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Compressed gas liquid carriers (CGLC) transporting remote gas

New concept for transporting stranded and remote gas
: An explorer having mid to small size gas reserves (8TCF and less) that are located in remote locations must have access to a pipeline transportation system. If not, their gas is stranded. To be able to drill up and bring on the production the explorer must realize an acceptable wellhead netback (or how much he gets) for his gas. The producer must also be able bring on his gas production with the least capital expense. With rising field development costs, the explorer faces serious challenges to get his field developed in a timely manner and within budget.

In receiving the gas, the market also faces significant challenges, that of rising receiving terminal costs, environmental issues and a flexible and reliable source or sources of gas supply having the lowest transportation cost possible. Leading gas explorers now developing a marine gas transportation system (CGLC) that not only provides the needed wellhead netback but also allows the explorer to produce and deliver the full value of his gas production to market.

Natural gas represents a source of clean energy for which global demand is increasing. Over three-quarters of the world’s known offshore reserves of natural gas remain undeveloped due to the high cost of transportation.

These reserves are found in far off and remote locations as gas pools or gas associated with to oil production. The size of these pools is often substantial (typically 8.0 TCF and below), yet they remain below the critical size required for the economics demanded for new long-term maritime LNG development.

LNG requires large capital needs and considerable process energy to achieve feasibility. Upstream capital costs are in the billions of dollars (US$) to establish the LNG liquefaction facilities. Additional capital expense is required at the market end to set up receiving terminals for re-gasification. There are separate and additional capital costs required to produce and deliver the LPG’s to market. Long lead times and considerable community opposition to receiving terminal locations or expansion in market areas have only served to focus industry on the returns of the largest of these gas fields.

LNG carrier underway
Fig:LNG carrier underway

Overall, a LNG ship carries natural gas product under storage conditions at a volumetric ratio of approximately 600 times that of the product at STP conditions. This is achieved with storage conditions of -260°F (-162°C) and atmospheric pressure. Large ships of this type carry approximately 3.0 BCF and more of natural gas.

Specific distillates of natural gas, Butane and Propane, both also produced from crude oil refining, are gaseous at ambient temperature and pressure and yet are liquid when stored and transported under modest pressure or in a moderate refrigerated state (hence the name LPG).

Specialised LPG ships have been developed to utilise these particular properties, being either pressurised, fully-refrigerated, or semi-refrigerated (trade as both pressure and refrigerated storages) containment systems.

CNG ship at sea
Fig:CNG ship at sea

Compressed Natural Gas (CNG) has also been developed as a shipping concept, relying on the high pressure containment technology used in conventional pressure vessel CNG storage and in pipeline systems to provide a form of concentrated gas storage which can be fitted onboard ships. The CNG concept that has been around for a long time, seeks to offer savings by removing the need for the expensive onshore refrigeration trains required for LNG.

However, CNG still needs separate gas conditioning and process systems to get the production gas segregated and suitable for transportation. A separate LPG processing and transportation system is also needed.

CNG carriers are a cost effective, reliable and safe alternative to the traditional ways of transporting natural gas via subsea pipelines or Liquefied Natural Gas (LNG) carriers.

When circumstances allow it, pipelines provide the best option for transporting gas over short distances, while Liquefied Natural Gas carriers offer various advantages for large quantities of natural gas to be transported over long distances.

With the innovative concept of the Coselle CNG Carriers, which utilize Coselles, a new technology consisting of large coils of pipes wound into a cylindrical storage container to contain compressed natural gas, gas producers are being offered an economically optimal solution for the transportation of moderate volumes of natural gas over medium distances.

Thus, the Coselle CNG carrier is the first method supporting this segment of the marine gas transportation market that is not economically served by pipelines or LNG ships.

The CNG carriers will provide the market with a safe, reliable and cost effective method to transport natural gas by sea and also deliver natural gas to underserved markets.

However, alternative gas transportation technologies exist which avoid the extremely low temperatures and expensive onshore liquefaction trains, or the high pressure containment systems, and offer more modest containment requirements better suited to raw production gas handling, sea transportation and pipeline quality gas delivery to market.


small scale LNG value chain
small scale LNG value chain

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Related article:

  1. Benifits of compressed gas technology

  2. Development and potential of todays emerging gas technologies

  3. Transporting economically viable compressed gas liquids from remote fields

  4. Increased Cargo Capacity for LNG ships & Advantages of the dual fuel diesel electric propulsion

  5. The Steam driven LNGCs & fuel option

  6. Duel fuel electrical propulsion system for LNG ships

  7. The sea transport of liquefied gases in bulk -Where do the products come from ?

  8. Defining various gas carrier types

  9. Fuel flexibility of LNG ships

  10. LNG ship spillage risk

  11. LNG shipment

  12. Initial Cool Down of cargo tanks

  13. Leaks on the Cargo System, Continuous Flow - how to prevent

  14. LNG tank leaks and immediate action by gas carriers

  15. Leaks from a Loading Arm due to Tidal or Current Effects

  16. Minor or major leaks from LNG tanks

  17. Procedures for LNG cargo loading

  18. Procedures for LNG cargo discharging

External links :

  1. : Center for Liquefied Natural Gas - Provides information on liquefied natural gas, US energy demand, and how LNG can help to safely diversify and expand our energy supply.

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