Query on cooking oil price

 WORLD crude oil prices have dropped significantly in the past 6 months or so. This has seen drastic drop in diesel, petrol & kerosene price in PNG. However cooking gas retail price remains unchanged. I thought that gas is a by-product of crude oil and so should be low as well. Can PNG’s monopoly supplier Origin Energy please shed some light on the reasons why they continue to fatten their margins and profitability?

Domestic gas user, via email