The image above represents gas initially in place.

To compute for gas initially in place, five essential parameters are needed and these parameters are **drainage area (A), initial gas FVF (B _{gi}), initial water saturation (S_{wi}), porosity (φ) and thickness (h).**

The formula for calculating gas initially in place:

G = ^{43560Ah φ (1 – Swi)} / _{Bgi}

Where;

G = Gas Initially in Place

A = Drainage Area

B_{gi} = Initial Gas FVF

S_{wi} = Initial Water Saturation

φ = Porosity

h = Thickness

Let’s solve an example;

Find the gas initially in place with a drainage area of 44, initial gas FVF of 23, initial water saturation of 32, porosity of 18 and exponent of 14.

This implies that;

A = Drainage Area = 44

B_{gi} = Initial Gas FVF = 23

S_{wi} = Initial Water Saturation = 32

φ = Porosity = 18

h = Thickness = 14

G = ^{43560Ah φ (1 – Swi)} / _{Bgi}

G = ^{43560 x 44 x 14 x 18 (1 – 32)} / _{23}

G = ^{43560 x 44 x 14 x 18 (-31)} / _{23}

G = ^{-14972791680} / _{23}

G = -650990942.6

Therefore, the **gas initially in place **is **-650990942.6**