System and method for making downhole measurements

Patent metadata

Field	Value
Publication number	US-10036828-B2
Application number	US-201415109340-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Jan 2, 2014
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

A system and method for making downhole measurements utilize a neutron source ( 12 ) to create a marker ( 122 ) in an underground formation ( 2 ), a nuclear radiation detector (D, 124 )) to detect gamma and/or other nuclear radiation emitted by the marker ( 122 ) and a downhole drilling progress monitoring unit ( 20 ) which generates real time information about incremental depth and/or associated Rate Of Penetration (ROP) of an automated or other drilling assembly ( 4 ) based on detection of the nuclear radiation and an axial distance L between the neutron source ( 120 ) and the nuclear radiation detector (D, 124 ) without requiring transmission of the real time incremental depth and/or ROP data to surface equipment via a complex wired or wireless data transmission system.

First claim

The invention claimed is:

1. A system for making downhole measurements in an underground borehole, the system comprising:
a neutron source for transmitting a neutron pulse to activate a target substance in an underground formation surrounding the borehole;
a nuclear radiation detector located at an axial distance L from the neutron source for detecting nuclear radiation emitted by the activated target substance; and
a downhole drilling progress monitoring unit configured to calculate incremental depth of a drilling assembly in the borehole based on detection of the nuclear radiation and the axial distance L.

2. The system of claim 1 , wherein the downhole drilling progress monitoring unit is arranged in a Bottom Hole Assembly (BHA) of the drilling assembly and is configured to provide real time data regarding the incremental depth, an associated Rate Of Penetration (ROP), azimuth and/or inclination of the BHA to an automated downhole drill bit navigation system.

3. The system of claim 2 , wherein the automated downhole drill bit navigation system is arranged in the BHA and the downhole drilling progress monitoring unit is configured to transmit the real time data to the automated drill bit navigation system via a signal transmission assembly in the BHA without requiring transmission of the real time data to data processing equipment located at the earth surface.

4. The system of claim 3 , wherein the automated drill bit navigation system comprises means for navigating the BHA towards a subsurface drilling target based on data stored in the system regarding:
three-dimensional geographic coordinates of a wellhead of the borehole and of the subsurface drilling target; and
an estimate of the borehole trajectory based on the real time data collected by the drilling progress monitoring unit regarding the incremental depth, azimuth and inclination of the BHA throughout the length of the borehole trajectory.

5. The system of claim 1 , wherein the a detector is cylindrical.

6. The system of claim 1 , wherein the detector has a height of at least 5 cm and/or is configured to detect nuclear radiation emitted by a target substance comprising Chlorine-37, Sodium-23 and/or Silicon-30.

7. The system of claim 1 , comprising at least two detectors, arranged at predetermined axial distances L 1 and L 2 from the neutron source.

8. The system of any of or any combination of the previous claims, wherein each axial distance L, L 1 and L 2 is equal to or smaller than a maximum value L max .

9. The system of claim 8 , wherein each axial distance L, L 1 and L 2 is at least 20 cm and larger than a spread of activated nuclei of the target substance along the axis of the borehole and/or L max is between 3 and 6 meters.

10. A method of making downhole measurements in an underground borehole, the method comprising the steps of:
transmitting a neutron pulse by a neutron source to activate a target substance in an underground formation surrounding the borehole; and
inducing a nuclear radiation detector located at an axial distance L from the neutron source to detect nuclear radiation emitted by the activated target substance; and
inducing a downhole drilling progress monitoring unit to calculate incremental depth of a drilling assembly in the borehole based on detection of the nuclear radiation and the axial distance L.

11. The method of claim 10 , wherein the nuclear radiation comprises gamma rays and/or the detector detects nuclear radiation emitted by a target substance comprising Chlorine-37, Sodium-23 and/or Silicon-30.

12. The method of claim 10 , wherein the downhole drilling progress monitoring unit is arranged in a Bottom Hole Assembly (BHA) of a drilling assembly and provides real time information about the incremental depth, an associated Rate Of Penetration (ROP), azimuth and/or inclination of the BHA to an automated downhole drill bit navigation system.

13. The method of claim 12 , wherein the automated drill bit navigation system is arranged in the BHA and transmits the real time data to the automated drill bit navigation system via a signal transmission assembly in the BHA without requiring transmission of the real time data to data processing equipment located at the earth surface.

14. The method of claim 13 , wherein the automated drill bit navigation system comprises means for navigating the BHA towards a subsurface drilling target based on data stored in the system regarding:
three-dimensional geographic coordinates of a wellhead of the borehole and of the subsurface drilling target; and
an estimate of the borehole trajectory based on the real time data collected by the drilling progress monitoring unit regarding the incremental depth, azimuth and inclination of the BHA throughout the length of the borehole trajectory.

15. The method of claim 14 , wherein the automated drilling process is terminated when the BHA has reached the subsurface target, whereupon the drilling assembly is removed from the borehole, the borehole is completed and configured as a hydrocarbon fluid production well and hydrocarbon fluid is produced from the well.

Assignees

• Shell Oil Co

Inventors

• Jain Praveen

Classifications

• E21B45/00

  Measuring the drilling time or rate of penetration · CPC title

• G01V5/101 Primary

  and detecting the secondary Y-rays produced in the surrounding layers of the bore hole · CPC title

• G01V5/105 Primary

  the neutron source being of the pulsed type · CPC title