Excess oil industry stockpiles are likely to disappear entirely in October or November as winter demand overwhelms supply constrained by OPEC export curbs, analysts said. Inventory statistics, always key to the international oil market, have assumed an even greater significance over the past week as OPEC officials singled out the indicator as the leading factor for judging when to ease supply limits. Now, even the most cautious of analysts expect OPEC's target of shrinking stockpiles to pre-1998 levels to be achieved before the end of the year - at least three months before an agreement on output cuts expires. "With no schedule for another quota review before March 2000…