GUWAHATI -- Indian oil experts have cautioned its crude reserves might last for another 15 to 20 years only with increasing the number of aging oil wells.

"Oil reserves are slowly getting exhausted and the present oil wells in India's northeastern state of Assam cannot meet the demand beyond 15 to 20 years," Pranab Bharali, retired director of Oil India Limited (OIL), said at a seminar in Assam's capital Guwahati.

Assam accounts for about five million tons of crude oil annually out of India's total crude production of 32 million tons. India's crude production target last year fell short by almost six percent with nearly 75 percent of the country's crude requirement to be met through imports.

The oil expert said unless new oilfields were found out the prospects of the Indian petroleum industry looks bleak.

India's crude production has remained stagnant in the past five years, causing concern among experts with the aging oilfields cited as the primary reason for the drop in production.

The oil and the Oil and Natural Gas Corporation Limited (ONGC), two of the country's premier oil exploratory firms, have among themselves about 2500 oil wells in assam of which 65 percent were aging oil wells and do not yield any crude at present.

Experts are now planning to dig one of Asia's biggest river, the Brahmaputra, flowing along Assam to look for crude oil reserves.

"We are carrying out two-dimensional seismic surveys in the river-bed and are confident to strike oil in the Brahmaputra," a senior oil official told IRNA.

The ONGCL, however, has taken a lead to revive some of the old wells using advanced technologies and raise the oil recovery rate up to 40 percent.

"We are trying to establish new reserves and pools to extend the current fields and also going for sophisticated technologies to boost production from the aging wells," I B Raina, executive director of ONGC's eastern region said.

A disturbed security situation in the region and frequent strike calls by pressure groups demanding job reservations for local youths in the oil industry has also added to the sluggish crude production.

"We have seen how the oil sector was made the prime target by separatists in the past one decade leading to several blasts on oil pipelines and installations", the oil official said requesting anonymity.

The 1160-kilometer long crude pipeline from the Oil Headquarters at Duliajan in eastern Assam to the Barauni Refinery in Bihar is one of Asia's longest and oldest trunk pipelines.

Crude in India was first struck in Assam when some British army officers reported gurgling sounds in the riverbed while touring the heavily forested terrain somewhere in Digboi, 527 kilometer East of Guwahati, sometime in 1825.

However, it was an elephant that helped prove conclusively there was oil in the area, when some men laying railway tracks in the area found the animal's feet smeared with crude.

This discovery led Mckillop Stewart and company of Britain to drill Asia's first successful mechanically drifted oil well at Naharpung near Digboi in 1867 -- barely seven years after Colonel Drake drilled the first well in Pennsylvania in the United States.

Assam boasts of two modern wonders of the world -- a 100-year-old oilfield still yielding oil and the world's oldest operating oil refinery producing in excess of its capacity.