RE: Core Perth API and H2S.23 Oct 2021 22:04
The issue is not the percentage sulphur but the amount of H2S. Johan Sverdrup has less than 1ppm. Scott is considered high at 150ppm. H2S is really nasty. Very poisonous in even quite small amounts (500ppm in air would kill you in seconds and 10ppm would cause serious issues). It also turns to sulphuric acid as soon as it comes into contact with water. For Perth this means 2 things, firstly it has to use a lot of very expensive coated pipework and secondly it needs to scrub the H2S from the oil before it is transported. Scrubbing the H2S (sweetening the oil) is pretty simple. You need an amine plant. These are very common on fields in the Middle East. They also remove the CO2 which is a bonus. They have issues, however. Amine plants are physically pretty big so difficult to work into offshore environments. They require power, which given the drive to net zero could be an issue. They also do not take kindly to shaking about on an FPSO in bad weather.
The other parameters for Perth are not great but not that bad. Oil gravity above 30 means it is not likely to be too viscous, although the wax content could cause issues (might need heated pipes). The reservoir porosity at 13% is on the low side for an oil field. Bits of Scott are 20% and some fields get up above 30%. Strictly porosity is not the issue, rather it is permeability but usually the two go hand in hand. The oil saturation at 70% indicates lowish permeability (you might hope for 80%). That probably means that you are going to struggle to get 20% of the oil in place out. It also means more wells or, more likely, horizontal wells to try to get rates and recover up. I fear Perth is becoming more difficult as the environmental pressure increase. They will certainly not be able to flare away the CO2 and scrubbed sulphur as might have been the case a few years ago.