Formation evaluation using estimated borehole tool position
AssigneeBaker Hughes Incorporated
InventorsGamal A. Hassan, Philip L. Kurkoski, Pingjun Guo
Life of this patent
Estimating the term…
Abstract
Caliper measurements made during rotation of a bottomhole assembly are processed to estimate the location of the BHA, and size and shape of the borehole. A piecewise elliptical fitting procedure may be used. These estimates may be used to correct measurements made by a standoff-sensitive formation evaluation sensor such as a neutron porosity tool.
Claims19
A method of evaluating an earth formation, the method comprising:
- conveying a bottomhole assembly (BHA) into a borehole;
- making measurements during rotation and a lateral displacement of the BHA of a distance to a wall of the borehole;
- processing the measurements of the distance to the borehole wall to estimate a geometry of the borehole and a location of the BHA in the borehole including the lateral displacement;
- and
- estimating a value of a property of the earth formation using a formation evaluation (FE) sensor, the estimated geometry and the estimated location of the BHA;
- wherein the measurements are specified in a tool-centered polar coordinate system and wherein estimating the geometry of the borehole and the location of the BHA in the borehole further comprises performing a least squares fit in a Cartesian coordinate system.
An apparatus configured to evaluate an earth formation, the apparatus comprising:
- a bottomhole assembly (BHA) configured to be conveyed into a borehole;
- a caliper configured to make measurements during rotation and a lateral displacement of the BHA of a distance to a wall of the borehole;
- a formation evaluation (FE) sensor configured to make a measurement of a property of the earth formation;
- and
- at least one processor configured to:
- use the measurements of the distance to the borehole wall to estimate a geometry of the borehole and a location of the BHA in the borehole including the lateral displacement, and
- estimate a value of the property of the earth formation using the measurement of the FE sensor, the estimated geometry and the estimated location of the BHA;
- wherein the measurements are specified in a tool-centered polar coordinate system and
- wherein the processor is configured to estimate the geometry of the borehole and the location of the BHA in the borehole by performing a least squares fit in a Cartesian coordinate system.
A computer readable medium accessible to a processor, the computer-readable medium including instructions which enable the processor to:
- convey a bottomhole assembly (BHA) into a borehole;
- make measurements during rotation and a lateral displacement of the BHA of a distance to a wall of the borehole;
- process the measurements of the distance to the borehole wall to estimate a geometry of the borehole and a location of the BHA in the borehole including the lateral displacement;
- and
- estimate a value of a property of the earth formation using a formation evaluation (FE) sensor, the estimated geometry and the estimated location of the BHA;
- wherein the measurements are specified in a tool-centered polar coordinate system and wherein estimating the geometry of the borehole and the location of the BHA in the borehole further comprises performing a least squares fit in a Cartesian coordinate system.
Dependencies are inferred from the claim text.