GB2218138A - Core barrel with adjustable joint - Google Patents

Abstract

A core barrel comprises an outer barrel 10 and an inner barrel 11 which has a threaded adjustment screw section 12 and an internally threaded adjustment nut section 13. A lock nut 14, from which a deflection tube 15 extends, is also fitted. in use the adjustment screw 12 and the adjustment nut 13 are rotated relative to one another until the correct overall length for the inner barrel 11 is obtained. The lock nut 14 is then tightened. In due course, if the relative lengths of the inner barrel 11 and outer barrel 12 are found to mismatch due to any required re-cutting of threaded joints adjustment screw 12 and adjustment nut 13 can once again be rotated to adjust the length of the inner barrel 11 as required. <IMAGE>

Description

"Core Barrel with Adjustable Joint" This invention relates to a core barrel with an adjustable joint.

Conventional core barrels used in drilling operations are provided with shim adjustment for the inner barrel so that the length of the inner barrel can be adjusted to correspond to the length of the outer barrel. This is necessary because the taper threaded joints used wear in repeated use which leads to the necessity to recut the joints which alters the length of the barrel, also the spacing between core catcher and throat of core heads needs to be altered to suit different formation types. The rearrangement of shims thus required involves considerable dismantling of the apparatus which is time consuming and thus leads to increased costs in operation.

According to the present invention there is provided a core barrel having an outer barrel and an inner barrel mounted within the outer barrel, the inner barrel having a first section and a second section having a screw threaded adjustable connection therebetween for adjustment of the overall length of the inner barrel.

Preferably the screw threaded connection comprises a reduced diameter externally threaded portion of the first section and an internally threaded portion of the second section.

Preferably also a locking nut is provided for retaining the first and second sections in a fixed relative position.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a part sectional side view of a conventional core barrel; and Fig. 2 is a sectional side view of part of a core barrel in accordance with the present invention.

Referring to Fig. 1 of the drawings a conventional core barrel 1 is illustrated. The core barrel 1 comprises an outer barrel 2 and an inner barrel 3. The various sections of the core barrel are connected by taper threaded joints.

As such joints may wear in use it becomes necessary to recut them and this alters the relative lengths of the inner and outer barrels. To accommodate this a number of spacers or shims 4 are included to alter the length of the inner barrel. As the replacement of shims 4 is time consuming the apparatus of the present invention has been developed to remove the need for such shims.

Referring now to Fig. 2 a core barrel in accordance with the present invention comprises an outer barrel 10 and an inner barrel 11. The inner barrel 11 has a threaded adjustment section made up of an externally threaded adjustment screw section 12 and an internally threaded adjustment nut section 13 fitted over the adjustment screw 12. A lock nut 14, from which a deflection tube 15 extends, is also fitted over the adjustment screw 12.

The adjustment nut 13 is attached to a bearing shaft 16 from which a deflection tube 17 extends.

In use the adjustment screw 12 and the adjustment nut 13 are rotated relative to one another until the correct overall length for the inner barrel 11 is obtained. The lock nut 14 is then tightened to retain the adjustment screw 12 and adjustment nut 13 in their adjusted positions. When, in due course, the relative lengths of the inner barrel 11 and outer barrel 12 are found to mismatch due to any required re-cutting of threaded joints adjustment screw 12 and adjustment nut 13 can once again be rotated to adjust the length of the inner barrel 11 as required.

In this way adjustments to compensate for differences in length between outer and inner barrels of the core barrel can be easily and quickly compensated for without the need for removal or replacement of shims as before. In the example shown six inches of adjustment is provided and the adjustment screw 12 is shown at the mid point of this adjustment in Fig. 2.

The deflection tube 17 prevents drill fluid or mud from being directed at the joint between the adjustment screw 12 and adjustment nut 13.

Modifications and improvements may be incorporated without departing from the scope of the invention.

MURGITROYD AND COMPANY MITCHELL HOUSE 333 BATH STREET GLASGOW G2 4ER

Claims (5)

1. Claims 1. A core barrel having an outer barrel and an inner barrel mounted within the outer barrel, the inner barrel having a first section and a second section having a screw threaded adjustable connection therebetween for adjustment of the overall length of the inner barrel.
2. 2. A core barrel as claimed in Claim 1, wherein the screw threaded connection comprises a reduced diameter externally threaded portion of the first section and an internally threaded portion of the second section.
3. 3. A core barrel as claimed in Claim 2, wherein a locking nut is provided for retaining the first and second sections in a fixed relative position.
4. 4. A core barrel as claimed in any one of the preceeding Claims, wherein a deflection tube is provided in the inner barrel positioned such as to prevent drill fluid or mud from being directed at the connection between the first and second sections.
5. 5. A core barrel substantially as hereinbefore described, with reference to and is shown in Fig. 2 of the accompanying drawings.