Determination of azimuthal offset and radius of curvature in a deviated borehole using periodic drill string torque measurements
AssigneePrecision Energy Services, Inc.
InventorSteven Reid Farley
Life of this patent
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Abstract
Methods and apparatus for determining the direction of borehole azimuthal offset and the borehole radius of curvature. Rotation rate of a borehole assembly is measured and mathematically converted into azimuthal torque imparted to the borehole assembly. Relative azimuthal offset is determined from variations in azimuthal torque over a rotation cycle of the borehole assembly. Relative radius of curvature is obtained from the magnitude of azimuthal torque over a rotation cycle. Relative azimuthal offset is converted to true azimuthal offset using an independent reference angle measurement. Relative borehole curvature is converted to true radius of curvature using a calibration constant determined in known borehole conditions.
Claims13
A method for obtaining a parameter of interest of a borehole segment in which a borehole assembly (BHA) is disposed, the method comprising:
- determining azimuthal torque imparted to said BHA;
- and
- determining said parameter of interest from a periodic variation of said azimuthal torque over a rotation cycle of said BHA;
- wherein
- said azimuthal torque is computed within said BHA using a response of a rotation rate sensor disposed within said BHA;
- said parameter of interest is relative direction of azimuthal offset of said BHA;
- and
- said relative direction of azimuthal offset is determined from maxima and minima in said periodic variations of said azimuthal torque over said rotation cycle of said BHA.
A method for obtaining azimuthal offset and radius of curvature of a borehole segment in which a borehole assembly (BHA) is disposed, the method comprising:
- determining, over at least one rotation cycle and in a plurality of predetermined arcs, rotation rates of said BHA using a sensor disposed within said BHA;
- from said rotation rates, determining in said plurality of predetermined arcs azimuthal torques acting upon said BHA;
- determining a difference of a maximum and a minimum of said torques over said at least one rotation cycle;
- from angular positions of said maximum and minimum with respect to a reference angle, determining said azimuthal offset;
- and
- from a magnitude of said difference of said maximum and minimum, determining said radius of curvature.
A borehole assembly (BHA) comprising:
- a sensor for measuring rotation rates of said BHA in a plurality of predetermined arcs in a segment of borehole in which said BHA is disposed;
- and
- a processor disposed within said BHA cooperating with said sensor and programmed to
- compute torques acting upon said BHA from said rotation rates in said plurality of predetermined arcs;
- compute a difference of a maximum and a minimum of said torques over at least one rotation cycle;
- compute azimuthal offset from angular positions of said maximum and minimum with respect to a reference angle;
- and
- compute radius of curvature from a magnitude of said difference of said maximum and minimum.
Dependencies are inferred from the claim text.