Method for surveying drill holes, drilling arrangement, and borehole survey assembly

1. A method for surveying drill holes, wherein the method comprises:

providing a drill tool having at least one drill rod and a drill bit assembly;

providing a borehole survey tool including a sensor for measuring a borehole;

arranging the borehole survey tool within the drill tool;

drilling with the drill tool a borehole by a drilling process including at least percussive drilling;

measuring the borehole by the borehole survey tool to obtain data of the borehole;

processing data of the borehole with a data processor including a non-transitory memory to obtain borehole status information, the drill tool having a central flushing channel for conducting flushing fluid to the drill bit assembly; and

arranging the borehole survey tool in the central flushing channel so that flushing fluid can flow in the central flushing channel past the borehole survey tool, wherein arranging the borehole survey tool within the drill tool includes suspending the borehole survey tool in the central flushing channel of the drill tool between dampers so that the dampers are situated outside the borehole survey tool in the central flushing channel of the drill tool so that the dampers are configured to be exposed to flushing fluid flowing in the central flushing channel of the drill tool and so that the flushing fluid flowing in the central flushing channel of the drill tool flows through the dampers.

2. The method according to claim 1 , comprising:

using the drill bit assembly having a flushing channel section; and

arranging the borehole survey tool at least partly in the flushing channel section of the drill bit assembly.

3. The method according to claim 2 , wherein the drill tool includes an adapter having a central flushing channel section and the arranging the borehole survey tool within the drill tool comprises:

fastening the drill bit assembly to the at least one drill rod of the drill tool by the adapter so that the central flushing channel section of the adapter forms a part of the central flushing channel of the drill tool; and

wherein arranging the borehole survey tool in the central flushing channel section includes arranging the borehole survey tool at least partly in the central flushing channel section of the adapter.

4. The method according to claim 1 , wherein the dampers are at least one of a spring damper made of a wire having a thickness between 0.5 and 3.0 mm, a hydraulic damper and a pneumatic damper.

5. The method according to claim 4 , wherein arranging the borehole survey tool within the drill tool comprises:

suspending the borehole survey tool in the central flushing channel of the drill tool between the dampers so that the borehole survey tool is supported in the central flushing channel of the drill tool solely by said dampers.

6. The method according to claim 1 , wherein the sensor of the borehole survey tool is at least partly embedded in polymer so that the polymer at least partly embedding the sensor also at least partly forms an outermost surface of the borehole survey tool and such that the polymer at least partly embedding the sensor also at least partly forms a protective casing of the borehole survey tool.

7. The method according to claim 5 , wherein arranging the borehole survey tool within the drill tool comprises:

forming a passage for flushing fluid between the borehole survey tool and walls of the central flushing channel for allowing flushing fluid to flow past the borehole survey tool in the central flushing channel of the drill tool.

8. The method according to claim 6 , wherein the borehole survey tool includes a piezoelectric device for harvesting energy, the method comprising:

harvesting energy during the percussive drilling by the piezoelectric device.

9. The method according to claim 1 , comprising:

performing the measuring as the drill tool is withdrawn from the borehole.

10. The method according to claim 1 , comprising:

performing the measuring during the drilling step.

11. The method according to claim 1 , wherein the drilling includes a waiting period during which the drill tool is kept in the borehole stationary with respect to a longitudinal direction of the borehole, the method further comprising:

performing the measuring during the waiting period of the drilling.

12. A drilling arrangement for percussive drilling, comprising:

a drill tool for drilling boreholes, the drill tool having at least one drill rod and a drill bit assembly;

a borehole survey tool for measuring the borehole to obtain data of a borehole drilled by the drill tool, wherein the borehole survey tool is arranged within the drill tool;

a data processor including a non-transitory memory for processing data of the borehole to obtain borehole status information, the drill tool including a central flushing channel for conducting flushing fluid to the drill bit assembly; and

the borehole survey tool being configured for arrangement in the central flushing channel so that fluid can flow in the central flushing channel past the borehole survey tool, the borehole survey tool being suspended in the central flushing channel of the drill tool between dampers

wherein the dampers are situated outside the borehole survey tool in the central flushing channel of the drill tool so that the dampers are configured to be exposed to flushing fluid flowing in the central flushing channel of the drill tool and so that the flushing fluid flowing in the central flushing channel of the drill tool flows through the dampers.

13. The drilling arrangement according to claim 12 ,

wherein the drill bit assembly comprises:

a flushing channel section; and

the borehole survey tool being arranged at least partly in the flushing channel section of the drill bit assembly.

14. The drilling arrangement according to claim 13 , comprising:

an adapter having a central flushing channel section,

the drill bit assembly being fastened to the drill rod of the drill tool by the adapter so that the central flushing channel section of the adapter forms a part of the central flushing channel of the drill tool; and

the borehole survey tool being arranged at least partly in the central flushing channel section of the adapter.

15. The drilling arrangement according to claim 12 , wherein the dampers are at least one of the following: a spring damper made of a wire having a thickness between 0.5 and 3.0 mm, a hydraulic damper and a pneumatic damper.

16. The drilling arrangement according to claim 12 , wherein the borehole survey tool is suspended in the central flushing channel of the drill tool between the dampers so that the borehole survey tool is supported in the central flushing channel of the drill tool solely by said dampers.

17. The drilling arrangement according to claim 12 , comprising:

a sensor of the borehole survey tool is at least partly embedded in polymer so that the polymer at least partly embedding the sensor also at least partly forms an outermost surface of the borehole survey tool and so that the polymer at least partly embedding the sensor also at least partly forms a protective casing of the borehole survey tool.

18. The drilling arrangement according to claim 12 , comprising:

at least one passage for flushing fluid between the borehole survey tool and the walls of the central flushing channel for allowing flushing fluid to flow past the borehole survey tool in the central flushing channel of the drill tool.

19. The drilling arrangement according to claim 12 , the borehole survey tool comprising:

a piezoelectric device for harvesting energy during percussive drilling.

20. A borehole survey assembly for percussive drilling comprising:

a borehole survey tool containing a sensor for collecting data of a borehole; and

two dampers for suspending the borehole survey tool in a central flushing channel of a drill tool for percussive drilling between said dampers;

wherein the dampers are situated outside the borehole survey tool in the central flushing channel of the drill tool so that the dampers are configured to be exposed to flushing fluid flowing in the central flushing channel of the drill tool and so that the flushing fluid flowing in the central flushing channel of the drill tool flows through the dampers.

21. The borehole survey assembly according to claim 20 , wherein said dampers are at least one of the following: a spring damper made of a wire having a thickness between 0.5 and 3.0 mm, a hydraulic damper and a pneumatic damper.

22. The borehole survey assembly according to claim 20 , wherein the borehole survey tool has an elongated form having two opposite ends, with one damper at each opposite end.

23. The borehole survey assembly according to claim 20 , wherein the sensor of the borehole survey tool is at least partly embedded in polymer so that the polymer at least partly embedding the sensor also at least partly forms the outermost surface of the borehole survey tool and so that the polymer at least partly embedding the sensor also at least partly forms a protective casing of the borehole survey tool.

24. The borehole survey assembly according to claim 20 , comprising:

a piezoelectric device for harvesting energy during percussive drilling.

25. The borehole survey assembly according to claim 24 comprising:

energy storing means for storing electrical energy produced by the piezoelectric device.

26. The borehole survey assembly according to claim 20 , wherein the borehole survey tool comprises:

a protective casing.