Some more detail on Shale Gas estimates25 Jan 2026 00:57
My very brief note on X, in answer to GRH's question on shale gas, has been re-posted here, so I'd better expand on it so that no one is misled.
A quick intro – shale gas is formed by the action of methanogenic bacteria chomping on organic matter deposited within the shale. The more organic content, the potentially higher the gas concentration. These bacteria die off above 75°C, so work best when the shale is at shallow depths. The gas remains in situ, and is not reliant upon migration to a suitable reservoir stratum as with conventional gas.
Extraction is by drilling multiple (8-12) horizontal boreholes through the gas-bearing shale, radiating out from a single drill pad, then blasting them open (aka fracking). The horizontal sections are typically 5000ft long (1500m), so the area drained by one pad can be around 6 – 10 km². A rule of thumb is that to be commercial, flow rates should exceed 3 mmcfgd per 1000ft (300m) of horizontal borehole.
In the Beetaloo Basin here in Australia, three companies (Tamboran / Empire / Falcon) have drilled and fracked pilot holes, suggesting a combined 2C resource of 5.52 TCF. Their combined market cap is equivalent to £469M, giving a value of around £80M per 2C TCF. Obviously it will be a lot more once it achieves Reserves status – suggestions are around US$ 1 Bn per TCF. Australia's tax regime is very poor compared to Morocco, and the Beetaloo is a very long way from anywhere.
My assumptions (guesses at this stage) for Guercif:
* Area – given as 150km² for the structure penetrated by MOU-1. However, the whole Guercif graben is maybe 10x this size, shale may have been deposited all across this, maybe not.
* Thickness – given as 200m. I do not know if this is uniform, average, or just at MOU-1.
* Depth – this has not been stated, for calculating gas pressures I have taken it as averaging 500m.
* Porosity – not at all simple, since gas also adheres to shale grains and is not just found in the pore space. US Permian shale is around 6%, but Guercif has not been buried as deeply or for nearly as long, so is likely to be less compacted, so I'm using 8% equivalent.
* Gas Charge – given as up to 40%. I have used a conservative 25%.
* Bg – this is the number of m³ of gas at surface temperature & pressure that you can stuff into one m³ of reservoir. I do not have the actual depths, pressures or temperatures, so my Bg of 50x is roughly what you could expect at 500m. However, the geothermal temperature gradient at Guercif is a lot higher than normal, and gas nearby has been overpressured due to sideways tectonic squeezing in addition to overburden pressure, so this number could be higher.
* 1 m³ = 35.3 ft³
That's how I arrived at 1.06 TCF for just the structure penetrated by MOU-1. We will have to wait for the ITR for some real numbers. In PRD-speak, January/February means we would like to have it by next week, but it is more likely a couple of weeks later!