Minerals Report - International Seabed Authority

thickness of the sediments, the thickness of the hydrate and the thickness
of the free gas.
Dr. Desa described waveform inversion as a technique that allows
the searcher to place tighter constraints on differences between the free gas
and the hydrate zone. With the waveform inversion technique, Dr. Desa
stated that a velocity model could be created such that the synthetic data
over all offsets fits the real data at the BSR.
He informed participants that in addition to the proxies that he had
described, there where are other methods and proxies available. In this
regard he mentioned hydro proxies that he said were of four types
consisting of the headspace, the pore water, the carbonate crusts and
bacterial indicators.
In order to study proxies Dr. Desa said that a surficial and shallow
sub-surficial sediment sampler is required. He emphasized the need for
such proxy data to be stored under special conditions. Dr. Desa informed
participants of an advanced technique of sampling using specially
designed pressure core samplers, (PCS). He said that using this sampler,
one is able to store gas samples up to minus 80 degrees for later analysis.
Some of the advantages of this sampler include the ability to examine
sediments and the free gas absorbed on sediment surfaces through ultra
sonic extraction. He also said that pore water chemistry could be
conducted with special squeezers
In relation to harvesting hydrates, Dr. Desa said that his Institute
undertook searches of the US, Japanese and the European Patent Offices
and found that in the last two years approximately 400 patents have been
registered. He therefore said that even though a lot of funding for hydrate
research is not taking place, it would appear that a lot of thinking is going
on resulting in patents being filed for the day that hydrate production and
recovery become a reality.
For the production and recovery of gas hydrates, Dr. Desa stated
that while several methods have been proposed, the main concept is to
mobilize the hydrates, melting them for easier access and recovery. In this
regard, Dr. Desa mentioned thermal stimulation as a means of melting the
hydrates, noting that only a small amount of energy is required. He also
said that depressurisation is also another method where the free gas
beneath the hydrate seal is accessed, releasing the gas and reducing the
INTERNATIONAL SEABED AUTHORITY 566