* Nipisi to carry 100,000 bpd of heavy oil
* Mitsue shipping up to 22,000 bpd of diluent
* Combined cost of lines C$400 mln, under estimate
* Second-quarter EPS C$0.29 vs. C$0.23 (Adds second-quarter results)
CALGARY, Alberta, Aug 3 (Reuters) - Pembina Pipeline Corp (PPL.TO) has begun shipping oil on two new regional pipelines in Alberta, it said on Wednesday while reporting a 27 percent increase in second-quarter profit.
The company, which operates several conduits that transport crude oil and gas liquids to major pipeline hubs, storage facilities and refineries, said the 100,000 barrel per day Nipisi line carries heavy oil 190 km (118 miles) to Edmonton from north of Slave Lake, Alberta.
The 22,000 bpd Mitsue line ships diluent -- ultra-light oil or natural gas liquids that are blended into tar-like bitumen so it can flow in pipelines -- 255 km (158 miles) to producers in the Slave Lake region from northwestern Alberta.
The company said the two lines cost C$400 million ($416 million) to build, below the original C$440 million estimate.
In the second quarter, Pembina earned C$48 million, or 29 Canadian cents a share, up from year-earlier C$37.7 million, or 23 Canadian cents a share.
Adjusted for one-time items, earnings were C$64.5 million, or 39 Canadian cents a share, up 48 percent from C$48.5 million, or 27 Canadian cents a share, in the second quarter of 2010.
Revenue, net of product purchases, increased 14 percent to C$148.1 million from C$124.5 million.
The company said its results were bolstered by strong performance in its midstream and marketing as well as its conventional pipelines divisions.
Pembina said it confirmed the size of a recent oil spill from the rupture of a small pipeline in northern Alberta to be between 800 and 1,000 barrels, which is below its initial estimate.
It continues cleanup efforts and environmental assessments from the rupture of the 8-inch Moosehorn gathering line and expects no material financial impact, it said.
Pembina shares were down 27 Canadian cents at C$25.23 on the Toronto Stock Exchange.
$1=$0.96 Canadian Reporting by Scott Haggett and Jeffrey Jones; editing by Rob Wilson