Changes

The product ''A'' × ''H'' is the reservoir bulk volume, and the product ''A'' × ''H'' × ϕ is the reservoir pore volume. The general determination of bulk reservoir volume involves mapping reservoir area in plan view and mapping net pay in terms of true vertical thickness to provide a common presentation of dipping beds or deviated wells. An [[Subsurface maps#Isochore|isochore]] map of net pay should be contoured using well control points and interpolated or extrapolated using available seismic and well test data and the geologist's interpretation of [[Depositional environments|depositional]] and [[Diagenesis|diagenetic]] history.

The product ''A'' × ''H'' is the reservoir bulk volume, and the product ''A'' × ''H'' × ϕ is the reservoir pore volume. The general determination of bulk reservoir volume involves mapping reservoir area in plan view and mapping net pay in terms of true vertical thickness to provide a common presentation of dipping beds or deviated wells. An [[Subsurface maps#Isochore|isochore]] map of net pay should be contoured using well control points and interpolated or extrapolated using available seismic and well test data and the geologist's interpretation of [[Depositional environments|depositional]] and [[Diagenesis|diagenetic]] history.

“Net” pay (see [[Effective pay determination]]) implies that some formation thickness has been excluded from consideration by either (1) occurring below an [[Fluid contacts|oil-water contact]] (or above a gas-water contact), or (2) having porosity and/or [[permeability]] values below a “cutoff” limit for productivity. Not all net pay is necessarily productive at a given well spacing. Discontinuous productive horizons between wells might be described, for example, by the concept of net pay to net connected pay ratio.<ref name=pt06r103>Poston, S. W., 1987, [https://www.onepetro.org/book/peh/spe-1987-36-peh Development plan for oil and gas reservoirs], in Bradley, H. B., ed., Petroleum Engineering Handbook: Richardson, TX, Society of Petroleum Engineers, p. 36-1–36-11.</ref>

“Net” pay (see [[Effective pay determination]]) implies that some formation thickness has been excluded from consideration by either (1) occurring below an [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=oil-water+contact oil-water contact] (or above a [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=gas-water+contact gas-water contact]), or (2) having porosity and/or [[permeability]] values below a “cutoff” limit for productivity. Not all net pay is necessarily productive at a given well spacing. Discontinuous productive horizons between wells might be described, for example, by the concept of net pay to net connected pay ratio.<ref name=pt06r103>Poston, S. W., 1987, [https://www.onepetro.org/book/peh/spe-1987-36-peh Development plan for oil and gas reservoirs], in Bradley, H. B., ed., Petroleum Engineering Handbook: Richardson, TX, Society of Petroleum Engineers, p. 36-1–36-11.</ref>

===Porosity===

===Porosity===