AU1001300A - Apparatus for and method of automatic sampling of drill cuttings - Google Patents

Description

Vk PATENT APPLICATION 4 4 4.44

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 PROVISIONAL SPECIFICATION BACKGROUND TO THE INVENTION This invention relates to 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 place varying quantities of sample, derived from a drill hole, manually into container/s. The samples represent given portions of the depth of the hole. The container/s must be replaced periodically, by hand, to collect the samples from successive portions of the depth of the hole. The cutting collected in the different container/s are then placed in sample bags which are manually labelled and then sent off for analysis.

*ooo This process tends to be laboured and inefficient for a number of reasons. The drill assistant may omit to replace the container when required, with the result that *oo* samples from different 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 :i place they are to be analysed they can themselves get mixed up.

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

SUMMARY OF THE INVENTION 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 comprising means 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 discreet samples of the cuttings, so the discrete samples which are collected in the sample receptacles are representative of different portions of the depth of the drill hole.

In the 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 ooooo receptacles under gravity. The sample receptacles may be provided by the o* compartments of a multi-compartment tray, in which case the sampling means .:oooi S comprises an indexing apparatus for indexing the tray relative to the collection S. 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, discreet, representative samples.

S" According to another aspect of the present invention there is provided a method of sampling drill cuttings flushed from a hole in a flow of air, the method comprising the steps of separating drill cuttings from the air and directing at least some of the separated drill cuttings to a collection point, and providing a sampling means which operates in response to the depth of the drilled hole to position successive sample receptacles at the collection point to collect discreet samples of the cuttings so that the discrete samples which are collected in the sample receptacles are representative of the different portions of 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.

BRIEF DESCRIPTION OF THE DRAWING The invention will now be described in more detail, by way of example only, with reference to the accompanying drawing which diagrammatically illustrates an apparatus according to the invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 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 S. at its lower end for the purposes 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 bellows-type sealing unit 28 which seals against the collar of the hole 24 and which may, for instance be of the type available under the trade mark DIVERTECH. The unit 28 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 cuttings to the separator 14 which is, in this embodiment, in the form of a cyclone 38. 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 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 ooooo 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 S 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 includes a support frame 46 carrying a pair of parallel rails 48. A carriage 50 has wheels 52 which rides 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 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 one metre, the hydraulic cylinder 54 is actuated under the 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, 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, i.e. each discreet sample, is representative of the rock through which ooo oi the drill bit is drilling in that potion of the depth of the hole. In each sample the drill o cuttings are well mixed as a result of the action of the diverter unit and the cyclone.

ooo•• 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 parameters are chosen so that a representative sample from each successive portion of the hole can be o 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.

Also 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 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 receivers.

*p ooooo 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 S. could also be a variety of splitter systems installed that will divide the cuttings in o 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.

oooo After the required number of discrete samples has been collected in the sample tray, a lid is placed over the tray to ensure 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 'vhile 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 has 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 opposed to the manual collection thereof.

Claims (9)

1. An apparatus for sampling drill cuttings flushed from a hole in a flow of air, the apparatus comprising means for separating drill cuttings from the air and for directing at least some of the cutting through some splitter unit 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 discrete samples of the cuttings, so that the discrete samples which are collected in the sample receptacles are representative of different portions of the depth of the drill hole.

2. An apparatus according to claim 1, wherein 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 directed cuttings to the collection point where cuttings are deposited into the sample receptacles under gravity.

3. An apparatus according to claim 1 or claim 2, wherein the sample receptacles are provided by the compartments of a multi-compartment tray, individual sample bags or other containers.

4. An apparatus according to claim 3, wherein the sample 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 the depth of the drill hole, thereby to position successive receptacles beneath the collection point to collect successive, discreet, representative samples.

A method of sampling drill cuttings flushed from a drill hole in a flow of air, the method comprising the steps of separating drill cuttings from the air and directing at least some of the separated drill cuttings to a collection point, and providing a sampling means which operates in response to the depth of the ooooo drilled hole to position successive sample receptacles at the collection point to collect discrete samples of the cuttings so that the discrete samples which are collected in the sample receptacles are representative of different portion S.of the depth of the drill hole.

6. A method according to claim 5, wherein the flushing air and entrained drill cuttings are diverted to a separator from the mouth of the hole. S-

7. A method according to claim 5, wherein the cuttings are removed to a separator via the inside of the drill string of the drill rig, through the drive head, in a reverse circulation drilling process.

8. An apparatus for sampling drill cuttings flushed from a drill hole in a flow of air substantially as herein described and illustrated.

9. A method of sampling drill cuttings flushed from a drill hole in a flow of air substantially as herein described and illustrated. o *o•