Quicksilver Resources Inc. (NYSE: KWK) announced May 1that it closed the sale of its Sand Wash Basin assets in Colorado to Southwestern Energy Co. (NYSE: SWN) for $180 million.

Southwestern's wholly owned subsidiary, Southwestern Energy Production Co., signed a purchase agreement for 312,000 net acres targeting the Niobrara formation in northwest Colorado from Quicksilver and SWEPI LP, a wholly owned subsidiary of Royal Dutch Shell Plc (NYSE: RDS-A, RDS-B). This marks the Houston-based company's entry into the Niobrara play.

Quicksilver received total cash proceeds of $93.5 million per the conditions as set forth in the purchase and sale agreement, which includes a deposit of $4.5 million received on March 4 when the agreement was executed.

The effective date of the sale is January 1. Quicksilver's first-quarter 2014 results will not include the impact of this transaction, as the sale to Southwestern Energy was reflected on the date proceeds were received, in accordance with accounting rules. The sale is not expected to create income effects.

Based in Fort Worth, Texas, Quicksilver has operations in Texas and in Canada through its Calgary-based subsidiary Quicksilver Resources Canada Inc.