The deal represents a doubling down by Ovintiv on the Permian, where exploration in many areas still promises lucrative returns.
Ovintiv will pay cash and also use some of its stock as currency for the deal, the sources said.
If the negotiations conclude successfully, a deal could be announced as early as this week, the sources said, cautioning that no deal is certain.
The deal will boost the percentage of Ovintiv's production coming from oil, at a time of low natural gas prices.
The deal comes as EnCap is attempting to raise a new fund focused on investments in oil and gas production, its first since 2017, sources told Reuters in November.