WO2023204764A2 - Directional soil coring and sampling apparatus and method - Google Patents

Abstract

The present invention describes a horizontal directional soil coring and sampling apparatus and method. With this invention, a location of a desired soil sample (201, 301) is determined and a drill profile is plotted from an entrance pit (30). A drill head is driven along the drill profile by drill pipes (136) to create a pilot drill-path (140); the pilot drill-path (140) is then enlarged to a bored path (150) with a forward reamer (160). In one embodiment, a coring head (210) and a soil extractor (270) are driven into the bored path (150) to obtain an undisturbed soil sample (201). In another embodiment, outer tubes (336) are driven along the bored path (150) with a coring head (310), and a wireline soil extractor (370) is sent down an interior bore of the outer tubes to obtain an undisturbed soil sample (301).

Description

Directional Soil Coring and Sampling Apparatus and Method

Related Application

[001] The present invention claims priority to Singapore patent application no. 10202204047U filed on 19 April 2023, the disclosure of which is incorporated in its entirety.

Field of Invention

[002] The present invention relates to a directional soil coring and sampling apparatus and method. In particular, this invention relates to forward directional drilling to obtain underground soil samples.

Background

[003] A conventional directional core drilling method involves steering a drill head into a ground to create a pilot drill path according to a planned trajectory for mining minerals or prospecting for oil and gas; core samples of soil are then collected, for example, at the end of the planned trajectory for soil analysis. For this method to work, the soil has to be sufficiently stiff to provide a differential reaction at a steerable drill head in order to steer the drill head along the planned trajectory; it is thus unsuitable for soft soils. Besides a radius of curvature of the planned trajectory is often in the range of several kilometers; in urban built-up environment, there is space limitations and thus makes this conventional directional core drilling unsuitable for use in an urban environment.

[004] In an urban environment, another conventional method known as horizontal directional drilling (HDD) has been in use, for eg., by contractors to lay pipelines. This method enables installation of pipelines and utilities beneath obstructions, such as, roads, rivers, buildings and so on, without a need to remove or reposition such above-ground obstructions. HDD also requires a pilot drill path; often, such a drill path is usually made up of straight tangents and a long radius arc, with the pilot drill path starting from an entry point to an opposite, exit point located at the other side of the ground. In practice, the pilot drill path is formed by actuating a pilot drill along the planned trajectory, and the pilot drill path is then enlarged by backward or reverse drilling, that is, with a borehead being actuated to move along the pilot drill path from the exit point to the entry point. This method does not allow for extraction of cored soil samples along the pilot drill path.

[005] It can thus be seen that there exists a need to provide another directional drilling apparatus and method to conduct underground directional soil coring and soil sampling. The underground soil may be relatively soft or stiff.

Summary

[006] The following presents a simplified summary to provide a basic understanding of the present invention. This summary is not an extensive overview of the present invention, and is not intended to identify key features of the invention. Rather, it is to present some of the inventive concepts of this invention in a generalised form as a prelude to the detailed description that is to follow.

[007] The present invention seeks a provide an underground soil boring, soil coring and soil sampling apparatus and method. Preferably, this apparatus and method is suitable to obtain undisturbed soil samples in both soft and hard grounds.

[008] In one embodiment, the present invention provides a directional soil coring and sampling apparatus comprising: a steerable drill head, which is connectable at an end of a drill pipe, with the steerable drill head and the drill pipe being rotatable by a pipe drilling machine to form a pilot drill-path according a predetermined profile; and a forward reamer, which is connectable to an end of a distal drill pipe, and the forward reamer is rotatable to enlarge the pilot drill-path to form a bored path of a predetermined bore diameter; wherein the drill pipe is made of an aluminium tube of a predetermined length and outside diameter, and the drill pipe is extendable in series with a plurality of drill pipes, with one end of each of the drill pipe being formed with a pin screw connection (PSC) and an opposite end being formed with a matching box screw connection (BSC).

[009] Preferably, the forward reamer comprises 3 regions, namely, a stem region, a conical region and a guide region, with the guide region being located at a forward location and formed with a diameter substantially matching that of the pilot drill path. Preferably, the guide region is configured in an oblong cylindrical shape, with a front tip thereof being deposited with an abrasive material. Preferably, the guide region comprises two parts that are joined by a pin screw connection (PSC) and a matching box screw connection (BSC) of a predetermined size, so that the PSC and BSC allow the front tip to be removeably replaced when the abrasive material is worn out.

[0010] Preferably, the conical region of the forward reamer comprises a front conical region, a centre cylindrical region and a rear conical region. Preferably, the front conical region subtends a conical angle that is smaller than a conical angle subtended by the rear conical region. Preferably, a conical surface of the front conical region is formed with a plurality of spiral bands of abrasive material. Preferably, the forward reamer further comprises an internal, longitudinal bore which leads to outlets formed on both the front and the rear conical regions, with the outlets on the front conical region located between the spiral bands of the abrasive materials. Preferably, a cylindrical surface of the centre cylindrical region is formed with a cylindrical band of abrasive material or a hard-facing material.

[0011] In another embodiment, the above apparatus further comprises a coring head joined to a soil extractor subassembly, with the soil extractor subassembly being threadedly connectable to a drill pipe.

[0012] Preferably, the soil extractor comprises a split mould to contain a soil sample; alternatively, the soil extractor comprises an integral mould with a longitudinal split sleeve disposed therein to contain a soil sample. Preferably, the soil extractor further comprises a sleeve sub and a stabilizer threadedly connectable to the sleeve sub; preferably, each of two ends of the sleeve sub is being formed with a box screw connection (BSC); preferably, the stabilizer is configured substantially as a cylindrical shell having two spaced apart cylindrical bands of abrasive material of a predetermined extended diameter DI.

[0013] In another embodiment, the above apparatus further comprises a series of connected outer tubes to line the bored path, with a coring head attached to a terminal end of the outer tube; and a wireline soil extractor is receivable inside the series connected outer tubes, with a lower end of the wireline soil extractor configured with a coring tube for receiving a soil sample. Preferably, the coring tube further comprises a longitudinal split sleeve to receive the soil sample. [0014] Preferably, the coring head is configured with a ring of cutting edge comprised of an abrasive material; the ring of the abrasive material may be arranged in a plurality of sectors. Preferably, the abrasive material is formed by coating, depositing, impregnating, welding or brazing the abrasive material onto the coring head.

[0015] In another embodiment, the present invention provides a method for conducting soil coring and soil sampling comprising, the method comprises: determining an underground location for soil sampling; plotting a drill profile from an entrance pit to reach the underground location for soil sampling; conducting pilot drilling along the drill profile with a steerable drill head attached to an end of a drill pipe, with the drill pipe is being extended during drilling; retrieving the drill pipes and the drill head to the entrance pit, replacing the drill head with a forward reamer and driving the drill pipes to enlarge the pilot drill path to form a bored path; retrieving the drill pipes and the forward reamer to the entrance pit, replacing the forward reamer with a coring head and a soil extractor, and driving the coring head and the soil extractor with the drill pipes into the bored path to obtain a soil sample; and retrieving the drill pipes, coring head, the soil extractor and the soil sample from the underground location.

[0016] In another embodiment of the above method, after forming a bored path, the method further comprises: driving an outer tube with an end having a coring head and extending the outer tube so that the coring head reaches an end of the bored path; and sending a wireline soil extractor down into an interior bore of the series connected outer tubes, rotating the outer tubes to conduct soil coring, and after a soil sample is received inside a coring tube connected to the soil extractor, retrieving the wireline soil extractor and the soil sample from the underground location.

Brief Description of the Drawings

[0017] This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:

[0018] FIG. 1 illustrates a conventional horizontal directional drilling system that uses reverse drilling to enlarge a pilot drill path; [0019] FIG. 2 illustrates a horizontal directional drilling apparatus that uses forward reaming according to an embodiment of the present invention;

[0020] FIG. 3 illustrates the horizontal directional drilling method shown in FIG. 2 for soil coring and soil sampling;

[0021 ] FIG. 4 illustrates a forward reamer to create a bored path by forward reaming of a pilot drill path according to an embodiment of the present invention;

[0022] FIG. 5 illustrates a coring head with a soil extractor for obtaining a soil sample according to another embodiment of the present invention;

[0023] FIG. 6 illustrates an arrangement of the abrasive material at the coring head shown in FIG. 5;

[0024] FIG. 7 illustrates an assembled view of a split mould that forms part of the soil extractor, whilst FIGs. 8 and 9 illustrate the split mould when it is disassembled in two halves;

[0025] FIG. 10 and 11 illustrate a pair of pin and aperture aligning and locking mechanism for assembling the two halves of the split mould shown in FIG. 8;

[0026] FIG. 12 illustrates a bored path profile at test site #1 where the soil is soft; FIG. 13 illustrates a soil sample obtained with the above split mould at site #1;

[0027] FIG. 14 illustrates a bored path profile at test site #2 where the soil is relative stiff; in addition, FIG. 14 also illustrates pilot drill paths plotted with pitch settings for steering the drill head; and FIG. 15 illustrates a soil sample obtained with the above split mould at site #2; and

[0028] FIG. 16 illustrates a wireline soil coring extractor according to another embodiment of the present invention, whilst FIGs. 17 and 18 show two enlarged views of FIG. 16. Detailed Description

[0029] One or more specific and alternative embodiments of the present invention will now be described with reference to the attached drawings. It shall be apparent to one skilled in the art, however, that this invention may be practised without such specific details. Some of the details may not be described at length so as not to obscure the present invention. For ease of reference, common reference numerals or series of numerals will be used throughout the figures when referring to the same or similar features common to the figures. In the following description, a forward direction refers to a direction for drilling or boring a pilot drill path or a bored path, and rear or reverse refers to an opposite direction from drilling or boring.

[0030] FIG. 1 is a simplified diagram to show a known conventional horizontal directional drilling system 1, which sets the background art of the present invention. As shown in FIG. 1, an underground pipeline 44 is to be laid underneath a ground 10, which has some surface obstructions or land structures, such as, buildings 20, roads, rivers and so on. A planned underground trajectory of the pipeline is plotted between an entrance pit 30 and an exit pit 32. A rotatory pipe drilling equipment 34 is then positioned at the entrance pit 30 to drive a drill rod 36 equipped with a drill head (not shown in FIG. 1) into the ground; the drill rod 36 is then successively joined in series as the drill head is driven into the ground along the planned underground trajectory to form a pilot drill-path 40, until the drill head reaches the exit pit 32. The drill rods 36 are made of steel tubes and are joined by typical screw connections, which in the present description are called female box screw connections BSC and matching male pin screw connections PSC; typically, the drill rods 36 are substantially 4m in lengths; as an example relevant to the present invention, the drill rods 36 have an outside diameter of substantially 70 mm (or substantially 2.875 inch) and an internal bore of substantially 55 mm. During horizontal directional drilling, drilling mud is pumped through the internal bore of the drill rods 36 to lubricate the drill head; during the pilot drilling process, the drilling mud is returned to the entrance pit 30 through the annular space between the bore of the pilot drill-path 40 and the outside diameter of the drill rods 36; the drilling mud may be processed again and re-used. At the exit pit 32, the extremity end of the drilling rod 36 is then re-connected to both a backward drill 42 and an end of the pipeline 44. By rotating and pulling the drill rods 36 back to the drilling equipment 34 (in a so-called reverse-drilling process), the pilot drill-path 40 is enlarged to form a bored path 41; at the same time, by retrieving of the drill rods 36, the pipeline 44 is successively pulled into the bored path 41 and the reverse-drilling process stops after the pipeline 44 appears at the entrance pit 30.

[0031 ] FIG. 2 is a simplified diagram to show a horizontal direction drilling (HDD) apparatus 100 or system of apparatus components according to an embodiment of the present invention. In FIG. 2, the surface obstructions or land structures, such as, buildings 20, are shown located on the ground 10. Like the above conventional HDD, a planned underground trajectory for underground soil coring is plotted from an entrance pit 30. A rotatory drilling equipment 34 is then positioned at the entrance pit 30 to drive a drill pipe 136 equipped with a non-magnetic drill head (not shown in FIG. 2) to follow the planned trajectory; the drill pipe 136 is then successively joined in series as the drill head is rotatory driven and pushed into the ground along the planned underground trajectory to form a pilot drill-path 140 to a reach a desired underground location at which a soil sample is to be obtained by soil coring; the drill pipes 136 are made of aluminium tubes, for example, of substantially 1.8 - 2m in lengths, with an outside diameter of substantially 70 mm (or substantially 2.875 inch) and an internal bore of substantially 55 mm. As in the conventional HDD, the ends of these drill pipes 136 are also formed with female box screw connections BSC and matching male pin screw connections PSC; in later descriptions, BSC and PSC of relevant sizes are used for threaded connections on component parts used in the present invention. Drilling mud, for example, a bentonite slurry, is pumped though the internal bores of the drill pipes 136 to lubricate the drill head and also to move the drilling debris to the entrance pit 30. After the pilot drill-path 140 is formed, for example, at a diameter of substantially 70 mm, both the drill pipes 136 and the drill head are retrieved into the entrance pit 30. The drill head is then replaced with a forward reamer 160 (as seen in FIG. 2) and the drill pipes 136 are successively extended in series, rotatory driven and pushed along the pilot drill-path 140 to enlarge the pilot drill-path 140 to form a bored path 150 of the desired diameter (for example, of substantially 100 mm) to reach a desired location to collect a soil sample 201, as shown in FIG. 3; the drill pipes 136 are then successively retracted together with the forward reamer 160; at the entrance pit 30, the forward reamer 160 is replaced with a coring head 210 and a series connected soil extractor assembly 270 (as seen in FIG. 3); the coring head 210 and the soil extractor assembly 270 are rotatory driven and pushed along the bored path 150 by extending and driving the drill pipes 136 until the coring head 210 reaches the end of the bored path 150 to collect the desired soil sample 201. For example, at the end of the bored path 150, the drilling pipes 136 are driven an additional distance of substantially 200 mm or more to obtain the soil sample 201 located at the end of the bored path 150. The process of soil coring will become clearer when FIGs. 4-11 are described below.

[0032] As can be seen from FIG. 2, the pilot drill-path 140 is shown to be made up of substantially straight sections; it is possible that two straight sections are joined by an intervening curved section of a predetermined radius of curvature, for example, of substantially several tens of meters; the radius of curvature of the curved section of the pilot drill path 140 is substantively lower than that formed using the conventional steel drill rods 36, given that the drill pipes 136 of the present invention made of aluminium tubes are more elastic or flexible; with the conventional steel drilling rods 36, the radius of curvature is in the range of substantially several km. To drill a straight section of the pilot drill-path 140, the drill pipes 136 are rotated at relatively high speeds; when a change of direction is desired, the drill speed is temporary ceased and the drill pipes 136 are being orientated, then pushed, possibly in steps, to follow an orientation blade disposed at the pilot drill head, before continuing to drill a continuing straight section of the pilot drill-path 140. In another embodiment, it is possible to adjust the orientation blade at a steeper pitch angle when drilling through soft soil to effect a change of direction.

[0033] As can be appreciated, the HDD drilling process 200, illustrated in FIG. 3, of the present invention described above includes 3 processes: namely, (1) a pilot drilling process, (2) a forward reaming process, and (3) a soil coring process. As will be appreciated, in the present invention, the soil coring process is conducted with the soil extractor 270 or a wireline soil extractor 370. Now, the forward reaming process is described with reference to FIG. 4. Fig. 4 shows the forward reamer 160 according to an embodiment of the present invention. As seen from FIG. 4, the forward reamer 160 is made up of 3 regions: a stem region 162, a conical region 164 and a guide region 166. The guide region 166 is oblong and slender in shape, and has a diameter of substantially a bore size of the pilot drill-path 140. Preferably, the guide region 166 is made up of two parts 167,168 which are threadedly connected with box screw connection BSC and pin screw connection PSC of an associated size; part 168 is located at a tip of the guide region 166, and its front tip is dressed with an abrasive material 180a; preferably, the abrasive material 180a may be made of tungsten carbide, industrial diamond, or a similar hard abrasive to reduce wear and tear as the forward reamer 160 is rotated and pushed to enlarge the pilot drill-path 140. When the abrasive material 180a has worn out, the tip part 168 can be replaced with a new component. The conical region 164 is made up of central cylindrical region 170, a front conical region 172 and a rear conical region 174. The front conical region 172 subtends a conical angle that is smaller than a conical angle subtended by the rear conical region 174, meaning the front conical region 172 defines a longer conical surface than a rear conical surface at the rear conical region 174; the diameter of the front conical region 172 at the guide region 166 transitions gradually to a diameter D at the cylindrical region 170; as an example, the diameter D is substantially 100 mm. In one embodiment, the conical surface of the front conical region 172 has a plurality of abrasive bands 180b that are spirally formed thereon; the spiral abrasive bands 180b may be 2 or more in numbers. At the cylindrical region 170, two or more spaced apart circumferential abrasive bands 180c are provided thereon; as like the abrasive material 180a, the abrasive bands 180b, 180c may be made of tungsten carbide, industrial diamonds, or a similar hard abrasive; as an alternative to the abrasive bands 180c, circumferential bands of hard-facing material may be formed on the cylindrical portion 170; for example, when the forward reamer 160 is made of carbon or alloy steel, the circumferential hard-facing bands may be formed by carburizing or nitriding. Extending from the rear conical region 174 is the stem region 162; the stem region 162 has a box screw connection BSC for threaded joint to a pin screw connection PSC located on an end of an associated drill pipe 136.

[0034] Referring back to FIG. 4, there is an internal bore d formed along a longitudinal axis of the forward reamer 160; through the internal bore d, the drilling mud is injected through the drill pipes 136 into the forward reamer 160 and the drilling mud comes out through outlets 176,177 located, respectively on the front and the rear conical surface 172 and 174, for lubricating the reaming process. On the rear conical surface 174, there are 3 outlets 177 that are spaced equally part at 120 degrees and, for example, of substantially 19 mm diameter. The number of outlets 177 located at the rear conical surface 174 is kept relatively fewer than the number of outlets 176 located at the front conical surface 172 so that sufficient drilling mud is delivered to the front region of the forward reamer 160 during forward reaming; with this structure of the outlets 176,177, a small portion of the drilling mud supplied flows out through the outlets 177 to help wash drilling debris to flow back to the entrance pit 30. At the same time, when the forward reamer 160 is in operation, drilling debris and drill mud flow through spaces between the forward reamer 160 and the bored path 150, and they eventually flow back to the entrance pit 30.

[0035] After the pilot drill-path 140 has been enlarged to the bored path 150 by operating the forward reamer 160, both the drill pipes 136 and the forward reamer 160 are retrieved back to the entrance pit 30. The forward reamer 160 at the end of the drill pipe 136 is then replaced by an assembly of the coring head 210 and the soil extractor 270 shown in FIG. 5.

[0036] FIG. 5 shows an exploded view of the assembly of the coring head 210 and the soil extractor 270. The coring head 210 is configured like a sleeve 212 and a forward annular end of the sleeve 212 is formed with an abrasive material 180d. Similarly as described above, the abrasive material 180d may be made of tungsten carbide, industrial diamond or similar hard abrasive. In one embodiment, the abrasive material 180d is formed in a ring arrangement; in another embodiment, as shown in FIG. 6, the abrasive material 180d is arranged in four sectors to constitute four cutting blades. The abrasive material 180d or the cutting blades can be formed by coating, depositing or impregnating in a processing chamber; alternatively, it is also possible that the abrasive sectors or cutting blades are provided in solid pieces and these are welded or brazed onto the forward end of the coring head 210. Preferably, a second or opposite end of the coring head 210 is formed with a box screw connection BSC.

[0037] Connectable to the BSC of the coring head 210 is the soil extractor 270 subassembly. As shown in FIG. 5, the soil extractor 270 is made up of a split mould 271, a sleeve sub 274, a stabilizer 276 and a bend sub 278 according to an embodiment. FIG. 7 shows the split mould 271 in assembly, whilst FIGs. 8-9 show the split mould 271 being separated in two halves. The split mould 271 is made up of substantially a split annular sleeve 271 with each of two ends being threaded with a pin screw connection PSC of an associated size to mate with the BSC formed on the coring head 210. The split annular sleeve 271 is split along a longitudinal axis to form two split halves 271a, 271b, as can be seen in FIGs. 8 and 9. These split halves 271a, 271b are aligned and held together by means of 3 sets of pin 272-aperture 273 mechanisms, as seen in FIGs. 9-11. In one embodiment, the pins 272 may be threadedly fixed to the split edge on a lower split half 271b whilst the matching apertures 273 are located on the upper split half 271a. However, due to symmetry of the split halves 271a, 271b, the pins 272 and the apertures 273 are on opposite sides, and therefore the upper and the lower halves can be reversible described. In an alternative embodiment, it is possible that the pin 272 are tight-fitted into the split edge, instead of being threaded fixed. Preferably, the fit between the pins 272 and the mating apertures 273 is loose fit, so that the split halves 271a, 271b can be assembled or disassembled relatively easily or quickly at a site of operation.

[0038] From FIG. 5, it is seen that both ends of the split mould 271 are formed with pin screw connections PSC; an advantage is to keep the interior bore of the split mould 271 cylindrical and smooth. Also as seen from FIG. 5, the stabilizer 276 is configured as substantially a cylindrical shell and on its exterior cylindrical surface, there are two extended, spaced apart bands of abrasive materials 180e,180f. In one embodiment, the bands of abrasive material 180e,180f are cylindrically dressed to a diameter of DI; in one embodiment, DI is substantially an extended diameter D (located at the coring head 210). It is possible that DI is a few % larger than the diameter D, for example, with the extended diameter DI being less than 10% more than the diameter D. With DI > D, the stabilizer 276 serves to further ream the bored path 150 during the soil coring process and by so doing the stabilizer 276 makes hugging contacts in the bored path 150; in this way, during the soil coring process, the stabilizer 276 dynamically stabilizes or centralises the coring head 210. In one embodiment, the front end of the stabilizer 276 is formed with a pin screw connection PSC, whilst the opposite end is formed with a box screw connection BSC. With this configuration, the sleeve sub 274 is provided to connect the PSC end of the split mould 271 with the PSC end of the stabilizer 276.

[0039] As can be appreciated from FIG. 5, in one embodiment, a rear end the stabilizer 276 is threadedly connectable to a proximal end of a drill pipe 136 (the drill pipe is not shown in FIG. 5) via a bend sub 278. In an alternative embodiment, the rear end of the stabilizer 276 is threaded directly to a proximal end of an associated drill rod 136.

[0040] Two field tests were carried out to prove the working principle of the above apparatus 100 and the directional pilot drilling, the forward bore reaming and the soil coring/sampling process 200. The soil at Site #1 (Kranji) was soft marine clay. The pilot drill path (now labelled 140a) and the bored path (now labelled 150a) were carried out with a length of substantially 30m and reached a depth of substantially 12m, as shown by a penetration profile in FIG. 12. Due to the soft soil condition, when the forward reamer 160 was being retrieved or withdrawn, the bored path traced a slightly deviated profile 150b; in soft soil, this deviated profile 150b was expected, and this result showed that the depth profiling method used in the above invention was reasonably accurate.

[0041] FIG. 13 shows the above split mould 271 was used to obtain the soil sample 201 located at the end of the bored path 150a at Site #1 (Kranji). FIG. 13 proved that the above directional pilot drilling, forward bore reaming and soil coring processes were successfully carried out in substantially soft marine soil.

[0042] FIG. 14 shows the above split mould 271 was used to obtain the soil sample 201 located at the end of a bored path 150c at Site #2 (Kent Ridge). The soil at Site #2 (Kent Ridge) was relatively stiff. As seen in FIG. 14, the bored path 150c was carried out with a length of substantially 30m and reached a depth of nearly 10m. The drill path was launched at an entry angle of between substantially 8 and 13 deg. at the entrance pit 30. In addition, a drill path profile 140b was plotted to a depth of substantially 14m with the orientation blade at the drill head set at substantially 3% pitch angle. Another drill path profile 140c was also plotted but with the orientation blade set at substantially 8% pitch angle; when the orientation blade was set at the higher pitch angle, the plotted drill path 140c has a substantially curved profile. In FIG. 14, a terrain profile of the ground 10 and the plotted drill path profiles 140b, 140c at Site #2 were shown to verify that the drill path profiling method used was reasonably accurate and reliable.

[0043] FIG. 15 shows the split mould 271a, 271b being separated in halves and a soil sample 201 was obtained from Site #2. FIGs. 13 and 15 show that the split mould 271 was successful used in obtaining undisturbed soil samples in both soft and hard grounds; this also proves the working principles of the forward reaming and the soil coring/sampling process 200, and the coring head 210 and the soil extractor 270 the present invention enabled undisturbed the soil coring and soil sampling to be obtained.

[0044] FIG. 16 shows a wireline soil coring extractor system 300 according to another embodiment of the present invention, whilst FIGs. 17 and 18 show, respectively, an upper and a lower part of the wireline soil coring extractor 300. Like the above embodiment, a drill profile into the ground is planned, and a pilot drill-path 140 is formed according to the drill profile; the drill path 140 is subsequently enlarged with the forward reamer 160 to form a bored path 150; in the present embodiment, a series of outer tubes 336, extended via BSC and PSC threaded connections, is provided to line the bored path 150 and the wireline soil coring extractor 300 is sent down to an end of the outer tubes 336 to obtain a soil sample 301. As shown in FIG. 16, the soil coring extractor system 300 is made up of the outer tube 336, an overshot 303, a soil extractor 370 and a coring head 310. The method of using the soil coring extractor system 300 is advantageous to obtain multiple soil samples 301 without having to retrieve the outer tubes 336.

[0045] As can be visualised from FIG. 16, the soil extractor 370 and the coring head 310 are sent down into the outer tubes 336, preferably by gravity or by a pneumatic means. An upper end of the soil extractor 370 is provided with an overshot coupling 304. At a location aft of the overshot coupling 304, two sections of the outer tubes 336 are joined by an adapter pipe 305; the adapter pipe 305 has an internal step 305a that cooperates with spring loaded latches 306 that extend from a head assembly 375 of the soil extractor 370. When the latches 306 are engaged with the step 305a of the adapter pipe 305, the soil extractor 370 becomes rotationally fixed with respect to the outer tube 336. To retrieve the soil extractor 370, the overshot 303 is sent down inside the outer tube 336 by a wireline 302 to connect with the overshot coupling 304; in the connection process, the latches 306 are released and by withdrawing the wireline 302, the soil extractor 370 is retrieved from the ground.

[0046] As seen in FIG. 17, at a location aft of the head assembly 375, the soil extractor 370 has a set of bearings 308. With the bearings 308, a lower part of the soil extractor 370 becomes rotationally free with respect to the outer tube 336; in other words, during soil coring, a coring tube 371 located at a lower part of the soil extractor 370 remains non- rotatable as both the outer tube 336 and the coring head 310 are being rotated; during soil coring, a soil sample 301 is received into the coring tube 371. The coring head 310 has a ring of abrasive material 180g (not shown in FIGs. 16-18), which may be formed by coating, depositing, impregnating, welding or brazing; preferably, the abrasive material 180g is similarly arranged as seen in FIG. 6 to form a soil coring or cutting edge; preferably, the abrasive material 180g is dressed to a diameter of substantially that of the bored path 150.

[0047] As seen in FIG. 18, near the coring head 310, the outer tube 336 has two bands of stabilizer 337; similar to the above description, the bands of stabilizer 337 are dressed with the abrasive material 180 or the hard-facing material 180c; the hugging contact provided by the bands of stabilizer 337 whilst the outer tube 336 is being rotated during soil coring in the bored path 150 helps to stabilizer the soil coring process at the coring head 310.

[0048] At a lower end of the coring tube 371, a core gripper assembly 390 is provided to break the soil sample 301 from the ground before the soil extractor 370 is being retrieved. The core gripper assembly 390 is made up of a grip case 391, a split collar 392 and a stop ring 393. The grip case 391 has a tapered socket surface and it cooperates with a mating tapered surface located on the split collar 392; the stop ring 393 defines a travel distance of the split collar 392. Preferably, the tapered surfaces on the grip case 391 and the split collar 392 are hardened. After a soil coring process has been performed and the soil extractor 370 is about to be pulled up from inside the outer tube 336, the split collar 392 squeezes on the soil sample 301 and breaks the soil sample 301 from its connection to the ground; in this manner, the soil sample 301 is retained inside the coring tube 371 in an undisturbed state after the soil extractor 370 has been retrieved from the ground.

[0049] Preferably, the soil extractor 370 together with the coring tube 371 are freely slidable inside the outer tube 336; to facilitate the sliding motion of the coring tube 371 inside the outer tube 336, a band of stabilizer 376 is provided on the coring tube 371.

[0050] While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations of variations disclosed in the text description and drawings thereof could be made to the present invention without departing from the scope of the present invention; for example, it is possible to provide the coring tube 371 with an internal, longitudinally split sleeve to contain the soil sample 301; similarly, the split mould 271 can be configured as an integral mould 271c (not shown in the drawings) and an internal, longitudinal split sleeve is provided inside the integral mould 271c to contain the soil sample 201; in this manner, the longitudinally split sleeves located inside the coring tube 371 or the integral mould 271c will facilitate easy extraction of the soil sample 201, 301 in an undisturbed state.

Claims

CLAIMS:

1. A directional soil drilling, soil coring and soil sampling apparatus comprises: a steerable drill head, which is connectable at an end of a drill pipe, with the steerable drill head and the drill pipe being rotatable by a pipe drilling machine to form a pilot drill-path according a predetermined profile; and a forward reamer, which is connectable to an end of a distal drill pipe, and the forward reamer is rotatable to enlarge the pilot drill-path to form a bored path of a predetermined bore diameter; wherein the drill pipe is made of an aluminium tube of a predetermined length and outside diameter, and the drill pipe is extendable in a series of connected drill pipes, with one end of each of the drill pipe being formed with a pin screw connection (PSC) and an opposite end being formed with a matching box screw connection (BSC).

2. The apparatus according to claim 1, wherein the forward reamer comprises 3 regions, namely, a stem region, a conical region and a guide region, with the guide region being located at a forward location and formed with a diameter substantially matching that of the pilot drill path.

3. The apparatus according to claim 2, wherein the guide region is configured in an oblong cylindrical shape, with a front tip thereof being deposited with an abrasive material.

4. The apparatus according to claim 2 or 3, wherein the guide region comprises two parts that are joined by a pin screw connection (PSC) and a matching box screw connection (BSC) of a predetermined size, so that the PSC and BSC allow the front tip to be removeably replaced when the abrasive material is worn out.

5. The apparatus according to any one of claims 2 to 4, wherein the conical region comprises a front conical region, a centre cylindrical region and a rear conical region.

6. The apparatus according to claim 5, wherein the front conical region subtends a conical angle that is smaller than a conical angle subtended by the rear conical region.

7. The apparatus according to claim 5 or 6, wherein a conical surface of the front conical region is formed with a plurality of spiral bands of abrasive material.

8. The apparatus according to claim 7, wherein the forward reamer further comprises an internal, longitudinal bore which leads to outlets formed on both the front and the rear conical regions, with the outlets on the front conical region located between the spiral bands of the abrasive materials.

9. The apparatus according to any one of claims 5 to 8, wherein a cylindrical surface of the centre cylindrical region is formed with a cylindrical band of abrasive material or a hard-facing material.

10. The apparatus according to claim 1, further comprises: a coring head joined to a soil extractor subassembly, with the soil extractor subassembly being threadedly connectable to a drill pipe.

11. The apparatus according to claim 10, wherein the soil extractor comprises a split mould to contain a soil sample, with the split mould being threadedly connectable to the coring head.

12. The apparatus according to claim 10, wherein the soil extractor comprises an integral mould and a longitudinal sleeve disposed inside the integral mould to contain a soil sample.

13. The apparatus according to claim 11 or 12, wherein the soil extractor further comprises a sleeve sub and a stabilizer threadedly connectable to the sleeve sub.

14. The apparatus according to claim 13, wherein the sleeve sub has each of two ends being formed with a box screw connection (BSC).

15. The apparatus according to claim 13 or 14, wherein the stabilizer is configured substantially as a cylindrical shell having two spaced apart cylindrical bands of abrasive material of a predetermined extended diameter DI.

16. The apparatus according to claim 1, further comprises: a series of connected outer tubes to line the bored path, with a coring head attached to a terminal end of the outer tube; and a wireline soil extractor is receivable inside the series connected outer tubes, with a lower end of the wireline soil extractor configured with a coring tube for receiving a soil sample.

17. The apparatus according to claim 16, wherein the coring tube further comprises a longitudinal split sleeve for receiving the soil sample.

18. The apparatus according to any one of claims 10 to 17, wherein the coring head is configured substantially as a sleeve, and an annular edge of the sleeve is formed with a ring of cutting edge comprised of an abrasive material.

19. The apparatus according to claim 18, wherein the ring of the abrasive material is arranged in a plurality of sectors.

20. The apparatus according to claim 18 or 19, wherein the abrasive material is formed by coating, depositing, impregnating, welding or brazing the abrasive material onto the coring head.

21. A method for conducting soil coring and soil sampling comprising: determining an underground location for soil sampling; plotting a drill profile from an entrance pit to reach the underground location for soil sampling; conducting pilot drilling along the drill profile with a steerable drill head attached to an end of a drill pipe, with the drill pipe is being extended during drilling; after conducting the pilot drilling, retrieving the drill pipes and the drill head to the entrance pit, replacing the drill head with a forward reamer and driving the drill pipes to enlarge the pilot drill path to form a bored path; retrieving the drill pipes and the forward reamer to the entrance pit, replacing the forward reamer with a coring head and a soil extractor, and driving the coring head and the soil extractor with the drill pipes into the bored path to obtain a soil sample; and retrieving the drill pipes, coring head, the soil extractor and the soil sample from the underground location.

22. A method for conducting soil coring and soil sampling comprising: determining an underground location for soil sampling; plotting a drill profile from an entrance pit to reach the underground location for soil sampling; conducting pilot drilling along the drill profile with a steerable drill head attached to an end of a drill pipe, with the drill pipe is being extended during drilling; after conducting the pilot drilling, retrieving the drill pipes and the drill head to the entrance pit, replacing the drill head with a forward reamer and driving the drill pipes to enlarge the pilot drill path to form a bored path; driving an outer tube with an end having a coring head and extending the outer tube so that the coring head reaches an end of the bored path; and sending a wireline soil extractor down into an interior bore of the series connected outer tubes, rotating the outer tubes to conduct soil coring, and after a soil sample is received inside a coring tube connected to the soil extractor, retrieving the wireline soil extractor and the soil sample from the underground location.