EP-4737680-A2 - DOWNHOLE TOOL ASSEMBLIES

EP4737680A2EP 4737680 A2EP4737680 A2EP 4737680A2EP-4737680-A2

Abstract

Downhole tool assembly 10 for mounting to a core barrel assembly 12 including a core tube 14 and a pair of split tubes 16. The downhole tool assembly 10 includes a downhole tool 18 and at least one sleeve 20 dimensioned to slidingly engage the split tubes 16 to inhibit radial movement of the split tubes 16 and receive and retain the downhole tool 18 coaxially with the core tube 14. Core ejection pistons 72, and methods for extracting a core from bedrock are also disclosed. A housing assembly 120 for a downhole tool, downhole assemblies 180, 200, and methods of assembling such assemblies are also disclosed.

Inventors

REILLY, James Barry
COPLIN, NICHOLAS
MOKARAMIAN, AMIR
Javorka, Marian

Assignees

Reflex Instruments Asia Pacific Pty Ltd

Dates

Publication Date: 20260506
Application Date: 20220719

Claims (13)

A downhole tool assembly for mounting to a core barrel assembly, the core barrel assembly including a core tube defining a bore and a pair of split tubes arranged within the core tube and adjacent to each other to surround the bore, the downhole tool assembly including: a data acquisition tool operable to measure one or more parameters; and at least one sleeve dimensioned to slidingly engage the split tubes to inhibit radial movement of the split tubes relative to the bore, and shaped to receive and retain the data acquisition tool coaxially with the bore and substantially within the core barrel assembly.
The downhole tool assembly of claim 1 including a pair of the sleeves, wherein a first sleeve is configured to receive and engage an end of the data acquisition tool, and a second sleeve is configured to be arranged partway along and engage the data acquisition tool.
The downhole tool assembly of claim 2, wherein the first sleeve defines a conical end portion configured to be arranged to face downhole within the bore.
The downhole tool assembly of any one of the preceding claims, wherein the, or each, sleeve is shaped to allow fluid flow along the bore and past the sleeve.
The downhole tool assembly of any one of the preceding claims, further including a retaining portion configured to be arranged against an uphole end of each split tube to inhibit axial movement of the split tubes relative to the bore.
The downhole tool assembly of claim 5, wherein the retaining portion is integrally formed with the at least one sleeve.
The downhole tool assembly of any one of the preceding claims, wherein the, or each, sleeve defines a cavity for receiving the data acquisition tool, and the assembly further includes at least one retainer ring configured to receive and engage the data acquisition tool and slidingly engage the cavity of the, or each, sleeve.
The downhole tool assembly of any one of the preceding claims further including a tool coupling configured to receive and retain the data acquisition tool, and threadedly engage the core tube.
A method for extracting a core from bedrock and measuring one or more parameters relating to the core, the method including: arranging at least one sleeve about a data acquisition tool and within a pair of split tubes of a core barrel assembly defining a bore, the, or each, sleeve dimensioned to slidingly engage the split tubes to inhibit radial movement of the split tubes relative to the bore, and shaped to receive and retain the data acquisition tool coaxially with the bore; operating a drilling rig to drill the core from the bedrock and be received in the split tubes, concurrently with operating the data acquisition tool to measure the one or more parameters; retrieving the core barrel assembly to the surface; operating the data acquisition tool to obtain measured data; mounting a piston plug within the core barrel assembly to seal the bore; and directing fluid against the piston plug to cause the core and split tubes to be expelled from the core tube.
The method of claim 9, wherein before mounting the piston plug, the at least one sleeve and the data acquisition tool are removed from the core barrel assembly.
The method of claim 10, wherein before mounting the piston plug, the plug is connected to an ejection piston to form a piston assembly, and mounting the piston plug includes fitting the piston assembly across the core tube to seal against the bore.
The method of claim 9, wherein before mounting the piston plug, the data acquisition tool is removed from the core barrel assembly, and mounting the piston plug includes sealingly engaging the plug with the at least one sleeve.
The method of any one of claims 9 to 12, wherein the data acquisition tool is a core orientation tool, and the measured parameters include orientation of the core when breaking from the bedrock.

Description

Cross-Reference to Related Applications This application claims priority to Australian provisional patent application no. 2021209301, filed 29 July 2021, the content of which is incorporated herein in its entirety. Technical Field The present disclosure relates, generally, to downhole assemblies used as part of a drilling rig operable to extract a core and, particularly, to assemblies including a downhole tool and configured to couple to a core barrel assembly for receiving drilled core. Background Core extraction allows analysis of underground rock formations by geologists. A core is typically extracted by operating a drilling rig mounted at surface level. The core is drilled from the bedrock and received within a core barrel, also known as an inner tube or core tube. A downhole tool (or alternatively, a downhole sensor or instrument) is usually threadedly engaged with an upstream end of the core barrel such that the tool extends axially away from the core barrel to be interposed between the core barrel and a back-end assembly. The tool is typically operated concurrently with drilling, to allow measuring various parameters, such as orientation of the core when broken from the bedrock. After drilling the core, the core barrel, containing the core, and tool is retrieved to the surface, the core and tool removed for analysis, and another or the same core barrel attached to the same or another tool and redeployed into the borehole to allow drilling and receiving another core. Boreholes are often 1 km or more deep, and typically filled with water and/or drilling fluid or mud, meaning that the descent time for the core barrel to reach the drill bit can be significant. Core barrels typically form part of an assembly and are configured to allow receiving a specifically dimensioned core. Core barrel assemblies are often dimensioned according to standardised sizes to allow obtaining standardised cores. The assembly sizing label typically relates to the core diameter which the assembly is configured to receive, common industry standard sizes including BQ™, NQ™, HQ™ and PQ™. It will be appreciated that various standardised sizes exist, and that the "Q" sizes described above are one example of a standard defined by Boart Longyear. Commonly, a core barrel assembly comprises an outer drilling barrel or tube which is rotationally coupled to the drill bit, and an inner tube arranged within the outer barrel/tube to be de-coupled from the drill bit and arranged to receive the drilled core. The inner tube is axially movable relative to the outer tube to allow retrieving to the surface. Some core barrel assemblies comprise the outer tube, the inner tube, and a pair of split tubes housed within the inner tube and arranged to receive a specifically dimensioned core - known as a "triple tube core barrel". Each split tube is shaped to define half of a cylindrical tube split along a longitudinal axis. Removing a core from a triple-tube core barrel assembly at surface level typically involves disconnecting the downhole tool from the core barrel assembly, sealingly engaging a plug across the inner tube, typically by engaging an ejection piston arranged within the inner tube, and pumping fluid into the inner tube and against the plug. This causes the plug and/or piston to urge against and push the split tubes and core out of the core barrel. Fitting the plug can prove difficult as the piston and/or inner tube may be covered in mud and/or other debris which can inhibit engaging the plug within the inner tube. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims. Summary Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. According to one aspect of the disclosure, there is provided a downhole tool assembly for mounting to a core barrel assembly, the core barrel assembly including a core tube defining a bore and a pair of split tubes arranged within the core tube and adjacent to each other to surround the bore. The downhole tool assembly includes a downhole tool, and at least one sleeve dimensioned to slidingly engage the split tubes to inhibit radial movement of the split tubes relative to the bore, and shaped to receive and retain the downhole tool coaxially with the bore. The assembly may include a pair of the sleeves, where a first sleeve is configured to receive and engage an end of the downhole tool, and a second sleeve is configured to be arranged partway along and engage the