July 11 (Reuters) - Grades were mixed on Friday, dealers said, with future supply expected to fall on a lower rig count, while refinery demand is set to grow.

U.S. energy firms this week cut the number of oil and natural gas rigs operating for an 11th week in a row for the first time since July 2020 when the COVID-19 pandemic cut demand for the fuel, energy services firm Baker Hughes BKR.O said in its closely followed report.

Baker Hughes said oil rigs fell by one to 424 this week, their lowest since September 2021, while gas rigs were unchanged at 108.

In Texas, the biggest oil and gas producing state, the rig count fell by one to 255, the lowest since November 2021.

On the demand side, U.S. oil refiners are expected to have about 195,000 barrels per day of capacity offline in the week ending July 11, increasing available refining capacity by 26,000 bpd, research company IIR Energy said.

Offline capacity is expected to fall to 171,000 bpd in the week ending July 18, and remain at that level in the subsequent week, IIR added.

Meanwhile, the U.S. Department of Energy on Friday said it would provide up to 1 million barrels of crude oil from the government's emergency reserve to Exxon Mobil's XOM.N Baton Rouge refinery in Louisiana, citing an offshore supply disruption.

A zinc contamination was identified in the Mars crude oil stream in recent days, tightening crude supply along the U.S. Gulf Coast.

* Light Louisiana Sweet WTC-LLS for August delivery fell 5 cents to a midpoint of a $2.75 premium and was seen bid and offered between a $2.65 and $2.85 a barrel premium to U.S. crude futures CLc1

* Mars Sour WTC-MRS rose 5 cents to a midpoint of a 15-cent premium and was seen bid and offered between a 5-cent and 25-cent a barrel premium to U.S. crude futures CLc1

* WTI Midland WTC-WTM fell 5 cents to a midpoint of a 50-cent premium and was seen bid and offered between a 40-cent and 60-cent a barrel premium to U.S. crude futures CLc1

* West Texas Sour WTC-WTS fell 5 cents to a midpoint of a 5-cent discount and was seen bid and offered between a discount of 15 cents and 5-cent a barrel premium to U.S. crude futures CLc1

* WTI at East Houston WTC-MEH, also known as MEH, traded between a 65-cent and 85-cent a barrel premium to U.S. crude futures CLc1

* ICE Brent September futures LCOc1 rose $1.72 to settle at $70.36 a barrel

* WTI August crude CLc1 futures rose $1.88 to settle at $68.45 a barrel

* The Brent/WTI spread WTCLc1-LCOc1 widened 6 cents to last trade at minus $3.32, after hitting a high of minus $3.24 and a low of minus $3.33

(Reporting by Georgina McCartney in Houston; editing by Diane Craft)

((Georgina.McCartney@tr.com))