Wellbore caliper measurement method using measurements from a gamma-gamma density
AssigneeSchlumberger Technology Corporation
InventorsDarwin V. Ellis, Mohammed Doghmi
Life of this patent
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Abstract
Methods are disclosed for determining the standoff of a well logging instrument from the wall of a wellbore and the shape of the wellbore itself. The methods include measuring a compensated gamma-gamma formation density at a rotary orientation proximate a bottom of the wellbore, and measuring an apparent density at at least one other rotary orientation. The apparent density is related to the compensated density, a density of a fluid disposed between the logging instrument and a wall of the wellbore, and the standoff. Repeated measurements at a plurality of axial positions along the wellbore provide a log of the wellbore.
Claims20
A method for determining a standoff of a well logging instrument from a wall of an earth formation wellbore, comprising:
- measuring a compensated formation density at a rotary orientation proximate a bottom of the wellbore;
- measuring an apparent formation density at at least one other rotary orientation about the wellbore;
- measuring a density of a fluid disposed between the logging instrument and a wall of the wellbore;
- and
- relating the apparent formation density, the compensated formation density, and the density of the fluid to determine the standoff.
A method for determining a shape of a wellbore, comprising:
- measuring a compensated formation density at a rotary orientation proximate a bottom of the wellbore;
- measuring an apparent formation density at at least one other rotary orientation about the wellbore;
- measuring a density of a fluid disposed between the logging instrument and a wall of the wellbore;
- relating the apparent formation density, the compensated formation density, and the density of the fluid to determine the standoff;
- and
- combining the standoff with a diameter of a well logging instrument used to make the density measurements to determine the shape of the wellbore.
A method for logging a wellbore, comprising:
- inserting a density well logging instrument into a wellbore;
- measuring a compensated formation density at a rotary orientation proximate a bottom of the wellbore;
- measuring an apparent formation density at at least one other rotary orientation about the wellbore;
- measuring a density of a fluid disposed between the logging instrument and a wall of the wellbore;
- relating the apparent formation density, the compensated formation density, and the density or the fluid to determine the standoff;
- combining the standoff with a diameter of a well logging instrument used to make the density measurements to determine the shape of the wellbore;
- moving the instrument axially along the wellbore;
- and
- repeating the measuring at the at least one rotary orientation, the measuring at the at least one other rotary orientation and the combining at a plurality of axial positions along the wellbore.
Dependencies are inferred from the claim text.