Soviet oil reserves may be less than estimated.

The reserves are probably no more than 51 billion barrels, rather than 61 billion as originally estimated, research firm Petroconsultants S.A. said. The company said it based its revised figures on falling output from two major Soviet oil fields--the Tyumen field in Western Siberia that accounts for about 60% of Soviet oil production and the Komi Timan-Pachora basin, which is the fifth-largest production area. The Geneva report follows by one day a leading U.S. energy research organization’s conclusion that Soviet crude oil output will decline into the 1990s because of domestic production problems and bureaucratic disarray.