One of the coal seamsYou could follow the link I provided and...

One of the coal seams

You could follow the link I provided and see for yourself.

I did two calculations...

1. One based ONLY on the main seam (i.e. not the full 2,963 PJ) where the PCD chamber is located, and I applied a number of other 'discounts' to arrive at 816 PJ
2. The other was based on an observation made by another poster who pointed out a table in one of LCK's announcements that shows the coal seams grouped into seams of similar composition. He hypothesized that the 2P upgrade might be based on that table, and if correct that would yield 1,261 Pjoules.

IMO
DYOR