MADRID -- Spanish oil giant Repsol YPF ended 2008 with a reserves replacement ratio of 64 percent, or nearly double the 35 percent achieved in 2007, with the goal being 100 percent in the 2009-2012 period, when the current strategic plan end, a high-level executive said Wednesday.

The figure was still in "the low range of what is acceptable," despite the improved performance last year, Repsol YPF exploration and production chief Nemesio Fernandez-Cuesta said.

The reserves replacement ratio, which is the ratio of new reserves found to oil produced, measures an oil company's performance and should ideally be more than 100 percent.

In the past three years, Repsol YPF discovered 840 million barrels of petroleum, or about seven times its output in 2008, a year when it participated in three of the five largest oil discoveries made in the world and proven reserves totaled 1.06 billion barrels of crude.

The 2008 performance was the result of the efforts made in recent years in exploration and production, an area in which the level of investment will not be "eased" despite the drop in oil prices, Fernandez-Cuesta said, adding that a reduction in investment would lead to problems in the future.

The company plans to invest $700 million in exploration and production this year, a figure based on an oil price of $57 per barrel, well above the current market price, Fernandez-Cuesta said.

The executive said he expected the price of oil, which has been hovering around $40 per barrel, to rise later in the year. EFE