OIL's 1157 Km fully automated trunk pipeline with a capacity of 8 MMTPA, which transports the combined crude oil production of OIL and ONGCL in North-East to the refineries in this region and imported crude from Barauni to Bongaigaon Refinery (delivered from ex Haldia port through IOCL pipeline), has become a lifeline of national importance. Commissioned in 1962, the crude oil pipeline traverses 78 river crossings through the states of Assam, West Bengal and Bihar. The network of 10 pumping stations and 17 repeater stations is a specimen of exemplary maintenance work by OIL personnel. OIL has the distinction of running the crude oil fuelled prime mover engines & the pumps in its Pump Stations for over 200,000 hours.

The 600 KM pipeline segment between Bongaigaon and Barauni has been re-engineered to enable oil flow in either direction and is now transporting RAVVA / Imported crude from Barauni to Bongaigaon.

The Company has recently undertaken a major project to replace all vintage equipments such as pumps, its prime movers along with all related auxiliaries in order to upgrade and optimize the Naharkatiya-Barauni pipeline system and meet all safety standards. The project is expected to be completed by end 2017. With the induction of technology in all fronts, this pipeline will become one of the technically updated pipelines in the country.

Supervisory Control & Data Acquisition (SCADA) system to constantly monitor movement of crude oil through the pipeline is in use since its very inception. The trunk communication system uses Optical Fibre Cable technology for voice and data communication. OIL has also leased some of the spare dark fibre and bandwidth to other companies, generating revenue from the same.

In 2009, OIL commissioned a 660 km long Numaligarh - Siliguri product pipeline. This product pipeline is continuously evacuating refined products from Numaligarh Refinery to the markets in other states. The Duliajan - Numaligarh Gas Pipeline (DNPL) where OIL has 23% equity stake has also been operating since 2010. This line feeds natural gas to Numaligarh Refinery for their captive use and, in future may transport gas beyond Numaligarh to other cities in Assam. OIL thus has the distinct experience of operating and maintaining pipelines to transport hydrocarbon like crude oil, natural gas and petroleum products.