MOSCOW, March 13 (Reuters) - Ukraine struck Russian oil refineries in a second day of heavy drone attacks on Wednesday, causing a fire at Rosneft's biggest refinery in what President Vladimir Putin said was an attempt to disrupt a presidential election this week.

What was targeted and what do they produce?

RYAZAN

Russia's Ryazan oil refinery , controlled by Rosneft, was set ablaze after a drone attack, a regional governor said on Wednesday.

The plant, with installed capacity of around 350,000 barrels per day, refines about 12.7 million metric tons of Russian crude a year (around 317,000 barrels per day), or 5.8% of total refined crude, according to industry sources.

It has shut down two damaged primary oil refining units after a fire, two sources familiar with the situation told Reuters. Rosneft did not reply to a request for comment.

Ryazan has stopped its main crude distillation unit (CDU) AVT-6 with a capacity of 170,00 barrels of crude per day (47.5% of the plant's total crude intake capacity) and a smaller CDU AVT-4 capable of refining about 84,000 barrels of crude per day (23.4% of the plant's total intake capacity), the sources said.

As a result of the attack, Ryazan's idle crude refining capacity may reach 70% of the plant's total during the maintenance period, according to sources and Reuters calculations.

NOVOSHAKHTINSK

The Novoshakhtinsk oil refinery in Russia's southern Rostov region suspended operations on Wednesday after downed drones fell on the site, but resumed later in the day.

Oil processing at the refinery in 2023 averaged around 96,000 barrels per day, according to industry sources. The plant produces no motor fuels for the domestic market. Its production is limited to straight-run fractions for exports.

NORSI

A fire broke out at Norsi, Russia's fourth largest refinery, after a Ukrainian drone attack, Russian officials said on Tuesday. It is located near the city of Nizhny Novgorod, 430 kms (270 miles) east of Moscow.

Owned by Lukoil, its formal name is Lukoil Nizhegorodnefteorgsintez.

NORSI refines about 15.8 million tons of Russian crude a year (317,000 barrels per day), or 5.8% of total refined crude, according to industry sources.

Its main crude distillation unit (AVT-6) was damaged, which means that at least half of the refinery's production is halted, industry sources told Reuters.

In 2023 NORSI produced about 4.9 million tons of gasoline - 11% of Russia's total - 6.4% of diesel fuel, 5.6% of fuel oil and 7.4% of the country's aviation fuel, according to industry sources.

Lukoil said in January that it had halted a unit at the refinery due to an incident.

Industry sources said before the March 12 drone attack, one of two catalytic crackers remained out of action at the plant.

KIRISHI

The governor of the Leningrad region, Alexander Drozdenko, said on Tuesday that a Ukrainian drone had been destroyed on the outskirts of Kirishi, which is home to Surgutneftegaz's Kirishinefteorgsintez (KINEF) refinery.

The Kirishi refinery is one of the top two refineries in Russia. It refines about 17.7 million tons per year (355,000 barrels per day) of Russian crude, or 6.4% of the total, according to industry sources.

It produces about 2.3 million tons of gasoline - 5.3% of Russia's total - 7.6% of diesel fuel, 16.3% of fuel oil and 3.4% of the country's aviation fuel, according to industry sources. (Reporting by Reuters; Editing by Emelia Sithole-Matarise)