DIMAPUR, SEPTEMBER 19 (MExN): The Nagaland Directorate of Geology and Mining today informed that a hydrocarbon gas leakage was detected while drilling a borewell for water in a private plot at Pongma ward of Tizit town, Mon on September 16.
A press release from the directorate said that the drilling works started on September 12 but the emission of gas occurred on September 16. The emission of gas occurred when the borehole was dug to about 140ft. The workers in order to check whether the gas was flammable lit the gas.
“The aquifer was struck at about 80ft to 98ft after which between 98ft to 140ft was clay. The gas was combustible in nature and was burning for nearly three hours,” the directorate stated. The workers through the directive of SP Mon, as per the advice of the Directorate of Geology and Mining, put off the fire by filling the borehole with sand on the same day.
As per direction of the Director, Directorate of Geology and Mining through telephonic conversation, a team comprising Er Toshiakum, Drilling Engineer and Chingao Konyak, Assistant Geologist was deputed to assess the extent of gas leakage on September 18 and they arrived at the spot at 12:00 noon.
As per field observation on September 18, gas leakage continued with a hissing sound. The leakage as per the gas detector instrument (Portable Voice Multi Gas Detector) shows the following readings: H2S (Hydrogen Sulfide) - 0 Parts of Gas Per Million (PPM); Carbon Monoxide (CO) – 0 Parts of Gas Per Million (PPM); Oxygen (O2) - 20.3%; and a Lower Explosive Limit (LEL) of greater than 50%.
The department stated that since the measurement shows >50% LEL (Lower Explosive Limit) which is highly explosive and since the release of methane gas is on the higher side, the residents are advised to keep distance from the leakage point.
Residents have also been advised not to dig any borehole within the perimeter of at least 50 sq feet. It further directed that the borewell be filled with sand to contain the emission. It added that the DGM with the help of residents will continue to monitor the gas emission for a week or two; and based on further observation the hole may be permanently sealed.
The department informed that the area of the leakage falls in Schuppen belt which is made up of imbricate thrusts with Naga Thrust in the west and Disang Thrust in the east. The geological Group/Formation comprises Barail (Tikak Parbat), Tipam, Girujan clay and recent alluvium deposits. Besides there is the Singphan transverse fault trending NW-SE across the belt of Schuppen along Tizit area, it added.
The department meanwhile informed that the foothill areas of Nagaland are geologically termed as the ‘Belt of Schuppen.’ It covers an area of approximately 3000 sq. Km from Mon district in the north to Peren district in the south. These areas are the bearing zones of oil, gas and coal.
It said that reports of hydrocarbon gas leakage in the Schuppen belt have been reported a number of times in the past. This gas leakage indicates presence of oil, gas and coal. Nagaland is rich in crude oil and coal, and so the presence of natural hydrocarbon gas is part and parcel of these minerals.
Hydrocarbon gas also called Natural gas is a fossil fuel energy source. Hydrocarbon gas contains many different compounds. The largest component of Hydrocarbon gas is methane, a compound with one carbon atom and four hydrogen atoms (CH4). Natural gas also contains smaller amounts of natural gas liquids (NGLs, which are also hydrocarbon gas liquids), and nonhydrocarbon gases, such as carbon dioxide and water vapour.