If Mr Eppig is right, the near-abolition of serious infections in these countries, by vaccination, clean water and proper sewerage, may explain much if not all of the Flynn effect.

Meanwhile, reverse imbibitions water blockage effect would be appeared to further damage the near the wellbore formation, especially in the low permeability and low productivity condensate gas Wells.

The transverse effect of the propeller blades at the top near the surface of the water is not strong enough to counteract the opposite effect of the lower blades.