Ann: Flow from Habanero 4 during well clean-up pr, page-16

re: Ann: Flow from Habanero 4 during well cle...
These are definite steps forward. The open flow rate of 35 kg/s is quite good considering that no new stimulation has yet been done. On the other hand, HAB 4 is within the same patch of HAB 3 that was stimulated and flowed 4 years or so ago so that one would expect similar flows (~25 kg/s) unless the localised effects of new drilling closed off the existing fractures. I expect the present intention is to seek to maximise the fracture gap width particularly around the immediate neighbourhood of the well, as well as to extend the effective reservoir area by a factor of 2.

The flow rate at the given flowing pressure (4200 psi) yields a measure of the total impedance to flow (the lower the better) but it is not clear whether this is mostly due to the fracture constriction or due to the choke used at the output. They will probably try to crank this up a bit at the second flow test. At the same time they will be making careful observations of strains in the well casing as it tries to thermally expand and contract under the (present) 170 C temperature difference cycles. If their estimates are correct then the reverse cementing process should allow for a much better grip on the casing surfaces.

Your anticipated sequence is correct, Dealer, although it is not the actual closed loop activity itself that caused the Big Bang last time but the cumulative result of a series of temperature cycle stresses in combination with a weakening through presence of caustic fluids.

No doubt, once the system operates in steady state producing power they will strive to keep the fluid flowing continuously as much as possible. Closed loop circulation testing in 2008 took 6 weeks and this time the intention is to gain long term test data to understand and model the reservoir behaviour.

Anecdote: Once upon a time as a student I was working on a steelworks battery of Coke Ovens that had been operating non stop for 27 years at yellow heat. If it had been allowed to stop, cool and shrink even once, major gap lengths (leaks) would have appeared between the firebricks, and the entire investment would be thrown away. It’s not quite that dire for well casing stabilised within the well aperture.

Getting the 1MW plant operational is mostly a PR exercise although brokers may then be prepared to write reports again.

What I would really like to know is the forward planning for HAB 5, the associated multi level fracturing, and a drilling schedule in achieving a 25 MW plant. That will be commercial demonstration. I suspect GDY is moving gingerly at snail’s pace partly in hope of enticing Origin back into the JV fold. (Little chance of that at the moment.)

Juke