October Nymex natural gas (NGV25) on Friday closed down -0.051 (-1.74%). Oct nat-gas prices on Friday added to Thursday's sharp losses and dropped to a 3-week low.   Nat-gas prices fell Friday on negative carryover from Thursday when the EIA reported that nat-gas inventories rose +90 bcf in the week ended September 12, above expectations of +81 bcf and well above the five-year average for this time of year of +74 bcf.  That brings current US nat-gas inventories to +6.3% above their 5-year seasonal average ...