India has completed its longest Horizontal Directional Drilling (HDD) bore to date. This feat was accomplished as part of the Indradhanush Gas Grid Limited’s (IGGL) North East Gas Grid Pipeline Project. The North East Gas Grid Pipeline Project is designed to meet the gas needs of the North Eastern states.

The project involved crossing the mighty Brahmaputra river and installing a pipeline spanning 4,102 meters using advanced HDD technology.

North East Gas Grid Pipeline Project

The North East Gas Grid Pipeline Project is designed to meet the growing energy demands of India’s northeastern region. While this is an ambitious project, it is expected to provide access to clean fuel for various sectors, including domestic, commercial, industrial, and transportation.
The project was led by NRP Projects Private Limited (NRP), which was responsible for the design, engineering, and installation of the HDD and any other associated works.
The project’s most significant challenge was laying a pipeline beneath the Brahmaputra River, spanning approximately 4,102 meters at a depth of 47 meters. It required an innovative approach in order to avoid disrupting the riverbed and surrounding environment.

Why HDD Technology?

Horizontal Directional Drilling (HDD) technology was chosen for this project due to its ability to navigate challenging terrains while minimising environmental impact. HDD involves drilling a pilot bore from one side of the river to the other, which is then, progressively enlarged to accommodate the desired pipeline size.
For this installation, two pilot bores were drilled using the intersect method, where two drill strings are installed from opposite sides of the river to meet at a midway point.
This approach preserved the integrity of the river ecosystem, thereby avoiding the environmental damage otherwise caused by traditional methods.

Equipment and Tools Used

As for tools and equipment, NRP Projects Private Limited selected two XCMG XZ6600 drilling rigs for pilot and reaming operations and a GOODENG GS8000-LS HDD rig for the main pipeline pull. These rigs had pulling capacities of 660 and 800 tons, respectively, and were strategically positioned on either side of the river.

The project used 10.6-inch diameter drill bits for the pilot bores, and custom-designed reamers were deployed to enlarge the hole.

The drilling fluid was managed using a Kemtron Tango 1000HDX recycling unit. The additives comprised a custom blend of sodium-based bentonite, Soda Ash, Xantham Gum, and PAC-R additives, an in-house design by NRP. Finally, the robust guidance system, PARATRACK II, ensured accuracy in alignment.

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Overcoming Challenges

As with any major project, the North East Gas Grid Pipeline Project was also riddled with challenges starting with the accessibility.
Accessing the remote project location was one of the biggest hurdles. The site was in a remote area with narrow roads leading through villages to the riverbank, not to mention the heavy rains. NRP invested in road improvements, and local infrastructure and deployed additional excavators to speed up the process.
The Brahmaputra River, itself presented unique environmental challenges, including frequent flooding and seasonal monsoons. The team had to work within a narrow four-month window to avoid the peak monsoon season. NRP implemented a ’round-the-clock’ work schedule with additional personnel and completed the bore within the stipulated timeline.

Successful Completion: Achieving a New Milestone

The successful completion of the longest HDD bore in India set a new record as the longest HDD installation in India at 4,102 meters.
The project involved installing two pipelines: a 6-inch conduit pipe and a 24-inch gas main. The pilot bore for the conduit pipe began on October 28, 2022, and was completed in 55 days. The drilling started for the gas main on January 7, 2023, and was completed within 86 days. The final pull-in operation lasted 56 continuous hours.
North East Gas Grid Pipeline Project set a new national record, surpassing the previous longest HDD installation of 4,088 meters.
The project marks a significant milestone in the Global trenchless technology sector. JB Trenchless is at the forefront of HDD technology, providing cutting-edge HDD tools and expertise to tackle the most challenging projects.