INDIA CELEBRATES ITS 100 YEAR DIGBOI FIND

March 12, 1990
S.K. Bhattacharjee (Kumar) Sita Oil Exploration House Inc. Houston On Jan. 24, 1990, India celebrated its 100 th year of commercial petroleum production from Digboi field, located in the northeastern part of the nation. This is a great achievement for a country of its size and problems. The first oil well was drilled in 1866, quite a few years before the great Digboi hit of 1890. The first well to be logged (by Schlumberger) dates back to 1933 and was a field development well in the Digboi
S.K. Bhattacharjee (Kumar)
Sita Oil Exploration House Inc.
Houston

On Jan. 24, 1990, India celebrated its 100 th year of commercial petroleum production from Digboi field, located in the northeastern part of the nation.

This is a great achievement for a country of its size and problems.

The first oil well was drilled in 1866, quite a few years before the great Digboi hit of 1890. The first well to be logged (by Schlumberger) dates back to 1933 and was a field development well in the Digboi field.

With the establishment of the national oil company, Oil & Natural Gas Commission (ONGC) in 1956, came the first serious attempt to study the Bay of Bengal basins and the East Coast basins and their petroleum potential.

Further interest was generated in these basins after the 1973-74 discovery of the giant "Bombay High Complex" off the West Coast of India.

Five major basins have been identified along the East Coast of India (Fig. 1). The extent of the continental shelf is shown on Fig. 1.

EXPLORATION HISTORY

The first seismic survey to identify basin configuration began in the onshore areas in 1960 and was followed by a massive recognissance offshore survey with technical assistance from the USSR.

Then ONGC began its own seismic data acquisition projects to map the subsurface structures along the entire east coast. This intensive geophysical study was quickly followed by a few wildcats in the onshore parts of the basins. The results were very encouraging-hydrocarbons were detected in the Mesozoic and Tertiary sections and also in the fractured basement rocks.

STRATIGRAPHY

Reservoir rocks: Reservoir rocks can be found in from early Paleozoic to Late Tertiary sections, in the form of sandstones and carbonates.

Hydrocarbons have been tested from reservoir rocks of Late Cretaceous to Miocene.

Source rocks: There is no lack of source rocks in these basins and types range from shales, siltstones to limestones.

Sealing rocks: The extensive presence of shales, siltstones from Cretaceous to Mio-Pliocene guarantees adequate sealing at least in the offshore areas. The very extremities of the onshore part of the basins might have sealing problems.

PROSPECTS

  1. Cauvery basin: This large basin has great future potential for further commercial discoveries.

  2. Palar basin: Hydrocarbon potential for this small basin is low.

  3. Krishna-Godavari basin: The blowout of the Naraspur well in the onshore part of the basin and a later oil & gas discovery by ONGC in the offshore area put this basin in the limelight.

  4. Mahanadi basin: A few wells drilled offshore indicate absence of Upper Eocene and Oligocene sections. This should not indicate lack of potential in the Cretaceous and Miocene sections. Encouraging oil shows from Eocene sediments do project the basin as fairly prospective.

  5. Bengal basin: This basin covers the major part of West Bengal-both onshore and offshore. This pericratonic basin has a very thick Tertiary section. Several wells located south of Calcutta had oil and gas shows within Miocene sections. No commercial discoveries have been reported yet, but the basin can be classified as a fairly potential one and a joint-venture exploration program with USSR is in progress.

CONCLUSION

ONGC and OIL the two Indian government owned companies are very aggressively exploring these basins. Recently, foreign companies were invited by the government to participate with PS type contract terms. Currently, Amoco, Chevron are operating a few blocks in the East Coast basins. Several discoveries have been reported by OGJ recently. With current production reaching about 650,000 b/d of oil and 29 bcf/d of gas, India is aggressively looking for new reserves.

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