These core barrels incorporate a patented core orientation mechanism in the core barrel head which indicates the rotational position of the inner tube, and is activated before the core is broken from the strata. On removal of the barrel from the borehole, the original rotation of the core can be determined by reference to an indicator within the mechanism.
To work effectively the borehole must be drilled at an angle of at least 5 degrees to the vertical. The indicator mechanism contains a steel ball which moves around a circular racetrack and settles at the lowest side of the inclined borehole when rotation stops. The ball is clamped in position just before breaking the core from the strata, by engaging a special overshot onto the inner-tube assembly (wireline system) or by pumping a steel trigger ball down through the rod string (conventional core barrel).
After removing the core barrel from the borehole, an alignment kit is used to enable the indicator mark on the core barrel head to be transferred to the lower end of the inner tube. A physical mark is then made on the core by drilling a hole, or using a waterproof marker pen. In highly fractured or broken formations we recommend the use of coreliner tubes to prevent the core breaking up when transferring to core boxes, which would cause the orientation data to be lost.
The advantage of this method over other techniques is that it allows a drilled core to be accurately oriented as it is removed from the borehole, with no rig down-time.
Corientator core barrels are available in wireline hole sizes N and H and hole sizes 76- 146 mm (N-S) as conventional barrels. Most parts of the barrel except head assembly and overshot are interchangeable with standard “W” series wireline, or with equivalent T2, T6 or DCDMA core barrel parts. For further information please contact our sales office.
|Size Designation||Hole Diameter(mm)||Core Diameter(mm)|
|N W/L Corientator||75.7||47.6|
|H W/L Corientator||96.1||63.5|