AU743936B2

AU743936B2 - Apparatus for and method of automatic sampling of drill cuttings

Info

Publication number: AU743936B2
Application number: AU10013/00A
Authority: AU
Inventors: Neill Clur
Original assignee: DRILLING PROJECT SERVICES AUST
Current assignee: DRILLING PROJECT SERVICES AUSTRALIA Pty Ltd
Priority date: 1999-02-10
Filing date: 2000-01-04
Publication date: 2002-02-07
Anticipated expiration: 2020-01-04
Also published as: AU1001300A

Description

11 PATENT APP ICATION v

COUNTRY:

DATE OF FILING: NAME OF APPLICANT: NAME OF INVENTOR: TITLE OF INVENTION:

AUSTRALIA

04 JANUARY 2000 DRILLING PROJECT SERVICES AUSTRALIA PTY LTD NEILL CLUR SAMPLING OF DRILL CUTTINGS -1- APPARATUS FOR AND METHOD OF AUTOMATIC SAMPLING OF DRILL

CUTTINGS

This invention relates to apparatus for and a method of the sampling of drill cuttings.

The sampling of drill material plays an important role in various aspects of mining operations, including the determination of the geological structure of rock, grading of ore contained in the rock, as well as the determination of the type of mining process suitable for mining the rock in question.

Sampling is traditionally carried out manually. In a conventional manual process, a drill assistant is required to manually place varying quantities of sample drill cuttings derived from a drill hole, into a container or containers. The samples represent given portions of the depth of the hole. The container/s must be replaced periodically, by hand, to collect li the samples from successive portions of the depth of the hole.

The drill cuttings collected in the different container/s are then placed in sample bags which are manually labelled and then sent off for analysis. Alternatively, the drill cuttings are formed into a pile during drilling and samples are collected after completion of the hole by manually dividing the pile and placing a suitable quantity of cuttings into a container. This S process tends to be labourious and inefficient for a number of reasons. The drill assistant may omit to replace the container when required, with the result that samples from different 5 portions of the depth of the hole can get mixed up. Manual labelling of the bags may also lead to inaccurate sample identification. Since a large number of samples are taken from each drill site and transported together to the place where they are to be analysed they can get mixed up.

As a result of the aforementioned and other problems, manual sampling techniques can lead to inaccurate analysis results, irrespective of the accuracy of the analytical methods used to analyse the samples.

According to one aspect of the current invention there is provided an apparatus for sampling drill cuttings flushed from a drill hole usually in a flow of air, the apparatus including -2means for separating drill cuttings from the air and for directing at least some of the separated drill cuttings to a collection point, and sampling means operating automatically or semi-automatically in response to the depth of the drill hole to position successive sample receptacles at the collection point to collect discrete samples of the cuttings, so the discrete samples which are collected in the sample receptacles are representative of different portions along the depth of the drill hole.

In a preferred embodiment, the apparatus includes means for diverting flushing air and entrained drill cuttings from the mouth of the hole, a separator for separating drill cuttings from the diverted air and means for directing a portion of the separated cuttings to the collection point where the cuttings are ~deposited into the sample receptacles under gravity. The sample receptacles may be provided by the compartments of a multi- S compartment tray, in which case the sampling means comprises an indexing apparatus for indexing the tray relative to the collection point, in response to the operation of the drill rig used to drill the hole and hence to the depth of the drill hole, thereby to position successive compartments of the tray beneath the collection point to collect successive, discrete, o representative samples.

According to another aspect of the present invention there S is provided a method of sampling drill cuttings entrained in flushing air diverted from the mouth of a drill hole being drilled by a drill bit attached to the lower end of a drill string, including: providing sampling means adapted to operate in response to the depth of the drill hole to position successive sample receptacles at a collection point; separating drill cuttings from the flushing air and directing at least some of the separated drill cuttings to said collection point; and sequentially collecting discrete samples of drill cuttings at said collection point so that the discrete samples are -3representative of different sequential portions along the depth of the drill hole.

The entrained drill cuttings are typically diverted to a separator from the mouth of the drill hole. Alternatively, the cuttings may be removed to the separator via the inside of the drill string of the drill rig, through the drive head, in a reverse circulation drilling process.

In another aspect the invention resides broadly in a diverter for diverting flushing air and entrained drill cuttings from the mouth of a drill hole being drilled by a drill bit attached to the lower end of a drill string, the diverter including: a lower part having a lower part side wall adapted to form a shroud about a portion of the drill string above the mouth of the drill hole and being adjustable in length, ground sealing "1 means sealingly connected to said lower part side wall and adapted to engage the ground in or about the mouth of the drill hole and to generally form a seal therewith, an outlet in said lower part side wall adapted to allow passage of flushing air and entrained drill cuttings therethrough, and adjustment means operatively connected to said lower part side wall for adjusting Sits length; and an upper part having an upper part side wall adapted to form eeoc a shroud about a portion of the drill string above said lower part, said upper part being sealingly connected to said lower .25 part for rotation with the drill stem relative to said lower part, and upper sealing means sealingly connected to said upper part side wall and adapted to engage with the drill stem to form a seal therewith while the drill stem is rotating.

Preferably, said lower part side wall includes a fixed length upper portion in which said outlet is provided and an extensible lower portion to which said ground sealing means is connected at its lower end, and said adjustment means is arranged to move said ground sealing means up and down relative to said fixed length upper portion. In a preferred form, said ground sealing means is a base member having a flexible and resilient lower face and said adjustment means includes a plurality of t'~ 7 re -4hydraulic rams spaced around said lower part, each being mounted at one end to said fixed length upper portion and at its other end to said base member and are operative to raise and lower said base member. In one such form of the invention the extensible lower portion is a flexible bellows.

Preferably, said upper sealing means includes two or more spaced apart sealing rings adapted to engage with the cylindrical face of the drill string. Suitably, the space between at least the outermost rings is greater than the length of the flats typically provided on drill stems for receiving thereon various screwing and unscrewing tools. Advantageously, such arrangement allows the sealing means to maintain an effective seal at all stages of the drill string passing through the diverter.

Preferably, the diverter also includes means for attachment to the drilling rig and for being raised and lowered relative to .1 the drilling rig. In a preferred form, a mounting plate is provided which is adapted to be mounted to the underside of the drill rig whereby the drill string can pass through the diverter, and a plurality of hydraulic rams are each connected at one end to the mounting plate and at their other ends to the upper portion of the lower part side wall and arranged to lower the upper and lower parts together as a unit towards the mouth of the hole. Advantageously, such arrangement allows the diverter to be raised as far as possible for travel between test hole sites.

In yet another aspect the invention resides broadly in apparatus for sampling drill cuttings including: a diverter for diverting flushing air and entrained drill cuttings from the mouth of a drill hole being drilled by a drill bit attached to the lower end of a drill string as previously described; means for separating drill cuttings from air diverted by said diverter and for directing at least some of the separated cuttings through a splitter unit to a collection point; and sampling means adapted to operate automatically or semiautomatically in response to the depth of the drill hole to position successive sample receptacles at said collection point to collect discrete samples of the drill cuttings so that discrete samples are representative of different portions along the depth of the drill hole.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings which diagrammatically illustrate apparatus according to the present invention.

The illustrated apparatus 10 includes a diverter 12, a separator unit 14, possibly a vibrating screen 16, a splitter unit 17, and a sampling unit 54. The numeral 18 indicates a conventional drill rig which drives a drill string 20 carrying a drill bit 22 at its lower end for the purpose of drilling a hole 24 in a rock formation 26 which is to be sampled for geological or other purposes.

The diverter unit 12 is incorporated under the deck of the drill rig 18 and includes a lower part 19 and an upper part I The lower part has a lower part side wall which forms a shroud about the drill string 20, comprising a fixed upper portion 19b and an extensible lower portion 19c, the lower portion being a bellows type sealing unit, for instance of the type available under the trade mark DIVERTECH while the upper part 25 has only a fixed upper part side wall 25b. The upper part side wall is sealingly connected to the fixed upper portion of the lower part side wall for rotation relative thereto at joint 27. A flushing oo air outlet 34 is provided in the fixed upper portion for S connection to the separator unit 14 as will be described later.

A base member 21 is sealingly connected to the lower end of the sealing unit and includes a flexible and resilient face pad which is adapted to deform to engage and seal against the ground surface 23 adjacent the hole 24. The sealing unit provides a sealed communication passage between the annular space 32 which exists in the hole 24 around the drill string 20 and the outlet 34. When the drill rig 18 is in operation and the conventional flow of flushing air is directed through the drill string to the drill bit 22, the drill cuttings which are produced are flushed from the bottom of the hole and pass upwardly, entrained in the air flow, through the annular space 32 and through the diverter unit to outlet 34. A line 36 then takes the air and entrained j: r m, -6cuttings to the separator 14 which is, in this embodiment, in the form of a cyclone 38.

A mounting plate 29 is connected to the fixed upper portion of the lower part by a set of three circumferentially spaced hydraulic rams 30 and guide rails 31. In use, the mounting plate is securely mounted to the underside of the drill deck of the drill rig, and the hydraulic rams are adapted to raise and lower the diverter to suit a particular drilling situation and to allow the diverter to be raised for travel between drill hole sites.

Suitably, a second set of three hydraulic rams 33 are connected between the fixed upper portion 19b and the base member 21 and are operative to extend the bellows so as to increase the length of the lower part. Advantageously this allows the base member to be forced into sealing engagement with the ground adjacent the mouth of the hole.

After leaving the diverter unit, the air and cuttings enter the cyclone tangentially at the upper end. In the cyclone, the air velocity is considerably reduced with the result that the drill cuttings fall out of suspension and report to the underflow 39. The air and a small amount of dust leaves the cyclone through overflow 42 and is diverted to a wetbox 15 that sprays water to reduce the dust emitted to atmosphere. An optional vibrating screen 16, of suitable configuration to handle the volume of cuttings, is installed directly below the cyclone 38. The vibrating screen 16 removes any oversize particles that will .2 5 block the system or influence the quality of the sample. The vibrating screen can be started manually or automatically when drilling commences. Cuttings pass through the vibrating screen into a splitter 17 that divides the cuttings in an acceptable manner to suit the size of sample required. The cuttings not becoming part of the sample are rejected as waste and fall to the ground from chute 40. The cuttings now forming part of the sample pass out of the bottom of the splitter unit 17 and fall or are fed from the sample chute 44 into a sample collection indexing mechanism. The sampling unit 18 is located beneath the collection point at the lower end of the sample chute 44. The unit 18 Sincludes a support frame 46 carrying a pair of parallel rails 48.

A carriage 50 has wheels 52 which ride on the rails as illustrated. A double acting hydraulic cylinder 54 has one end connected to the end of the frame 46 and the other end connected to the carriage 50. A sample tray which includes a number of open-topped compartments 58, is mounted on the carriage 50. A control unit 60 controls the operation of the cylinder 54 in response to the operation of the drill rig 18, and is described in more detail below. As illustrated in the drawing, a first of the compartments 58, designated 58a, is initially positioned at the collection point, just beneath the lower end of the sample chute 44. With the drill rig operating to drill the hole 24, a portion of the drill cuttings reporting to the underflow 39 of the cyclone is directed through the vibrating screen 16 and the splitter 17 under gravity, into the compartment 58a. When the drill hole 24 has advanced through a predetermined distance, say 5 one metre, the hydraulic cylinder 54 is actuated under the o* *o* control of unit 60 to index the carriage 50 and with the sample tray 56 through a small increment in the direction of arrow 62.

This brings the next compartment, designated 58b, to the collection point for the collection of a further sample from the next interval of the hole 24 as the drilling continues. It will be appreciated as drilling and sampling proceeds continuously, S with the sampling unit automatically indexing the sample tray through the required small increments to bring the next compartment to the collection point each time the predetermined potion of the depth of the hole has been drilled. It will furthermore be appreciated that the drill cuttings which collect in each compartment, that is, each discrete sample, is representative of the rock through which the drill bit is drilling in that potion of the depth of the hole. In each sample the drill cuttings are well mixed as a result of the action of the diverter unit and the cyclone.

The sampling system described above is not dependent on the rate at which the hole is drilled. This is because the total volume of the drill cuttings produced during the drilling of the of a given depth of hole remains fairly constant irrespective of the drilling rate. In practice, the various operating and design -8parameters are chosen so that a representative sample from each successive portion of the hole can be accommodated in a single compartment of the tray.

The control unit 60 can be sensitive to any relevant parameter of the operation of the drill rig 18. It may, for instance, receive the output from one or more position sensing instruments which are sensitive to the physical position of a component, such as a drive head, that moves with the drill bit.

Or it could receive a signal from a switch in the operators cab that is activated at the relevant intervals for the area being drilled.

Although specific mention has been made of a sampling unit which uses a periodically actuated hydraulic cylinder to achieve indexing of the sample tray under the control of a control unit, it will be appreciated that many other types of indexing j5 mechanisms, operating in response to the operation of the drill rig, are also possible. The indexing mechanism could, for instance be purely mechanical with a mechanical linkage between the drill rig and the actuator which indexes the sample tray. As yet another alternative indexing could be achieved by, for instance, a lead screw arrangement actuated by a stepper motor under the control of a control unit, or there could be a simple on/off switching arrangement for the motor. The control system could be operated remotely using suitable transmitters and S receivers.

25 Various other alternatives are also within the scope of the invention. For instance, referring to the cyclone separator, it will be appreciated that other types of separator could equally well be used to separate the drill cuttings from the air flow.

There could also be a variety of splitter systems installed that will divide the cuttings in a suitable manner to provide a representative sample, for instance a riffle system or a rotating splitter system. Further the drill cuttings could be removed to the separator via the inside of the drill string, through the drive head, in a reverse circulation drilling process.

After the required number of discrete sample has been collected in the sample tray, a lid is placed over the tray to -9ensure that the cuttings in the various compartments cannot mix with one another, and the entire tray can be sent off for analysis. If the sample were deposited in a bag or other type of container these would also be sealed to maintain integrity of the sample while being transported for analysis.

The sampling unit may include an automatic labelling apparatus for labelling the successive samples to provide an accurate correlation between each sample and the portion of the hole 24 from which the cutting forming part of the sample were recovered. The analysis of the samples can thus be simplified and this in turn will assist with the accuracy of the analysis of the rock which had been drilled.

It is believed that the invention, as exemplified above, can lead to enhanced accuracy in sample collection, this being the primarily attributable to the automatic collection of samples as 15 opposed to the manual collection thereof.

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Claims

2. A diverter according to Claim i, wherein said lower part i 5 side wall includes a fixed length upper portion in which said outlet is provided and an extensible lower portion to which said ground sealing means is connected at its lower end.
3. A diverter according to Claim 2, wherein said ground sealing means is a base member having a flexible and resilient lower face adapted to deform so as to seal with a slightly uneven ground surface adjacent the mouth of the drill hole.
4. A diverter according to Claim 2 or Claim 3, wherein said adjustment means is arranged to move said ground sealing means up and down relative to said fixed length upper portion. A -11- A diverter according to Claim 4, wherein said adjustment means includes a plurality of hydraulic rams spaced around said lower part, each being mounted at one end to said fixed length upper portion and at its other end to said base member, said hydraulic rams being operative to raise and lower said base member relative to said fixed length upper portion.
6. A diverter according to Claim 5, wherein said extensible lower portion is a flexible bellows.
7. A diverter according to any one of the preceding claims wherein said upper sealing means includes two or more spaced apart sealing rings adapted to engage with the cylindrical face of the drill string.
8. A diverter according to Claim 7, wherein the space between at least the outermost sealing rings is greater than the length of the flats typically provided on drill stems for receiving thereon various screwing and unscrewing tools.
9. A diverter according to any one of the preceding claims, the diverter includes mounting means for mounting the diverter to the etee r drill rig and for raising and lowering the upper and lower parts as a unit relative to the drilling rig.
10. A diverter according to Claim 9, wherein said mounting means includes a mounting plate adapted to be mounted to the underside of the drill rig whereby the drill string can pass through the diverter, and a plurality of hydraulic rams each connected at one end to the mounting plate and at their other ends to the upper portion of the lower part side wall. 11ii. A diverter substantially as hereinbefore described with reference to the accompanying drawings.