Essentially, econ 201. The price of a commodity is set by the marginal cost to produce that commodity.
Wrong. The price is set by what the market will bear. Marginal production cost merely sets a floor.
The cost of bringing the final product to the market which meets the price folks are willing to pay.
For sake of describing the point, I am just going to pull some numbers out of thin air just to explain the point. I have no idea what the real numbers are.
In Saudi, the cost of producing a barell of oil is like $2. In Iran it is like $20. In Texas it is like $50 In the north Sea it is like $85. The cost of Oil Shale is like $200
The price is set where the demand for the product at a particular price is equal to the marginal cost of producing the last marginal bit of the product. As price goes up, the demand goes down, but it still exists. People don't change behavior as quickly as they used to as the price goes up, but as prices increase you do see some elasticity which gets more pronounced over time. At 195 a barrel, it is not profitable to produce oil from shale. At $201 a barrel, fracking becomes profitable. As prices rise, it becomes possible to produce stuff that was impossible before.
The article is noting that as prices rise, we go to more marginal sources which are only available at these higher prices. More production in marginal areas won't reduce the price because they are only tenable for production at these higher prices.
In a way, the article is being disingenuous. Higher prices bring on more production in marginal areas and more drilling here WILL NOT reduce prices.
However, we have lots of areas in the US which are not marginal for production. Oceans of stuff under the north slope for example which is recoverable at a price a great deal lower than we are currently paying. We drill there, we will be producing large quantities under the current marginal price which will cause the marginal cost to drop precipitously.