EXCLUSIVE UPDATE, 12:13 PM : Multiple sources tell me Peter Berg will replace JC Chandor and reteam with his Lone Survivor star Mark Wahlberg on Deepwater Horizon. Berg has a strong relationship with writer Matthew Michael Carnahan in The Kingdom and of course with Wahlberg on the hit heroic tale Lone Survivor.

PREVIOUS EXCLUSIVE, 11:43 AM: JC Chandor is leaving Deepwater Horizon, the Summit Entertainment pic detailing the true-story account of the devastating 2010 BP oil spill. This is happening very fast, but I hear there were creative differences, and now Summit’s Lionsgate will go out to directors very quickly on this — maybe as early as Monday — because producers want to stay on track for an April start of production.

Mark Wahlberg already is set to star and the film, from Participant Media and Lorenzo di Bonaventura’s di Bonaventura Pictures, already has a September 30, 2016 release date.

Names like Peter Berg — who directed Wahlberg in Lone Survivor and was once attached to this project — are being mentioned.

Chandor has a good relationship with Summit parent Lionsgate stemming from his debut Margin Call and All Is Lost, and with Participant on this year’s awards-season drama A Most Violent Year, which A24 is expanding in theaters beginning today. He came aboard Deepwater Horizon in July 2011. He has several projects he is building now, including a Vince Lombardi film for Legendary Pictures.

Wahlberg came aboard in August to play the No. 2 manager on the doomed oil rig in the story about what happened behind the scenes in the 48 hours leading up to and the day of the disaster. Based on the New York Times article “Deepwater Horizon’s Final Hour,” the pic highlights the courage of those who worked on the oil rig when it blew, killing 11 and injuring 16 others.

At the time of the casting, the project was targeting a late spring/early summer 2015 start.