PetroChina and Calgary-based Encana have abandoned plans for a joint venture to develop a large shale gas deposit in western Canada, marking the latest in a series of retreats by Chinese companies from proposed natural resource deals overseas.

PetroChina’s investment, set at $5.4bn when the deal was unveiled in February, would have been China’s biggest investment in Canada’s energy sector. It would also have been its largest in shale gas, a type of natural gas deposit that is difficult to extract and for which Chinese companies want to master the technology.

Encana said on Tuesday that after a year of talks with Petro-China “there were different views on various key components” of the deal, including the joint operating agreement determining the responsibilities of each company. It declined to elaborate, citing a confidentiality agreement.