# Oil in Place

on . Posted in Reservoir Engineering

Oil in place, abbreviated as OIP, is the total quantity of crude oil that is originally found in a subsurface reservoir.  It encompasses all the oil contained in the rock formations within a specific reservoir, regardless of whether it can be technically or economically recovered.  Determining the reservoir oil in place is crucial for understanding the potential productivity of an oil field and involves a combination of geological, petrophysical, and engineering data.

### OIP is generally categorized as

• Original Oil in Place (OOIP)  -  This is the total amount of oil present in the reservoir before any production starts.
• Remaining Oil in Place (ROIP)  -  This refers to the amount of oil left in the reservoir after some production has occurred.

### Oil in Place formula

• 7758 = conversion factor from acre-ft to bbl
• STB (stock tank barrel) is the same volume defined at some surface standard conditions in a stock tank, which are usually 60°F and 14.7 psi.

$$OIP \;=\; 7758 \; A \; h \; n \; (1 - W_s ) \;/\; B_o$$     (Oil in Place)

$$A \;=\; OIP \; B_o \;/\; 7758 \; h \; n \; (1 - W_s )$$

$$h \;=\; OIP \; B_o \;/\; 7758 \; A \; n \; (1 - W_s )$$

$$n \;=\; OIP \; B_o \;/\; 7758 \; A \; h \; (1 - W_s )$$

$$W_s \;=\; 1 - ( OIP \; B_o \;/\; 7758 \; A \; h \; n )$$

$$B_o \;=\; 7758 \; A \; h \; n \; (1 - W_s ) \;/\; OIP$$

Symbol English Metric
$$OIP$$ = Oil in Place $$bbl$$ -
$$A$$ = Reservoir Area, acres from map data $$acre$$ -
$$h$$ = Reservoir Thickness $$ft$$ -
$$n$$ = Porosity $$dimensionless$$ -
$$W_s$$ = Water Saturation $$dimensionless$$ -
$$B_o$$ = Oil Formation Volume Factor (barrels of oil per barrel of reservoir oil) $$bbl \;/\; STB$$ -

Tags: Soil Reservoir