Sources said the SGFL with its own fund has deployed national exploration company Bapex to drill the fifth well up to a depth of 3,200 metres in this old gas field.

Available data says that the field has promising oil sand at a depth of 3,300 metres.

Though some experts have suggested drilling of this well to tap the oil sand, due to bureaucratic tangles and lack of understanding at the top level of Petrobangla --the mother company of SGFL-- the well is all set to be finished without reaching the oil sand.

The expenditure for this additional drilling would be only a few lakh taka and it would take just a couple of days to reach the target.

In 1988, when the SGFL drilled the third and fourth development wells in this field with funds from the Asian Development Bank (ADB), it had hit the oil sand. It also ran test flow of the oil and produced 522 barrels of oil per day for a few days till the ADB stopped the venture, asking the authorities to focus on gas production only.

"There is clear evidence that Kailashtila field is oil rich. The fact that this field produced 522 barrels a day on test run tells us that the potential is quite good," said one source.

The source pointed out that three months back, the SGFL assigned Bapex to drill the well at a cost of Tk 25 crore. The drilling is almost complete now with a solid drilling case in place. The drilling rig and all drilling equipment funded by it are still at the site and it is still not too late to undertake the additional task.

"If we miss this chance now, we will have to spend more than Tk 25 crore in future to tap this valuable oil resource. If we go for additional drilling now, there is nothing to lose and everything to gain," he added.

Kailashtila field was discovered in 1962 in Golapganj upazila on the south of Sylhet town. It is estimated that this field has a total recoverable gas reserve of 1.931 trillion cubic feet (TCF). The actual reserve can be assessed only when the recoverable is exhausted.

Kailashtila gas is wet in nature since it is rich with condensate, one kind of liquid petroleum. The level of production from this field was doubled in 1988 by drilling two wells together to resolve an on-going gas crisis. During that drilling, oil was found and tested but the ADB's intervention ultimately stopped the bid to tap oil.

"At that time, increasing gas supplies were more important than tapping an oil field. Oil was internationally being sold at $10 a barrel while the country's power plants and fertiliser factories were all dependent on increasing the gas supplies," said a senior official.

He went on, "Right now, we don't have any gas crisis. We have some major gas field development schemes in the pipeline. In contrast, oil price in the global market is $70 per barrel. This is a good time to tap oil resources."

About 50 percent of the estimated recoverable reserve of Kailashtila field has been exhausted. Of the four existing wells, three now produce gas from the upper level sand as the lower and mid-level gas sands have been exhausted. The fourth well is producing gas from its mid-level gas sand.

The official further said Petrobangla will soon begin drilling of another development well in Habiganj gas field, which also produces wet gas and promises oil. "We hope that when they do it, they opt for tapping the maximum potential," he added.