Method of Measuring and Imaging RXO (Near Wellbore Resistivity) Using Transient EM
AssigneeBaker Hughes Incorporated
InventorGregory B. Itskovich
Life of this patent
Estimating the term…
Abstract
A transient electromagnetic wave is generated using an electromagnetic instrument in a borehole. An apparent resistivity is estimated using a received signal responsive to the generated wave and further used to estimate a resistivity property of a fluid in the borehole.
Claims20
A method of estimating a property of an earth formation, the method comprising:
- changing a current through a transmitter on an electromagnetic instrument conveyed in a borehole and inducing a current in the formation;
- receiving a transient signal resulting from the induced current in at least one receiver;
- estimating an apparent resistivity of the earth formation from the received signal;
- and
- estimating from the apparent resistivity a resistivity property of a fluid in the borehole.
An apparatus configured to estimate a property of an earth formation, the apparatus comprising:
- an electromagnetic instrument configured to be conveyed in a borehole in the earth formation;
- and
- at least one processor configured to:
- (A) change a current through a transmitter on the electromagnetic instrument and induce a signal in the formation;
- (B) estimate an apparent resistivity of the earth formation from a received signal resulting from the induced signal;
- and
- (C) estimate from the apparent resistivity a resistivity property of a fluid in the borehole.
A computer-readable medium accessible to a processor, the computer-readable medium including instructions which enable the processor to:
- estimate an apparent resistivity of an earth formation using a signal measured by an electromagnetic instrument in a borehole resulting from a change of a current through a transmitter on the electromagnetic instrument;
- and
- use the estimated apparent resistivity to estimate a resistivity property of a fluid in the borehole.
The medium of claim 20 further comprising at least one of:
- (i) a magnetic medium, (ii) a RAM, (iii) a ROM, (iv) an EPROM, (v) an EAROM, (vi) a flash memory, and (vii) an optical disk.
Dependencies are inferred from the claim text.