The price of the hypothetical NGL barrel broke through $24 this week for the first time since December 2014.

The Mont Belvieu, Texas, hub’s rise was driven by average weekly increases of 12.4% for isobutane and 6.8% for propane. Isobutane’s 85.6 cent per gallon (/gal) price marked the first time it has eclipsed 80 cents/gal since the week of Thanksgiving 2014.

At the Conway, Kan., hub, the barrel pushed past $23 to return to a point last seen in early March 2015. The jump was triggered by a 10.4% weekly increase in the price of ethane, which surpassed 21 cents/gal for the first time since mid-November 2014. Mont Belvieu’s ethane recovery was even more dramatic: it closed at just a shade below 24 cents/gal, a level not seen in the market since July 2014.

Frac spread chart for Oct. 14. Beyond dizzying statistics, the significance of the recent price jolt is a return to positive margins for ethane. The margin narrowed some this week at Mont Belvieu but remained positive, and Conway experienced some growth over last week.

NGL prices are tethered to market prices for West Texas Intermediate crude oil, which has found a home above $50/bbl in October, and natural gas, which is up 12.3% in the last month at the Houston Ship Channel and 9.6% at the Chicago Citygate. The hub prices are used to determine Hart Energy’s frac spread. The benchmark Henry Hub price is up 9.5% in that time period.

Since the rally began, the barrel’s price is up 27% in the past five weeks at Mont Belvieu and 32% in the past six weeks at Conway. Ethane alone has seen a 34% rise at Mont Belvieu and a 35% increase at Conway.

Propane at Mont Belvieu is up 18.2% over the price at this time last year and almost 28% since the start of September. At Conway, the year-over-year increase is just shy of 20% and almost 38% since September began.

Butane sustained consecutive weeks above 70 cents/gal for the first time since late January 2015 to hit its highest point since December 2014. Its price has risen 21.4% since the beginning of September and was 11.2% over the price 12 months ago. At Conway, butane cracked 70 cents/gal for the first time since January 2015. It is up more than 31% since the start of September and 16% over the year-ago price.

NGL prices for Oct. 14. Isobutane’s 40% jump since the start of September barely exceeds its 38% increase over the price at this time last year at Mont Belvieu. Conway’s difference was starker: 33% since September and 20% from a year ago.

C5+ reached its highest level at Mont Belvieu since late June 2015 and was 22% higher than when the rally began. Conway experienced the same result, though its price of $1.126 was 25% higher than early September.

Storage of natural gas in the Lower 48 rose by 79 billion cubic feet (Bcf) in the week ended Oct. 7, the U.S. Energy Information Administration reported. The increase, below the Bloomberg consensus average of 88 Bcf, results in a total of 3.759 Tcf. That’s a 1.5% increase over the 3.703 Tcf total at this time in 2015 and 5.4% above the five-year average of 3.567 Tcf.

Joseph Markman can be reached at jmarkman@hartenergy.com and @JHMarkman.

Resin prices for Oct. 14.