Friday, January 7, 2011

Possibilities of Petroleum in Bhagalpur district in Bihar State of India.

Deep well emits gas in Bhagalpur.
by
Dr. Nitish Priyadarshi


A borewell that started giving out inflammable gas on Christmas Eve has now become a community chullah (earthy stove) at Darpur village in Bhagalpur district in Bihar state of India.

Villagers from surrounding areas have made a mud chullah over the mouth of the borewell to cook food and warm themselves up in chilly weather.

Such incidents were reported earlier too from various parts of North India including that of Jharkhand state, where catching fire in water of deep wells especially in coal fields area were seen.

The areas were so called emission of inflammable gas is taking place lies in Ganga Basin. Several drilling works has been carried out to explore the possibilities of Hydro carbons in Ganga Basin by different Government organizations of India.

According to the reports, the hydrocarbon potential Ganga Basin is till in the stage of preemptive prognostication despite drilling 12 wells. Vast area to be covered with seismic data and other geophysical and geological investigation leaves a large scope of further exploration.

Quantity of hydrocarbon seep is not always indicative of size of subsurface hydrocarbon accumulation.

Adsorbed gas surveys have been carried out in different parts of Ganga Basin and are indicative of hydrocarbon generation/ accumulation potential. Certain alleged gas shows/ seepages have been reported in various parts and the latest such shows was reported from Bhagalpur district. It may be the example of minor occurrences.

Minor occurrences often furnish clues that lead to the discovery of commercial deposits. Nearly every producing region (petroleum province) was discovered as the result of drilling prompted by the recognition of a nearby surface or subsurface showing of gas, oil, or asphalt. Visible surface evidences, or outcrops of petroleum, have often furnished the only reason for drilling an exploration well, especially in the early days of the industry. Minor occurrences indicate the presence of a “source rock”. Although the origin of petroleum is not known, most geologists believe that it comes from some kind of source rock or source environment.

Petroleum seepages are common in the sedimentary regions of the world, and many pools and producing regions have been discovered by drilling near seepages. Occasionally a seepage and a pool are connected.

Surface seepages, either as oil or as gas, are frequently associated with water springs. The oil floats to the surface of the water, and the gas bubbles out and escapes into the atmosphere. If the water is stagnant, the oil may accumulate as a viscous-to-solid mass that remains after the water evaporates. Oil films floating on water have a characteristic iridescent luster and are some-what similar in appearance to films of iron oxide; but, unlike oxide films, they do not break when stirred. Gas seepages are more readily observed when they occur in swamps or bubble through water.

Surface oil seepages may be of large dimensions. There are many such cases in the world e.g. California, Venezuela, Trinidad etc. Petroleum- whether gas, oil, or liquid asphalt-that exudes in the form of springs and seepages may reach the surface along fractures, joints, fault planes, unconformities, or bedding planes, or through any of the connected porous openings of the rocks.

The occurrence of petroleum is widespread but very uneven. In some rocks its occurs only in infinitesimal amounts, measured in parts per million or even in parts per billion, whereas rocks of other areas contain enormous accumulations measured in billions of barrels. Petroleum occurs on all the continents of the world, although some continents are much richer in petroleum than others. And it occurs in all the geologic systems from Precambrian to Recent.

Possibilities of petroleum in Ganga basin in Bhagalpur district cannot be ruled out. Seeing the nature of the seepage of gas the occurrence of petroleum may be either surface or subsurface.

Detail geological survey and drillings are needed.
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