Pay is an expression used in hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 mining

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

. 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

Permeability

Permeability, permeable and semipermeable may refer to:*Permeability , the degree of magnetization of a material in response to a magnetic field...

and hydrocarbon saturation) are net pay.