Xog Operating, LLC and Geronimo Holding Corporation v. Chesapeake Exploration Limited Partnership and Chesapeake Exploration, L.L.C.

This case and a companion, Endeavor Energy Resources, L.P. v. Discovery Operating, Inc. , 1 also decided today, require us to interpret retained-acreage provisions in oil-and-gas lease instruments. We lay out more fully in Endeavor the regulatory and industry contexts in which the provisions are used and the principles that guide our analysis. Each case turns on the text of the retained-acreage provision at issue. In Endeavor , we hold that "a governmental proration unit assigned to a well" refers to acreage assigned by the operator, not by field rules. 2 Here, we hold that acreage "included…