Oct 21 (Reuters) - Altus Midstream Co (ALTM.O) said on Thursday it would merge with BCP Raptor, the parent company of EagleClaw Midstream, in an all-stock deal to form the largest integrated midstream company in the Delaware Basin of Texas with an enterprise value of $9 billion. BCP"s unitholders, mainly funds affiliated with Blackstone(BX.N)and I Squared Capital, will own about 75% of the combined company. Apache Corp (APA.O) , an oil and gas producer and backer of Altus, will own about 20%, while 5% will be held by Altus" investors. The combined company will have natural gas processing capacity of 2 billion cubic feet per day located near the Waha Hub in West Texas. Natural gas prices have soared in recent months due to supply constraints and higher demand, raising the need for additional processing, gathering and storage infrastructure. The new management team will be led by current EagleClaw Midstream Chief Executive Officer Jamie Welch. The deal is expected to close during the first quarter of 2022.