PetroChina Co., the country’s biggest oil and natural gas producer, will buy Petroleo Brasileiro SA’s assets in Peru for $2.6 billion, expanding its portfolio in the region. The Beijing-based company will take over three blocks of oil and gas fields in Peru from the seller, known as Petrobras, it said in a statement to the Hong Kong stock exchange. Petrobras owns two blocks entirely and has a 46 percent stake in the third, according to the statement. Petrobras, the most indebted publicly traded oil company, has been selling assets to help finance projects in Brazil’s deep waters. China National Petroleum Corp., PetroChina’s state- owned parent, already owns oil and gas assets in Peru as well as in Venezuela. If approved, it will be Peru’s second-largest acquisition after Royal Dutch Shell Plc’s purchase of liquefied natural gas assets from Repsol SA in February for $4.4 billion, according to Bloomberg data. “This will help PetroChina diversify its assets internationally,” Gordon Kwan, a Hong Kong-based analyst at Nomura Holdings Inc., said in a phone interview today. “This will help them learn operating lessons from their partners that they can apply elsewhere.” PetroChina shares fell 2.4 percent to HK$8.50 at the close in Hong Kong today, taking their decline this year to 23 percent. The city’s benchmark Hang Seng Index dropped 1.9 percent. Petrobras was little changed at 19.55 reais in Sao Paulo at 12:43 p.m. local time.