2006 - Oil India Limited

Oil Shales in North East India
C. Ratnam
Chudamani Ratnam was born in 1933 and was educated at Delhi University. He was awarded an Assam
Oil Co. scholarship to study at the Imperial College, London, where he specialised in petroleum
exploration and development. After completing his studies in London he joined the erstwhile Assam Oil
Co. which after nationalisation became Oil India Limited. During his career he served in various parts of
India, both onshore and offshore, as well as internationally in Pakistan, Bangladesh, Myanmar and U.K.
(North Sea). Since retirement he has been involved in an advisory capacity with both the public and private
sector oil industry. He has written and lectured extensively on energy related matters.
Oil shales are a kind of rock, having a high content of
carbonaceous organic matter, which when heated, for example
in a retort (diagram1), exude hydrocarbon oils. Under natural
subsurface conditions over a period of millions of years the
same rocks generate crude oil which accumulate in oil fields. In
North East India, the presence of such rocks in the subsurface
Diagram 1 : Cross Sectional diagram of a retort
can be logically inferred as they are the source of prolific oil
fields which are under production for more than a century.
However investigations by Oil India Ltd., and others, have
shown that similar rocks with most of their oil generating
potential still preserved are present at the surface over a large
area in Upper Assam, Arunachal Pradesh and Nagaland and
could in all probability form a very large source of crude oil in
the future. A production of nearly 100 mtpa for a 100 years is
not beyond imagination.
The USA has the world's largest known deposits of oil shale and
were producing about 50,000 barrels per day, with
government subsidy, for a few decades just after World War II.
They set up a task force to review the results and the report is
available to the public. The report, which is an excellent model
of what a report should be, was technically favourable, but at
the then prevailing crude prices could not justify the project
commercially. Currently Estonia, Brazil and China have
ongoing commercial shale oil production. In earlier centuries
Scotland, France, etc. also had small but significant
commercial shale oil production.
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