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ROCK CAVERNS FOR LNG

Kamal Deshapriya

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Going Underground

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70 yrs History….

Up to second world war.. First solution mined cavern in the

Canada reportedly conceived in early 1940

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Underground Caverns in France

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Geogaz-Lavera- France

60000T storage facility for commercial propane -1971

Storage facility for butane 85000T - 1984

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Geosel- Manosquesalt leached caverns

7.5 million m3 capacity- 1969

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Gas Caverns in US,48 regions…

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LNG storage caverns in Ontario, Canada

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Sydney LPG Cavern

First natural underground storage facility in Australia

135m under port botany in Sydney

65000 MT of LPG storage

Completed in 1999

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Other Caverns…

Yeosu Terminal-1983 First Rock Cavern in Korea

Incheon LPG Cavern –Korea Sarajeh in Iran- 2009, 16 billion tons

of LNG Shurijeh in Iran- 2009, 20 billion

cubic meters of LNG Qingdao facility China- 117000 T LPG

capacity

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Other Caverns in South Asia…

Source: Report of Kim, Tae Moon, Advisor, The Korean Institute of Gas, Republic of Korea

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Visakhapatnam -India

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Visakhapatnam -India

Visakhapatnam (Andra Pradesh)-2007 60000 MT LPG capacity for largest LPG terminal

in india Owners are South Asia LPG company and

Hindustan Petroleum Corporation Design and consultancy by GEOSTOCK France▪ Process▪ Geological▪ Hydro geological▪ Geo mechanical design

LARSEN & TOURBO Indian construction company

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Visakhapatnam India

Suitable sub soil stratum for cavern Hard gneissic rock 162 m below in sea level Two main caverns 19m in height , 20

m in width and 160 m in length connected with small galleries

Receive large tankers Re-exporting potential for south east

Asia

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Visakhapatnam India

Construction stages Diaphragm wall excavated from surface

to 20m in sandy and unconsolidated rock

Shaft sinking in rock from -30m to -162m Water curtain gallery at boreholes at -

147 m Storage cavern excavation Installation of castings and tubing's in

shafts Construction of concrete plug above the

cavern

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Visakhapatnam India

Above ground facilities To receive largest size LPG vessels

( 40000T) LPG loading arms Chilling and booster pumps Seawater heat exchanger and pump

house Mixing skid and a vapor ejector

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Gas Cavern Storing

Technology

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Example of Rock Cavern constructed using road headers for top heading & blasting for benching followed by trimming by road headers. Cross section is 85 sq m

Source : Geostock

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Flow of LPG Cavern Storage

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Cavern Techniques

Mined Caverns Lined Mined Caverns Salt-leached Cavern Porous Media

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Mined Caverns….

Access Ramp (AR)

Upper Connection (UC)

Intermediate connection (IC)

Upper Shaft Connection (USC)

Access Shaft (AS)

Operation Shaft (OS)

Lower Shaft Connection

(LSC)

Water Gallery – Operation Shaft

Connection (WOC)

Water Gallery – Access Shaft

Connection (WAC)

Water Curtain Gallery (WCG

Sump which houses the submersible

pumps

Lower connection (LC)

22The finished rock cavern for LPG at

Visakhapatnam

Example of an Underground Unlined Rock Cavern

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Salt Dome

Salt Leached Caverns

Borehole

Water injection

Brine

Several hundred meters Tens of

meters

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Aquifers

Impermeable stratum

Porous & Permeable Geological formation

Hydrocarbon Storage

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Disused Mines

Water table

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Caverns using vertical shafts for access…

Access Ramp (AR)

Upper Connection (UC)

Intermediate connection (IC)

Upper Shaft Connection (USC)

Access Shaft (AS) Operation Shaft

(OS)

Lower Shaft Connection

(LSC)

Water Gallery – Operation Shaft

Connection (WOC)

Water Gallery – Access Shaft

Connection (WAC)

Water Curtain Gallery (WCG

Sump which houses the submersible

pumps

Lower connection (LC)

27Source : Geostock

Example of cavern using a ramp for Access

Inclined Ramp

Water Curtain

Main Storage Galleries

Operation Shafts

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Rock Caverns

Depth varies from 70m to 200m from ground..

Size vary according to the geological condition

There are two types Mined caverns Mined Lined caverns▪ For Poor geological condition▪ Plastic or metal lining with concrete plaster

mine surface

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Suitable Rocks for Caverns Igneous

Granite, diorite Metamorphic

Gneisis Schists hornfels

Sedimentary rocks Sandstone Limestone Chalk shale

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Tightness Principle

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Mined Caverns

Cavity created in rock using mining techniques

Consist one or more galleries excavated in rock

Unlined Caverns, prevent product escape by hydraulic containment principle

Rock must be hard enough to cavern to be stable

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Cavern Stability

GOOD GEOLOGYMEDIUM TO BAD GEOLOGY

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Lined Rock CavernsThese types of storage facilities can be used for small or medium sized caverns. The lining can be steel or plastics. In the depths are large the linings have to be designed to counter the hydrostatic pressure or the can get

Steel or plastic lining

Over breaks and rock falls

Over breaks as shown can slow down progress to a large extent. Also a major safety issue.

Method of addressing poor rock conditions

To ensure there is good stability of the cavern, rock bolts need to be installed and shortcrete applied. Poorer the rock strata, larger is the support requirement.

Rock bolts

Shotcrete

Example of Poor Rock Conditions

Large number of cracks and fissures in the rock could lead to large over breaks .and excessive supports

Example of a water bearing zone

Water bearing zones could result in large water ingress if pre-grouting is not resorted to. The time taken up by grouting could delay excavation.

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Pre-Grouting in excessive water bearing zones

Pre-Grouting involves drilling a number of holes on the face and pumping cement paste under pressure into them till sealing is achieved.

High permeability and water bearing strata could result in higher grouting and slow excavation progress.

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Mined Lined Caverns….

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Gas Cavern Construction

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LPG Caverns to be constructed….

Access Ramp (AR)

Upper Connection (UC)

Intermediate connection (IC)

Upper Shaft Connection (USC)

Access Shaft (AS)

Operation Shaft (OS)

Lower Shaft Connection

(LSC)

Water Gallery – Operation Shaft

Connection (WOC)

Water Gallery – Access Shaft

Connection (WAC)

Water Curtain Gallery (WCG

Sump which houses the submersible

pumps

Lower connection (LC)

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Process Steps…

Pre- Feasibility Feasibility study and site

investigation Project decision Complimentary site investigation Basic engineering Design Permitting, Project financing Contract award Construction First LPG import

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Codes of Practices

CAN/CSA Z341 Series -98 Storage of Hydrocarbons in Underground Formations

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View of Construction Site- VishakaPatnam

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Shaft excavation

Excavation Using Drill & Blast (For Hard Rock) Two Boom Jumbo (Used for drilling in hard rock)

Excavation using Road Headers (For Soft Rock) Road Headers (Used in case of soft to medium hard rock

Limestone, Chalk etc)

Equipment lowering through Shaft

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Drilling & Blasting Method of Excavation

Holes are charged with explosives after drilling and controlled blasting carried out

Jumbo used for drilling holes in rock

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Pull

Drilling & Blasting Method of Excavation

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Drilling in water gallery

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Drilling of bench 1

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Drilling of top Heading

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Example of Rock Cavern constructed using road headers for top heading & blasting for benching followed by trimming by road headers. Cross section is 85 sq m

Source : Geostock

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Operating Shaft

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Concrete plug in operation shaft

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Surface Installations

Product injection and withdrawal Gas recirculation compressor Seepage water degassing before

disposal (Water treatment plant) Refrigeration system Gas heating system

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Surface Installations

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Sea Water Heat Exchanger

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Sea Water Intake

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Caverns on Surface Storages..

62Storage capacity

Cost

/ m

3 o

f st

ora

ge

Caverns in less favorable geological

conditions

Caverns in favorable geological conditions

Lower Marginal Costs – For larger volumes

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Caverns Vs. Others in 2000…

Volume Cost in USD/ Cu.m

Leached Salt Caverns

100-200

Rock Mined Caverns

10, 000 800-1200

50,000 340-580

100,000 300-500

500,000 180-280

Mounded Storage

2000-4000 800-1600

Pressurized Spheres

600-800

Refrigerated Tanks

600-800Source: Report of Kim, Tae Moon, Advisor, The Korean Institute of Gas, Republic of Korea

For All Volumes

For All Volumes

For All Volumes

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Advantages of going underground

Beyond certain capacities, the capital cost per ton of storage is low.

Product is located at a depth and is fully isolated.

External Fires will not affect Storage

Maximum security. Safety hazards on account of sabotage, storms, earthquakes and explosions are minimized.

Surface land requirement is low

Caverns by their very nature require very low maintenance.

Environment benefits. The rock debris generated can be used for infrastructure development.

Longer life

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Disadvantages…

Time consuming construction Continuous monitoring required with

sufficient staff for operation Moisture contamination Critical, expensive temperature

control Inefficient heating and cooling Gas Cushion and working volume

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LPG Caverns for Hambanthota….

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Tips from Geology Of Sri Lanka..

Sri Lanka is Part of a “Shield” area which includes Peninsular India

“Iland along with peninsular India is part of a segment of the earth crust made up of an ancient crystalline complex sufficiently rigid to withstand crustal movements and thus has remained in inflexible land mass.”

Source: Science Education Series, No 17, by L.J.D. Fernando. NERD, 1986

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Special Credits for “Geostock”, France