The deal with Halliburton was first flagged before Christmas and has the backing of Fred Olsen, the Norwegian shipping tycoon who has a 25 per cent stake in OGC. The offer price is 119.3p a share in cash.
Halliburton has agreed to retain all the executive directors, including John Hyslop, managing director.
OGC shares plunged from a high of 251p last July following the profit warning. The warning came just four months after the group reported a 10 per cent rise in profits for 1995 and after several directors had sold hundreds of thousands of shares and options at prices in excess of 200p.
Brokers halved profit forecasts on the warning and the share price slumped to 130p in a matter of days. Interim profits for the first half of last year in August showed a 30 per cent drop in turnover and a 60 per cent drop in profits, and the shares subsequently drifted to a low of 75p last month before the announcement that Halliburton had made a bid approach.
OGC's flotation in 1993 was heavily oversubscribed when the shares were offered at 130p.
OGC has found the going tough to increase turnover since the flotation. The company specialises in project management and maintenance services and is a big supplier of contract workers to the offshore oil and gas fields.
Analysts said that OGC, in common with other service suppliers to the oil industry, had been caught by a cyclical drop in new orders and the powerful squeeze imposed by the oil giants at a time when several large service contracts were coming up for renewal.
The takeover will help Halliburton implement its strategy of progressively extending its activities in the North Sea where it will be able to offer a complete range of services to the large oil firms.
It is already one of the main operators of North Sea supply boats and last year signed a contract to produce with Cairn Energy which will handle development and production of a gas field in Bangladesh. But industry experts concede that the balance of negotiating power will remain with the giants.
The two companies already have a 50:50 joint venture, Brown & Root AOC. They also have joint operations in Australia.