"As a major player in this frontier area of petroleum exploration, BP has one of the best technology to engage, and certainly we are looking forward to participating in the deep offshore bidding likely to be announced soon in Bangladesh," he said.

With some multinationals like Chevron, Cairn and Total, already engaged in gas exploration in the country, several major petroleum players from around the world have their eyes focused on offshore Bangladesh, specially the deep-sea blocks. This is for the first time that Bangladesh has delineated its deep offshore exploration blocks, and is likely to announce bidding very soon.

Bangladesh offshore area has not been sufficiently explored for its petroleum potential, and the deep sea is certainly a totally unknown area in this respect. Petroleum exploration carried out in the shallow sea has not brought much fruit. Only two small to modest sized gas fields were discovered in 12 exploration wells in the Bay of Bengal.

On the other hand, India and Myanmar have seen significantly larger gas discoveries in their offshore blocks over the last few years. A look at a map of the area shows that the Bay of Bengal is a large oceanic entity, with three countries sharing its marginBangladesh, India and Myanmar.

Significant successes in recent years have been reported on the Indian and Myanmar sides, which up bring up the question of rating Bangladesh's offshore territory for its gas potentials.

What is meant by shallow sea and deep sea? The height of water above the sea bottom increases gently as one goes seaward from the shoreline upto a depth of about 200m. The area between the shoreline and the 200m-water depth is called a continental shelf, and is known as shallow sea. Beyond the continental shelf the depth suddenly increases and, in a short distance, reaches from 200m-to 500m-to1000 m.

The deep sea is generally referred to the area with depths in the range of 500m to 3000m or more. Considered as the frontier area, petroleum exploration in the deep sea is technologically and economically far more challenging than it is the shallow sea.

Shallow sea prospect:
The continental shelf off the Bangladesh coast (upto a depth of 200m) has been the target of petroleum exploration from immediately after liberation. The shallow offshore was divided into seven exploration blocks, and six international oil companies were awarded these blocks for exploration during 1974.

After hundreds of kilometers of seismic survey, and drilling of 8 exploration wells, only a small gas field was discovered. It was named Kutubdia, but was not developed because it was too small to be economic. The reasons why all the companies left Bangladesh by 1978 were, firstly, the result of the drillings was not encouraging enough and, secondly, oil was their prime target, and geology dictated that the area was more likely to have gas rather than oil.

The world petroleum scenario has changed since then, and interest in gas rather than oil was in the minds of the international oil companies (IOC) when the next round of bidding was announced in Bangladesh in 1988. Four offshore blocks were awarded to IOCs in the mid-1990s, and they drilled several deep wells.

Cairn Energy of UK discovered Sangu gas field, with modest reserves, and started production in 1998. Offshore exploration activities again came to a halt as no other IOC could find a gas field.

In the meantime, there was news of very large gas discoveries off the Indian east coast and Myanmar's west coast. The discoveries off the coast of Andhra Pradesh in India are the largest in India, and this has significantly changed the gas reserve of that country (see map).

The gas fields are named Dhirubhai after the name of the founder of the Indian firm Reliance Oil, which discovered the fields. At about the same time, large gas discoveries were made in the sea off the Orissa coast.

On the other side of the Bay of Bengal, off the Arakan coast in Myanmar, the offshore blocks A-1 and A-3 have seen several large gas field discoveries (see map) by a consortium of oil companies, including the Indian ONGC and GAIL and Korea's Daewoo.

The Indians wasted no time in planning for pipeline import of Myanmar gas from the newly discovered offshore Shew gas field. This has been delayed because Bangladesh is not ready to give a pipeline corridor through its territory.

As a result of the large gas finds offshore (in India and Myanmar), the Bay of Bengal has came to the notice of world petroleum players. This brings the Bangladesh offshore area once again to the attention of the IOCs interested in South Asia.

Of special interest are the southern offshore blocks of Bangladesh, off the Teknaf-St.Martins Island coast, because of the close proximity of the area to Myanmar offshore discoveries. In fact, the geological set up of the Arakan offshore and that of Teknaf-St.Martins offshore areas are strikingly similar, and geologists believe that there is a strong likelihood that gas deposits similar to the Myanmar discoveries could be found in that area.

Apparently, the recent take-over of exploration license by the France based IOC, Total, in the southern Bangladesh offshore blocks 17 and 18 in the Bay of Bengal points to the above fact.

Deep-sea prospect:
While the Indians had announced their offshore (in depths upto 3000m) block bidding several years ago, and the Myanmar also did the same more than a year ago, Bangladesh has kept uncomfortably quite.

It was only after the media pointed out that some of the Indian and Myanmar deep-sea blocks were in the Bangladesh deep sea water zone that the authorities seemed to come to their senses.

Twenty exploration blocks have now been drawn for announcement in the deep-sea area south of the existing shallow sea blocks in the Bay of Bengal in Bangladesh (see map). The water depths in the blocks range from 500 m to 2500m.

Since India and Myanmar have announced some of their blocks within the Bangladesh deep-water zone, these will remain disputed until the three countries settle their respective deep-sea boundaries. Indian and Myanmar blocks overlap an area of 5000 sq km on the western side, and 16,000 sq km on the eastern side, of Bangladesh deep-sea blocks respectively.

Bangladesh should not waste time in claiming these blocks as its own and, thus, effectively make them disputed, so as to discourage IOCs from entering into contracts with India or Myanmar before the three countries mutually settled the problem.

With very little data, nobody can confidently rate the Bangladesh deep-sea area for its gas resource. But from the analogy with other deep-sea areas of the world, geologists believe there are reasons to be hopeful.

The energy-starved Bangladesh is faced with energy insecurity because the present gas reserve is likely to be exhausted by 2020. With overwhelming dependence on natural gas, and limited options for alternatives, Bangladesh should immediately move forward with the bid announcement for its shallow and the deep sea blocks. One may wonder if the latest frontier in petroleum exploration, the deep offshore, would bring much needed gas resource to rescue the country from an impending energy crisis.

Dr. Badrul Imam is Professor, Geology Department, Dhaka University.