Jan 22 (Reuters) - Saudi Arabia's state oil company

Aramco bought its first cargo of WTI Midland, a U.S.

crude oil grade that underpins the global Brent benchmark,

oil-index publisher S&P Global Commodity Insights said on

Wednesday.

Aramco, the world's largest oil firm, snapped up the cargo

on Tuesday in the so-called Platts trading window, buying from

trading firm Gunvor. Platts is a division of S&P Global.

This was Aramco's first WTI purchase in the window, said

Joel Hanley, global director of crude and fuel oil markets at

S&P, via email on Wednesday. Aramco declined to comment.

More players have become involved in trading crude that can

set the Brent price via Platts since it added WTI to the

benchmark in 2023. Aramco, which has been expanding its trading

activity, first traded WTI last February, as a seller.

"National oil companies are building up trading activity to

gather information and top up income," said Adi Imsirovic,

director at consultant Surrey Clean Energy and a veteran oil

trader who has written extensively on Brent.

"Aramco has clearly made a decision to get more involved in

trading - we will see more and more of this."

Aramco CEO Amin Nasser told Reuters on the sidelines of

the World Economic Forum in Davos on Tuesday he sees the oil

market as healthy and expects an additional 1.3 million barrels

per day of demand this year.

WTI Midland is one of six crude oil grades assessed by

Platts that can set the value of dated Brent, part of the wider

Brent complex used to price more than three-quarters of the

world's traded oil.

The dated Brent price is set by the cheapest of the six

crudes and Midland, the largest of the six streams, often plays

a role in setting its value. The other five are North Sea

crudes.