OREANDA-NEWS. Mont Belvieu, Texas, spot ethane prices have remained firm in recent sessions despite declines seen in the Henry Hub natural gas market, as petrochemical producers are using more of the lighter feedstock.

Ethane prices have deviated marginally, averaging about 18.885?/USG since the start of last week's session, but ethane remained firm when natural gas prices fell.

Ethane's premium to its fuel value increased from 0.631?/USG on 14 September to about a 2?/USG premium today.

More petrochemical producers have been heard switching back to cracking more ethane as the lighter feedstock stands as second best for ethylene production.

Last week, ethane cracking margins stood at 8.67?/lb, compared with 9.48?/lb for propane and 7.22?/lb for butane.

While petrochemical producers increase the use of ethane as a feedstock, US ethane rejection is still talked steadily at about 550,000 b/d. The increase in demand for the lighter NGL has resulted in a temporary shortage in the Mont Belvieu spot marketplace.

Ethane rejection occurs when a gas processor leaves ethane in the natural gas stream rather than extracting it because it is uneconomical to do so.

The steeper ethane's premium to natural gas is, the more of an incentive to extract more ethane from the gas stream. That eventually results in ethane prices dropping back down.

As of June, US ethane inventories stood at 30.48mn bl, up by about 816,000 bl from where inventories were in May, according to the US Energy Information Administration (EIA).

As a result in steady EPC ethane prices at the US Gulf coast, E/P mix, which typically follows the natural gas and Mont Belvieu ethane markets, has also remained firm.

Midcontinent E/P mix firmed to 16.25?/USG today, up from 15.875?/USG at the start of last week.