— Dr. Tarakeswar Kataki In the North-Eastern region the most promising areas of oil exploration in future seem to be the foothill belt of Arunachal Pradesh, Patkai ranges, Naga Hills, Kohima synclinorium and the folded belt extending North Cachar, Tripura, Mizoram and Manipur. In the region of Kohima synclinorium oil and gas are leaked from subsurface reservoir and as such the region is considered as highly potential belt. Present oil fields like Champang, Digboi and Kuchijan are located within this belt.
Geologists believe that Carbonate reef rock having very high accumulation of oil may be found in the area bordering Assam Plain and Nagaland hilly areas where transition from shallower to relatively deeper part of the Assam Arakan sedimentary basin occurred. Geological mapping along with gravity magnetic and seismic survey reveals the presence of promising areas below the so called thrust belt. In this part lots of seepage of oil are seen.
Oil accumulation is considered more in the shallower as well as deeper geological formation. More oil may be found in deeper horizons. Drilling in marshy, swampy land and in the Brahmaputra river bed may also indicate huge accumulation of oil and gas. On the whole most of the areas covered by Assam – Arakan basin are most interesting and promising for oil exploration.
“Yet to find” potential of oil resource data are published by the Directorate General of Hydrocarbon (DGH) of Government of India from time to time. Accordingly estimated resource of the country is stated as 28085 MMT of which 8460 MMT has been discovered registering conversion percentage of about 30. For the Assam Shelf in place reserves of ONGC and OIL are about 1550 MMT against resource of 3180 MMT which is about 49 per cent conversion. But this conversion is less than 10 per cent for the fold belt with about 150 MMT in place reserves against resources of 1860 MMT. Thus in the Assam-Arakan basin we are dealing with a case where 50 per cent to 90 per cent resources remain to be discovered, developed and produced. In contrast the resource of Cambay basin is 2050 MMT and already about 70 per cent of this has been converted into oil and gas reserves.
In Tripura ONGC has discovered nine gas fields with total in place gas and condensate reserves of over 60 MMT of oil equivalent. Current production of gas in Tripura is around 1.5 MMSCD. Production will be more than doubled in few years for meeting the requirement of 740 MW gas based power plant being constructed by a ONGC led consortium.
In the North Eastern Region future drilling in the tectonically controlled synclinal and anticlinal lineament in the terrain of hilly region will affect small as well as large scale disturbance on natural balance, topographical domain, soil horizon, land, etc. causing disruption in natural ground water regime. Any drilling and exploration activity is of transitory nature, both destruction and development occur simultaneously and can only take place where oil pool is located. There is little room for maneuver in influencing location. During the exploration and exploitation there may be change of economic condition in the adjacent areas and social expectation may last / vary over life time, rendering it more or less acceptable or not acceptable to people of the area.
The proposed seismic survey of the Brahmaputra river bed for hydrocarbon deposits and its possible environmental effects raised hue and cry in the State. Concern for protecting Brahmaputra river environment is a major issue. Impact of seismic survey mayoccur on floral and faunal species that are components of the biological regime within and adjacent of the river basin. Specific impact may occur in the life cycles of rare and endangered species inhabiting the river.
The North-Eastern Region is geodynamicaliy, economically and socially so sensitive that it is very hard to develop a workable synergy between exploration and environmental realities. Most of the area is covered by primary and secondary forests. Rain forest support exceptional abundance of vegetation of great economic, scientific and medicinal value. Exploration and exploitation of oil and gas should have a direct contribution in development and economic well-being of the present and future generation of a region for which maintaining a healthy environment is necessary. Fear of disturbance of surrounding environment, uncertainties for future generation, fear of keeping areas natural, cultural heritage intact and to maintain an economically viable community in future are some of the reasons for which extraction of oil and gas are not favoured in some places.
Sustainable development of the region based on oil and gas resources should be planned in such a way so that there is little effect on environmental degradation. Balance is to be maintained between the exploration activity and the capacity of environment to absorb the impact of extraction. Sustainable and environmental protection should go hand in hand. In this aspects natural resource of a particular area in a sense be regarded as ‘natural capital’ such that they can be thought of as ‘invested capital’ which can be inherited, used, created and bequeathed to future generation. Natural resource exploration, particularly petroleum and coal should be managed in such a way so that a balance be maintained between development and environment.
Limit to growth is set not so much by expansion by natural resources but by low level of technological efficiency and productivity. Low level resource utilisation results in stagnation and low level of growth. This is true in case of India in general and North-East in particular. The growth of North-East States and regional distribution of petroleum resources leads to the conclusions that in spite of sufficient resource NE States are not having the desired level of growth. This is partly due to low utilisation of mineral resources including oil and gas.
There are huge reserves of petroleum in the North Eastern Region which are still to be explored. Dr A W Bally, one of the world’s top petroleum expert of Rice University, U.S.A.. who assessed the Assam - Arakan basin in 1997-98 for petroleum accumulation opined that more oil and gas resources to be discovered in Assam than what has been discovered hitherto. He also commented that Tripura, Cachar along with Bangladesh can be considered as ‘Mega Gas Province” and so not only large number of discoveries but large sized discoveries are expected.
Exploration and exploitation of petroleum resources in the North Eastern Region should be made in such a way that it meets the needs of the present without compromising the ability of future generation to meet their own needs. Development programmes should be consistent with proper and best use of natural resources of a region. No human activity can be conducted without some connection to environment. In future for exploration activity in the North Eastern region, we have to look for sustainable development on regional, state, local even on individual scale. Sustainable development should occur within a dynamic and evolving set of interlocking ecosystems, economic and social environment. It will be a challenge in future to develop a workable synergy between economic development and environmental problems during large scale exploration activities of oil and gas, particularly in the unaccessible terrain of the North Eastern Region.
(The author is former Keshav Dev Malaviya Chair Professor and now Emeritus Fellow at Gauhati University.) ASSAM TRIBUNE
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