ExxonMobil, Nigeria's second largest upstream exploration and production multi-national oil company, said at the weekend that it has successfully restored its production capacity to the level it attained prior to the recent strike action by its workers.

A senior official of the American oil firm, who pleaded anonymity, told Daily Independent that if the current production figure falls short of the company's 800,000 barrels per day (bpd) capacity before the strike declared by the Petroleum and Natural Gas Senior Staff Association of Nigeria (PENGASSAN), it would be less than an average of five and 10 percent.

The official explained that since the strike forced the company to shut-in production throughout the weeklong period the strike lasted, it would take some time for the gas re-injection into the oil wells to boost production and bring the capacity to meet the pre-strike output level.

"The gas re-injection process into the oil wells to boost more oil production takes some time to bring output to its peak. But, the level achieved so far since the strike was called off is almost at pre-strike levels," the official said.

The strike, which had forced the company to declare force majeure on exports from the 400,000 bpd Qua Iboe terminal, also resulted in the shut-in of about 800,000 bpd production out of Nigeria's total capacity of about 1.8million bpd average for the first quarter of the year.

A survey by Platts for the first quarter of the year indicated that crude oil production from the 13 members of the Organization of Petroleum Exporting Countries (OPEC) in April dropped by about 350,000 bpd from its March output to an average of 31.87 million bpd.

The report of the survey published at the weekend attributed the sharp drop to the result of steep output losses in Nigeria.

Excluding Iraq, the 12 members, which participate in output agreements, supplied an average of 29.49 million bpd, about 360,000 bpd down from an estimated 29.85 million bpd output in March.

"OPEC production has been relatively steady in recent months, but the sharp fall in Nigerian output shows how vulnerable overall supply from the group can be to developments in one country," said John Kingston, Platts global director of oil.

"Given that spare capacity is also relatively tight, any disruption has a bigger impact on markets."

Other smaller decreases came from Angola, Iran, Qatar, Saudi Arabia and Venezuela.

Iraqi volumes were a shade higher at 2.38 million bpd, with a slight dip in exports offset by slightly higher internal supply. Libyan output also edged up, to 1.75 million bpd from 1.74 million bpd in March.