1. Top Structure: Choose a horizon or specify a constant to define the top of the structure. If a horizon is chosen, an offset distance (TVD) can be added. The horizon must be in depth or convertible to depth (see How it Works (Time-Depth Conversion)).
2. Base Structure: ("Dual" case only). Choose a horizon or specify a constant to define the base of the structure.
3. Contact(s): Choose Horizon, Constant, or Multiple Constants to define the contact.
   • Horizon: a horizon with optional depth offset
   • Constant: a depth value (TVDSS)
   • Multiple Constants: one or more depth values (separated by commas) AND/OR a sequence (as min-max[step] format).
     • e.g. 1000.0 - 1400.0 [100.0]
     • e.g. 1100, 1275, 1300 - 1400 [50]

Note: All volumes are from the top of the structure to contacts. Subtract the lesser volume from the larger volume to get the volume between contacts.

4. Units: Choose the units to use for the output, including oil and/or gas volumes if Oil and/or Gas ratios are provided.
5. Polygon: Constrain the area of calculation with a map polygon. If a polygon is not selected, the area is defined by the entire horizon.
   • A polygon must be selected if constants are used for the structure and contact(s).

Note: Volumetrics calculates the Gross Rock Volume (GRV) unless the following parameters are specified.

For the remaining parameters, provide a single constant or a horizon to define a spatially varying value. Porosity and Water Saturation are interpreted as ratios (0 to 1) or as percentages (0 to 100) if any value in the horizon is greater that 1.

• Provide Net/Gross Ratio to calculate net volume. Valid range: 0.0 to 1.0.
• Provide Porosity to calculate pore volume. Valid range: 0.0 to 1.0 (or 0.0 to 100.0).
• Provide Water Saturation to calculate hydrocarbon volume. Valid range: 0.0 to 1.0 (or 0.0 to 100.0).
• Provide Oil Formation Volume Factor (also called shrinkage factor), to calculate stock tank oil originally/initially in place (STOOIP/STOIIP). This parameter converts the volume of oil at reservoir conditions to the volume at the surface. The value varies depending on the fluid and the temperature and pressure of the reservoir and the surface. Typical values are from 1 to 1.7.
• Provide Oil Recovery Factor to calculate estimated ultimate recovery (EUR) volume. Valid range: 0.0 to 1.0.
• Provide Gas Formation Volume Factor, to calculate original gas in place (OGIP/GIIP). This parameter converts the volume of gas in the reservoir into the volume at the surface. The value varies depending on the fluid and the temperature and pressure of the reservoir and the surface. Typical values are below 0.1.
• Provide Gas Recovery Factor to calculate estimated ultimate recovery (EUR) volume. Valid range: 0.0 to 1.0.

Note: If a horizon is provided as the structure or contact, the horizons must all be consistent. For example, if a horizon has an undefined location, each horizon provided must have the same undefined location within the polygon (if selected).

Click Next to perform the volumetrics calculation.