Downhole closed loop drilling system with depth measurement

Patent metadata

Field	Value
Publication number	US-9963936-B2
Application number	US-201314049430-A
Country	US
Kind code	B2
Filing date	Oct 9, 2013
Priority date	Oct 9, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A method, system and drilling apparatus for directional drilling are disclosed. A drill bit is located at a downhole end of a drill string in a borehole. A length of the borehole between a surface location and the drill bit at the downhole end of a drill string is determined and an azimuth angle and inclination of the drill bit is obtained. The length of the borehole may be determined by recording an arrival time at a downhole location of an acoustic pulse travelling from a surface location to the downhole location and determines the travel time and borehole length therefrom. A downhole processor determines a position and orientation of the drill bit from the determined length, azimuth angle and inclination and alters a steering parameter of the drill bit using the determined position and orientation of the drill bit to obtain a selected trajectory for drilling the borehole.

First claim

What is claimed is:

1. A system for drilling a borehole, comprising:
a drill string including acoustic reflectors and an acoustic impedance, the drill string having a drill bit at a downhole end;
an acoustic transmitter at a surface location that generates periodically spaced acoustic pulses in the drill string;
a surface location clock for providing a time to the acoustic transmitter to generate the acoustic pulses;
a downhole clock at the downhole end of the drill string configured to record arrival times of the acoustic pulses at the downhole end; and
a downhole processor configured to:
calculate travel times of the acoustic pulses using the recorded arrival times and without referring to generation times from the surface location clock,
determine a length of the drill string using the calculated travel times,
correct the determined length using a known acoustic impedance of the drill string,
determine a position and orientation of the drill bit using the corrected length and an obtained azimuth angle and inclination of the drill bit, and
alter a steering parameter of the drill bit using the determined position and orientation of the drill bit to obtain a selected trajectory of the borehole, wherein the selected trajectory is determined at the downhole processor using in-situ formation measurements obtained downhole.

2. The system of claim 1 , wherein the selected trajectory further comprises at least one of: (i) a preselected trajectory stored in a downhole memory location; and (ii) a trajectory determined using a formation model stored at the downhole memory location and the determined position and orientation of the drill bit.

3. The system of claim 1 , wherein the processor is further configured to determine the length of the drill string by obtaining travel times for the generated acoustic pulses to traverse the drill string from the surface location to the downhole end.

4. The system of claim 3 , wherein the acoustic transmitter generates the acoustic pulses at a scheduled time and wherein the downhole processor is further configured to obtain the travel times using the recorded arrival times and a known schedule for generating the acoustic pulses.

5. The system of claim 3 , wherein the downhole processor is further configured to determine the position of the drill bit using the obtained travel time and a known previous position and previous orientation of the drill bit.

6. The system of claim 1 , wherein a surface clock used for controlling generation of the acoustic pulse at the acoustic transmitter is synchronized with the downhole clock.

7. The system of claim 1 , wherein the downhole processor is further configured to perform calculations for altering the steering parameter of the drill bit without receiving instructions from an operator or a processor at the surface location.

8. A drilling apparatus, comprising:
a drill string including acoustic reflectors and an acoustic impedance in a borehole;
a drill bit at a downhole end of the drill string;
an acoustic transmitter at a surface location that generates periodically spaced acoustic pulses in the drill string;
a surface location clock for providing a time to the acoustic transmitter to generate the acoustic pulses;
a receiver at the downhole end of the drill string configured to receive the acoustic pulses;
a downhole clock configured to generate time stamps when the acoustic pulses are received at the downhole receiver; and
a downhole processor configured to:
calculate travel times of the acoustic pulses using the time stamps and without referring to generation times of the acoustic pulses from the surface location clock,
determine a length of the drill string using the calculated travel times,
correct the determined length using a known acoustic impedance of the drill string,
determine a position and orientation of the drill bit using the corrected length, a obtained azimuth angle of the drill bit and an obtained inclination of the drill bit, and
alter a steering parameter of the drill bit using the determined position and orientation of the drill bit to obtain a selected trajectory, wherein the selected trajectory is determined at the downhole processor using in-situ formation measurements obtained downhole.

9. The drilling apparatus of claim 8 , wherein the selected trajectory further comprises at least one of: (i) a preselected trajectory stored in a downhole memory location; and (ii) a trajectory determined using a formation model stored at the downhole memory location and the determined position and orientation of the drill bit.

10. The drilling apparatus of claim 8 , wherein the downhole processor is further configured to determine the length of the drill string by obtaining travel times for the generated acoustic pulses to traverse the drill string from the surface location to the downhole end.

11. The drilling apparatus of claim 8 , wherein the acoustic transmitter generates the acoustic pulses at a scheduled time and the downhole processor is further configured to obtain the travel times using the recorded arrival times and a known scheduled time for generating the acoustic pulses.

12. The drilling apparatus of claim 11 , wherein a surface clock synchronized with the downhole clock is used to control generation of the acoustic pulse at the acoustic transmitter.

13. The drilling apparatus of claim 8 , wherein the downhole processor is further configured to determine the position of the drill bit using the obtained travel time and a known previous position and previous orientation of the drill bit.

Assignees

• Kruspe Thomas
• Estes Robert A
• Difoggio Rocco
• Hanak Francis Chad
• Baker Hughes A Ge Co Llc

Inventors

• Kruspe Thomas
• Estes Robert A
• Difoggio Rocco
• Hanak Francis Chad

Classifications

• E21B47/095

  by detecting an acoustic anomalies, e.g. using mud-pressure pulses · CPC title

• E21B44/005

  Below-ground automatic control systems · CPC title

• E21B7/04 Primary

  Directional drilling · CPC title

• E21B47/091

  Fixed Constructions · mapped topic

• E21B47/16

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