* Canada crude output seen at 6.7 mln bpd by 2030
* 2015 oil production 3.9 mln bpd, 2020 at 4.9 mln bpd
* Study sees higher oil sand, conventional production
* 'Collection of pipelines' needed to handle additional oil
CALGARY, Alberta, June 5 (Reuters) - Canada's most influential oil lobby boosted its long-term forecast for the country's oil production as it expects higher output from the oil sands and a resurgence in conventional oil drilling despite near-term constraints on pipeline capacity.
The Canadian Association of Petroleum Producers (CAPP) raised its estimate for 2030 production to 6.7 million barrels per day in a closely watched annual outlook for Canada's oil industry, up from 6.2 million bpd it forecast a year earlier.
Output from the United States' top energy supplier averaged 3.2 million bpd in 2012 and is expected to grow to 3.9 million bpd by 2015. By 2020, production will be 4.9 million bpd, 200,000 bpd more than CAPP estimated a year ago.
That growth will come even as the industry awaits U.S. approval for TransCanada Corp's contentious Keystone XL pipeline project.
Canada's oil production will bump up against the country's export pipeline capacity as soon as next year, according to the study. While rail shipments can take some of the excess production, new pipelines will be needed or the industry will see further discounting of Canadian oil as supply builds and is unable to reach markets.
"The forecast is contingent on having the pipeline capacity there," said Greg Stringham, vice president, markets, for the lobby group. "But it's not one pipeline, not just Keystone or a line going east. We need a collection of pipelines to move this additional oil."
Canada's pipeline network can currently handle 3.6 million bpd.
Besides Keystone XL, several new projects have been proposed to send crude east, west and south, that will add as much as 3.1 million bpd of new capacity by 2018. OIL SANDS GROWTH
Canada has the world's third-largest oil reserves, behind Venezuela and Saudi Arabia, but the bulk of the crude is trapped in the oil sands of northern Alberta and producing it is more expensive and carbon intensive than for conventional crude.
Still, CAPP is expecting oil sands output to rise from 1.8 million bpd in 2012 to 2.28 million bpd in 2015 and 3.22 million bpd in 2020.
Much of the growth will come from in-situ thermal projects, where steam is pumped into the ground to liquefy the tar-like bitumen trapped in the sands so it can be pumped to the surface.
The lobby group estimates that such projects - which in 2012 accounted for 55 percent of all oil sands production while oil sands mines produced the remainder - will produce 62 percent of oil sands crude.
The output from Western Canada's conventional fields, including shale oil, is expected to rise from 1.25 million bpd in 2012 to 1.37 million bpd by 2015 and 1.38 million bpd by 2020 as producers increase output from shale-oil deposits like Alberta's Duvernay formation.