PTTEP expected its petroleum reserves to reach 3 billion barrels of oil equivalent (boepd) by 2020, board director Pichai Chunhavajira told reporters.

"In the next 10 years, PTTEP will need up to $45 billion. We are short of about $11-12 billion. Therefore we are looking at financial options to raise more funds," Pichai said, adding PTTEP generated EBITDA of about 100 billion baht ($3.27 billion) a year.

PTTEP, the flagship in the upstream exploration business of top energy firm PTT Pcl, has petroleum reserves of just 1.1 billion boepd. That means it has to buy assets overseas to boost reserves and meet the country's energy needs, he said.

"An equity issue is an option, just in case we need a lot of money to acquire a large petroleum field," Pichai added.

On Tuesday, PTTEP Chief Executive Anon Sirisaengtaksin said his company was looking at whether to raise funds through an equity issue to finance expansion.

Some analysts have recently cut earnings forecasts for PTTEP due to high investment costs related to its acquisition of an oil sands project in Canada, and some have expressed concern that the company may opt to raise funds through issuing new shares.

PTTEP, which ranks among Asia's top 10 explorers and competes with big Chinese oil firms such as CNOOC and Sinopec, is involved in 44 oil and gas exploration and development projects.

At 0520 GMT, PTTEP's shares were up 3.2 percent at 180 baht, outperforming a 0.4 percent rise in the broad market, on expectations the company would benefit from rising oil prices.