole from caving or collapsing.
Ø Formation Protecting
Prevent or minimize the damaging effects to the reservoir (chemical and physical
interactions).
Ø Mudlogging
Assist in the gathering of the information from the formations.
Functions of
Drilling Fluid

Main Operations - 3. Cementing
u Cementing is an operation of running casing into the wellbore and
placing working fluid (cement slurry) into the annular space between the
wellbore and casing.
u It is an key part of the drilling and completion process.
u A conventional cementing job Including two processes: running casing
and pumping cement slurry.
Casing
Cement
Formation
Displacing process of cementing

Rig
Mud line
Sea level
Conductor
Surface
casing
Intermediate
casing
cement
Liner
Production casing
u Conductor
The first and shortest casing string, serves as a conduit to
raise the circulating drilling fluid high enough to return to
the mud system.
u Surface casing
The second string of casing, serves to case off relatively
shallow unconsolidated formations and aquifers.
u Intermediate casing or intermediate liner
The casing string running between surface casing and
production casing. It usually helps to seal off shallower
producing zones, allowing the operator to drill deeper.
u Production casing or production liner
Can be the last tubular element cemented in the well. It
creates an annular space with production tubing and
isolates different zones above and within the production
zone.

Objectives of Cementing
u Isolate complex formations with collapse or loss, consolidate the drilled hole.
u Provide the basis for the installation of the wellhead device.
u Isolate oil, gas and water layer, prevent channeling of different layers, provide good conditions for the
test and exploitation of oil and gas.
u Protect the fresh water in the upper formation from being contaminated by oil, gas, brine and other fluids
in the deeper formations.
u During the development stage, provide good conditions for stimulation operations like acidizing and
fracturing.

Main Operations - 4. Well Completion
u Well completions is the installation of a downhole pipe and
related equipment so that oil and gas can be efficiently and
safely extracted from a well.
u Well completion refers to everything that takes place in a well
between the end of the drilling process and the moment when a
well is put into production.
u Well completion is the last operation of drilling operation and
the beginning of oil production engineering.
u It is closely related to oil production, water injection and the
development of the entire oil and gas field.
u The quality of oil well completion directly affects the production
capacity and economic life of production wells, and even relates
to the reasonable development of the entire oil field.
u There are three main objectives in the completion process.
l Allow oil or gas into the well so that it can be brought to the surface;
l Minimise water coming into the well or water production;
l Minimise the production of sands.

u Different wells reuiqre different completions. Deciding what to do depends on a number of factors,
including:
l size and shape of the oil reservoir；
l Surroundings of the reservoir;
l Types of rock and oil.
u Two regular types of well completion methods:
l Cased hole completion:
ü Run production liner or casing, cemented, perforated.
l Open-hole completion
ü Barefoot completion
ü Slotted liner completion
ü Screen liner completion
ü Gravel packed completion

Cased Hole Completion
u Cased hole completions, or liner completions, or perforation
completions, is casing or liner run and cemented across the reservoir
zone, then connect the wellbore and reservoir by perforation.
u The perforation gun shoots through the casing, cement ring
and reservoir into a certain depth in the reservoir to form a
passageway for oil and gas to enter the wellbore.
u In this operation, perforations are the only passageway for oil
and gas.
Application criteria:
u Fractured reservoir.
u Reservoirs with gas cap, water drive, aquifer interlayer, and
collapsible interlayer which require to be isolated.
u Various reservoirs with different properties.
u Low permeability reservoirs requiring large-scale hydraulic
fracturing operations.
Surface casing
Production casing
Cement shealth
Perforated hole
Production zone

Open Hole Completion: 1. Barefoot Completion
A completion method of setting production casing to the top of the production zone, and let the production
zone fully exposed.
Production
casing
Cement
sheath
Surface
casing
Application Criteria:
u Formation Lithology is intact.
u Wellbore with no collapse.
u Normally be used in carbonate rock, hard
sandstone, well cemented and relatively
simple horizontal oil layer.
Addvantages:
u Large exposed area of the production layer.
u Small resistance of oil and gas flow into the
well.

Open Hole Completion: 2. Slotted liner Completion
u During completion, a liner is run into the open-hole, and will pass through the production layer to protect
unstable formation.
u In the liner, long slits or holes are used to allow oil and gas from the layer to flow to the bottom of the well.
Application Conditions:
u Reservoirs without gas cap, water drive, aquifer
interlayer, and collapsible interlayer.
u Reservoirs not produced separately with individual
layers and no plan for selective treatments.
u Relatively loose reservoirs, medium coarse
sandstone.
u Single thick reservoir with homogeneous properties,
or various reservoirs with similar properties.

Open Hole Completion: 3. Gravel Packed Completion
u A completion method in which a specified size and amount of gravel is packed between liner and wellbore.
Application Conditions:
u Reservoirs without gas cap, water drive, aquifer interlayer, and
collapsible interlayer.
u Reservoirs not produced with individual layers and no plan for
selective treatment.
u Relatively loose reservoirs with serious sanding problem,
medium, coarse and fine sandstone.
u Single thick reservoir with homogeneous properties, or various
reservoirs with similar properties.
Open hole Gravel Packing

Open Hole Completion: 4. Screen Liner Completion
u Screen liner completions is similar to the slotted liner completion,
a screen liner is run into the open-hole.
u A screen liner is set in the open hole section of the wellbore.
Application Criteria
u The screen liner completion is used primarily in unconsolidated
formations to prevent the movement of formation
materials(Sands, etc.) into the wellbore, restricting the flow of
reservoir fluids.

Questions
u The classifications of drilling rigs and their characteristics?
u The main functions of drilling?
u The main functions of drilling fluid?
u The main functions of cementing?
u The main functions and classifications of well completion?

Questions
u The classifications of drilling rigs and their characteristics?
l Fixed drilling rig
l Jack-up drilling rig
l Semi-submersible drilling rig
l Drilling ship
u The main functions of drilling?
l Penetrate the formation into a certain depth
u The main functions of drilling fluid?
l Hole cleaning
l Pressure Control
l Borehole stability
l Formation Protecting
l Mudlogging

Questions
u The main functions of cementing?
l Isolate complex formations with collapse or loss, consolidate the drilled hole.
l Provide the basis for the installation of the wellhead device.
l Isolate oil, gas and water layer, prevent channeling of different layers, provide good conditions for the test and
exploitation of oil and gas.
l Protect the fresh water in the upper formation from being contaminated by oil, gas, brine and other fluids in the
deeper formations.
l During the development stage, provide good conditions for stimulation operations like acidizing and fracturing.
u The main functions and classifications of well completion?
Functions
l Allow oil or gas into the well so that it can be brought to the surface;
l Minimise water coming into the well or water production;
l Minimise the production of sands.
Classifications：
l Cased hole completion:
l Open-hole completion。

Part 4: Production & Processing
Introduction
Fixed production process
Wellhead
platform
Production and
processing platform
To land
Oil and gas production refers to
u Extraction of oil and gas from oil and gas reservoirs to surface;
u Collection, transportation, processing, on-site storage;
u Mine management in the mining area.
Production & Processing Methods
u Fixed Production Platform;
u Floating production storage offloading (FPSO);
u Semi-submersible production, storage and unloading platform.

Model 1: Fixed Production Platform
Fixed production process
Wellhead
platform
Production and
processing platform
To land
Production at sea
Processing on land
u Characteristics:
Production at sea + Processing on land
u Applicable conditions:
l Oil field is closer to the coast;
l Large area, high output of oil;
l Pipeline laid under the sea.

Model 2: Floating production storage offloading (FPSO)
u Characteristics:
Production at sea + Processing at sea
l Oil field is far away from coast;
l In deeperwater.
Wellhead platform FPSO
Mooring tower
FPSO HYSY 118
Max. processing capacity: 9000m3/day

Model 3: Floating Production Storage Offloading (FPSO)
u Characteristics:
Subsea Production + Processing at sea
u Applicable criteria:
l Oilfield is far away from coast;
l Water depth ＞300m/985ft.

Model 4: Semi-submersible production, storage and unloading platform
u Characteristics:
Subsea Production + Processing at sea, better stability
l Oilfield is far away from coast;
l Water depth ＞300m/985ft.
SHENHAI 1(Build in Jun. 2021)
Max. workding water depth: 1500m/4926ft
The world's first 100,000-ton deepwater semi-submersible production, storage and
offloading platform
DEEPWATER 1

Questions
u The main methods of production and processing?
u The characteristics of each method?

Questions
u The main methods of production and processing?
l Fixed Production Platform;
l Floating production storage offloading (FPSO);
l Semi-submersible production, storage and unloading platform.
u The characteristics of each method?
l Fixed Production Platform: Production at sea + Processing on land;
l Floating production storage offloading (FPSO):Production at sea + Processing at sea, Subsea
Production + Processing at sea;
l Semi-submersible production, storage and unloading platform: Subsea Production + Processing at sea.

Part 5: Summary
Part 1: Introduction
Offshore Oil
• Importance
• Classification
• Characteristics
• Oil Development Process
• Shallow water: ＜500m
• Deepwater:500-1500m
• Ultra Deepwater: ＞1500m
• Hight technology requiremetns
• Large investment
• High risk
• Geophysical Exploration
• Drilling Operation
• Production & Processing

Part 5: Summary
Geophysical
Exploration
• Definition:
• Procedure
• Send artificial sound waves underground by
geophysical vessel;
• Receive and analyze the reflected waves from
different formations;
• Deduce the distribution of formations;
• Deduce the distribution of oil and gas resources.
• Geophysical exploration refers to the research and
observation of various geophysical field changes to
detect the formation of lithology, geological structure and
other geological conditions.

Part 5: Summary
Drilling
Operation
• Introduction: difference of drilling rig between offshore and onshore
• Drilling rig
• Main operations
• Fixed drilling rig
• Jack-up drilling rig
• Semi-submersible drilling rig
• Drilling: Definition
• Drilling fluid: definition, functions
• Cementing: definition, functions
• Well completion:
Ø Characteristics
Ø Advantages
Ø Disadvantages
Ø Selection in applications
• Cased hole completion
• Open-hole Completion
• Barefoot completion
• Slotted liner completion
• Screen liner completion
• Gravel packed Completion

Part 5: Summary
Production
&
Processing
• Definitions:
• Methods
• Fixed Production Platform:
Production at sea + Processing on land
• Floating production storage offloading (FPSO):
• Semi-submersible production, storage and unloading platform:
Ø Characteristics
Ø Advantages
Ø Disadvantages
Ø Selection in applications

COSL-CS-001 Introduction to Offshore Oil Industry.pdf

COSL-CS-001 Introduction to Offshore Oil Industry.pdf

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