Oil and gas pipeline and processing company Enterprise Products Partners LP is making a move to acquire Duncan Energy Partners LP in a noncash deal worth $2.41 billion. The acquisition will really be a reunion, since Duncan was originally part of Enterprise Products, but was spun off in 2006.

Duncan Energy is controlled by a trust established by Dan Duncan, a Texas billionaire who died last year. (Because of the lapse in estate tax in 2010, his family inherited nine billion dollars tax-free.) Duncan and Enterprise are already intertwined through master limited partnerships, or MLPs. Enterprise owns Duncan's general partner and about 58% of Duncan's common units. In addition, Enterprise holds joint interest in some Duncan assets. Enterprise merged with Enterprise GP Holdings LP, last year. Enterprise GP owned shares of multiple mid-stream energy companies.

If you had any trouble deciphering the relationships in that last paragraph, you can understand one of the reasons for Enterprise's offer: to untangle the knots in the companies' convoluted separate-but-not-separate management structure.

A spokesman for both companies declined to give details on any other motives that might be behind Enterprise's offer.

San Diego mergers and acquisitions attorneys note that in 2009 Enterprise made a $3.3 billion merger with Teppco Partners LP. This merger created one of America's biggest pipeline companies.

Natural gas supplies are increasing as advances in technology give companies the ability to tap resources that were unreachable before, such as supplies trapped in shale rock formations.

Source: Wall Street Journal "Enterprise Products Offers to Acquire Duncan Energy" 2/23/2011