Which among the following is the oldest oil (petroleum) producing state of India?

The correct answer is Assam. Key Points Assam is the oldest oil (petroleum) producing state of India. India's oldest oil refinery Digboi is located in Assam. India's first oil well was dug in 1866. The first commercial discovery of crude oil in India was made in 1889 at Digboi. The first refinery was started in Digboi in 1901. Digboi is the oldest oil well still in use. Other oil refineries in Assam are: Numaligarh Refinery. Bongaigaon Refinery. Guwahati Refinery. Additional Information Paradip Refinery is the oil refinery in Odisha. Madhya Pradesh is famous for its diamond production. Jharkhand is one of the leading producer of Uranium and Mica in India.