China and Russia are expected to sign a series of deals in the energy sector, strengthening the countries' economic ties, during President Xi Jinping's visit to Moscowon Friday.

Ahead of Xi's meeting with his Russian counterpart, Vladimir Putin, Chinese Vice-Premier Zhang Gaoli met with Arkady Dvorkovich, the Russian deputy prime minister, in late April in Beijing to discuss big projects in the oil, gas, coal and power industries.

Zhang, co-chairman of the China-Russia Energy Cooperation Committee, said the two countries should implement a long-term crude oil trade cooperation and a China-Russia eastern natural gas line project.

Negotiation of a western natural gas pipeline project, expanded cooperation in upstream oil projects and acceleration of a refinery joint venture in Tianjin are also actively under discussion, Zhang said.

"The energy sector has been at the top of the priority list of China and Russia's cooperation, especially as the United States has realized energy independence driven by its shale gas revolution, which has forced resources-rich Russia to turn to the eastern world, seeking a new market," said Han Xiaoping, chief information officer of the China Energy Net Consulting Co.

In November, Putin and Xi signed a 30-year contract for gas supply to China through the western route, making China the biggest consumer of Russian gas.

The new supply line comes in addition to a $400 billion deal between the countries, which will annually deliver 38 billion cubic meters of gas to China through the eastern route, starting in 2018.

China began construction of the eastern supply line route in September and plans to complete it by 2018.

Last year, China imported around 33 million metric tons of crude from Russia, according to Wind Information Co, a financial research provider. That is a 36 percent increase compared with the previous year.

"China and Russia's relationship is now at its best," said Pang Changwei, a professor with the China University of Petroleum.

In addition to natural gas and crude supply, China National Petroleum Corp, the country's largest energy producer, acquired a 20 percent stake in Novatek's major Arctic liquefied natural gas project in 2013. Novatek is Russia's largest independent natural gas producer.

Other State-owned giants, including China Petrochemical Corp and Shenhua Group, also have entered into several cooperation projects in petrochemical and coal exploration sectors with Russian companies.