The Indradhanush Gas Grid (IGGL) has completed Asia's largest underwater hydro-carbon pipeline beneath the Brahmaputra, connecting Jorhat and Majuli in Assam, according to the company's CEO Ajit Kumar Thakur.
The challenging endeavour of laying a 24-inch diameter hydrocarbon pipeline beneath the mighty Brahmaputra river using the Horizontal Directional Drilling (HDD) method was completed on Friday, marking a major milestone in the construction of the North East Gas Grid (NEGG), which connects North East India to the National Gas Grid.
The total length of the pipeline in this single HDD crossing is 4,080 metres across the Brahmaputra river's main water channel. According to him, this is the longest river crossing by any hydrocarbon pipeline of 24-inch diameter or greater in Asia and the second longest in the world. This one-of-a-kind HDD river crossing was completed using the intersection method, in which two HDD rigs simultaneously began drilling from opposite sides of the Brahmaputra, with the two drilling heads intersecting in the middle at 30 metres beneath the river bed.
The laying of a 4,080-metre pipeline section was completed after overcoming numerous challenges, primarily caused by monsoon rains and flooding, he said. The total length of the HDD crossing the Brahmaputra river, including all major and minor water channels, is 5,780 metres.
The pipeline was constructed in three separate HDD sections of 1000 M, 4080 M, and 700 M lengths, with the first and third sections completed earlier. The next step will be to connect the three sections at two points, 15 M and 8 M below Natural Ground Level (NGL).
"With the completion of the Brahmaputra HDD, IGGL has achieved more than 71% physical progress on the NEGG Project and will be able to complete the Guwahati-Numaligarh section by February 2024," Thakur said. He thanked the Assam government for its assistance in carrying out the project.
Indradhanush Gas Grid Limited is a joint venture between five major oil public sector enterprises: IOCL, ONGC, GAIL, OIL, and ONGC. It is implementing the North East Gas Grid Project connecting the major cities and demand centres of North East India with the National Gas Grid. The 1656 km long natural gas pipeline is constructed at a project cost of Rs 9,265 crore.
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