Canada still hopeful on Keystone approval after Obama speech

* Obama speech gave no hints of Washington's leanings

* Ottawa expects decision in second quarter

OTTAWA, Feb 13 (Reuters) - Canada remains cautiously optimistic that Washington will approve the Keystone XL oil pipeline even though President Barack Obama made no mention of it in his State of the Union speech, Natural Resources Minister Joe Oliver said on Wednesday.

The TransCanada Corp pipeline would link the oil sands of northern Alberta, the world's third largest crude resource, to refineries and ports in Texas. TransCanada has been waiting for approval for 4-1/2 years.

"I'm still cautiously optimistic about it, but we respect the U.S. approval process and they're going to make their determination, we hope, in the second quarter," Oliver said when asked for his reaction to Obama's Tuesday address.

Obama pleased both supporters and opponents of Keystone in the speech, Oliver said, because he touched on climate change as well as the need to build energy infrastructure such as new pipelines.

"I'm not disappointed," Oliver said. "I don't think we know any more now about what his decision will be than before the State of the Union address."

Environmentalists reject the pipeline because the oil sands extraction process is carbon intensive. Backers of the project, which would transport 830,000 barrels of oil per day, say it would provide thousands of jobs in the United States and increase North American energy security.