Lost Oil in Migration
Oil lost in migration is the portion of petroleum that, after being generated in a source rock, migrates toward a reservoir but is lost along the way. This loss can occur due to various geological and physical processes. These losses affect the amount of oil that ultimately accumulates in the reservoir, impacting the potential yield of an oil field.
Here are some key reasons why oil might be lost during migration
- Absorption by Rock Formations - Some oil can be absorbed or adsorbed by porous rocks it encounters during migration.
- Trapping in Secondary Reservoirs - Oil might get trapped in smaller, less economically viable reservoirs before reaching the main reservoir.
- Biodegradation - Microbial activity can degrade oil during migration, especially in shallow and warmer environments.
- Dilution or Mixing with Water - Oil might mix with water or other fluids, leading to losses.
- Loss Through Faults and Fractures - Oil can escape through faults, fractures, or other discontinuities in the rock layers.
Oil Lost in Migration formula
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. |
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\( n_i \;=\; 7758 \cdot \dfrac{ A \cdot h \cdot n \cdot S }{ B_o } \) (Lost Oil in Migration) \( A \;=\; \dfrac{n_i \cdot B_o }{ 7758 \cdot h \cdot n \cdot S }\) \( h \;=\; \dfrac{n_i \cdot B_o }{ 7758 \cdot A \cdot n \cdot S } \) \( n \;=\; \dfrac{n_i \cdot B_o }{ 7758 \cdot A \cdot h \cdot S } \) \( S \;=\; \dfrac{n_i \cdot B_o }{ 7758 \cdot A \cdot h \cdot n} \) \( B_o \;=\; \dfrac{7758 \cdot S \cdot A \cdot h \cdot n }{ n_i } \) |
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| Symbol | English | Metric |
| \( n_i \) = Volume of Oil Lost | \(bbl\) | - |
| \( A \) = Average Area Cross-sectional of the Gas-Oil Contact | \(acres\) | - |
| \( h \) = Average Change in Depth of the Gas-Oil Contact | \(ft\) | - |
| \( n \) = Porosity | \(dimensionless\) | - |
| \( S \) = Residual Oil Saturation in The Gas Cap Shrinking Zone | \(dimensionless\) | - |
| \( B_o \) = Oil Formation Volume Factor at Abandonment | \(bbl \;/\; STB\) | - |
Tags: Reservoir