Patent Application
20150300117
The present invention relates to core sampling of ground formations in general. The invention is also for a novel core sampling impact apparatus and related apparatus, systems, and methods and uses.
Within the drilling industry and more specifically core sampling within the mineral exploration industry there is a need to continually lower the cost of exploration; this is normally achieved by making the process faster, and or the machinery simpler or cheaper. This application achieves these objectives.
Typically core drilling is carried out using sophisticated drill rigs which rotate thin walled drill rods (casing) at high speeds (often >1,000 rpm) with a diamond impregnated (or other) core bit attached to the lower end of the drill rod (casing).
As the bit is rotated it advances into the formation and the resulting rock “core” advances inside the drill rods (casing) and into a core barrel. The core barrel is usually 1.5-3 metres long. Once the core barrel is full (measured by the length the drill rod has advanced from surface) a latching tool is lowered on a wire line from surface inside the drill rods (casing). The latching tool attaches to the core barrel and as it is pulled from the inside of the drill rods (casing) the lower end of the core barrel snags hold of the rock core breaking it from the rock formation and the entire assembly is pulled to surface for core recovery. The drill rods (casing) stay in the ground forming a temporary casing which prevents the bore hole from collapsing.
The core barrel etc., is then lowered back down inside the drill rods (casing) and the process continues until the required depth of core has been recovered. While this system works well it is expensive and relatively slow. In addition the diamond impregnated core bits, which work by abrading the rock are expensive, relatively fragile and are often damaged if too much weight is applied (pushed too hard) or if there is a change in the formation being drilled.
Tibussek U.S. Pat. No. 4,279,315 describes a wire line retrievable core sampling device which uses a rotating cam arrangement to apply low frequency—low force impact to a non-rotating core sampling barrel. This mechanism by its very nature precludes its ability to drill (rotate and therefore penetrate) hard rock when core sampling. Additionally this cam impacting arrangement is not able to generate the considerable forces required for crushing and therefore penetrating hard formations.
While the core sampling barrel is rotationally static in this device—there is no mechanism to protect the core from the up and down axial movement that the core sampling barrel uses to advance into the formation.
Sweeny U.S. Pat. No. 3,854,539 describes a wire line retrievable hammer which unlike Tibussek uses pressurised drilling fluid to energise a piston which transfers energy to a core sampling bit. However in practise this mechanism is flawed as there is no method for securely locking the hammer to the outer casing which therefore stops the tool from delivering sufficient impact force to the bit and therefore the rock. Instead the hammer bounces within the outer housing as the hammer blows are delivered.
They try to solve this problem by using the hydraulic pressure above the hammer to hold the hammer in place, but as the hammer has porting through to the bit this will not work. This impact force is further diminished as the anvil and core sampling tube impact directly to the drill bit, as the drill bit is not able to move axially relative to the outer casing with each impact. This means that each impact from the hammer is trying to stretch the outer casing, not only diminishing the energy available to crush rock, but also placing considerable stress on the outer casing rods, which limits its working life.
Again as with the Tibussek art, the core sample is not protected from the axial impact movement of the coring hammer—which testing has shown to damage or destroy otherwise valuable core samples.
Applicants propose and their analysis has shown that a small diameter hammer of any type such as air, fluid, magnetic, electromagnetic, or a mud motor (PDM) oscillator can be lowered inside the drill rods (casing) and seated inside the assembly so that when activated the hammer impacts upon a core bit and allows for faster core sampling and/or protects the core sample itself.
It is an object of the present invention in its various aspects to provide a core sampling apparatus and/or assembly, and optionally related apparatus, systems, methods and uses that will satisfy one, more and preferably most or all of such capabilities and/or those listed below.
A core sampling assembly/apparatus would have one or more (most preferably all) of the following capabilities:
Embodiments can use conventional impact type bits with carbide or diamond impact bits (or similar) but with the centre removed to leave a rock core intact. These bits are very durable, are not easily damaged by a change in formation or by excessive weight on bit—and in addition they only require slow rotation (typically less than 100 RPM) meaning that specialised high speed diamond core rigs are not required.
In an aspect the invention is a core sampling apparatus to allow the capture and retrieval of a core from a subterranean formation, the apparatus comprising or including: a rotatable tubular housing, a core taking bit constrained to rotate with the housing yet able to move axially with respect to the rotatable tubular housing, a retrievable core sampling assembly latchable to or relative to the rotatably tubular housing comprising: a core catcher barrel for a core, the barrel being rotationally isolated from the tubular housing and cooperable with the core taking bit to retain a core, and a hammer for providing impact to the core taking bit along a longitudinal impact path that is or is substantially decoupled from the core catcher barrel, wherein the tubular housing is operable to rotate the bit and the hammer is operable to impact the bit to capture and pass core material from the formation to the core catcher barrel in manner that isolates a core in the core catcher barrel from rotation and impact forces.
Preferably the longitudinal impact path comprises an impact tube or structure surrounding the core catcher barrel that receives impact from the hammer at a first end and bears against the core taking bit at another end to transfer the impact.
Preferably the core taking bit is splined to the rotatable tubular housing to rotationally constrain the core taking bit yet enable it to move axially, and upon receiving an impact, the core taking bit moves axially with respect to the rotatable tubular housing.
Preferably the retrievable core sampling assembly is latchable to or relative to the rotatable tubular housing using a latching assembly that latches the assembly to or relative to the rotatably tubular housing.
Preferably a compliant member is provided between the latching assembly and the hammer to hold the hammer directly or indirectly on the bit, yet during hammer operation restrict stress on the latching assembly to maintain latching of the assembly to or relative to the rotatable tubular housing.
Preferably the hammer is actuated by drilling fluid, wherein the drilling fluid exhausts between the core catcher barrel and impact tube or structure that surrounds the core catcher barrel and through the core taking bit thus bypassing a core in the core catcher barrel.
Preferably the hammer comprises a rotor that upon rotation generates longitudinal movement in an impact member that provides the impact to the core taking bit, wherein the rotor is coupled via a swivel joint to the core catcher barrel so that the barrel can be retracted yet is rotationally decoupled from the rotor to isolate a core in the catcher barrel from rotation forces.
Preferably the hammer is a magnetic hammer, and the rotor is an inner magnetic array that rotates relative to an outer magnetic array that is the impact member, wherein the inner magnetic array is coupled via the swivel joint to the core catcher barrel so that the barrel can be retracted yet is rotationally decoupled from the rotor to isolate a core in the catcher barrel from rotation forces.
Preferably the latching assembly, compliant member, hammer, and core catcher barrel of the core sampling assembly are coupled so that they can be inserted into the rotatable tubular housing and latched to or relative to the rotatable tubular housing and retrieved from the rotatable tubular housing by delatching the latching assembly and removing the core sampling assembly using a wire latch.
In another aspect the invention is a retrievable core sampling assembly for latching to or relative to a rotatable tubular housing of a core sampling apparatus to allow the capture and retrieval of a core from a subterranean formation, the assembly comprising or including: a core catcher barrel for a core, the barrel being rotationally isolated from the tubular housing and cooperable with a core taking bit coupled to the rotatable tubular housing to retain a core, and a hammer for providing impact to the core taking bit along a longitudinal impact path that is or is substantially decoupled from the core catcher barrel, so that when latched, rotation and impact of the core taking bit captures and passes core material from the formation to the core catcher barrel in manner that isolates a core in the core catcher barrel from rotation and impact forces.
In another aspect the invention is a method of obtaining a core sample comprising using an apparatus/assembly of any preceding paragraph and operating the apparatus/assembly to rotate and hammer a bit in a manner to isolate the core from rotation and impact forces.
In another aspect the invention is a method of obtaining a core sample comprising using an apparatus/assembly of any preceding claim and operating the apparatus/assembly to rotate and hammer a bit in a manner to isolate the core from rotation and impact forces Described herein is a core sampling apparatus to allow the capture and retrieval of a core from a subterranean formation, the apparatus comprising or including
Described herein is a core sampling apparatus to allow the capture and retrieval of a core from a subterranean formation, the apparatus comprising or including
Preferably, the bit is splined to the housing.
Preferably, interposed between the retrievable assembly and the housing is at least one member to transfer the hammer impact to the bit.
Preferably, said at least one member is a tube.
Preferably, the tube is not withdrawable uphole with the retrievable assembly.
In one range of embodiments, the hammer arrangement is a magnetic hammer arrangement.
Preferably, the magnetic hammer arrangement has a hammer mass to rotate with the housing and carrying an outer array of magnets and an inner assembly carrying an inner array of magnets able to be fluid driven to rotate relative to the hammer mass and housing.
Preferably, the inner assembly is swivel connected to said core catcher.
Preferably, a PDM empowers the magnetic hammer arrangement.
In another range of embodiments, the hammer arrangement is other than a magnetic hammer arrangement.
Preferably, the hammer arrangement is empowered (e.g. as if a piston) by a fluid or gas downflow.
Preferably, the hammer arrangement exhausts fluid from one or more outlets. Between the outer housing and the core catcher so as to not damage the core sample and the fluid exits into the bore hole via the core bit—to assist with drill cutting evacuation etc.
Preferably, the hammer arrangement is swivel connected to said core catcher, to help minimise any rotational damage from being imparted to the core sample.
Preferably, the hammer arrangement is not required to rotate with the housing.
Described herein is a downhole apparatus comprising or including
Described herein is a withdrawable assembly comprising or including
Described herein is also, in combination, in use, or in assembly, both
Described herein is the use in conjunction with a retrievable core catching and a rotatable drillstring casing within which the core catcher is located in use of both
Described herein a method of core extraction from a subterranean formation, the method involving
Described herein is a core receiving and retrieving assembly for use or suitable for use downhole within a rotatable drillstring casing having a hammerable core taking bit captive to rotate with the casing yet move axially with respect thereto, the assembly comprising or including
Described herein is an assembly insertable downhole into a drillstring casing having a core taking impact bit, the assembly comprising or including: a hammer mechanism, a core catcher associated with but not to be hammered by the hammer mechanism, and a hammer impact transfer tube upliftable with the hammer mechanism and core catcher yet axially movable with respect to the core catcher and able to be both endwise hammered and to endwise impact the impact bit in use.
Preferably the hammer mechanism is swivel connected to the core catcher.
Preferably there is a releasable latching system whereby the assembly can be held from upward movement during hammering.
Preferably it has a shock absorber or shock spreader to protect the latching system against uphole shock.
Preferably any use, combination, method, system or apparatus substantially as herein described with or without reference to any one or more of the accompanying drawings.
Described herein is any use, combination, method, system or apparatus substantially as herein described with or without reference to any one or more of the accompanying drawings.
Described herein are various embodiments of a wire line or the equivalent retrievable core sampling hammer system (the hammer mechanism can be of any type such as pneumatic or fluid driven, magnetic hammer, electromagnetic, or any other that imparts an impact directly or indirectly to the core sampling drill bit, which causes the core sampling bit to advance into the formation being sampled), but in its most preferred forms have the attributes discussed below.
As used herein “spring” includes any resilient system able to prevent or at least reduce an uphole momentary shock loading of the withdrawable systems engagement at the latching zone. It may be of a single member or a plurality of members able, over a contacting zone, to spread in time and thus momentary magnitude the shock loading away through the latching system loads. The “spring” may couple to an energy absorption system (e.g. damper) or not [preferably not if the “spring” is sufficiently tuned to be in phase to the cycling of the associated hammer].
A spring may be one or more members of metal [e.g. a helical metal spring or a series of disc spring elements]. It can be of a non-metal [e.g. a suitable synthetic rubber]. It can be pneumatic.
Likewise “compliant”, “compliant mechanism” and related terms can be used in respect of any alternative to a spring system.
The spring or compliant system preferably acts to buffer with or without damping.
As used herein “and/or” means “and” or “or”, or where appropriate, both “and” and “or”.
As used herein “gripper” or any other term referring to an arrangement to engage a core in the receiver and/or bit (the “tooling”) can be of any suitable type. Preferably it is a self-deploying wedge based arrangement whether of a split ring or of individually captive sliding members.
As used herein “core catcher barrel”, “core receiver” or “barrel” preferably incorporates a “gripper”.
As used herein “formation”, “formations”, and “formation(s)” should be considered as interchangeable to render irrelevant any strata, consistency, or other change in any subterranean matrix (e.g. the ground, the seabed, a hill, etc).
As used herein reference to “magnetic”, “magnetic arrays”, “magnetic hammer” includes, but is not restricted to, those devices, apparatus, systems as in downhole hammers of the type disclosed in PCT/NZ2008/000217 (published as WO2009/028964) and PCT/IB2012/050875.
As used herein “downhole” in respect of any apparatus, system or the like does not exclude when any such apparatus is not actually downhole. The term refers to its intended purposes and/or when in situ for use at the bottom end of a drillstring.
As used herein “fluid” includes liquid(s), liquid systems [e.g. slurry, drilling mud etc], liquid/gas mixtures, gas or gas mixtures. Its use alongside any reference to pneumatics or gas is not restrictive of its scope.
Preferred embodiments of the present invention will now be described with reference to:
The apparatus is for taking core samples in a manner that protects the core sample. The drilling apparatus 40 comprises an outer drill housing 1 (also termed “drillstring” or “drill rod” or “casing”) coupled to a core taking impact bit (“drill bit” or “core (taking) bit”) 2 (
The drill housing 1 can be rotated from the surface by a drill rig (known to those skilled in the art), which in turn rotates the drill bit 2 allowing for drilling of a bore and advancement into a formation in the usual manner. The housing thus becomes or is a “rotatable tubular housing”. The drill bit 2 has cutting components which cut material from the formation bore face of the bore. The drill bit 2 has an outer casing 2a that couples by rotationally splining 20 to the outside of the rotatable tubular housing 1 so that it is constrained to rotate with the housing 1, but also so that it can move longitudinally/axially (left and right in the Figures) relative to the rotatable housing 1 for hammer purposes. To allow for efficient hammering and advancement into the formation, and core taking, a core sampling assembly is incorporated into the rotatable housing 1 of the drilling apparatus 40 to hammer the drill bit 2, collect a core sample 19, and enable withdrawal of the core sample 19. The core sampling assembly in the drilling apparatus 40 creates a core sampling apparatus 40 as explained above for capture and retrieval of a core from a subterranean formation. The core sampling assembly is retrievable from the drilling apparatus so that the core is retrievable. The core sampling assembly comprises a hammer 100 that oscillates or otherwise shuttles (left/right in the Figures) between two longitudinal (axial) positions in the drill housing 1 to provide uphole and downhole strokes (left/right in Figures) that hammer the drill bit 2.
In the embodiment of
Referring to
A positive displacement motor (PDM) 8 driven by drilling mud or similar is coupled beneath the latch assembly 4. There are fluid ports 7 beneath the latch assembly 4 to allow drilling or other fluid to progress to a PDM 8, which converts hydraulic force from the fluid into mechanical rotation of a PDM output shaft 11. Pump in seals 9 are provided that can be usefully engaged in non-vertical core sampling. Thus drilling fluid can be used to pump the assembly into place and help seat the latch assembly to enable the non-vertical core samples to be obtained.
The PDM output shaft 11 extends downhole from the PDM 8 and through a bearing section provided below the PDM 8 comprising a bearing housing 10 and bearings 10a-10d that help support the rotating PDM output shaft 11. The PDM output shaft 11 is coupled at 53 to a hammer rotor input shaft 54 by a splined, threaded or other suitable coupling. (Note, the hammer rotor input shaft 54 could just be considered to be part of the output shaft 11 and the distinction of whether these are the same or different components is not critical to the invention). The hammer rotor input shaft 54 extends through the centre of a spring 13 (or other compliant component) that sits inside the rotatable tubular (drill) housing 1 with sufficient clearance so that as the shaft 54 rotates, it does not contact the spring. A first uphole end of the spring 8 is threadedly or otherwise coupled 83 to the bearing assembly 10 and a second downhole end is threadedly or otherwise coupled 80 to the magnetic hammer 100.
The spring 13 is used to cushion the uphole force from the magnetic hammer 100 as it returns to the top of its stroke during shuttling, therefore reducing stresses on the latch arms 5 and shoulder 6 of the latch assembly 4. As it is desirable to capture as large a diameter core as possible relative to the outer housing diameter, the housing 1 preferably comprises thin walled drill rods. This means that the latching assembly only has a small cross sectional abutment area to lock against. Substantial impact forces could compromise latching. As such, the spring or other compliant component helps cushion the uphole shock from hammering. Therefore, the spring 13 or other compliant component: a) reduces uphole damping, which could otherwise damage uphole components; b) helps to recapture some of the kinetic energy which is otherwise lost during shuttling; and/or c) enables a more stable shuttle oscillation. Without the spring 13, the latch arms 5 and shoulder 6 might not survive the uphole force from the hammer 100. It is not essential for operation that the spring 13 is coupled as described above (for example, it could simply bear against these components), although it is preferable as otherwise the shuttle oscillations and the spring life and fatigue are less controllable.
The magnetic hammer 100 is downhole from the output shaft 11 and spring 13. It has an outer hammer body 61 (see
A core catcher barrel 18 sits within the impact transfer tube (or other structure) 16 such that the impact tube or other structure surrounds the barrel 18. It has an opening downhole that sits adjacent the back of the drill bit 2 such that it is cooperable with the drill bit 2 to receive (core) material excavated by the drill bit. As the drill bit rotates and impacts the formation at the bore face, it excavates material which is captured in the core catcher barrel 18 resulting in a core sample 19. The core catcher barrel 18 is decoupled from the impact transfer tube 16 so it is independent from any longitudinal movement of the impact transfer tube 16. Keeping the core catcher barrel 18 longitudinally stationary isolates the core 19 therein from impact forces and is helpful in avoiding damaging the core sample. As such, the outer magnetic array 14 provides impact/hammering to the core taking bit 2 directly or indirectly along a longitudinal/axial impact path (through the impact tube 16 or other structure that surrounds the core catcher barrel 18) that is decoupled (or substantially decoupled) from the core so that the impact force bypasses the core. This protects the core 19.
A swivel section 17 couples the magnet hammer 100 (and in particular the rotor thereof) to the core catcher barrel 18 and core sample 19. The swivel is shown in more detail in
This swivel 17 enables the core catcher barrel 18 and sample 19 to be retracted from the drilling apparatus (rotatable housing 1) upon removal of the core sampling assembly using the overshot system 3, yet still allow the core catcher barrel 18 to remain rotationally stationary (that is, rotationally decoupled from the rotor to isolate a core in the barrel from rotation forces). Keeping the core catcher barrel 18 rotationally stationary is helpful to avoid damaging the core sample. Isolating the core sample 19/core catcher barrel 18 from the rotational forces of the assembly (necessary to advance the drill bit 2) is achieved using the mechanical swivel 17. This stops the rotational action of the inner magnetic array 15 (itself rotated by the PDM output shaft 11/hammer rotor input shaft 54) from rotating the core catcher barrel 18. It can also be seen that the impact action of the impact transfer tube 16 happens around the core catcher barrel 18 (there is clearance between the core catcher barrel 18 and the impact transfer tube 16) so this does not damage the core sample.
The core drilling apparatus 40 works in the following manner. The core sampling assembly, comprising with the overshot system 3, PDM 8, spring 13, magnetic hammer 100, swivel 17, core catcher barrel 18 and impact transfer tube 16 is inserted into the rotatable housing 1 and positioned (optionally using drilling fluid) so that the impact transfer tube 16 sits against the back of the drill bit 2/anvil 72. The extendable latch arms 5 engage in the shoulder 6 to retain the apparatus in place in the drill housing 1. The drilling rig puts weight on bit and rotates the drill housing, which rotates the splined drill bit 2 to drill into the formation. Drilling fluid 75 is pumped (see
Referring to
Once a core sample 19 is captured, the overshot system 3 is operated (in a manner known to those skilled in the art) to remove core sampling assembly from the rotatable housing 1 to retrieve the core catcher barrel 18 and the core sample 19. To do this, when drilling stops, the upper end of the overshot is lowered on a wire cable inside the housing until it latches onto the top end of overshot 3 (
In the embodiment above, the impact zone is shown in region 71/72. It will be appreciated that this impact zone can be at any point between the magnetic hammer 100 and the drill bit 2. For example, and as will be demonstrated with reference to
As mentioned above, in alternative embodiments, the core sampling apparatus could utilise other hammer types such as pneumatic or fluid hammers, using pressurised fluid or compressed air to energise the hammer assembly could replace the magnetic hammer section 100 to allow successful core sampling. The choice of the hammer itself is not so important, as various hammer mechanisms have been used for many years and a detailed explanation of how they work is not warranted.
Irrespective of the type of hammer arrangement used, preferably a core sampling apparatus/assembly according to the invention is one that has the attributes 1-6 listed below.
In operation, the core sampling assembly, comprising the overshot system 33, hammer 38, core catcher barrel 22 and impact transfer tube 23 is inserted into the rotatable housing 1 and positioned so that the impact transfer tube 23 sits against the back of the drill bit 24. The extendable latch arms engage in the shoulder 29 to retain the apparatus in place in the housing 1. The drilling rig puts weight on bit and rotates the housing 1, which rotates the splined drill bit 2 to drill into the formation at the bore face. Drilling fluid 75 energises the hammer 38 with its hammer mass to coerce the hammer mass towards the impact transfer tube 23. The shoulders on the hammer 38a impact against the uphole annular surface 23a of the impact transfer tube 23 at an impact zone. This causes the impact transfer tube 23 to impact against the drill bit 24. The weight on bit, rotation of the drill bit 24 and hammering of the drill bit 2 excavates material into the core catcher barrel 22 and advances the drill bit 2.
During operation, drilling fluid exhausts 75 between the core catcher 22 and the impact transfer tube 23 and exits at 25 from the bit 24. Some fluid is also allowed to escape at 26 in the hammer impact zone to help reduce the fluid damping the impact force.
The hammer is held in place during impact by the latch assembly 27. The spring 28 allows the latch assembly 27 and shoulder 29 (small cross sectional abutment) to survive and reduces the stress on the drill rod 30 above the latch assembly.
In
The drill bit 24 is splined at 31 to the drill housing 30, allowing the impact force to be transferred via impact transfer tube 23 from the hammer mass via the bit 24 to the formation—without damaging the drill housing 30. The rotary swivel joint 32 allows the captured core 21 to be rotationally static.
Once a core sample is captured, the overshot system 3 is operated to remove core sampling assembly from the drill housing 1 to retrieve the core catcher barrel and the core sample. As shown by
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2013/059987 | 11/8/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61724007 | Nov 2012 | US |
