UPDATE 1-Petrochina reports big shale gas additions in Sichuan basin

* Petrochina reports 740.97bln cubic metres of shale gas reserve

* Reports 358mln tonnes of reserve at Qingcheng oil field

* Says made breakthrough in unconventional oil, gas exploration (Adds details)

SINGAPORE, Sept 29 (Reuters) - Petrochina said on Sunday that certified, newly added proven shale gas geological reserves at Changning-Weiyuan and Taiyang blocks in the Sichuan basin totaled 740.97 billion cubic metres.

China’s state-run energy producers are raising spending on domestic oil and gas drilling to a multi-year high this year, answering Beijing’s call to boost energy supply security as import reliance soars amid an escalating trade war with the United States.

Petrochina released the latest estimates in a statement posted on the Shanghai stock exchange.

The company also said it had newly proven geological reserve at Qingcheng oil field in Ordos basin certified at 358 million tonnes.

PetroChina said the firm has made a breakthrough in unconventional oil and gas exploration. The newly proven reserves at both Qingcheng oilfield and the Sichuan shale gas blocks have been certified by the Ministry of Natural Resources.

Qingcheng has a total estimated geological reserve at 693 million tonnes, while the Sichuan shale gas blocks have a total proven geological reserve at 1.06 trillion cubic meters, the firm said.

Reporting by Aizhu Chen in Singpore Writing by Engen Tham in Shanghai; Editing by Kim Coghill