Which of the following methods is used to collect oil samples from a reservoir?

Which of the following methods is used to collect oil samples from a reservoir?

• A. Bottom Hole Sample
• B. Separator Sample
• C. Core Sample
• D. Mud Sample

Answer: (A)

Collecting an oil sample from a reservoir means obtaining fluid directly from inside the well so it reflects the conditions in the formation. This is done with bottom-hole sampling tools during drilling or testing, which pull a sample from the formation at or near formation pressure and temperature. Because the sample stays at reservoir-like conditions, its properties—such as composition, API gravity, viscosity, and gas-oil ratio—are representative of what exists underground and are suitable for PVT and reservoir calculations. Other options don’t capture the reservoir fluid in its native state: a separator sample is taken after the oil has been separated at the surface, which alters its composition; a core sample is a rock piece used for geological and petrophysical studies; a mud sample is taken from the drilling fluid and informs about drilling conditions, not the reservoir oil itself.

Collecting an oil sample from a reservoir means obtaining fluid directly from inside the well so it reflects the conditions in the formation. This is done with bottom-hole sampling tools during drilling or testing, which pull a sample from the formation at or near formation pressure and temperature. Because the sample stays at reservoir-like conditions, its properties—such as composition, API gravity, viscosity, and gas-oil ratio—are representative of what exists underground and are suitable for PVT and reservoir calculations. Other options don’t capture the reservoir fluid in its native state: a separator sample is taken after the oil has been separated at the surface, which alters its composition; a core sample is a rock piece used for geological and petrophysical studies; a mud sample is taken from the drilling fluid and informs about drilling conditions, not the reservoir oil itself.