DETERMINATION OF AZIMUTHAL OFFSET AND RADIUS OF CURVATURE IN A DEVIATED BOREHOLE USING PERIODIC DRILL STRING TORQUE MEASUREMENTS
First Claim
1. A method for obtaining a parameter of interest of a borehole segment in which a BHA is disposed, the method comprising:
- (a) determining azimuthal torque imparted to said BHA; and
(b) determining said parameter of interest from a periodic variation of said azimuthal torque over a rotation cycle of said BHA.
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Accused Products
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.
16 Citations
16 Claims
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1. A method for obtaining a parameter of interest of a borehole segment in which a BHA is disposed, the method comprising:
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(a) determining azimuthal torque imparted to said BHA; and (b) determining said parameter of interest from a periodic variation of said azimuthal torque over a rotation cycle of said BHA. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for obtaining azimuthal offset and radius of curvature of a borehole segment in which a BHA is disposed, the method comprising:
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(a) 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; (b) from said rotation rates, determining in said plurality of predetermined arcs azimuthal torques acting upon said BHA; (c) determining a difference of a maximum and a minimum of said torques over said at least one rotation cycle; (d) from angular positions of said maximum and minimum with respect to a reference angle, determining said azimuthal offset; and (e) from a magnitude of said difference of said maximum and minimum, determining said radius of curvature. - View Dependent Claims (10, 11, 12, 13)
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9. The method of claim 9 wherein said predetermined arc is about 2 degrees.
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14. A BHA comprising:
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(a) 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 (b) a processor disposed within said BHA cooperating with said sensor and programmed to (i) compute torques acting upon said BHA from said rotation rates in said plurality of predetermined arcs azimuthal; (ii) compute a difference of a maximum and a minimum of said torques over at least one rotation cycle; (iii) compute said azimuthal offset from angular positions of said maximum and minimum with respect to a reference angle; and (iv) compute said radius of curvature from a magnitude of said difference of said maximum and minimum. - View Dependent Claims (15, 16)
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Specification