# US 2018/0024266 A1 · Modular Resistivity Sensor for Downhole Measurement While Drilling

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- Number: US 2018/0024266 A1
- Document ID: US20180024266A1
- Status: Published application
- Kind: A1
- Application number: 15/466,220
- Filed: 2017-03-22
- Published: 2018-01-25
- Earliest claimed: 2013-06-18
- Assignees: Well Resolutions Technology
- Applicants: Well Resolutions Technology
- Inventors: Tsili Wang; Borislav J. Tchakarov
- Web page: https://patentgrep.com/patent/US20180024266A1

## CPC

- E21B 49/003: {by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00)}
- E21B 47/017: Protecting measuring instruments
- E21B 47/024: of devices in the borehole (determining slope or direction of the borehole E21B47/022)
- E21B 47/12: Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
- E21B 47/13: by electromagnetic energy, e.g. radio frequency
- G01V 3/00: Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V 3/28: using induction coils
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

A resistivity-measuring sensor disposable within a drillstring includes a sensor body having a longitudinal axis, wherein the sensor body is separable from and disposable in the drillstring at a radially offset distance from the longitudinal axis of the drillstring. The sensor further includes a transmitting antenna disposed along a length of the sensor body, a receiving antenna disposed along a length of the sensor body, and an electronics section contained within the sensor body for generating and receiving signals to and from the transmitting and receiving antennas.

## Claims

### Claim 1

A resistivity-measuring sensor disposable within a drillstring, the sensor comprising:
a sensor body having a longitudinal axis,
wherein the sensor body is separable from and disposable in the drillstring at a radially offset distance from the longitudinal axis of the drillstring;
a transmitting antenna disposed along a length of the sensor body;
a receiving antenna disposed along a length of the sensor body; and
an electronics section contained within the sensor body for generating and receiving signals to and from the transmitting and receiving antennas.

### Claim 2 (depends on 1)

The sensor of claim 1, wherein at least one antenna is configured to generate magnetic moments parallel with the longitudinal axis of the sensor body.

### Claim 3 (depends on 1)

The sensor of claim 1, wherein at least one antenna is configured to generate magnetic moments misaligned with the longitudinal axis of the sensor body.

### Claim 4 (depends on 1)

The sensor of claim 1, further comprising a calibrating device configured to calibrate signals generated from the receiving antennas.

### Claim 5 (depends on 4)

The sensor of claim 4, wherein the calibrating device comprises a signal generator configured to generate a voltage signal at a desired frequency.

### Claim 6 (depends on 4)

The sensor of claim 4, wherein the calibrating device comprises an antenna configured to generate a voltage signal at a desired frequency in the receiving antennas.

### Claim 7 (depends on 4)

The sensor of claim 4, wherein the calibrating device is substantially equally spaced between a pair of receiving antennas.

### Claim 8 (depends on 1)

The sensor of claim 1, wherein at least part of the sensor body comprises a non-conducting material.

### Claim 9 (depends on 1)

The sensor of claim 1, further comprising circumferential grooves in an outer surface of the sensor body, each groove having an insulating layer deposited therein on which the antennas are wound.

### Claim 10 (depends on 1)

The sensor of claim 1, further comprising a sensor cover that fits over the sensor body, wherein at least part of the sensor cover comprises a non-conducting material.

### Claim 11 (depends on 10)

The sensor of claim 10, wherein the sensor cover further comprises one or more slots aligned substantially along a direction of magnetic moments generated by respective antennas underneath.

### Claim 12 (depends on 1)

The sensor of claim 1, wherein a radially outermost surface of the sensor body is at a distance from the longitudinal axis of the drillstring substantially equal to or less than an outer diameter of the drillstring.

### Claim 13 (depends on 1)

The sensor of claim 1, further comprising a tool face measurement sensor configured to measure the angular position of the drillstring relative to the wellbore.

### Claim 14 (depends on 1)

The sensor of claim 1, further comprising multiple sensor bodies disposed in drillstring pockets, wherein electromagnetic signals are transmitted and received at multiple antennas on the multiple sensor bodies.