Bangladesh: Prospect of Gas Reserves
Bangladesh being a deltaic country is moderately enriched with this resource. So far 26 gas fields have been discovered in the country.
Till early 90s of the last century the gas reserves in Bangladesh had been worth mentioning but as the pace of industrialisation together with power generation increased over the past decades the reserves of natural gas started dwindling. With the yearly increase in demand of natural gas estimated at over than 5 per cent, the probability of gas being exhausted within a decade or a decade half perturbs all.
is easily palpable how the industries, power plants and many others could be affected if gas is depleted in near future. In spite of the fact that government is serious and sincere in finding alternative energy resources there has not been much progress visible in this respect yet. According to Petrobangla, the remaining reserve of gas in the country at present is about 13 trillion cubic feet (Tcf). In the face of ever increasing use of gas in the country this reserve would run for 10 to 12 years. But what will happen after that? Many presume this will ultimately result in Bangladesh being devoid of gas.
The expectation that reserve can grow and new reserves could be added does not generate enough room in the mind of the energy specialists. This is due to a lack of foresightedness that a sustainable and long term exploration campaign could change the way we take for granted the scenario of depleting gas sources. Practically, what we see is a weak exploration strategy, whereby drillings are few far between.
However, reserve growth and reserve addition has been noticed in Bangladesh in the previous decades and it would by all likeliness happen if a robust exploration drive is launched. Added to this is the very recently found a gas reserve at Shabajpur in Bhola, which is primarily estimated at about one tcf. The Bangladesh delta, being the largest in the world, is least likely to be exhausted of gas in its exploration history, because delta throughout the world, tend to be rich in gas and oil. The exploration in our country still remains at a primary and immature stage and it is too early to be apprehensive of a gas depletion scenario.
The reserve growth scenario: In 1993, the remaining reserve of gas in the country was estimated at about 10 Tcf which would run, as it was suggested at that time, for about 10 to 12 years. But in 2001, the remaining reserve of gas was recorded at about 15 Tcf (Petrobangla data 2001). It was again thought that it would be exhausted in and around 10 to 15 years. Yet, in 2011, the remaining reserve was found to be 15 Tcf. It suggests that instead of depleting the reserve actually grew.
Would this trend of reserve continue? Certainly not. Reserve growth will cease at a time in the future depending on the maturity stage of exploration in the area concerned. For an area where exploration reaches a mature stage, depletion of gas appears to be more realistic. But for an area like Bangladesh where exploration is far from reaching a mature stage, it is naïve to presume that gas would be exhausted after the consumption of presently known reserve. Bangladesh is unlikely to find very large new onshore gas fields, but there are certainly many small sized gas fields waiting to be discovered.
The onshore prospect: Exploration carried out till date in the onshore gas fields has restricted to simple and ‘easy to find’ fold structures. These are identified by simple geographical mapping in hilly terrains or by seismic survey in plain lands. Almost all gas fields discovered in the country are found in such anticlinal (arch-like that has its oldest beds at its core) structures in the eastern part of the country. There are many smaller to small fold structures which may still be identified by further surveys for drillings. This will find individual small gas reserves but a large number of such small discoveries would add to a notable reserve.
A second stage of the exploration programme could target more ‘difficult to find’ and subtle gas pools (traps). These are not formed by any fold structure but by the inherent lithological changes (called facies changes) within the subsurface rock layers, and makes their identification difficult. Geologists argue that these types of gas pools should be abundant beneath delta plain of Bangladesh, considering the experiences of other deltas around the world like the Niger Delta, the US Gulf Coast etc.
A third stage of exploration lies beyond the conventional stages; such unconventional targets include synclinal (sloping downward to form a trough) plays, high pressure plays, thin bedded plays and so on, none of which has been targeted seriously in Bangladesh. With modern technologies being introduced in explorations, unconventional plays have started showing their worth. Attaining a mature stage of exploration implies that has to take all these into active consideration.
The offshore prospect: If Bangladesh has not been able to reach mature stage of exploration in its onshore fields, it remains truly immature in its exploration ventures. Activities in the offshore today are going on slowly, with only 3 exploration blocks out of 26 being active by International Oil Companies (IOCs) under production sharing contracts (PSC). There has been no exploration drilling in the offshore in the last seven years, and success in negotiations is not visible enough. Yet, just on the other side of the maritime boundary with Myanmar, the offshore Arakan basin has the speed of matching the success of discoveries. The most recent gas discovery, the Thanin gas field, as it is named, took place in January 2016. It is located in the Myanmar offshore block AD-7, adjacent to one of the offshore blocks of Bangladesh. Peter Coleman, chief executive of the Australian based Woodside Oil Company – which has discovered this and another gas field – has said that these discoveries testify the high gas potentials of the surrounding blocks.
The offshore Arakan basin is a natural continuation of the offshore Cox’s Bazar-Teknaf coastal basin and hence, both have similar geological frameworks and structures. There is no reason why the primary exploration and success in Myanmar’s offshore basins should not be replicated in Bangladesh’s side of the Bay of Bengal. Based on the available data, geologists are almost convinced that Bangladesh offshore adjacent to the maritime boundary is sitting on major gas field reserves. It is believed that a number of gas fields would surely be discovered if an effective exploration is launched.
To sum up, we may agree with the geologist’s belief that a large delta area like Bangladesh should form a very rich gas province. In reality, the expected gas richness has not been visible because of lack of exploration. Far more exploration drive needs to be carried out in order to unearth its true gas potential. The sooner it is done, the better.