Defining the Continental Shelf

An invitation to learn more about the continental shelf and coastal states' rights and responsibilities.

It's been 10 years in the making, but the time has finally arrived.

The deadlines begin this year for claims of maritime sovereignty made by coastal states throughout the world to secure exploitation rights to millions of square kilometers of seafloor and sub-seafloor resource base, including hydrocarbons and other non-fuel materials.

For the past decade one of the largest legitimate land-grabs in the history of maritime space has been under way throughout all of the world's oceans. This is because states have had 10 years since their ratification of the United Nations Convention on the Law of the Sea (UNCLOS) to do this.

UNCLOS, which came into power in 1994, has provided a regulatory framework for the definition of rights responsibilities of coastal states on maritime areas.

An important issue in all of this is defining the continental shelf — which will be the subject of an exclusive session about the oil industry and maritime exploration and exploitation rights that will be held in Dallas during the AAPG Annual Meeting.

The session, offered by the Southampton (UK) Oceanography Centre, will be held from 9:30 a.m. to 4 p.m. Wednesday, April 21, at the Hyatt Regency Hotel. Cost for the session is $150.

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It's been 10 years in the making, but the time has finally arrived.

The deadlines begin this year for claims of maritime sovereignty made by coastal states throughout the world to secure exploitation rights to millions of square kilometers of seafloor and sub-seafloor resource base, including hydrocarbons and other non-fuel materials.

For the past decade one of the largest legitimate land-grabs in the history of maritime space has been under way throughout all of the world's oceans. This is because states have had 10 years since their ratification of the United Nations Convention on the Law of the Sea (UNCLOS) to do this.

UNCLOS, which came into power in 1994, has provided a regulatory framework for the definition of rights responsibilities of coastal states on maritime areas.

An important issue in all of this is defining the continental shelf — which will be the subject of an exclusive session about the oil industry and maritime exploration and exploitation rights that will be held in Dallas during the AAPG Annual Meeting.

The session, offered by the Southampton (UK) Oceanography Centre, will be held from 9:30 a.m. to 4 p.m. Wednesday, April 21, at the Hyatt Regency Hotel. Cost for the session is $150.

Background Information

Most of the 330 Articles included in the UNCLOS are passively acquired responsibilities, such as rights to innocent passage, preservation of the environment and allowance of marine scientific research.

Article 76, however, "Definition of the Continental Shelf," requires action from the coastal state to secure maximum territorial advantage and resource potential.

Article 76 provides technical guidance in the process of claiming continental shelf beyond 200 nautical miles if there is a "natural prolongation" of the coastal state's landmass outside of that distance.

The section describes how the outer limit of the continental shelf may be defined according to the position of the foot of the continental slope and either geodetic measurements or patterns of sediment thickness variation oceanward of it.

Even the most casual glance across a bathymetry chart of the world's oceans margins suggests many shallow areas of seafloor that might readily constitute such "natural prolongations" by dint of the fact that they developed along rifted passive margins during break up.

Also, volcanic ridges — which form an intimate component of a continental margin — and local sediment thickness anomalies, such as deltas and fans, are likely to constitute "natural prolongations."

In total, these continental shelf areas beyond 200 nautical miles cover an estimated 15 million square kilometers — almost the same area as that calculated for the sum of the world's coastal states Exclusive Economic Zones.

There is much work to be done, however, before a successful claim can be completed.

Coastal states who consider that they should claim shelf beyond 200 nautical miles need to prepare a robust geological, geophysical and geomorphological case to support the claim, directed to a UN-appointed commission (the Commission on the Limits of the Continental Shelf, CLCS). These 21 technical experts will:

  • Evaluate the basis of any claim.
  • Determine whether it is in accordance with guidance provided by the UN Department of the Oceans and the Law of the Sea (DOALOS).
  • Make recommendations to the secretary-general regarding acceptability of sovereignty claim.

In terms of the oil industry exploration/exploitation processes, the areas of potential "extended" continental shelf are characterized by mostly "deep" or "ultra-deep" water. Average water depths outside of the 200 nautical miles typically reach four figures and can reach full ocean basin depths of more than 4,000 meters rapidly.

But it is not necessarily the water depth that is the limiting factor in exploration/exploitation considerations — in many cases it is the distances between location of site of interest and available infra-structure on land.

The issue that brings sharp focus to the debate is the 10-year statutory period of time following a coastal states ratification of the Convention, during which fully supported and substantiated claims have to be presented to the CLCS for examination.

It is not clear yet as to any possible repercussions if a state fails to make that deadline, but it is certainly a legal obligation that in some countries is being used by authorities and some state oil companies as a lever to release funds from central government to support research in this area.

One such claim has been submitted to the CLCS to date, and others are anticipated.

The potential loss of resource by a coastal state if it was to fail to claim their continental shelf beyond 200 nautical miles is huge. There also is a widespread shortage of knowledge of the parameters involved in the development of a claim — the data required, type of data analysis, acquisition and processing, as well as a lack of availability of expertise and experience in this field to synthesize and present cases for territorial claims.

The Southampton Oceanography Centre, UK, in conjunction with the United Kingdom Hydrographic Office, has run a series of intensive technical training courses over the past four years in order to bring diplomats, petroleum geologists, exploration managers, technicians, hydrographers and lawyers up to speed in issues of the Law of the Sea and especially matters arising from Article 76.

Representatives of 46 countries investigating potential claims to continental shelf beyond 200 nautical miles on six continents have attended the courses over the years.

Essential issues pertinent to the hydrocarbon industry will form the core of the briefing session set for during the AAPG Annual Meeting in Dallas.

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