Downhole sensor assembly for alignment measurement
AssigneeScientific Drilling International, Inc.
InventorsCarsten FREYER, Karsten ZEISKE
Life of this patent
Estimating the term…
Abstract
A downhole alignment tool includes a guidance device, the guidance device having a center and a reference mark and a downhole sensor assembly, the downhole sensor assembly attached or positioned within the guidance device. The guidance device includes electronics, the electronics including an oscillator, an evaluation unit, and an output stage. A sensor detects a signal supplied to the evaluation unit for determining orientation of the reference mark relative to an object, such as another wellbore or casing.
Claims20
A downhole alignment tool, comprising:
- a guidance device to direct orientation of well operations;
- and
- a downhole sensor assembly coupled to the guidance device, wherein the downhole sensor assembly includes:
- first, second, third and fourth exciting coils displaced from one another in an arch arrangement having a midpoint with the first and second exciting coils on a first side of the midpoint and the third and fourth exciting coils on a second side of the midpoint;
- a sensing coil;
- oscillator electronics that energize the exciting coils such that a first electromagnetic field from the first and fourth exciting coils is out of phase with a second electromagnetic field from the second and third exciting coils;
- and
- an evaluation unit that uses the sensing coil to detect a signal phase and amplitude resulting from the electromagnetic fields to determine distance from an object based on the signal amplitude and angular orientation relative to the object based on the signal phase.
A method, comprising:
- supplying a downhole alignment tool comprising:
- a guidance device, the guidance device having a center and a reference mark;
- and
- a downhole sensor assembly, the downhole sensor assembly coupled to the guidance device, wherein the downhole sensor assembly includes:
- an oscillator;
- a first sensor;
- and
- a second sensor, the first and second sensors separated by a 45° to 120° angle, the 45° to 120° angle measured from the center of the guidance device;
- supplying power to the oscillator resulting in an electromagnetic field and causing a signal at the first sensor and the second sensor;
- measuring the signal strength at the first sensor and the second sensor;
- and
- determining the angle between the reference mark and a casing circle point based on the signal strength at the first sensor and the second sensor.
A downhole alignment tool, comprising:
- a guidance device having a center and a reference mark in-line with a casing mill exit point of the guidance device;
- and
- a downhole sensor assembly coupled to the guidance device, wherein the downhole sensor assembly includes:
- an oscillator to create an electromagnetic field;
- a first sensor to detect strength of the electromagnetic field;
- a second sensor to detect strength of the electromagnetic field, the first and second sensors separated by a 45° to 120° angle, the 45° to 120° angle measured from the center of the guidance device;
- and
- an evaluation unit to compare signals from the first and second sensors, wherein the evaluation unit determines the reference mark is aligned with a center of a proximate wellbore when the signals of the first and second sensors match.
Dependencies are inferred from the claim text.