For a new high

Print edition : January 31, 2003

OIL and Natural Gas Corporation has got down to business with the Mumbai High Redevelopment Programme, one of its biggest projects in recent years. The aim is to step up the production rate of oil and gas from the field, which had declined in the late 1980s. ONGC is investing more than Rs.12,000 crores in 15 projects to achieve improved oil recovery and enhanced oil recovery from its various fields. Of this, the Mumbai High Redevelopment Programme Rs.8,200 crores, for its two projects called Mumbai High North Redevelopment and Mumbai High South Redevelopment. The programme aims to line up an additional 76 million tonnes of producible reserves of oil and gas.

Mumbai High North Development project began in January 2001 with a capital investment of Rs.2,900 crores. This project alone will yield 30.65 million tonnes' equivalent of additional hydrocarbons. It involves drilling 73 additional wells erecting four new platforms and laying 85 kilometres of sub-sea pipelines. The expected recovery by 2030 will be more than 30 per cent of the total oil in-place.

Mumbai High South Redevelopment project commenced in October 2001. Under this, 140 additional wells will be drilled, 17 new platforms erected, and 245 km of sub-sea pipelines laid. The capital cost is Rs.5,300 crores. The expected recovery by 2030 will be more than 33 per cent of the original oil in-place. The programme will provide a lot of opportunities to indigenous industry.

The Mumbai High field is situated about 160 km west of Mumbai city in the Arabian Sea. It is the India's largest and most prolific oilfield. It is 75 km long and 25 km wide. ONGC discovered oil in Mumbai High in 1974, a sensational find because until then it was believed that there was no oil in India's offshore regions.

The Mumbai High field is divided into the north and south blocks. The principal producer here is the L-III reservoir. A zone of relatively low permeability in the L-III reservoir acts as a barrier between these two blocks, facilitating independent exploitation of the north and south fields.

In 1976, ONGC started producing oil from the field a mere 18 months after erecting platforms and laying pipelines. This was an achievement by offshore production standards. Production, which was 1,000 barrels a day in 1976-77, shot up to 80,000 barrels in 1978. ONGC took technical help from Compaigne Francaise Du Petrol of France in the early years for the development of the field. Later, the Institute of Reservoir Studies, Ahmedabad, drew up the Accelerated Development Programme. As a result, the field reached a peak production of 4 lakh barrels a day in 1985 and the same pace of production continued till 1989. But production started declining thereafter, leading to a debate over whether Mumbai High was being overexploited.

ONGC introduced gas lift facilities and drilled in-fill wells and horizontal wells, among other measures. The field now produces about 2.20 lakh barrels of oil a day and about 10 million cubic metres of gas a day. ONGC did a 3-D seismic survey in 1997; it drew up the Mumbai High Redevelopment Programme in association with oil field consultant Gaffney, Cline and Associates.

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