The hypothetical NGL barrel jumped to its highest level in more than five months in August as margins expanded in double figures for almost all components.

Ethane at Mont Belvieu, Texas, pushed toward 26 cents per gallon (gal) as it reached its highest level since the first week of the year. At Conway, Kan., the average price surpassed 22 cents/gal for the first time since early February.

U.S. crude oil inventories declined by almost 10% from the start of the second quarter until the start of August, which is the steepest drop in that time frame in the past 20 years, En*Vantage Inc. said in a report. The Cushing, Okla., hub’s stocks were more than 14% below its level at the same point in 2016 and En*Vantage expected the U.S. crude inventory to slide by another 14 million barrels by the end of August.

While the average weekly price of ethane at Mont Belvieu was 39.1% above the price of a year earlier, the rise at Conway was 57.1%. Prices were constrained at the high end by record-high inventories. They were supported at the low end by strong cracking and export demand, En*Vantage explained.

Propane was 72% above what it was in 2016 at Mont Belvieu and 90.3% higher at Conway. U.S. inventories are tight and propane was selling at a 60% ratio to West Texas Intermediate crude oil, compared with a 44% relationship at the same time in 2016.

Butanes continued their rallies at both hubs, with Mont Belvieu’s butane price cracking 80 cents/gal for the first time since April and hitting its highest point since late February. Conway butane also surpassed 80 cents/gal for the first time since late February, and the 12-month increases were 55.9% at Mont Belvieu and 57.9% at Conway.

Joseph Markman can be reached at jmarkman@hartenergy.com or 713-260-5208.