Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
DRILLING HEAD SYSTEM WITH INTEGRATED ACOUSTIC SOURCE AND ARM WHICH IS EQUIPPED WITH ELECTRODYNAMIC DETECTORS
Document Type and Number:
WIPO Patent Application WO/2017/103126
Kind Code:
A1
Abstract:
The invention relates to a technique for subsurface prospection by means of a drilling head system (10) having an integrated acoustic source (101, 102, 103) and an arm (20) which is equipped with electrodynamic detectors (201). The drilling head system (10) for subsurface prospection comprises a drilling head having a plurality of drilling bits, and a seismic impulse source integrated in the drilling head, comprising a drop weight (102) inside a hollow cylinder (101), which drop weight is configured to generate seismic waves and an end piece (103) as a stop for the drop weight. The arm (20) is transportable and comprises a plurality of electrodynamic detectors (201) which are configured to detect seismic impulses from a subsurface, wherein the electrodynamic detectors (201) are positionable relative to one another in accordance with a predetermined positional relationship.

Inventors:
BOSE GUIDO (DE)
BALKE JENS (DE)
Application Number:
EP2016/081452
Publication Date:
June 22, 2017
Filing Date:
December 16, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
AIRBUS DS GMBH (DE)
International Classes:
G01V1/147; B64G1/66; E21B10/62; E21B47/00
Foreign References:
DE19944032A12001-03-15
US20070114062A12007-05-24
US2898084A1959-08-04
US4207619A1980-06-10
US20050249039A12005-11-10
Attorney, Agent or Firm:
SCHICKER, Silvia (Patentanwälte PartG mbBSchweigerstrasse 2, München, DE)
Download PDF:
Claims:
Claims

1. Drilling head system (10) for subsurface prospection, comprising:

a drilling head having a plurality of drilling bits; and

a seismic impulse source (101, 102, 103) which is integrated in the drilling head.

2. Drilling head system according to claim 1, wherein:

the seismic impulse source comprises a hollow cylinder (101) inserted in the drilling head, a drop weight (102) inside the hollow cylinder, which drop weight is configured to generate seismic waves, and an end piece (103) as a stop for the drop weight.

3. Drilling head system according to claim 2, wherein:

the hollow cylinder is disposed inside the drilling head.

4. Drilling head system according to claim 2, further comprising:

a deployment mechanism which is configured to deploy the hollow cylinder downwards out of the drilling head in the vertical direction.

5. Drilling head system according to claim 4, wherein:

the deployment mechanism is further configured to press the hollow cylinder against the surrounding material with increased pressure.

6. Drilling head system according to at least one of claims 2 to 5, further comprising:

a pre-loading mechanism which is configured to pre-load the drop weight before it is dropped in such a manner that the drop weight strikes the end piece with an acceleration greater than the site-dependent gravitational acceleration.

7. Drilling head system according to at least one of claims 2 to 6, further comprising:

a hollow drilling rod (10a),

wherein the hollow drilling rod receives the hollow cylinder, or

wherein the hollow drilling rod itself comprises the drop weight and the end piece.

8. Drilling head system according to claim 1, wherein the seismic impulse source comprises at least one of the following:

a pyrotechnic impulse generating unit,

an electric or electronic impulse generating unit, and

a loudspeaker system.

9. Drilling head system according to at least one of the preceding claims, further comprising:

a GPS system which is configured to determine a position of the drilling head.

10. Transportable arm (20), comprising:

a plurality of electrodynamic detectors (201) which are configured to detect seismic impulses from a subsurface,

wherein the electrodynamic detectors are positionable relative to one another in accordance with a predetermined positional relationship.

11. Arm according to claim 10, wherein:

the electrodynamic detectors are geophones.

Description:
Drilling head system with integrated acoustic source and arm which is equipped with electrodynamic detectors

The present invention relates to a drilling head system with an integrated acoustic source and an arm which is equipped with electrodynamic detectors.

According to current prior art, no indication was given during the drilling operation of the distance from an oil deposit or sensitive geological regions. As a result, there is a high risk that lengthy drilling times will have to be accepted or even that the target site will be missed. In the case of highly resistant rocks, there is the additional risk that the drilling head will be damaged when it bores into them. Since drilling generally accounts for at least forty percent of the exploration costs, it would be highly advantageous if only one borehole were needed.

Background to seismology

Seismology is a method of geophysics which was introduced a long time ago and which provides important structural information for the engineering and environmental fields. In seismic methods, elastic waves and wave fields are used as information carriers, which can be processed to give two-dimensional images of the subsurface. It is thereby possible to gain a direct insight into the complex structure of the subsurface.

The geology or also other anthropogenic changes in the subsurface influence the propagation of seismic waves by mechanisms such as reflection, refraction, diffraction, absorption and scattering. The seismic waves for such investigations are generated artificially and recorded by means of electrodynamic pickups. The waves transmitted by the seismic source can reach the surface again both by reflection and by multiple refraction and can there be received.

Established methods of seismology are reflection seismology and refraction seismology.

Reflection seismology is distinguished, in terms of the measuring arrangement, by a short source distance relative to the target depth. Reflections are recorded by means of a multichannel receiver chain and provide the possibility of producing an image of the subsurface structure which can be interpreted directly. The objects investigated are mostly small-scale, compared with the exploration of deposits, and require high- frequency, broadband signals in order to achieve a high resolution. Pores and loose subsurface therefore absorb the wave propagation to a greater degree.

Refraction seismology, on the other hand, requires a significantly larger layout of the receiver chain on the surface relative to the target depth in order to permit improved reception of refracted waves. These are waves which have covered the quickest path between the source and the receiver and thus produce the first inputs in the seismic signals. The method can likewise produce two-dimensional images of the subsurface, similarly to reflection seismology.

The use of the so-called "drilling noise" of drilling heads during their use as a sound source for seismic subsurface investigations has been introduced as a method. The method has weaknesses in that it uses merely a non-directional source (both in temporal and in spatial dimension) which is not optimised for efficient coupling of the seismic source to the adjacent rock. As a result, energy is lost for transmission to the surrounding material.

The present invention strives for an improved coaxial diplexer and a corresponding signal coupling device. In this description there is proposed a drilling head system concept which is provided with an embedded acoustic source (and in one embodiment with a GPS positioning system). Furthermore, two fields of application in which the innovation can be used with the inclusion of an established geophysical method (seismology) are put forward.

In a first aspect there is provided a drilling head system for subsurface prospection, comprising a drilling head having a plurality of drilling bits, and a seismic impulse source which is integrated in the drilling head.

In a first form of the first aspect, the seismic impulse source comprises a hollow cylinder inserted in the drilling head, a drop weight inside the hollow cylinder, which drop weight is configured to generate seismic waves, and an end piece as a stop for the drop weight. In this case, the hollow cylinder is preferably disposed inside the drilling head. As an alternative, the drilling head system further preferably comprises a deployment mechanism which is configured to deploy the hollow cylinder downwards out of the drilling head in the vertical direction. In the latter case, the deploy- ment mechanism is preferably further configured to press the hollow cylinder against the surrounding material with increased pressure.

In a second form of the first aspect, the drilling head system further comprises a preloading mechanism which is configured to pre-load the drop weight before it is dropped, in such a manner that the drop weight strikes the end piece with an acceleration greater than the site-dependent gravitational acceleration.

In a third form, the drilling head system further comprises a hollow drilling rod, wherein the hollow drilling rod receives the hollow cylinder, or wherein the hollow drilling rod itself comprises the drop weight and the end piece.

In a fourth form of the first aspect, the seismic impulse source comprises at least one of the following: a pyrotechnic impulse generating unit, an electrical or electronic impulse generating unit, and a loudspeaker system.

In a fifth form, the drilling head system further comprises a GPS system which is configured to determine a position of the drilling head.

In a second aspect there is provided a transportable arm comprising a plurality of electrodynamic detectors which are configured to detect seismic impulses from a subsurface, wherein the electrodynamic detectors are positionable relative to one another in accordance with a predetermined positional relationship.

In a first form of the second aspect, the electrodynamic detectors are geophones.

The accompanying drawings show embodiments of the invention, to which the present invention is not, however, to be limited in any way. In the drawings, the same reference numerals denote the same or similar constituent elements. It should be noted that the representation of individual constituent elements does not exclude the possibility that the particular underlying functionality in question can be implemented in a plurality of elements. In the drawings:

Fig. 1 shows the system according to the invention as a whole, applicable both to a Mars rover and to terrestrial use; Fig. 2A is a schematic view of a drilling head system according to the invention in accordance with a first embodiment of the invention;

Fig. 2B is a schematic view of a drilling head system according to the invention in accordance with a second embodiment of the invention;

Fig. 3A is a schematic view in particular of the arm according to the invention in accordance with a third embodiment of the invention; and

Fig. 3B is a schematic view in particular of the arm according to the invention in accordance with a fourth embodiment of the invention.

The measuring method

A large proportion of the measuring methods used in borehole geophysics are potentially suitable. A distinction is to be made between methods which allow predictive analyses to be made and those which merely permit a survey of the already existing borehole wall formed by the drilling operation.

A fundamental challenge when defining a suitable measuring method is the detection architecture which can be used for detecting subsurface structures or discriminating between physically distinguishable rock formations. Most methods of borehole geophysics use a laterally acting geometric arrangement for recording measurements. This means that, from a specific vertical position of the probe in the borehole, electrical or also acoustic parameters are detected horizontally. However, this technique is not suitable for effecting a resolution of the region situated beneath the drilling head.

Remaining possible methods and measuring arrangements are therefore acoustic (seismic) methods for the two-dimensional resolution of the subsurface. This is only possible if the drilling head is not in advance, since the acoustic sounds of the drilling head would otherwise interfere with the measurements:

1. Arrangement 1: Acoustic transmitter in the drilling head (with downward excitation, localised centrally at the tip of the drilling head), preferably with horizontally distributed geophones as the receiver chain on the ground;

2. Arrangement 2: Acoustic transmitter in the drilling head (with downward excitation, localised centrally at the tip of the drilling head), preferably with vertically distributed geophones as the receiver chain in an adjacent borehole. The materials, or their structures, which are to be detected at an early stage in the subsurface must differ from the surrounding material by physically measurable parameters. To that end, there are suitable for seismology material-typical differences which are reflected physically in the following two parameters:

1. density of the materials

2. water content (and thus likewise effect on the density).

The following subsurface anomalies can thereby be detected in principle by seismology:

• layer boundaries

• loosening

• cavities

• change of material

• geological faults

The advantage of seismology is that the seismic source can be located both on the surface and in the subsurface. In dependence on this decision, the evaluation methods are to be correspondingly adapted so that the propagation of the acoustic ray paths between the transmitter source and the receiver chain can adequately be back- calculated and converted by means of inversion methods into a two-dimensional diagram. It is thus possible to image the geological formations in the subsurface.

In the following description, specific details are described, for the purposes of explanation but not of limitation, in order to ensure a fundamental understanding of the technology presented herein. It is clear to the average person skilled in the art that the present technology can be realised in other embodiments which depart from these specific details.

Fig. 1 shows the system according to the invention as a whole, applicable both to a Mars rover and to terrestrial use. The system 1 as a whole comprises a drilling head system 10 having a sound generator or seismic impulse source, an arm 20 having electrodynamic detectors (in particular geophones) 201, and a carrier vehicle 30 having corresponding control and monitoring units for controlling/regulating and for reading out values of the drilling head system 10 and of the arm 20. Fig. 1 relates in particular to the drilling head system 10 for subsurface prospection, comprising a drilling head having a plurality of drilling bits; and a seismic impulse source 101, 102, 103 which is integrated in the drilling head.

The seismic impulse source comprises in particular a hollow cylinder 101 inserted in the drilling head, a drop weight 102 inside the hollow cylinder, which drop weight is configured to generate seismic waves, and an end piece 103 as a stop for the drop weight. As an alternative (not shown), the seismic impulse source preferably comprises at least one of the following: a pyrotechnic impulse generating unit, an electrical or electronic impulse generating unit, and a loudspeaker system.

Applicable to all embodiments, the drilling head system comprises in particular a GPS system (not shown) which is configured to determine a position of the drilling head.

Fig. 2A shows a schematic view of a drilling head system according to the invention in accordance with a first embodiment of the invention. The hollow cylinder is here disposed inside the drilling head, in other words it is a seismo-drill according to the invention with indirect seismic impulse transmission.

The drill 10 comprises a drilling rod 10a. The (hollow) cylinder 101 (preferably metal and inserted) functions (preferably inside the drilling rod 10a) as the drop weight

102. The resonance is generated by the (hollow) cylinder striking the resonance plate

103. Finally, the resonance is transmitted directly to the rock via the drilling head.

The seismic signal generator, or the seismic impulse source, in the drill or drilling rod can likewise be a pyrotechnic unit or an electronic/electrical impulse generating unit.

Fig. 2B shows a schematic view of a drilling head system according to the invention in accordance with a second embodiment of the invention.

The drilling head or drilling head system 10 according to the invention likewise has the drilling rod 10a and moreover, as compared with previous drilling heads with drilling bits, additionally the inserted, metal hollow cylinder 101. This is closed at the bottom by a metal plate 103. If the drilling head 10 is viewed from beneath, it is thus preferably situated centrally in the middle of the hollow cylinder 101 and therefore lies along a virtual extension of the drilling rod that is used. The hollow cylinder 101 is provided on the inside with the drop weight 102, which can be moved in the vertical direction and serves as the trigger for generating seismic (= acoustic) waves. In the rest position (= starting position), the hollow cylinder is preferably flush with the outer skin of the drilling head and is therefore exposed to only slight mechanical, external stresses during the drilling operation.

In both embodiments, the drilling rod 10a is preferably hollow and can contain the hollow cylinder 101. As an alternative, the hollow drilling rod itself can serve as the hollow cylinder 101, which comprises the drop weight 102 and the end piece 103.

According to the invention, the drilling head system 10 preferably further comprises a deployment mechanism (not shown), which is configured to deploy the hollow cylinder 101 downwards out of the drilling head 10 in the vertical direction.

In other words, the hollow cylinder 101 is preferably equipped with the hydraulic mechanism which allows the hollow cylinder 101 to be pushed out of the drilling head 10 in the vertical direction until it strikes the adjacent surrounding material.

According to the invention, the deployment mechanism is preferably further configured to press the hollow cylinder against the surrounding material with increased pressure.

The hollow cylinder 101 is thus preferably not only pushed out and pressed against the surrounding material with the normal force of gravity (or the gravitational acceleration acting at the site in question), but is pressed against the surrounding material with increased pressure. Improved seismic coupling to the surrounding material (mostly rock) can be ensured as a result.

Within the hollow cylinder 101 there is situated the drop weight 102, the construction of which is preferably matched to the hollow cylinder 101 to such an extent that it is not braked during its accelerated fall by the air contained in the hollow cylinder. This is preferably ensured by providing air slots (see the ventilation bore in Fig. 2B).

According to the invention, the drilling head system 10 preferably further comprises a pre-loading mechanism (not shown), which is configured to pre-load the drop weight 102 before it is dropped, so that the drop weight 102 strikes the end piece 103 with an acceleration greater than the site-dependent gravitational acceleration. The accel- eration of the drop weight and/or the deployment of the resonance sleeve can preferably take place by way of a hydraulic system, spring pre-loading, pyrotechnic actuation, a cable spring mechanism or similar acceleration methods/deployment mechanisms.

In other words, the drop weight 102 is preferably coupled to a mechanism which allows the drop weight 102, after it has been pre-loaded, to strike the plate-like end piece 103 of the hollow cylinder 101 with accelerated force, and also allows the drop weight 102 to return to its original position again.

The movement of the push-out hollow cylinder 101 and also the movement of the drop weight 102 inside the hollow cylinder 101 are preferably controlled externally (see Fig. 1) by connecting this region of the drilling head to the control station 30 situated on the surface, for example via connecting lines; however, this does not exclude a wireless coupling, where practicable. Control of the pre-loading and actuating mechanism for the drop weight 102 and control of the advancement of the hollow cylinder 101 are preferably likewise carried out by the control station 30.

The control station 30 preferably further receives measured data (depth, angular positions) relating to the position of the hollow cylinder 101 and the drop weight 102 inside the drilling head 10, for example by sensors provided on the drilling head. This can be supplemented by the use of a GPS receiver.

Most suitable are seismic sources which can preferably generate a Dirac-like impulse, as is the case with waves formed when hammer-blow seismology is used. This physical ability can be fulfilled with the drilling head 10 according to the invention since it is itself capable of functioning as a seismic source with defined effective power. By integrating the seismic source into the drilling head 10, the ray path between the transmitter and the receiver chain 20 situated on the surface of the ground can be shortened. A higher output of acoustic waves can thus be delivered directly to the subsurface, so that higher penetration depths and optionally improved resolution are thus achieved by reducing the scattering effect.

Furthermore, this method can permit better clarification of the geological conditions directly beneath the drilling head as compared with conventional seismic arrangements, since the drilling head can interfere with the seismic results through shielding and/or scattering. This combined seismo-drill technology can be used in the commercial field (see Fig. 3B described below) and the space field (see Fig. 3A described below).

According to the invention, the transportable arm 20 comprises a plurality of electro- dynamic detectors 201 which are configured to detect seismic impulses from a subsurface, wherein the electrodynamic detectors can be positioned relative to one another in accordance with a predetermined positional relationship. The electrodynamic detectors 201 are preferably geophones.

Fig. 3A is a schematic view in particular of the arm according to the invention in accordance with a third embodiment of the invention.

As a non-limiting example, reflection seismology can be used in the Mars rover mission because of the near-surface exploration depth and the limited influences in outer space. In addition, reflection seismology is advantageous because of the required closeness to the Mars rover (i.e. the geophones must be disposed relatively close to the rover since the rover transports and must itself deposit the geophone chain (arm)).

The drilling head 10 contains an acoustic source as the impulse generator in the form of the drop weight 102. With this construction, the seismic source can be used both on the surface and in the borehole itself. The receiver chain 20 consisting of geophones 201 is preferably deposited on the horizontal survey area for measurement by means of a grappler (arm).

By means of the geophones 201, a 2D seismogram can be prepared so that the geological formation in the subsurface can be imaged. The seismic 2D data that are measured and represented graphically are sent to earth.

The method sequence is as follows:

1. The rover travels to a suitable survey site.

2. The drilling head 10 is lowered onto the surface of the ground. The receiver chain is likewise lowered to the ground in a position specified by the control station 30 and is pressed into the surface of the ground by means of an external lever arm. The hollow cylinder 101 moves out of the drilling head 10 and is pressed onto the surface of the ground. The drop weight 102 inside the hollow cylinder 101 is pre-loaded and then made to strike the inner base 103 of the hollow cylinder in an accelerated manner. The resulting seismic waves are transmitted into the ground, reflected or refracted at geological horizons and faults and finally recorded along the receiver chain 20 (consisting of geophones 201). The measured data of the geophones are digitised and converted into a time diagram by means of software. Further process steps follow so that conclusions can be drawn about the recorded geological subsurface structure. The extent to which the measured data are evaluated on board the rover or in the base station, which also controls the rover, depends on the computing capacities and the requirements of the mission. If it is decided that repeat measurements are required at the same site, steps 5 to 7 can be carried out again.

If it is decided that it is worth drilling, a bore can first be made and, when it has been completed, a seismic measurement can again be performed. In this case, the hollow cylinder 101 is retracted into the drilling head 10 before the drilling so that it does not interfere with the drilling operation.

If it is decided that further exploration at the current site is not expedient, steps 1 to 7 are to be carried out again. For calibration of the travel time data, it is necessary to know the drilled material in order to acquire information about the density and thus the speed of the material. Finally, therefore, a sample from the irradiated region is to be provided. This embodiment offers the following advantages:

• targeted drilling in the subsurface saves time and material

• more compact measuring unit as compared with established methods.

Fig. 3B shows a schematic view in particular of the arm according to the invention in accordance with a fourth embodiment of the invention.

As a further non-limiting example, both methods (reflection and refraction seismology) can be used commercially. In both methods, the information recorded by the geophones can be converted into a 2D seismogram in order to image the geological formation in the subsurface.

The drilling head 10 contains an acoustic source as the impulse generator in the form of the drop weight 102. With this construction, the seismic source can be used both on the surface and in the borehole itself. The receiver chain 20 consisting of geophones 201 is preferably deposited on the horizontal survey area for measurement by means of a grappler (arm).

By means of the geophones 201, a 2D seismogram can be prepared so that the geological formation in the subsurface can be imaged. The seismic 2D data that are measured can be processed on site.

The method sequence is as follows:

1. The vehicle 30 travels to a suitable survey site.

2. The drilling head 10 is lowered onto the surface of the ground.

3. The receiver chain 20 is likewise lowered to the ground in a position specified by the control station and is pressed into the surface of the ground by means of an external lever arm.

4. The hollow cylinder 101 moves out of the drilling head 10 and is pressed onto the surface of the ground. 5. The drop weight 102 inside the hollow cylinder 101 is pre-loaded and then made to strike the inner base 103 of the hollow cylinder 101 in an accelerated manner.

6. The resulting seismic waves are transmitted into the ground, reflected or refracted at geological horizons and faults and finally recorded along the receiver chain 20 (consisting of geophones 201).

7. The measured data of the geophones 201 are digitised and converted into a time diagram by means of software. Further process steps follow so that conclusions about the recorded geological subsurface structure can be drawn. The extent to which the measured data are evaluated on board the vehicle or in a separate evaluation station depends on the computing capacities and the requirements of the mission.

8. If it is decided that repeat measurements are required at the same site, steps 5 to 7 can be carried out again.

If it is decided that it is worth drilling, a bore can first be made and, when it has been completed, a seismic measurement can again be performed. In this case, the hollow cylinder 101 is retracted into the drilling head 10 before the drilling so that it does not interfere with the drilling operation.

If it is decided that further exploration at the current site is not expedient, steps 1 to 7 are to be carried out again.

Without loss of generality, the invention can be summarised as follows:

A concept for development of a drilling head system which has an integrated acoustic source and is equipped with a GPS receiver system and integration thereof for application for subsurface prospection has been researched and developed. The development is in combination with commercial use for raw material prospection and extraction as well as further development of the Mars rover.

In other words, there is proposed in this patent description a drilling head system concept which is provided with an embedded acoustic source and a GPS positioning system. Furthermore, two fields of application in which the innovation can be used with the inclusion of an established geophysical method (seismology) are put forward.

The present invention permits inter alia the following advantages:

• efficient and rapid drilling without loss of time

• no downtimes as a result of unnecessary repairs to drilling heads

• targeted monitoring of subsurface deposits

• no separate seismic source required

• improved resolution and depth of penetration in the case of measurements of the subsurface possible by use of the acoustic source at the site of the drilling head at depth

• dual use of the drilling head possible, that is to say both on the surface and at depth