UPDATE 2-Chevron's Richmond refinery CDU shut for rest of year

* Announcement matches worst-case forecasts for outage

* Motor fuel output cut by at least half since fire

* Richmond outage cut Chevron's 3rd quarter 2012 output

(Adds analyst comment)

HOUSTON, Oct 9 (Reuters) - Chevron Corp said on Tuesday the central crude oil refining unit at its 245,000 barrel-per-day (bpd) Richmond, California, refinery would remain shut for the rest of the year.

The announcement of a shutdown lasting about five months confirms worst-case scenario forecasts for the outage, which sources familiar with operations at the refinery and industry analysts had said would extend between three and six months from the Aug. 6 fire which shut the CDU.

The San Francisco Bay-area refinery's production of motor fuel has been cut by at least half since the blaze, making California gasoline wholesale and retail markets volatile.

Wholesale prices shot up 97 cents last week, when a Los Angeles-area refinery was hit by a power outage. Retail prices have hit a record $5 a gallon in some locations.

"When Chevron went down in August, other refiners took up the slack and were able to keep going," said David Hackett, president of Stillwater Associates, an Irvine, California, energy consultancy. "When the problems developed last week, there wasn't anyone left to take up the slack."

Chevron said the shutdown has already affected production.

"During the first two months of the third quarter, U.S. refinery crude-input volumes decreased by 92,000 barrels per day compared to the second quarter, largely reflecting the shutdown of the Richmond refinery crude unit," Chevron said in an interim update to investors on the third quarter.

"The Richmond crude unit is expected to remain offline through the fourth quarter of 2012."

The fire, which erupted from a pipe on the crude unit, is being investigated by federal and state agencies. As many as 15,000 people in the San Francisco Bay area claim to have been affected by the smoke released by the fire.

A crude distillation unit does the initial refining of crude oil coming into a refinery and produces feedstocks for all other units.

(Reporting by Erwin Seba.; Editing by Jim Marshall and Andre Grenon)

((erwin.seba@thomsonreuters.com)(713 210 858)(Reuters Messaging: erwin.seba.reuters.com@reuters.net))