Hydrocarbon

'Hydrocarbon' any organic compound, gaseous (natural gas), liquid (crude oil), or solid (asphalt) consisting solely of carbon and hydrogen. Hydrocarbons are divided into groups of which those of especial interest to geologists are the paraffin, cycloparaffin and aromatic groups. Bangladesh is rich in natural gas specially in the eastern part and some crude oil has also been found.

By the year 2000, a total of 22 natural gas fields have been discovered in Bangladesh, with a total gas in initial place reserve of about 26 TCF, of which about 16 TCF is considered as recoverable. By the beginning of 2000, a total of about 3.5 TCF of gas has been produced leaving a reserve of about 12.5 TCF. Out of the 22 gas fields, two are offshore in the bay of bengal and the rest are located in the eastern onshore area. Hydrocarbon gas occurs in Miocene (5 to 24 million years before present) and Pliocene (2 to 5 million years before present) sandstone reservoirs at depths of about 1,000m to 3,500m below the surface.

The natural gas of Bangladesh is very pure, with about 95% to 99% methane and an insignificant amount of sulphur. The average gas composition of Bangladesh gas is 97.33% methane, 1.72% ethane, 0.35% propane and 0.19% higher hydrocarbons. Gas in most of the fields is dry, but in a few fields it is wet, with considerable amounts of condensate, eg at beanibazar (16 bbl/mmcfg), Jalalabad (15 bbl/mmcfg), and Kailashtila (13 bbl/mmcfg). The total condensate reserve in the country is estimated at about 65 million barrels.

Geological evidence suggests that in addition to hydrocarbon gas already discovered, the prospect of further gas discovery in the country is very bright. Natural gas is playing a vital role in the economic development of the country. About 89% of the electricity generated in the country comes from gas fired power plants.

Crude oil, the liquid form of hydrocarbon, has been discovered in commercial quantity only in the Haripur oil field in sylhet. The oil field has an estimated in-place oil reserve of about 10 million barrels, with a recoverable reserve of about 6 million barrels. The oil field produced 0.56 million barrels of oil in six years, but production remained suspended from 1994. The Haripur oil field has not been fully evaluated and it has been suggested that there is much scope for full-scale exploitation after proper appraisal work is carried out. Crude oil bearing reservoir horizons were also found in Kailashtila and fenchuganj gas fields but these are yet to be proved commercially viable. [Badrul Imam]

See also hydrocarbon exploration;hydrocarbon generation. [Imam, Badrul Professor of Geology, Dhaka University]