Among the many good reasons to jettison our failed economic embargo against Cuba is one with timely new resonance: oil.

Cuba has plenty of it -- offshore in its exclusive economic zone (EEZ) -- and exploration is about to being in earnest with American companies stuck on the sidelines.

The U.S. Geological Survey estimates the nation has about 4.6 billion barrels and nearly 10 trillion cubic feet of natural gas in the North Cuba Basin, and possibly four times that much in its portion of the Gulf of Mexico. The lower estimate would put Cuba on a par with Ecuador or Colombia.

But monetizing these resources is a real challenge: The 48-year old U.S. embargo and Washington's diplomatic muscle have thwarted any real progress so far. But this edifice is under siege. The Spanish, through their energy giant, Repsol, are bringing a deep-water oil drilling rig to Cuba this fall.

Trade sanctions dictate that the rigs can not contain more than 10% of U.S.-made components, which can include software. Most rigs worldwide typically top that. To get around the restrictions, Repsol contracted for a Chinese, purpose-built rig from Saipem, the offshore drilling unit of Italy's Eni, SpA, which will operate the rig.

When Repsol first drilled off Cuba's shore in 2004, its core samples were promising enough to bring on partners for this go-round, including Norway's Statoil and India's national oil company. Repsol did not reply to repeated requests for comment.

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