Midstream assets, specifically pipelines and processing centers, play a crucial role in America's energy future. The industry is growing rapidly, and may also play a crucial role in the future of your portfolio. There are many companies to keep an eye on, and it's an industry worth watching. Here's a recap of this week's highlights and lowlights.

Reverse, reverse
Pipeline reversals are all the rage this year, and on Monday Enbridge (NYSE: ENB) announced plans to reverse its Line 9 crude oil pipeline that runs between Sarnia, Ontario, and Montreal.

Reversing the flow of a pipeline can maximize the efficiency of a pipeline network, something that is becoming more important for companies like Enbridge that face increasing opposition to new projects.

Much of that opposition is driven by news similar to what the company reported on Wednesday, when 230,000 liters of oil leaked from a pipeline at a pumping station in Alberta. Cleanup is under way.

Please, sir, may I have some more?
On Tuesday, Chevron (NYSE: CVX) submitted an application to Canada's National Energy Board, requesting priority access to capacity on Kinder Morgan Energy Partners' (NYSE: KMP) Trans Mountain pipeline.

Chevron's Burnaby refinery receives oil from the pipeline, and in turn produces almost a third of the gasoline in British Columbia. The 300,000-barrels-a-day pipeline has been overbooked since 2010, however, and access to crude is getting more difficult.

Kinder Morgan plans to add capacity to the pipeline but faces strong opposition.

Adding infrastructure
Enterprise Products Partners (NYSE: EPD) is building a new propane dehydration facility on Texas' Gulf Coast. Expected to begin operations in the third quarter of 2015, the plant will be one of the world's largest, with the ability to produce 1.65 billion pounds of propylene a year.

Once the propylene is produced, it can then be fractionated at another Enterprise plant, turned into PGP, and shipped to domestic customers and foreign markets, all through company-operated pipelines or its export terminal in Seabrook, Texas.

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 My Watchlist.