TransCanada Corp. on Thursday filed paperwork for approval to begin the work needed to get U.S. regulators' approval for its proposed multibillion-dollar natural gas pipeline from Prudhoe Bay to Alberta, Canada.

The Calgary-based company is pursuing one of the two pipelines proposed. The rival project, a joint venture of North Slope producers BP and Conoco Phillips -- already has applied for the so-called pre-filing status with the Federal Energy Regulatory Commission.

The pre-filing allows the backers of the projects to coordinate and communicate better with FERC staff as they prepare for a formal application to have their projects sanctioned.

Both pipeline proposals are in early stages of development as the companies involved study the strengths and weaknesses of different routes, conduct initial engineering, estimate costs and do other work. A decision on whether to proceed with construction could be a couple of years from now.

Federal regulators have said that both competing projects are unlikely to be completed.

Copyright (c) 2009, Anchorage Daily News, Alaska. Distributed by McClatchy-Tribune Information Services.