After a recent flurry of second-quarter earnings releases, this week was a relatively quiet one for the midstream industry. There were still a couple of important announcements, though, so let's get to it. Here's a recap of this week's highlights and lowlights.

Ground breaking
Construction on the southern leg of TransCanada's (NYSE: TRP) Keystone XL pipeline has officially begun. This section of the pipeline is heavily anticipated by the North American oil industry because it is expected to relieve the bottleneck at Cushing, Okla., that is keeping the domestic price of oil low.

Protests against the pipeline have also ramped up and will likely continue for the foreseeable future.

Building business in East Texas
On Monday, American Midstream Partners announced its plans to construct midstream infrastructure to serve the natural-gas liquids production coming from the Eaglebine, Woodbine, Georgetown, Buda, and Glen Rose formations in East Texas. The company's system will add 60 million cubic feet of gas gathering and processing capacity to the region.

American Midstream expects to bring the project online in 2013.

Asset sale
BP (NYSE: BP) announced plans to sell two Texas natural-gas processing plants and corresponding gathering system to Eagle Rock Energy Partners (NYSE: EROC). Eagle Rock will pay $227.5 million in cash for the assets.

The two plants have a combined processing capacity of 220 million cubic feet per day, while the gathering system is about 2,500 miles of pipelines. The deal is expected to close in the fourth quarter of this year.

Foolish takeaway
Midstream is where it's at, folks. The energy industry will spend an estimated $130 billion to $210 billion expanding natural-gas infrastructure over the next 20 years. After all, the more oil and gas that flows through those pipelines and processing centers, the more cash there is to flow into your pockets. Stay on top of all the midstream action by adding the companies above to your watchlist.