Acoustic coupler for downhole logging while drilling applications

Patent metadata

Field	Value
Publication number	US-2018347349-A1
Application number	US-201815991645-A
Country	US
Kind code	A1
Filing date	May 29, 2018
Priority date	May 31, 2017
Publication date	Dec 6, 2018
Grant date	—

Abstract

A deviated or horizontal wellbore is drilled in a geologic formation with a multiphase fluid including a gas by a rotating drill bit positioned at a downhole end of a drill string. Portions of the gas are released into the wellbore during the drilling. During the drilling, soundwaves are emitted into the geologic formation from within the wellbore by a set of acoustic emitters attached to the drill string. The received reflected soundwaves are transmitted by the set of solid acoustic couplers to a set of acoustic sensors contacting the solid acoustic couplers. The reflected soundwaves are received by the acoustic sensors. Rock properties of the geologic formation are determined based on the less attenuated reflected soundwaves transmitted to the acoustic sensors by the solid acoustic couplers. A drilling direction of the wellbore is adjusted based on the determined rock properties.

First claim

What is claimed is:

1 . A method comprising:
drilling, by a rotating drill bit positioned at a downhole end of a drill string, a deviated or horizontal wellbore in a geologic formation comprising a multiphase fluid comprising a gas, wherein portions of the gas are released into the wellbore during the drilling; and during the drilling:
emitting, by a plurality of acoustic emitters attached to the drill string, soundwaves into the geologic formation from within the wellbore,
receiving, by a plurality of solid acoustic couplers attached to the drill string, reflected soundwaves from the geologic formation, the reflected soundwaves carried from the geologic formation to the plurality of solid acoustic couplers at least in part through the portions of the gas released into the wellbore during the drilling,
transmitting, by the plurality of solid acoustic couplers, the received reflected soundwaves to a plurality of acoustic sensors contacting the plurality of solid acoustic couplers, wherein the reflected soundwaves transmitted by the plurality of solid acoustic couplers are less attenuated compared to the reflected soundwaves transmitted through the portions of the gas released into the wellbore during the drilling,
receiving, by the plurality of acoustic sensors, the reflected soundwaves transmitted by the plurality of solid acoustic couplers,
determining rock properties of the geologic formation based on the less attenuated reflected soundwaves transmitted to the plurality of acoustic sensors by the plurality of solid acoustic couplers, and
adjusting a drilling direction of the wellbore based on the determined rock properties.

2 . The method of claim 1 , wherein drilling the wellbore comprises drilling the wellbore in an underbalanced condition.

3 . The method of claim 1 , wherein the wellbore is less than 3 and ¾ inches in diameter.

4 . The method of claim 1 , wherein the drill string comprises coiled tubing.

5 . The method of claim 1 , wherein the plurality of solid acoustic couplers is a first plurality of solid acoustic couplers, wherein the method further comprises transmitting, by a second plurality of solid acoustic couplers contacting the plurality of acoustic transmitters and to the geologic formation, the soundwaves emitted by the plurality of acoustic transmitters.

6 . The method of claim 5 , wherein the first plurality of solid acoustic couplers have a different stiffness compared to the second plurality of solid acoustic couplers.

7 . The method of claim 6 , wherein the first plurality of solid acoustic couplers have less stiffness compared to the second plurality of solid acoustic couplers.

8 . The method of claim 1 , further comprising centralizing, by the plurality of solid acoustic couplers, the drill string in the wellbore.

9 . The method of claim 1 , wherein the plurality of solid acoustic couplers contact an inner wall of the wellbore to transmit the received reflected soundwaves to the plurality of acoustic sensors.

10 . The method of claim 1 , wherein the drilling direction of the wellbore is adjusted in real-time based on the determined rock properties of the geologic formation.

11 . A bottom hole assembly comprising:
a drill string configured to be placed in a wellbore, the drill string comprising coiled tubing; a drill bit positioned at a downhole end of the drill string, the drill bit configured to form the wellbore within a geologic formation; a drill motor positioned uphole of the drill bit, the drill motor configured to rotate the drill bit independent of the drill string; and an acoustic sub-assembly attached to the drill string, uphole of the drill motor, the acoustic sub assembly comprising:
a plurality of acoustic emitters, the plurality of acoustic emitters configured to emit emitted soundwaves into the geologic formation from within the wellbore;
a plurality of acoustic couplers configured to receive reflected soundwaves from the geologic formation within the wellbore, the reflected soundwaves being reflections of the emitted soundwaves; and
a plurality of acoustic sensors configured to be placed in the wellbore and attached to the plurality of acoustic couplers, the plurality of acoustic couplers configured to transmit the received reflected soundwaves from the geologic formation to the plurality of acoustic sensors with less signal attenuation compared to a direct transmission of the reflected soundwaves from the geologic formation to the plurality of acoustic sensors.

12 . The bottom hole assembly of claim 11 , wherein the plurality of acoustic coupler are sized to contact the acoustic sensor and to extend into an annulus formed by an inner wall of the wellbore and an outer surface of the acoustic sub-assembly.

13 . The bottom hole assembly of claim 11 , wherein the plurality of acoustic couplers are sized to contact an inner wall of the wellbore.

14 . The bottom hole assembly of claim 11 , wherein each of the plurality of acoustic couplers are radially separated from each other at 90 degree intervals.

Assignees

• Saudi Arabian Oil Co

Inventors

• Marsala Alberto F

Classifications

• E21B47/0224

  using seismic or acoustic means · CPC title

• E21B47/024

  of devices in the borehole (determining slope or direction of the borehole E21B47/022) · CPC title

• G01V1/52

  Structural details · CPC title

• E21B47/16 Primary

  through the drill string or casing {, e.g. by torsional acoustic waves} · CPC title

• E21B7/04

  Directional drilling · CPC title