Denver's DCP Midstream Partners and affiliated companies have completed a $635 million deal that puts their natural gas-processing business into the Piceance and Powder River basins.

DCP Midstream LLC, a 50-50 joint venture between Houston companies Spectra Energy and ConocoPhillips, bought all the stock of Momentum Energy Group, a Wall Street-backed partnership founded in Durango but now based in Houston. As part of the $635 million purchase, DCP Midstream LLC got processing assets in the Fort Worth Basin, a six-county area in Texas and in the Piceance and Powder River basins in the Rocky Mountains.

DCP Midstream LLC then turned around and sold the Piceance and Powder River assets for $135 million to DCP Midstream Partners, a publicly traded partnership.

They're related because DCP Midstream LLC owns the general partner of DCP Midstream Partners.

The Piceance Basin assets consist of a 70 percent interest in the 31-mile Collbran Valley gas gathering system joint venture, which gathers and processes natural gas from more than 20,000 acres in western Colorado.

The other partners in the joint venture, Houston-based Plains Exploration and Denver-based Delta Petroleum, are also the producers on the system.

The Powder River Basin assets include the 1,324-mile Douglas gas gathering system, which covers more than 4,000 square miles in Wyoming.