MEXICO CITY, Jan 20 (Reuters) - Mexican state oil company Petroleos Mexicanos (Pemex) will on Thursday take control of the Deer Park refinery in Texas, after concluding the purchase of Royal Dutch Shell's half of that plant, two people familiar with the matter said.

Pemex and Shell in May announced the transaction, which is worth almost $600 million and will make the Mexican firm the sole owner of the refinery in Houston. The facility has a capacity to process 340,000 barrels per day (bpd).

"The formal event will take place at around noon on Thursday in Texas," one of the sources said.

Pemex Chief Executive Officer Octavio Romero is on site for the handover, the sources said.

The Mexican company did not immediately respond to a request for comment on the handover, which Reuters reported last week.

After mentioning Pemex's purchase of Deer Park, Mexican President Andres Manuel Lopez Obrador told a news conference on Thursday that he would on Friday announce some "very good news" on energy matters, without providing details.

The sources said the Mexican side carried out the transaction as agreed: $596 million for the refinery's assets - equivalent to Shell's 50% stake in the joint venture's debt - as well as the liquidation of the $596 million that made up Pemex's stake in the refinery. (Reporting by Ana Isabel Martinez Editing by Paul Simao)