Method and system for enabling acquisition of borehole survey data and core orientation data

1 . A method of enabling the acquisition of borehole survey data and core orientation data in a single instrument trip in a core drill having a drill string and an inner core barrel assembly having a longitudinal axis, the method comprising:

running a borehole survey tool through the drill string in which is installed the inner core barrel assembly, wherein the borehole survey tool is arranged to at least log its position in three-dimensional space;

enabling the inner core barrel assembly to provide or facilitate detection of an indication tool face of a core sample held in the inner core barrel assembly; and

transferring the indication of tool face to the borehole survey tool;

wherein enabling the inner core barrel assembly comprises arranging the inner core barrel assembly so that a head assembly and an inner core tube of the inner core barrel assembly have a known or otherwise detectable rotational position about the longitudinal axis relative to each other for a core orientation period which commences from a time at least immediately before breaking of a core sample from in situ strata to a time at which the indication of tool face is transferred to the borehole survey tool;

wherein the inner core barrel assembly is provided with a spindle coupling the head assembly to the inner core tube, and

wherein the method further comprises:

providing a core tube marker on or in the inner core barrel assembly wherein the core tube marker has a known rotational position relative to the known point, and

enabling communication between the borehole survey tool and the core tube marker at a time before or during the core orientation period,

wherein transferring the indication of the known rotational position to the borehole survey tool comprises communicating a location of the core tube marker with respect to the longitudinal axis to the borehole survey tool via a relay device on the head assembly,

wherein the method further comprises fitting a core orientation system to the inner core barrel assembly which is capable of determining a rotational position of the core sample held within the inner core tube, and wherein transferring the indication of the rotational position to the borehole survey tool comprises electronically communicating the rotational position from the core orientation system to the borehole survey tool, and

wherein the method further comprises:

mechanically coupling the borehole survey tool to the inner core barrel assembly and retrieving the inner core barrel assembly with the borehole survey tool,

using the logged position of the borehole survey tool and the transferred indication of a rotational position to determine an in situ position of the core sample, and

releasing latent rotational torque in the drill string prior to running a borehole survey tool through a drill string.

2 . The method according to claim 1 , wherein the step of arranging the inner core barrel assembly comprises permanently rotationally fixing the head assembly to the inner core tube in a manner which maintains a fixed rotational position of the head assembly to the inner core tube.

3 . The method according to claim 2 , comprising keying the borehole survey tool to the inner core barrel assembly in a predetermined rotational orientation about the longitudinal axis relative to a known point, wherein the known point has a known or ascertainable spatial relationship to the tool face of the core sample.

4 . The method according to claim 2 , wherein the step of arranging the inner core barrel assembly comprises providing a marker on the inner core barrel assembly wherein the marker has a known rotational position relative to a known point and enabling communication between the borehole survey tool and the marker.

5 . The method according to claim 1 , wherein the inner core barrel assembly is provided with a spindle coupling the head assembly to the inner core tube; and the step of arranging the inner core barrel assembly comprises releasably locking the spindle to prevent rotation of the head assembly about the longitudinal axis relative to the inner core tube during the core orientation period.

6 . The method according to claim 5 , wherein releasably locking the head assembly to the inner core barrel assembly comprises activating a mechanism carried by the inner core barrel assembly by action of any one of:

(a) physical contact of the borehole survey tool with the inner core barrel assembly;

(b) reducing rotational speed of the drill string to below a coring speed;

(c) changing fluid pressure within the drill string; or

(d) applying tension between the head assembly and the inner core tube.

7 . The method according to claim 6 , wherein enabling the inner core barrel assembly comprises: providing a core tube marker on or in the inner core barrel assembly, wherein the core tube marker has a known rotational position relative to a known point; and enabling communication between the borehole survey tool and the core tube marker.

8 . The method according to claim 7 , wherein transferring the indication of the known rotational position to the borehole survey tool comprises communicating a location of the core tube marker to the borehole survey tool via a relay device on the head assembly.

9 . The method according to claim 1 , wherein releasing latent rotational torque comprises rotationally decoupling the drill string from the inner core barrel assembly.