The sizable gains in iso-butane and butane prices at Mont Belvieu, combined with lower feedstock prices, continue to improve frac spread margins at the hub.

However, lower NGL prices coincided with lower frac spread margins at Conway.

Butane was the biggest gainer in margin at Texas this week, as its frac improved 31% to 65¢/gal. Iso-butane had the second largest improvement in margin at Mont Belvieu, as it rose 25% to 74¢.

Typically, C5+ is the most profitable NGL to fractionate. But for now at Mont Belvieu, iso-butane remains the ...