How is China heading towards the deep sea?

This article was specially produced by China National Offshore Oil Corporation

ocean

Vast area and rich resources

Contains more than

34%

Oil and gas

However

These oil and gas resources are not within reach.

Among them are

44%

Buried in water more than 300 meters deep

Under the Deep Sea

The same is true in China

Especially in the South my country Sea

In this sea area with an average water depth of more than 1,000 meters

55%

Oil and gas resources

Buried deep in the sea

(International standards for dividing deep water areas include >300 meters, >400 meters, >500 meters, etc. This article adopts the >300-meter classification standard, where waters within 300 meters are shallow waters, 300-1500 meters are deep waters, and more than 1500 meters are ultra-deep waters. The following figure is a topographic map of China's seas, drawn by @郑艺/Planetary Research Institute)

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But the marine environment

But it is extremely complex and extremely bad

For every meter increase in water depth

The difficulty of resource extraction will increase exponentially

So that in the long years that have passed

Facing the treasure at your doorstep

We always struggle

Until recent years

We finally rely on our own strength

Successively realized

The first deep sea exploration

The first deep sea drilling

The first

Large gas field with a water depth of 1,500 meters

China officially started offshore oil and gas exploration

Ultra-deepwater era

(Please watch in horizontal mode. In June 2021, China's first self-operated natural gas field "Deep Sea No. 1" with a water depth of 1,500 meters was officially put into production. The behemoth in the picture is China's largest production, storage and unloading platform. Photographer: @韩庆)

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Looking across the country

Our Bohai Sea, East China Sea and South China Sea

145 oil and gas fields are operating day and night

Energy from the depths of the ocean

Continuously sent to the whole country

The operating capacity also increases from tens of meters

Flying up to 3000 meters

Why

Is the road to the deep sea so difficult?

How do we do it?

01

Refining a pair of "fire eyes and golden pupils"

Want to go to the deep sea

We must first know

Oil and gas resources on the seabed

Where exactly

But

The deep sea is like a fog

The depths beneath the ground are unfathomable

Unless you have a pair

Able to penetrate seawater and strata

"Fiery Eyes and Golden Pupils"

(Weizhou Island is embedded in the boundless sea, photographer @陈肖)

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On land

People can send artificial sound waves underground

By receiving and analyzing

Reflection waves from different layers

The distribution pattern of the strata can be inferred

The distribution of oil and gas resources can be inferred

Similar detection methods

Also applies to offshore

But there is no place to stand on the sea

To place all equipment and personnel

People must have a special

Large ships capable of physical exploration

Geophysical exploration ship

(This method of using sound waves and other physical means to study stratum information is called geophysical exploration, or geophysical exploration for short. Artificial sound waves are also called artificial seismic waves, and their exploration method is called seismic exploration in the industry. Schematic diagram of the principle of offshore seismic exploration, please watch in horizontal mode, map by @罗梓涵&郑伯蓉/Planetary Research Institute)

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The most distinctive feature of this ship

It is the extra-long cable that is dragged at the tail.

They are used to pick up sound waves reflected from the seafloor.

Equivalent to each cable

They scanned a section of the stratum.

(Single cable exploration diagram, drawn by @Luo Zihan & Zheng Borong/Planetary Research Institute)

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But only one aspect

The judgment made is obviously not accurate enough

If we can scan more layers at the same time

And put them together

A three-dimensional stratigraphic model

It jumps into view

Hidden oil and gas clues

They will also appear one by one

(Sketch of multiple parallel cables surveyed, drawn by @Luo Zihan & Zheng Borong/Planetary Research Institute)

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This also means

When a ship tows a cable

The longer the length, the more quantity

The larger the area swept at one time

If there is a faster speed and longer endurance

The scanning efficiency is naturally higher

(Please watch in horizontal mode, the seismic ship and the long cable being dragged, photographer @赵仲兴)

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But to have such a geophysical exploration ship

But it's not easy

As a result, in the early stage of offshore oil and gas exploration in my country

People had to fill plastic bags with explosives

To stimulate sound waves

Only wrap the cable with tape

Even using balloons to suspend cables

It took a lot of effort to get an old boat

Transformed into a simple geophysical exploration vessel

But since then

A 50-year upgrade journey

Pulling back the curtain

Jointly built by China and foreign countries

Equipped with 4 cables of 6000 meters in length

"Oriental Pearl" geophysical exploration ship

Then to self-modified

Equipped with 8 cables with a length of 6000 meters

"Hai Yang Shi You 719" geophysical exploration ship

final

Equipped with 12 cables with a length of 8,000 meters

"Hai Yang Shi You 720" deepwater geophysical exploration vessel

Finally born

When the tail cable is unfolded

The sea area covered is huge

Even equivalent to more than 1,200 standard football fields

(The small boat on the left is providing supplies to the large ship on the right, which is the geophysical exploration ship Haiyang Shiyou 720. Photographer: @陈志玮)

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Not only that

Its cruising speed and range

Ability to resist wind and waves and break ice

Both significantly improved

Not only can it withstand the strong winds and huge waves in the South China Sea

You can also travel in extremely cold waters such as the Arctic.

Therefore, it has also become

Asia's most advanced and capable geophysical exploration vessel

(Please watch in horizontal mode, the Haiyang Shiyou 720 in operation, note the comparison between the cable length and the size of the ship itself, photographer @陈志玮)

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So far

A geophysical exploration ship

Like a pair of "fire eyes and golden pupils"

Traveling across China’s major seas

The underwater information collected by their scanning

After analysis by geologists

Numerous oil and gas distribution areas were discovered

But only here

We still can't go to the deep sea

Because these explored areas

Is it worth mining?

Only when the well is actually drilled into the formation

To find out

However

From the rolling sea

Drilling wells thousands of meters down into the seabed

How easy is that?

02

Building a "sea fortress"

Drilling wells at sea

The premise is that we must build a

"Sea Fortress"

With a fortress

Equipment and personnel have a place to stand

The stronger the fortress,

Drilling operations can cope with

Sea breeze, waves, currents, sea ice, etc.

Various harsh marine environments

(The surging waves hit the coast, photographer @胡颖)

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at first

People use steel pipes

Build a pipe rack that goes directly from the sea to the seabed

The deck is then laid and equipment is placed on it.

Fixed drilling platform

It was born

(Sketch of a fixed drilling platform, drawn by @Luo Zihan & Zheng Borong/Planetary Research Institute)

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But this "fixed fortress"

Once installed, it cannot be moved

For drilling platforms that need to be reused

There really isn't much advantage.

So except for some specific environments

Now it has almost disappeared

Instead,

A "mobile fortress"

It consists of

One platform, several legs

And special lifting device

Combination

Under the action of the lifting device

The platform and legs can be raised and lowered vertically

So as to achieve

Drilling when fixed, shifting when floating

This is

Jack-up drilling platform

(Skip of a jack-up drilling platform, courtesy of @Luo Zihan & Zheng Borong/Planetary Research Institute)

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It relies on

Advantages of flexible movement and reuse

It soon became the first of the drilling rig family.

One of the protagonists

(Please watch in horizontal mode. The jack-up drilling platform is being moved by a tugboat. Photographer: @王振宇)

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but

This fortress is not perfect.

Its biggest weakness

The legs standing tall

Because it needs to adapt to greater water depth

Leg length, dimensions, weight

Will continue to grow

The platform structure has become more complex.

Making it difficult to cope with harsh marine environments

so

Among the platforms currently being built in China,

122 meters

The limit of its working depth has been reached

(The "Haiyang Shiyou 944" self-elevating drilling platform has specially made large "boots" at the bottom of its pile legs, which can "keep your feet on the ground" in soft seabed areas. Photographer @王振宇)

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then

A more flexible "sea fortress"

Born out of necessity

It consists of an upper platform and a lower floating body.

And the middle connecting column

Three parts

When towed, it floats on the sea like a large ship

When working, the lower floating body is filled with water and submerged

Hence the name

Semi-submersible drilling platform

(A semi-submersible drilling platform standing firmly in the waves, photographer @郑建富)

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This semi-submerged state

It can move the center of gravity of the platform downward.

Keep the platform stable in the vertical direction

Anchor chains installed on the four corners of the platform

It can also maintain stability in all directions

(Semi-submersible drilling platform diagram, drawn by @Luo Zihan & Zheng Borong/Planetary Research Institute)

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1978

Imported from Norway

The first semi-submersible drilling rig

"Nanhai No. 2"

The maximum operating depth is

200 meters

(Nanhai No. 2, photographer @宫瑞卿)

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Since 2010

With the continuous breakthrough of technology

A number of deepwater drilling platforms built by China

Entered the historical stage

Even breaking again and again

World record for working depth

From the "Innovation" semi-submersible drilling platform

750m

To the "Xingwang" semi-submersible drilling platform

1500m

("Xingwang" semi-submersible drilling platform, photographer @李佑坤)

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Then to the "Haiyang Shiyou 981" semi-submersible drilling platform

3000m

and the "Blue Whale 1" semi-submersible drilling platform

3658m

(Please watch in horizontal mode, multiple semi-submersible drilling platforms are in the same frame, photographer @唐克/Visual China)

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To better adapt to deep water environment

Some semi-submersible drilling platforms

Not only does it have a huge anchor chain

Also installed at the bottom of the platform

High-powered propeller that can rotate 360°

Assisted by satellite positioning, meteorological monitoring, etc.

Even without anchor chain

Still as steady as a rock in the stormy seas

(Thrusters to be installed, image source: China National Offshore Oil Corporation)

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For example, the operating water depth is 3000 meters.

"Haiyang Shiyou 981"

It can be used when the water depth is less than 1500 meters

Use anchor chains to stabilize the platform

When the water depth is greater than 1500 meters

Enable thrusters

(The "Hai Yang Shi You 981" semi-submersible drilling platform under tow, photographer @Mao Ya Lin)

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that's all

Above the vast sea

The Chinese finally built

Stable and solid "sea fortresses"

On top of the giant fortress

The derrick is erected and the drilling rig is roaring

(Workers are drilling down, photographer @王振宇)

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Under the Fortress

A half-meter thick steel pipe is inserted directly into the seabed

Huge drill bit

Then drill into the ground along the steel pipe

Maximum depth exceeds 15,000 meters

(Offshore Oil 981 is drilling. The white pipe is a watertight pipe. The drill pipe is inserted directly into the seabed from the middle of the watertight pipe. Photographer: Zhao Liang)

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then

In the proven oil and gas areas

Verified by drilling again and again

Including China's largest offshore oil field

Penglai 19-3

China's largest offshore gas field

Yacheng 13-1

Hundreds of oil and gas fields, including

(Distribution diagram of major oil and gas fields in China’s waters, drawn by @郑艺/Planet Research Institute)

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but

These "sea fortresses"

Unable to achieve continuous oil and gas production

After drilling is completed

They will go to new oil and gas fields

Continue your mission

therefore

To truly realize deep sea oil production

We also need to build a day and night

“Factory at Sea”

03

Building a "Factory on the Sea"

This "floor factory"

It is a combination of oil and gas production and processing

And the service life is up to decades

Super Combination

to this end

Cannot be reused

But it can provide long-term stable support for the catheter frame

Re-entering people's sight

Similar to fixed drilling platforms

People use the pipe frame as the base

Install production equipment above

A fixed production platform

(Sketch of offshore production, drawn by @Luo Zihan & Zheng Borong/Planetary Research Institute)

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Complex structure and diverse functions

Processing sections that require more space

Deployed on land

(Hainan Nanshan onshore crude oil processing terminal, photographer @宫瑞卿)

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then

Offshore production, onshore processing

A factory that is half sea and half land

It was born

But this "offshore factory"

The requirements for oil and gas fields are relatively high

Not far from the coast

Large area and high yield

The seabed must also be suitable for laying pipelines

so

To go to the deep sea

Build an offshore production and processing

Fully offshore “offshore factory”

Imperative

The most important one is

Offshore processing

then

People will use complex processing equipment

Compact layout on a large ship

Plus the automated control system

And the storage function of the cabin

A chemical plant was cleverly stuffed into a ship

This is the production of oil storage vessels

(FPSO for short)

(The full name of this equipment is floating production storage and offloading unit, which is called production storage and offloading vessel in China. The picture below shows the production storage and offloading vessel at work. Please watch it in horizontal mode. The picture is from @China National Offshore Oil Corporation)

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With it

Offshore oil and gas production and collection

Processing can be completed directly at sea

Then it is transported to land via tanker.

(Offshore production + offshore processing mode, in which the mooring tower structure is fixed in different ways at different water depths. In shallow waters, it is mostly fixed with a jacket, while in deep waters it is fixed with an anchor chain. Map by @罗梓涵&郑伯蓉/星球研究院)

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Compared with the half-sea and half-land factory

This is a fully offshore factory that produces and processes offshore.

Short construction period and low initial investment

Plus it can be reused

It became popular all over the world as soon as it was released

Also since 1989

It has gradually become the main source of offshore oil and gas production in my country.

One of the most widely used modes

(The upper part of the picture shows the production oil storage vessel, and the lower part shows the oil tanker, which is extracting oil from the production oil storage vessel. Photographer: Li Xuesong)

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Among them, the

Bozhong 28-1 Oilfield

It is the first oil field in my country to adopt this model.

And it is equipped with the "Bohai Friendship"

It is also the first self-built

Production of oil storage vessels

(The dense pipeline system on the production and storage ship, photographer @秦宇)

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Even if it is widely used

This model still cannot achieve deep-sea mining

Because I want to adapt to greater water depth

Jackets supporting offshore production

It is necessary to increase the height and extend the construction period.

The installation difficulty will also increase

(Please watch in horizontal mode. Offshore oil and gas production equipment forms a beautiful landscape on the sea. Photographer: Gong Ruiqing)

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This means

Our production method

Must be upgraded again

2020

Liuhua 16-2 oilfield in the South China Sea starts production

Its average water depth reaches 410 meters

But above the vast sea

A huge production and storage ship

The fixed pipe rack is missing.

How is this done?

(Please watch horizontally, the production and storage vessel of Liuhua 16-2 oilfield, photographer @林川)

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As we passed through the water

You can find the answer to your question

You will see

It is a submarine pipeline network crisscrossed by

Subsea production system

In conjunction with the production of oil storage vessels

A sort of

Mining model of underwater production and offshore processing

"Breaking the Water"

(Underwater production + offshore processing mode, drawing by @Luo Zihan & Zheng Borong/Planet Research Institute)

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Such an underwater production system

Not only is it less affected by weather, but it is also highly reliable

If combined with remote control system

It can also reduce costs and streamline manpower

Plus reusable production storage and offloading vessels

The overall investment is also greatly reduced

So naturally

It has become the "new favorite" when the water depth exceeds 300 meters

But even so

A production tanker is, after all, a ship.

Limited stability of the hull

Cannot cope with the harsh deep-sea environment

For greater stability

It can also be reused

Must build

Such a huge creature

(Please watch in horizontal mode, the huge semi-submersible production storage and offloading platform, picture source: @China National Offshore Oil Corporation)

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That's right

This is the same as the semi-submersible drilling platform.

Semi-submersible production storage and offloading platform

It is partially submerged during production

Helps to enhance stability

The most typical representative is

China's first independently built and operated

The world's first 100,000-ton deepwater semi-submersible production, storage and offloading platform

Deep Sea One

(Please watch in horizontal mode, the "Deep Sea No. 1" standing on the sea, picture source: @China National Offshore Oil Corporation)

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Its size is huge

Total height of 120 meters

Equivalent to a 40-story building

If you look down from the air

Its area is equivalent to two standard football fields.

Maximum displacement of 110,000 tons

Equivalent to nearly 2 Shandong aircraft carriers

The operating depth reaches 1500 meters

(Aerial view of "Deep Sea No. 1", photographer @韩庆)

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It has a very long "standby time"

Even in the face of high temperature and high humidity

South China Sea with high salt fog and super typhoon

Still can work continuously for 30 years

No return to dock for repair

The most noteworthy

Its columns not only support the platform

It was also developed into a huge oil tank.

Its capacity is equivalent to 10 standard swimming pools.

It has therefore become

The world's first semi-submersible platform to use vertical columns to store oil

(Deep Sea No. 1 being installed, image source: @China National Offshore Oil Corporation)

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June 2021

This steel behemoth

Precise positioning in designated waters in the South China Sea

Plus the subsea production system

And the oil tankers shuttling back and forth

and submarine pipelines that go directly to land

An extremely efficient mining model

Out of nowhere

Its production of natural gas

It only takes one day to get from the bottom of the sea to every household

Every year,

Gas supply 3 billion cubic meters

Equivalent to 1/4 of the gas demand for people’s livelihood in the Greater Bay Area

(Deep Sea No. 1 mining model, in which the length of the anchor chain is generally 3-5 times the water depth, so the anchor chain will be more dispersed underwater. The picture is only for illustration. Map by @罗梓涵&郑伯蓉/Planetary Research Institute)

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So far

Using "eagle eyes and golden pupils" to explore the way

Drilling with "Sea Fortress"

Production with "offshore factories"

Three major facilities are in place one by one

Finally, the Chinese people can rely on their own strength

Step by step towards the deep sea

04

The birth of the deep-sea fleet

certainly

That’s not all

In addition to geophysical exploration vessels, drilling platforms, and production platforms

This core strength

A combat-capable "deep-sea fleet"

It must also include the laying of submarine pipelines.

Pipe laying vessel

(Please watch in horizontal mode, two subsea pipe-laying vessels running side by side, image source: @China National Offshore Oil Corporation)

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Building offshore equipment

crane ship

(The world's largest single-arm crane ship "Blue Whale" is in the process of lifting. Image source: @China National Offshore Oil Corporation)

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Towing and supplying supplies

Work boats, etc.

Various members with different abilities

(Please watch in horizontal mode. Three work boats are towing the Deep Sea One forward, like an ocean fleet. Image source: @China National Offshore Oil Corporation)

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And behind this

Tens of thousands of people silently dedicate themselves to

Deep Sea Explorer

We are thousands of kilometers away

We are far above the land

Maybe you can never imagine

How do they use their tiny bodies

Driving steel behemoths

(The scene of the jacket straightening operation, photographer @张鹏)

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How to survive in the stormy sea

Drilling oil wells thousands of meters deep

(Drilling workers are installing drilling pipelines at sea, photographer @林俊西)

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How can we

Persevere day after day

(A production platform standing on the vast South China Sea, photographer @姚术成)

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But this is

Daily life of this deep-sea fleet

That’s why

Our country’s dependence on imported oil and gas

Today, the percentages are still as high as 73% and 43%.

Proportion of increase in offshore oil and gas production

For three consecutive years

Reaching nearly 80% of the national increase

Becoming a new engine for my country's energy growth

certainly

The road ahead is still long

Because China's current offshore oil and gas production

It only accounts for 18% of the country's total oil and gas production.

30% of the world average

There is still a big gap

But that's why

We must continue to the deep sea

Towards a wider sea

(Please watch horizontally, China's offshore oil fleet, only some of its equipment is shown in the picture, drawn by @罗梓涵&郑伯蓉/Planet Research Institute)

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This article was created by

Written by: Ai Lanxing

Design: Luo Zihan & Zheng Borong

Image: Grateful Heart Map: Zheng Yi

Proofreading: Li Xueli Zhang Wei

Cover Photographer: CNOOC & Wang Zhenyu

Special thanks

Feng Jiaguo, Senior Engineer of CNOOC Offshore Engineering

Ruan Fuming, Chief Engineer of Equipment R&D and Manufacturing Center of COSL Geophysical Exploration Division

Wang Wei, manager of CNOOC Haiyang Shiyou 981 platform

Expert review

Associate Professor Jiang Wenming of Oil and Gas Storage and Transportation Engineering, China University of Petroleum (East China)

Dr. Kang Qi, Flow Assurance Research Group, China University of Petroleum (Beijing)

【Explanation】This article is based on the development history of China's offshore oil industry and answers the question "How does China go to the deep sea?" from the perspective of marine engineering equipment. Founded in 1982, China National Offshore Oil Corporation, as the main force of China's offshore oil industry, has completed the 100-year journey of the offshore oil industry in Western countries in 40 years, and will continue to participate in the competition of the world's offshore oil industry in the future.

【References】

[1] Qiu Zhongjian et al. Oil and Gas Exploration in China (Volume 4: Offshore Oil and Gas Areas)[M]. Geological Press, 1999.

[2] Fu Chengyu. Contemporary China's Offshore Oil Industry[M]. Contemporary China Press, 2008.

[3] Qin Wencai et al. China Seas: A Century Journey[M]. Xinhua Publishing House, 2003.

[4] "40 Years of Progress" Creation Team. 40 Years of Progress[M]. Petroleum Industry Press, 2018.

[5] China National Offshore Oil Corporation Annals Editorial Committee. China National Offshore Oil Corporation Annals[M]. Reform Press, 1999.

[6] China Offshore Petroleum Geophysical Exploration Editorial Team. China Offshore Petroleum Geophysical Exploration[M]. Geological Publishing House, 2001.

[7] Xiahou Mingsheng, Li Zhiyu, Wang Dong, et al. Key technologies and development trends of geophysical prospecting vessels[J]. Ship Engineering, 2019.

[8] 2019 Large Equipment Performance Manual - Mobile Platforms, Ships and FPSOs.

Planetary Research Institute

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