Williams Partners LP (WPZ) agreed late Tuesday to expand its business venture in the Utica Shale with Caiman Energy II by funding almost half of a midstream infrastructure development in Ohio and northwestern Pennsylvania.

About $800 million is slated to be spent to develop natural gas, natural gas liquids (NGL) and crude oil infrastructure by Caiman and WPZ, and their partners EnCap Flatrock Midstream of San Antonio and Highstar Capital of New York. WPZ has agreed to fund $380 million of the total.

“This new midstream venture can leverage the commercial relationships and success of Caiman’s management and investors, along with Williams Partners’ long experience in successfully constructing and reliably operating large-scale midstream infrastructure,” said Williams CEO Alan Armstrong. Williams owns 72% of WPZ.

WPZ and Caiman already have a business relationship in Appalachia. In March WPZ paid $2.5 billion to buy Caiman’s midstream business to give it a bigger footprint in northern West Virginia, southwestern Pennsylvania and eastern Ohio (see Shale Daily, March 20). At that time the companies established the partnership to build a Utica midstream business.

WPZ now has a gathering system and processing facility that is being expanded to serve producers in the Ohio Valley in northern West Virginia, southwestern Pennsylvania and eastern Ohio. In addition, construction is under way on fractionation and additional processing facilities, and there are plans to construct NGL pipelines.