INTRODUCTION Offshore structures may be used for a variety

of reasons:Oil and gas exploration Navigation aid towers Bridges and causeways Ship loading and unloading facilities

OFFSHORE PLATFORM

Left to right: onshore platform; fixed platform; jackup rig; semi-submersible; drill ship; tension leg platform.

How petroleum exploration and refining process

OFFSHORE PLATFORMS

FACTOR CONSIDERATIONS

The design and analysis of offshore platforms must be done taking into consideration many factors, including the following important parameters:

 Environmental (initial transportation, and in-

place 100-year storm conditions)  Soil characteristics

American Institute of Steel Construction (AISC) codes, and recommendations

 Intensity level of consequences of failure

BASIC COMPONENTS AND FUNCTIONS

A hole drilled into

the earth cased with

metal tubular for

the extraction of oil

or gas or both.

Well

Wellhead

The assembly of spools,

valves, hangers & seals on

which the casing and

tubing strings are

supported. The assembly

that fits atop the wellhead

is called X-mas Tree.

Flow line

Piping that conveys

hydrocarbon fluids from

the wellhead to the

Production Manifold.

Sapura Acergy Pipe lay and Wellhead Construction, Devil Creek Development Project

Manifold

Is an arrangement of large

bore piping to where flowlines

tie-in. Each manifold handles

different pressure regimes

depending on the bottom-hole

pressure of the well.,.i.e. Low

Pressure(LP), High

Pressure(HP), Intermediate

Pressure(IP)

Separator

Is a pressure vessel,

either horizontal or

vertical, used for

separation of well

fluids into gaseous

and liquid

components(usually

oil and water).

Surge Vessel

A pressure vessel

receiving and neutralizing

sudden transient swings

or surges in the fluid

stream. Surge Vessels are

often used on systems

where fluid stream flow

by heads or “batches” due

to the presence on

entrained vapours(gas).

Crude Oil Pumps

Are pumps that convey metered

export crude oil from the production

platform to the next transit

platform, to a gathering bulk line,

or directly to an onshore crude oil

storage terminal.

These pumps are usually multi-

stage centrifugal pumps driven by

natural gas engines or by heavy-

duty electric motors.

Crude Oil Metering Skid Is a flow measurement

package with associated piping, valves and control and measurement instrumentation that measures and registers primarily the volume and density of crude oil produced and exported from a particular platform or field.

This package is normally equipped with a Meter Prover used for periodic calibration of the flow meter to ensure its accuracy.

Gas Metering Skid Is a flow measurement package with associated piping, valves and control

and measurement instrumentation that measures and registers the mass of

gas which is then converted to volume. Mass Flow Meters which are

somewhat more accurate than Orifice Meters, are used in many production

platform or onshore refineries where large volumes of gas flow are handled.

offshore platform component

TOP SIDE AND JACKETGRAVITY BASE STRUCTURE (GBS)

TOPSIDE AND JACKET

a) Topside and Jacket

A Topside is a dry structure totally above water which contains all the facilities necessary for production, processing of hydrocarbon fluids (oil and gas) as well as facilities for artificial lifting of hydrocarbons (gaslift, water injecton, gas injection..etc). A Jacket is a free-standing substructure that stands on the sea bed and supports the Topside keeping it above water. The Jacket is secured onto the seabed by piles which runs through its main tubular legs or through skirt rings attached to its legs.

Fixed Platform (Topside and Jacket)

Offshore Platform Construction Jacket Leg Installation

Topside during Load-Out and Tie-down

Topside during Tow-Out to Sea

Topside and Jacket Structure configured for Float-Over Installation

MSL

SEA BED

JACKET STRUCTURE

VOID FOR FLOATOVER OPERATION

CARGO BARGE

TOPSIDE

Topside and Jacket Structure configured for Offshore Float-Over Installation : Preparing for Float-Over Entry

Topside and Jacket Structure configured for Float-Over Installation Offshore : Entry in Progress

Topside and Jacket Structure configured for Float-Over Installation Offshore : Clearance Check to ensure no clashes in the process of Entry

Topside and Jacket Structure configured for Float-Over Installation Offshore : Setting above Jacket Legs

Topside and Jacket Structure configured for Float-Over Installation Offshore : Ballasting(Water Intake), Alignment and Touch Down

Topside and Jacket Structure configured for Float-Over Installation Offshore : Disengage Transport Frame, Further Ballasting to create clearance before tow-away.

Topside and Jacket Structure configured for Float-Over Installation Offshore : Barge Tow-Away

GRAVITY BASE STRUCTURE (GBS)

b) Gravity Base Structure (GBS)

Gravity Base Structure A Gravity Base Structure is a superstructure made of

several concrete caissons constructed of high-strength concrete reinforced with steel rods and prestressed tendons. Such design are impact-resistant against ice bergs and are suitable for North Sea environment.

A Gravity Base Structure can extend from seabed level to above seawater level, support the topside above seawater level and protect it from iceberg impacts. A Gravity Base Structure comprises a monolithic reinforced concrete caisson which includes a bottom slab which can rest on the seabed, a top slab.

Main Caissons of a Gravity Base Structure undergoing Construction

Top slab of the gravity base structure (GBS) consists of a 105.5m diameter concrete caisson, constructed using high-strength concrete,

reinforced with steel rods and pre-stressed tendons

The Topside that will later be set over the GBS

Positioning the topsides over the GBS

Tow-Out of a GBS and Topside to Sea

Gravity Base Structure (GBS)

Offshore Platform- Fixed Tower

JACK-UP STRUCTURE

JACK-UP PLATFORM

The Jack-up Platform consists of a triangular shaped (sometimes rectangular), box section barge fitted with three (sometimes four) moveable legs which enable the vessel to stand to the seabed in water depths of up to approximately 120 m (400 ft).

Jack up rig

Jack-Up Rigs - How's It Works!

TENSION LEG PLATFORMS (TLPs)

TENSION LEG PLATFORM (TLP) A Tension Leg Platform (TLP) is a

buoyant platform held in place by a mooring system.

The TLP’s are similar to conventional fixed platforms except that the platform is maintained on location through the use of moorings held in tension by the buoyancy of the hull.

The mooring system is a set of tension legs or tendons attached to the platform and connected to a template or foundation on the seafloor. The template is held in place by piles driven into the seafloor.

This method dampens the vertical motions of the platform, but allows for horizontal movements. TLPs are used in water depths from 1500 ft to 7000 ft.

TENSION LEG PLATFORM (TLP)The "conventional" TLP is a

4-column design which looks similar to a semisubmersible.

Proprietary versions include the Seastar and MOSES mini TLPs; they are relatively low cost, used in water depths between 600 and 4,300 feet (200 and 1,300 m).

Mini TLPs can also be used as utility, satellite or early production platforms for larger deepwater discoveries.

Tension Leg Platform(TLP)

TLP from Yard Fabrication to Offshore Installation

STATIONARY FLOATING SPARs

4) STATIONARY FLOATING SPARS/FLOATING PLATFORMS

Floating Platforms are either mobile or semi-mobile.

SPAR A SPAR is a single large-diameter semi-submerged

Cylinder or Caisson moored by some 6-20 taut catenary lines that are anchored to the sea bed. The Spar supports a Topside and is equipped with void tanks and ballasting chambers fitted with pumps, piping and control instrumentation that works to keep the SPAR stable and floating on water.

a. Truss Sparb. Classic Spar

Floating, Semi-Mobile Platforms (SPAR)

Spar Transportation and Installation

Two Types of Spar(Classic & Truss)

Malaysia’s first and only Spar with TAD alongside

Spar Platform from Yard Fabrication to Offshore Installation

Spar Platform as Completely Installed

Spar platform

Floating Structure

platform accident

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