HOUSTON, Aug 26 (Reuters) - An Exxon Mobil production

consortium's crude output in Guyana fell to between 400,000 and

500,000 barrels per day from July 2 through the end of the

month, according to government data seen by Reuters on Monday, a

sign that work on production facilities has begun.

Exxon earlier this year said it would shut down two offshore

oil production vessels in Guyana for two weeks each between July

and August to connect a natural gas pipeline.