Encana Corp. (NYSE: ECA) on Jan. 9 estimated fourth-quarter production from its core assets would top its own forecast, helped by the Canadian oil and gas producer's efforts to revamp its business.

The company—in the middle of a five-year plan to boost its output growth rate—has benefited from focusing on four core North American basins: the Montney and Duvernay shales in Canada, and the Eagle Ford Shale and Permian Basin in the U.S.

Calgary, Alberta-based Encana said it estimates production from these assets increased about 31% in the three months ended December, topping the forecast of a 25% to 30% rise it gave in September.

That would imply Encana's production from these core assets rose to 310,601 barrels of oil equivalent per day (boe/d) in the latest quarter, from 237,100 boe/d a year earlier.

Encana also forecast production from these assets would increase between 25% and 35% in the fourth quarter this year without the company spending more than it did last year.

Oil investors have been pressuring producers to improve production without increasing their capital budgets.

Encana said it plans to invest almost all its anticipated 2018 capital in these four core assets, with around 70% directed towards the Permian and Montney basins.

Last year, Encana spent around $1.8 billion in developing its assets. The company will report full fourth-quarter results on Feb 15.