India's state-controlled refiner IOC will expand its 13,000 b/d Digboi refinery in Assam following the request of the state's chief minister Himanta Biswa Sarma.

Sarma in September requested the oil minister for a capacity enhancement of the country's oldest operating refinery, in a conference organised to showcase the upstream oil and gas opportunities in the northeast states of India.

"IOC has already initiated action for expansion of its Digboi refinery from 650,000 t/yr (13,000 b/d) to 1mn t/yr (20,000 b/d). The configuration study is expected to be completed by January 2022 followed by first stage investment approval by March 2022," oil minister Hardeep Puri said in a letter to Sarma, who posted it on Twitter.

"IOC has also taken up the matter for increasing the existing Duliajan-Digboi crude pipeline capacity from 650,000 t/yr to 1mn t/yr with [state-controlled] Oil India Limited to meet the crude requirement for the enhanced capacity of Digboi refinery," the minister said in the letter.

He also added that the capacity enhancement of IOC's 20,000 b/d Guwahati refinery in Assam, which the company is planning to expand to 24,000 b/d, is in progress and is expected to be completed by October 2023.

IOC aims to increase its crude throughout by 25pc, or about 350,000 b/d, in the next four years through four refinery expansions, with Guwahati one of the four being increased.