Pay is an expression used in
hydrocarbon mining. It denotes a portion of a reservoir that contains economically recoverable hydrocarbons. The term derives from the possibility of "paying" an income surpassing the costs. Equivalent terms are
pay sand or
pay zone. Overall interval in which pay volumes occur is the
gross pay; smaller portions of the reservoir that meet further criteria for pay (such as
permeability and hydrocarbon saturation) are
net pay.