3. Introduction
• Reservoir: rock having sufficient porosity and permeability to store and transmit
fluids.
• Resource: Known to be the proof of Crude Oil
• Reserves: Can be produce or extract commercially
• Ultimate oil recovery depends on reservoir rock properties, fluid properties, current oil
prices, and reservoir heterogeneities.
• Reserves overview:
classification is based on various factor
1- Based on recovery method
• Primary reserves (crude can be produce by primary recovery)
• Secondary reserves (can be produced by secondary recovery)
• Tertiary reserves (produced by EOR)
4. Primary reserves classification
• Sub categorized in 3 types based on degree of certainty:
• Proved : can be produced (dc is greater then 65%)
• Probable: can be produced (dc greater than 50%)
• Possible: below 10% certainty
5. Proved Reserves Classification
• Based on their productivity status. Proved Reserves are classified into
3 types:
1- Developed
2- Developed-Non-Producing
3- Un-Developed
6. Reserves
• Reserves = petroleum initially in place * estimated recovery factor
• Recovery factor is defined as the ratio of recoverable oil volume over
original oil in place
• Recovery factor of an oil reservoir can be expressed in terms of
formation volume factors and saturations
• Saturation : pore volume occupied by a particular fluid in the
presence of other fluids.
• Formation volume factor : It is the ratio between the space occupied
by a barrel of oil containing solution gas at reservoir conditions and a
barrel of dead oil at surface conditions
7. Saturation classification
• Based on fluids:
• Oil saturation, Gas saturation, and water saturation
• Connate saturation: the saturation that cannot be recoverable by any
of recovery methods and it always remains in reservoir
• Irreducible saturation:
• Movable saturation= 1-Swc-Soc
• Residual saturation:
• The fluids remains after primary recovery mechanism
• Critical saturation:
• Minimum saturation required for a oil to flow
