Russia is looking to expand its influence through oil trade. And a little-reported deal this week may give it access to an entirely new part of the planet when it comes to crude exports.

That's the Persian Gulf. Where reports suggest Russia is close to negotiating a "secret passage" for its oil shipments.

The move is coming through a deal with Iran, which that government says could open the door for crude oil swaps between the two countries -- facilitating exports of "Russian" oil out into Asia and beyond.

Iran's Deputy Petroleum Minister Amir Hossein Zamaninia told local press Monday that Russian energy company representatives will be arriving in Iran this week to discuss such a swap deal.

Here's how it would work.

Russia lacks access to ocean shipping routes beyond the Pacific and Arctic. Iran has better access, through its ports on the Persian Gulf.

But Russia does have ports on the Caspian Sea. And as the map below shows, that provides a short shipping route into Iran.

Russia and Iran can exchange crude oil shipments along the Caspian Sea