CN116547435A - Method and system for optimizing drilling parameters during an ongoing drilling process - Google Patents

Abstract

The invention relates to a method for optimizing at least one drilling parameter during an ongoing drilling process, the drilling being performed by a percussion drilling machine (105), the drilling machine (105) being set to drill at an operating point, the operating point of the drilling being determined by setting a plurality of control parameters. The method comprises determining a first plurality of drilling machine operating points (401 a to 401d, 402b to 402d, 404 c to 404d, 404a to 404 d), the operating points (401 a to 401d, 402b to 402d, 404 c to 404d, 404a to 404 d) being set by the plurality of control parameters. Furthermore, percussive drilling is performed at each of the first plurality of operating points (401 a-401 d;402 b-402 d;404 c-404 d;404 a-404 d), and at least one final drilling parameter for each of the plurality of operating points (401 a-401 d;402 b-402 d;404 c-404 d;404 a-404 d) is evaluated. The method further comprises determining a new plurality of drilling machine operating points (401 a to 401d, 402b to 402d, 404 c to 404 d;404a to 404 d) to be drilled based on the evaluation, and subsequently drilling the new plurality of drilling machine operating points (401 a to 401d, 402b to 402d; 404 c to 404 d;404a to 404 d).

Description

Method and system for optimizing drilling parameters during an ongoing drilling process

Technical Field

The present invention relates to percussive rock drilling and more particularly to a method for optimizing at least one drilling parameter during an ongoing drilling process. The invention also relates to a system for carrying out the method according to the invention, and a rock drilling rig comprising such a system.

Background

Rock drilling rigs can be used in many fields of application. For example, rock drilling rigs may be used for tunnelling, surface mining, underground mining, rock reinforcement, raise boring, and may be used for example for drilling blast holes, grout holes, holes for installing rock bolts, water and other wells, piling, foundation boring, and the like. Accordingly, the rock drilling rig has a wide range of applications.

The actual breaking of the rock is usually performed by a drill bit contacting the rock, wherein the drill bit is usually connected to the drilling machine by means of a drill string. Drilling may be done in various ways and may for example be percussive, wherein, for example, a percussive element of a drilling machine, for example in the form of a percussive piston, often repeatedly impacts the drill bit by striking a drill string connecting the drill bit to the drilling machine, to transmit a percussive pulse in the form of a shock wave, i.e. a stress wave, to the drill bit and further into the rock. Percussion drilling may be combined with rotation in order to obtain the following drilling: in such drilling, the buttons, or buttons of the drill bit strike new rock on each stroke, thereby improving the efficiency of the drilling.

The drill bit may be pressed against the rock during drilling by means of a feed force to ensure that as much impact energy as possible is transferred from the percussion device to the rock.

In order to obtain an efficient percussive drilling process, it is important to set various drilling parameters such that the percussive drilling is performed in a manner that allows as much as possible of the percussive wave energy induced by the percussion element into the drill string to be transferred into the rock for breaking the rock. In this way, an efficient breaking of the rock can be obtained. In case too low shock wave energy is transmitted by the impact of the impact element, this may have a negative impact on the productivity of the drilling. In addition, detrimental reflections may also occur in cases where the shock wave energy is too low and/or too low to fracture the rock with respect to the force with which the drill string is pressed against the rock. This is also the case when the shock wave contains more energy than is required to break the rock.

In the event that the drill bit is not firmly pressed against the rock, energy may be reflected to an undesirable extent and returned to the drilling machine to potentially cause excessive wear or damage. This is also the case if the joints of the drill string are not sufficiently tightened.

Disclosure of Invention

It is an object of the present invention to provide a method and a system capable of optimizing at least one drilling parameter during an ongoing drilling process.

According to the present invention, a method for optimizing at least one drilling parameter during an ongoing drilling process is provided. Drilling is performed by an impact drilling machine. The drilling machine is set to drill at an operating point, wherein the operating point of the drill is determined by setting a plurality of control parameters.

The method includes determining a first plurality of drilling machine operating points to be drilled, the operating points being set by the plurality of control parameters. Further, percussive drilling is performed at each of the first plurality of operating points, and at least one final drilling parameter for each of the plurality of operating points is evaluated. The method further includes determining a new plurality of drilling machine operating points to drill based on the evaluation, and then drilling the new plurality of drilling machine operating points.

With respect to the terms "optimizing", "optimized" and the like, it should be understood that the optimization of drilling is to find a better operating point than the operating point at the location where drilling is currently taking place. The optimization according to the invention is thus to find a better operating point than the current operating point from the point of view of the final drilling parameters, such as the drilling rate.

With respect to rock drilling, there is generally a need for efficient drilling, wherein the efficiency is typically measured in terms of productivity, and wherein the rate of penetration, i.e. the unit distance per unit time at the location where drilling is performed, may form a measure of such productivity. However, while high productivity is desirable, it must also be ensured that drilling is performed in a manner that does not unnecessarily subject the drill to excessive wear that can lead to damage. The drilling machine is usually manually operated and this places a great responsibility on the operator in terms of drilling results. Inexperienced drillers may cause ineffective drilling, resulting in low production while subjecting the drilling rig to excessive wear. On the other hand, experienced drillers can control drilling in a manner that achieves high productivity while still protecting the drilling rig from wear. The drilling machine may also be automatically controlled, in which the automatic operation will depend to a large extent on drilling with control parameter settings, which initially originate from settings made by experienced drillers or which have been empirically considered to provide effective drilling.

With respect to productivity and wear, in general, efficient drilling may be obtained when a shock wave containing as much energy as possible is transmitted through the drill string to the rock being drilled without a substantial portion of the shock wave energy being reflected back to the drilling machine. Another important factor is that the normally threaded joint of the drill string remains firmly tightened, as otherwise further reflections occur and degrade the drilling. Loose joints also generate heat, which is both a loss of energy and may itself be detrimental to drill string components.

In accordance with the present invention, problems caused by less than ideal drilling may be alleviated by a system and method in which a first plurality of drilling machine operating points are determined, wherein the drilling machine is set to continuously perform drilling at the operating points, and wherein the drilling machine is set to operate at a particular operating point by setting a plurality of control parameters that control the drilling. These control parameters may vary depending on the type of drilling technique used, and may include at least two of the following with respect to the hydraulically driven drilling process: a representation of the percussion pressure, a representation of the feed pressure, a representation of the rotational speed of the drill string, a representation of the flushing flow for flushing drilling residues out of the hole being drilled. Instead of or as one or more of the above-mentioned representations of pressure, a representation of hydraulic flow may also be utilized.

In case the drilling process is pneumatically driven or driven by an electrical device, the drilling machine is set to operate at a specific operating point with corresponding control parameters.

According to the invention, drilling is performed at each of the determined plurality of operating points, and at least one final drilling parameter, i.e. a parameter as a result of the drilling, is evaluated for each of the plurality of operating points. A new plurality of operating points is then determined based on the evaluation, wherein the new plurality of operating points may be selected based on the drilled operating points that are believed to exhibit the best drilling results for the operating point being drilled, i.e., the best results for the at least one resulting drilling parameter being evaluated. A new plurality of drilling machine operating points are then drilled and a new evaluation may be made, on the basis of which another new set of operating points may be determined based on the operating points currently considered to be optimal. The final drilling parameter upon which the evaluation is based may be, for example, a rate of drilling, wherein the higher the rate of drilling, the more desirable the drilling may be considered, but may also include other or additional drilling parameters as described below.

During drilling, the operating point may be continuously determined and evaluated with respect to at least one final drilling parameter for which an evaluation is performed, and a new set of operating points may be continuously selected based on the operating point currently considered to be optimal. When determining a plurality of operating points to drill, the value of at least one control parameter may be increased and/or decreased.

Thus, the drilling may be subjected to ongoing optimization at least until a better operating point than the one already evaluated can no longer be identified, in which case the drilling may be set to operate at that operating point. According to an embodiment of the invention, the optimization is continued during the drilling.

In this way, the drilling machine can be automatically arranged to control the drilling in such a way that the optimal operating point will be identified substantially independently of the starting value of the control parameter, since the optimization according to the invention will strive to achieve an increasingly ideal drilling, wherein the optimization is performed while drilling is taking place. This means that when the drill is controlled, for example, by an inexperienced drill operator, the inexperienced drill operator may set the drill to drill at an unfavourable setting, and the control according to the invention may alleviate the inexperienced drill operator to a large extent by optimizing the setting according to the invention. The invention is also useful in automatic drilling, where automatic drilling can be optimized, and also in the case of experienced rig operators controlling drilling, since according to the invention the evaluation can be performed continuously to further optimize drilling.

According to embodiments of the invention, each operating point may be drilled by the impact element of the drilling machine for a predetermined period of time, e.g. 1 to 10 seconds and/or a predetermined number of impacts, e.g. 50 to 300 impacts, before switching to a subsequent operating point to be drilled. In this way, drilling may be performed long enough to allow for proper assessment of the operating point while drilling is not performed too long in preparation for drilling at other operating points would be more advantageous.

In accordance with an embodiment of the present invention, the method further comprises evaluating a plurality of final drilling parameters for each of the plurality of operating points when evaluating the plurality of operating points that have been drilled. As mentioned, the rate of drilling is often an important factor, and the rate of drilling is often to be maximized. However, as discussed above, situations may arise where there is a hazard to the drilling rig and where there may be a potential hazard to the drilling rig. This includes situations where the impact of the impact element causes a loose joint, and/or where the impact occurs when the drill string is pressed too tightly against the rock with respect to the energy transferred to the drill string by the impact element, and/or where the impact occurs when the drill string is in poor or no contact with the rock. Thus, according to embodiments of the present invention, other parameters, in particular parameters that are a result of a current setting of control parameters, may be considered when evaluating the operating point being drilled. Such final drilling parameters may also penalize the result, and thus such final drilling parameters may make operating points exhibiting high drilling rates less ideal than operating points exhibiting lower drilling rates, but also less penalized. Another example of a parameter that may be considered is the energy consumption of the drilling machine, wherein the operating point of the drilling machine, for example, at the same drilling rate but with a lower energy consumption, is generally better than the operating point with the same drilling rate but with a higher energy consumption.

According to an embodiment of the invention, a plurality of drilling parameters are assigned different weights and/or priorities in the evaluation. In this way, the most important drilling parameters, such as the drilling rate, may be given higher priority than energy consumption. The priority may also be given to drilling parameters that may penalize the result, wherein, for example, operating points exhibiting, for example, high drilling rates may be considered unused in cases where the penalty is high.

According to an embodiment of the invention, the method further comprises, in determining a new plurality of drilling machine operating points: a new plurality of operating points is selected starting from a drilling machine operating point of the plurality of drilling machine operating points that has been drilled that is considered to be the optimal operating point for the plurality of operating points that have been drilled. In this way, the drilling can be continuously improved by finding an increasingly better operating point, whereby the drilling converges towards an optimum.

According to an embodiment of the invention, the optimization is continued at least as long as a better drilling machine operating point is identified. In case the drilling cannot be further optimized, the drilling may be arranged to be performed using an operating point which has been considered to be optimal.

According to an embodiment of the present invention, when a point considered to be optimal has been found, other operating points in which the control parameters vary to different extents may be selected. This may be performed to determine whether the best that has been located is only a local best or a more general best that takes into account constraints that drilling using a rig is subject to in terms of maximum and minimum values, etc.

In accordance with an embodiment of the present invention, in the event that an evaluation of the plurality of drilled operating points does not identify a better operating point relative to the operating point from which the plurality of drilled operating points were determined, at least one of the other plurality of operating points to be drilled may be determined from the previously drilled operating points. In accordance with an embodiment of the present invention, the operating point may also be determined in this case from previously drilled operating points that have not formed the basis for determining a new set of operating points. For example, the following operating points may exist: the operating point has shown substantially the same results as the operating point that has been used to determine other operating points to drill, and thus may be utilized to generate a new operating point to drill.

According to embodiments of the present invention, a drilling machine operating point may be evaluated while the operating point is being drilled, and a determination may be made as to whether to cease drilling at the evaluated operating point before a predetermined number of shocks and/or drilling periods are completed. For example, it may be determined whether drilling at the operating point causes a penalty such as according to the detrimental reflections and/or loose joints described above and/or the bit getting stuck, in which case drilling at the operating point may be discontinued and instead switched to drilling a previously drilled operating point or a subsequently to be drilled operating point.

According to an embodiment of the invention, at least one resulting drilling parameter, such as a reflected or loose joint, may be determined by measuring a reflected stress wave caused by an incident stress wave produced by at least one impact of a percussion device of a drilling machine on a drill string of a drilling machine.

The results with respect to the at least one drilling parameter may be arranged to be estimated by the percussion piston for each stroke, wherein the length of the shock wave may be in the order of 200 mus and travel through the drill steel at a speed of, for example, 5000 m/S. The impact of the impact piston typically occurs at an impact frequency of 30Hz to 120Hz, depending on the particular drilling machine used.

A sensor that can be in contact with the drill string, or the following sensors can be used: the sensor uses a sensor disposed in close proximity to the drill string to perform a non-contact measurement of a stress wave in the drill string. Such a non-contact sensor may operate, for example, according to a principle based on measuring a change in magnetization of the drill string in response to a stress wave travelling in the drill string. Various suitable sensors or sensors of this type are known to those skilled in the art of rock drilling and are therefore not discussed in detail herein.

It is also contemplated that data such as the shockwave and control parameter values and ultimately the drilling parameters may be collected during drilling so that the unwanted shockwave may be associated with particular parameter values. Such data may then be used to identify potentially harmful reflections without actually using the shock wave sensor.

According to an embodiment of the invention, the method further comprises determining a control parameter setting to be used when drilling at the specific operating point when drilling is to be performed at the specific operating point, and setting the drilling control parameter to the determined control parameter setting before drilling is performed at the specific operating point.

According to an embodiment of the present invention, before a new plurality of operation points are generated, it may be determined whether a difference in control parameter values between the operation points is increased or decreased. For example, in the case where an operating point of a plurality of operating points that have just been drilled exhibits similar results in the evaluation, the difference in control parameter values for the subsequent plurality of operating points may be increased to allow for faster detection of an operating point that may be better than the current operating point. Conversely, in the event that there is a large variation in the results obtained, and also in the event that the drilling appears to be near the optimum, the variance may be reduced.

According to embodiments of the present invention, when drilling is started, an initial operating point from which an operating point to be drilled starts may be determined as an operating point previously used as an optimal operating point in an early drilling period or an empirically determined operating point or an operator-initiated operating point. The initial operating point may also be selected, for example, as a previous operating point that has been found to be the best point when drilling another hole at a similar depth at a similar location, which best point may be determined, for example, using any suitable positioning method of the drilling machine.

According to an embodiment of the invention, the method further comprises optimizing the drilling by maximizing at least one drilling parameter, such as the rate of penetration, and/or minimizing at least one drilling parameter, such as the power consumption, while maintaining a high rate of penetration. Furthermore, the impact resulting in detrimental reflections can also be minimized.

According to an embodiment of the invention, the method further comprises adhering to a maximum limit and/or a minimum limit of the at least one drilling parameter in determining a subsequent plurality of operating points to be drilled, in order to avoid subjecting the drilling machine to injuries due to exceeding the limit and using the operating points at which the drilling machine is not designed to operate.

It will be appreciated that the embodiments described in relation to the method aspects of the invention are applicable to the system aspects of the invention as well. That is, the system may be configured to perform the method defined in any of the embodiments described above. Furthermore, the method may be a computer-implemented method, which may be implemented in one or more control units of the drilling machine, for example.

Additional features of the invention and advantages thereof are indicated in the detailed description of exemplary embodiments set forth below and in the accompanying drawings.

Drawings

FIG. 1 illustrates an exemplary drilling rig in which embodiments of the present invention may be utilized;

FIG. 2 illustrates a schematic overview of optimization control in accordance with an embodiment of the present invention;

FIG. 3 illustrates an exemplary method according to an embodiment of the invention;

fig. 4 illustrates exemplary results in optimizing drilling according to an embodiment of the present invention.

Fig. 5 illustrates the result of the optimization process according to fig. 4.

Detailed Description

Embodiments of the invention will be exemplified hereinafter in view of a specific type of drilling machine in which drilling is performed by using a percussion device in the form of a top hammer. The drilling machine may also be any other type of drilling machine in which drilling is performed by using a hydraulic percussion device for transmitting stress waves into the drilling tool for breaking rock. The invention is also applicable to drilling rigs comprising other types of percussive drilling machines than hydraulically driven drilling machines, such as those operated by electrical or pneumatic means.

Fig. 1 illustrates a rock drilling rig 100 according to an exemplary embodiment of the invention, and an inventive method of optimizing at least one drilling parameter during an ongoing drilling process will be described with respect to the rock drilling rig 100. The drill 100 is in the process of drilling a hole, wherein the current drilling has reached the depth x.

The rock drilling rig 100 according to the present example constitutes an open air drilling rig, although it will be appreciated that the drilling rig may also be a percussion drilling rig of the type primarily intended for underground drilling or for any other use, for example. The rock drilling rig 100 comprises a carrier 101, which carrier 101 carries a cantilever 102 in a conventional manner. Further, a feed beam 103 is attached to the cantilever 102. The feed beam 103 carries a carriage 104, which carriage 104 is slidably arranged along the feed beam 103 to allow the carriage 104 to travel along the feed beam 103. The carriage 104 in turn carries an impact device (drilling machine) 105, for example also comprising a rotation unit (not shown, but rotation indicated by 117), so that the impact device 105 can travel along the feed beam 103 by sliding the carriage 104.

The percussion device 105 is in use connected to a drilling tool, such as a drill bit 106 according to the present example, by means of a drill string 107. For practical reasons (except for the potentially very short bore), the drill string 107 typically does not comprise a one-piece drill string, but rather typically comprises a plurality of drill rods. When drilling has advanced a distance corresponding to the length of drill pipe, a new drill pipe is threaded together with one or more drill pipes that have been threaded together to form a drill string, whereby drilling may be advanced another drill pipe length before the new drill pipe is threaded together with the existing drill pipe. This is illustrated by rods 202-204, rods 202-204 being joined together by threaded joints 206, 207. The drill bit 106 is engaged with the drill pipe 204 by means of a threaded joint 208. Furthermore, the percussion device 105 comprises a drill shank (not shown) on which a percussion element in the form of a percussion piston 115 impinges and which is connected to the drill rod 202 by means of a threaded joint 205. Drill rods of the disclosed type may extend substantially to any desired length as drilling progresses.

In use, the impact piston 115 of the impact device 105 repeatedly impacts the drill shank and thereby the drill rod, so as to transfer impact wave energy to the drill string 107 and thereby to the drill bit 106 and further into the rock to break the rock. In addition to providing rotation of the drill string and thus rotation of the drill bit 106 during drilling, the percussive device 105 and/or the carriage 104 by being subjected to forces acting in the drilling direction also provides a feed force acting on the drill string 107 to thereby press the drill bit 106 against the rock face being drilled.

According to the illustrated example, the percussion device 105, in particular the percussion piston 115, is powered by pressurized hydraulic fluid supplied to the percussion device by a hydraulic pump 116 and a suitable hose 118 arranged on the carrier 101. The vehicle 101 also includes a hydraulic fluid tank 119 from which hydraulic fluid is drawn and returned to power the impact device using a hydraulic circuit. Other hydraulic pumps may be present for providing pressurized hydraulic fluid in one or more additional hydraulic circuits, such as a damping circuit.

According to the illustrated example, compressed air is led to the drill bit 106 through a passage (not shown) inside the drill string 107, wherein the compressed air is supplied from the tank 109 to the drill string 107 through a suitable coupling 110 and hose 113 or other suitable means in a manner known per se. Compressed air is generated by a compressor (not shown) which can charge the tank 109, the compressed air being supplied from the tank 109 to the drill string. Compressed air may be vented through holes in the drill bit 106 for cleaning the borehole from cuttings. The compressed air may alternatively be, for example, a mixture of compressed air and water or any other suitable type of mixture. With regard to, in particular, open air drilling, the power consumption of the flushing system can be considerable and constitute a significant part of the total power consumption of the drilling machine. Thus, in accordance with embodiments of the present invention, the applied irrigation flow may be a control parameter that is desired to be optimized by minimization.

The hydraulic pump 116 and other power consuming devices, such as a compressor, are driven by the power source 111, which power source 111 is for example in the form of an internal combustion engine, such as a diesel engine, or any other suitable power source, such as an electric motor or a combination of power sources. Fig. 1 also illustrates a sensor 209 for measuring the stress wave induced into the drill string by the impact piston 115 and the reflections occurring at different locations in the drill string and when the stress wave hits the rock. As described above, the sensor 209 may operate, for example, according to a principle based on measuring a change in magnetization of the drill string in response to a stress wave traveling in the drill string, wherein various such sensors are known in the art. For example, when performing an estimation according to the present invention, sensors as exemplified in any of the documents EP 2811110 A1, EP 3266975 B1, WO 2007/082997A1, US 6,640,205 B2, US 7114576 B2, WO 2017/217905A1 may be used. The drilling machine of the disclosed type also comprises, in a manner known per se, for example, various pressure sensors in order to measure, for example, the pressure in the supply path providing the impact piston 115 with pressurized hydraulic fluid and the pressure of the supply mechanism pressing the drill string against the rock, for example, during drilling.

The rock drilling rig 100 further comprises a rig control system comprising at least one control unit 120. The control unit 120 is configured to control various functions of the drilling machine 100, such as controlling the drilling process. In the case where the drilling rig 100 is manually operated, the control unit 120 may receive control signals from an operator located in the operator compartment 114, for example, through operator controllable devices, such as joysticks and other devices requesting various actions to be taken, and wherein the control signals, such as operator induced joystick deflections and/or manipulation of other devices, may be converted by the control system into suitable control commands. The control unit 120 may, for example, be configured to request movements performed by various actuators, such as cylinders/motors/pumps, etc., for example, to manipulate the boom 102, the feeder 103, and to control the impact device 105, as well as various other functions. The described control and other functions may alternatively be controlled partially or fully autonomously by the control unit 120.

The disclosed type of drilling machine may also comprise more than one control unit, e.g. a plurality of control units, wherein each control unit may be arranged to be responsible for monitoring and performing various functions of the drilling machine 100, respectively. However, for simplicity, it will be assumed hereinafter that various functions are controlled by the control unit 120. Such a control system may further utilize any suitable type of data bus to allow communication between the various units of machine 100. In the event that the drill 100 is manipulated by an operator, various data may be displayed, for example, on one or more displays in the operator compartment 114.

According to an embodiment of the invention, the method for optimizing at least one drilling parameter is performed by a control unit of the drilling machine, such as the control unit 120 of fig. 1, but the optimization may also be configured to take place in any suitable location.

As discussed above, the present invention relates to a method for optimizing a drilling process when drilling. An illustrative principle according to the invention is shown in fig. 2, in which an exemplary representation of parameters that may participate in the optimization according to an embodiment of the invention is illustrated. Embodiments of the present invention will be described below in terms of an example in which optimization is controlled to achieve as high a rate of penetration as possible while avoiding operating points that may lead to deleterious conditions over time. This is illustrated in fig. 2 as the rate of penetration, which is the input drilling parameter to be maximized. The illustrated example also uses drilling control parameters in the form of percussion pressure and feed pressure, which are varied in order to optimize the rate of penetration.

There is also a penalty drilling parameter input into the control. As explained, even though the drilling rate may be high, a particular operating point may still be undesirable. This involves, for example, loose joints, where, for example, an indication of one or more loose joints may be used to determine an operating point that causes a high rate of drilling may still be undesirable. This also involves impacts with poor or no rock contact, in which case most of the initial impact energy will be reflected and returned to the drilling machine. Similarly, when the drill string is pressed too tightly against the rock, the impact energy may be insufficient to break the rock and will therefore also be reflected back towards the drilling machine. These parameters are thus illustrated in fig. 2 as penalty parameters, wherein, for example, the number of occurrences during a predetermined time or the number of collisions by the impact element may be used as an indication that a specific operating point should not be used. Control according to the present invention will be further explained with reference to fig. 3, wherein the basic search method is utilized to optimize drilling. However, this constitutes but an exemplary method and any other suitable method may be used, such as, for example, simplex algorithm optimization or any other optimization algorithm.

Furthermore, according to the following example, two control parameters, namely percussion pressure and feed pressure, are utilized to control the drilling. As indicated in fig. 2, other control parameters, such as rotational speed and flushing flow, which also constitute parameters that desire to be minimized, may be used. As mentioned above, especially with respect to surface drilling, the flushing flow may constitute a major part of the total power consumption of the drilling machine. Furthermore, if the power consumption can be reduced while maintaining a high rate of penetration, lower power consumption will naturally be considered better than higher power consumption for the same rate of penetration. With regard to the example of fig. 2, the optimization thus aims at achieving as high a drilling rate as possible, wherein this is performed by controlling the percussion pressure and feed pressure (and optionally the flushing flow and/or the rotation pressure). These parameters are also typically subject to maximum and minimum limitations that must be complied with as described below.

The drilling machine is set to drill at an operating point, wherein the operating point of the drill is determined by setting a plurality of control parameters. The control parameters may be, for example, rotation pressure, percussion pressure and feed pressure.

An exemplary method 300 according to an embodiment of the invention will be discussed below with reference to fig. 3. The method 300 is performed to optimize at least one drilling parameter during an ongoing drilling process performed by a percussion drilling machine, such as the rock drilling machine shown in fig. 1.

With respect to the exemplary method of fig. 3, the method begins in step 301 with determining in step 301 whether drilling is to be performed according to an automatic drilling optimization in accordance with an embodiment of the present invention. According to an embodiment of the invention, this may be arranged to be performed once drilling has started, i.e. whether drilling of a new hole has started or whether drilling of a hole is continued, e.g. after adding drill rod. The optimized use may also be arranged to be selectable, for example, selectable by the operator of the drilling machine, in preparation for the drilling to be performed manually, which will sometimes be desired. However, it is contemplated that automatic optimization will be essentially in use all the time while drilling is in progress.

When a drilling optimization according to the invention is to be performed, the method continues to step 302, where initial settings for the optimization are determined in step 30. The initial setting may comprise, for example, setting the control parameters (percussion pressure and feed pressure according to the present example) to initial values, which thus represent an initial operating point for drilling.

The initial operating point may be, for example, an operating point that has been found to be optimal for a previously drilled hole or optimal for a control parameter that has been previously determined to provide effective drilling, for example. In the case of a recently drilled hole, the parameters found to be optimal when drilling the hole may be advantageously utilized. Alternatively, for example, stored parameters that have been previously drilled may be utilized, wherein, for example, the type of rock may be entered by an operator to select parameters that were previously believed to provide the desired result. The initial operating point may also be predetermined, e.g. empirically determined, and stored during the manufacture of the drilling machine. According to an embodiment of the present invention, the initial setting may also be obtained in accordance with the setting by the operator.

The method then continues to step 303 where a "box" is generated in step 303, the "box" defining a set of operating points to be drilled and evaluated relative to the initial operating point. The initial operating point will be replaced by the current optimal operating point, which will vary as the optimization progresses, as follows.

When determining the operating points to be drilled in step 303, these operating points are determined taking into account the difference in the parameter values relative to the initial operating point of the particular parameter being controlled, namely the percussion pressure and the feed pressure according to the present example. That is, when a set of operating points to be drilled is determined for subsequent evaluation, the operating points will have different values in terms of at least one of the control parameters by means of which the drilling is controlled. The operating point to be drilled may be arranged to differ in one or more of such drilling control parameters. According to the present example, there are two control parameters and four operating points are defined, wherein each control parameter is allowed to increase and decrease with respect to the initial operating point, thereby generating four operating points. Other operating points may be defined and parameter values need not both be increased and decreased relative to initial values according to embodiments of the present invention. In case three control parameters are used, this may result in eight operating points if all possible combinations of increasing and decreasing values are used. Similarly, four control parameters produce 16 operating points using this particular method. It should be noted, however, that any number of operating points may be determined, i.e., both a higher number and a lower number may be used. The allowable differences in particular control parameter values define a "box" in which a set of operating points is to be selected, wherein the allowable differences may be arranged to vary during optimization.

According to the present example, since the operating points are determined by varying two control parameters, namely the percussion pressure and the feed pressure, different percussion pressures and/or different feed pressures are used in a set of operating points to be drilled, and according to the illustrated example, the boxes represent two-dimensional areas.

Possible other control parameters may be for example the rotation pressure or the flushing flow as described above.

It should also be noted that the invention is exemplified herein with respect to a hydraulic drilling system in which, in particular, the pressure is controlled. As discussed above, for example, the flow rate may be controlled instead, and in the case of drilling using any other drilling technique, such as electric or pneumatic drilling, any other suitable control parameter may be controlled and varied in the same manner as discussed herein for feed pressure and rotation pressure. It should also be noted that hydraulic flow may be utilized in place of one or more of the percussion pressure, feed pressure, rotation pressure.

Thus, in step 303, the operating point to be drilled is determined by the spacing between the drilling control parameters for the settings to be drilled. As will be explained below, this spacing or difference may be arranged to increase or decrease as the drilling progresses. According to embodiments of the present invention, drilling may begin with taking advantage of the large differences between parameter values, and then selecting the most promising of the relatively widely spaced operating points. The spacing between the individual operating points may then be reduced, for example, gradually, to allow optimization with respect to the most promising operating point. Conversely, the spacing between the control parameters may also be arranged to increase if, for example, substantially the same result is obtained for a set of drilled operating points. Gradients may also be determined. If, for example, the optimization tends to proceed in a particular direction, the box may be selected to have points in that direction only, for example.

Further, when generating the box in step 303, the maximum and minimum limits for drilling control parameters may be used to ensure that the machine is not set to drill with parameters that deviate from, for example, the maximum and minimum allowable values from a structural standpoint. These limits may include maximum and minimum percussion pressures, maximum and minimum feed pressures, maximum and minimum rotation pressures, etc. These maxima and minima may be predetermined, for example, to ensure that the component is not subjected to higher stresses and strains than the component is designed for. In addition to or as an alternative to having maximum and minimum limits on pressure, these limits may also relate to other corresponding parameters, such as, for example, hydraulic flow. Furthermore, similar limitations may generally be utilized for the particular drilling technique used without the use of a hydraulic drilling machine to perform the drilling.

When the operating point to be drilled has been determined, the method continues to step 304, where it is determined which operating point to drill in step 304. The selection may be performed, for example, by first selecting a lower value of the drilling control parameter, first selecting a higher value of the drilling control parameter. The order of drilling may also be random. When the operating point to be drilled has been determined, the operating point is drilled in step 305.

In step 305, in case the determination according to an embodiment of the present invention is also performed in the rig control system as the case may be, the specific parameters upon which the drilling is to be performed are first provided to the Rig Control System (RCS) or the part of the rig control system performing the actual drilling. When the drilling control parameters to be used have been provided to the drilling machine control system, a predetermined period of time may be allowed to elapse in order to ensure that the desired parameter values are set so that the drilling is actually performed using the desired parameter values. The drilling may also be arranged to perform a predetermined number of hits and/or a predetermined period of time to stabilize the drilling, using the new control parameter values, before collecting data to be used for evaluation of the drilling, to thereby obtain representative measurements.

Then, the final drilling result caused by the impact of the impact piston using the set drilling control parameters according to the present example is monitored, and the result of the drilling for the specific setting is stored for later evaluation. This includes, for example, a representation of the rate of penetration and possibly other parameters involved in the evaluation. Drilling using a particular operating point may be arranged to perform a predetermined number of hits (e.g., any suitable number of hits in the interval 50 to 500) and/or a predetermined period of time. During which data relating to drilling is collected for later evaluation, and examples of specific data collected for evaluation are illustrated below.

When drilling at a particular operating point has been completed, the method returns to step 304 where a determination is made as to whether a different set of operating points have been completed, or whether there are other operating points to be drilled first.

As soon as there are additional operating points to be drilled, the method returns to step 305 for drilling according to the next setting. When all sets of predetermined operating points have been drilled and data has been collected for these different settings, the method continues to step 306 for evaluation according to the following.

However, with further regard to step 305, the situation where the drill is performed the full number of hits/the full time period may not always be the case for a particular operating point. This is because the particular operating point being drilled may in some way exhibit poor and possibly detrimental results, even though, for example, the drilling rate may be high. As discussed, during actual drilling at a particular operating point, various penalty generation parameters may be monitored to determine whether to prematurely terminate drilling to avoid excessive wear at a particular setting. The penalty parameter may be any parameter or event that is deemed to cause unwanted drilling. Referring to fig. 2, this may be the case if it is detected that the joint becomes loose or may become loose, or that drilling produces a bump when the drill string is firmly pressed against the rock with respect to the bump pressure/energy. This results in stress wave energy being reflected back towards the drilling machine. Similarly, when the impact piston strikes the drill string and thus an undesirable reflection is obtained, it can be determined whether the drill string is in little or no contact with the rock. For example, it may also be determined whether drilling has resulted in a bit being stuck, i.e., stuck, and whether the operating point has caused a blockage, i.e., flushing of drill cuttings is not proceeding properly. This may be evaluated in particular in case the flushing flow is used as one of the drilling control parameters.

Thus, while drilling according to a particular setting is ongoing, drilling may be continuously assessed, and if it is determined that the existence of a penalty generation event is deemed too high, e.g., exceeds a threshold, drilling at the current operating point may be discontinued before all anticipated impacts for the particular setting have been performed. For example, if the number of hits that caused the penalty generation event exceeds a predetermined threshold, this may be the case, in which case drilling at a current setting is discontinued before drilling at the particular setting is completed.

With respect to determining whether a detrimental reflection is generated, this may be performed in any suitable way and according to the present example by analyzing the reflection caused by the stress wave induced by the impact element. This is performed by measuring reflected waves in the drill string using the non-contact sensor 209, wherein any suitable method may be used to estimate whether one or more joints are loose and whether the reflection reaches detrimental levels. Such a determination is well described in the art and a parallel application SE 2051XXX-X with the same assignee and application date as the present application illustrates a method in which for example a loose joint may be identified by estimating the stiffness of the joint of the drill string and wherein this may be performed for each stroke of the impact element. However, as mentioned, the determination according to the invention may be performed using any other suitable method.

As mentioned, when all operating points have been drilled, the method continues to step 306, where the results of the various settings are evaluated in step 306 to determine which of the currently drilled settings/operating points provides the best result with respect to at least one final drilling parameter. As appreciated, the term "optimal" is relative herein, and drilling is optimized when a new operating point is found that provides better drilling than a previous operating point.

As discussed, the final rate of penetration is utilized in accordance with the present example to determine the optimal operating point. However, in order to obtain efficient drilling over time, it is also important to ensure that the drilling is not performed using control parameters that result in drilling that may cause excessive wear of the components. Thus, the evaluation in step 306 may include determining a particular operating point of the set of operating points that has been drilled that provides the highest drilling rate without violating penalty limits for loose joints and the like. Various parameters may thus be involved in the evaluation in step 306 so that a high drilling rate may be obtained, but while taking into account the negative contribution of parameters that may cause the drilling machine to exhibit excessive wear.

After the evaluation in step 306, an optimal drilling setting of the round of settings just drilled is selected in step 307 and may also be transmitted to the drill control system as a setting to be used when no other settings are received. The method then continues to step 308, where a new precondition is determined in step 308, and where the new precondition will be used in step 303 in determining the next round of operating points to be drilled. This will include selecting the operating point that results in the best drilling and may also include determining whether the difference in parameter values between the operating points is to be increased or decreased. In case the different operating points just drilled show similar results, the difference may be increased such that the next set of operating points to be drilled are further spaced apart, whereas in case highly different results are obtained, the next set of parameters to be drilled may instead be arranged closer to each other. In step 309 it is determined whether the method is to be ended in step 310, e.g. because drilling is ended, otherwise in step 303 the preconditions of step 308 are utilized to determine a new set of operating points to be drilled in accordance with the above. The operating points are then selected with respect to the operating points that were considered to be optimal in the evaluation in step 307, and these operating points may also be stored as new initial operating points for use in determining the operating point to be drilled next time the optimization process according to the invention is started. As appreciated, the initial operating point may be changed a number of times during the drilling period.

Further, when determining the operating point in step 303, it may be ensured that there is no overlap with previously drilled operating points according to embodiments of the present invention. The following may also be the case: none of the just drilled operating points exhibit better drilling than the set of operating point origins. The new setting may then be selected based on the last used "old" operating point and thus still be considered optimal. The "box" may then be e.g. increased and/or e.g. arranged such that the value is only increased (or decreased). It is also contemplated that the operating point in this case may be determined from previously drilled operating points, and may still exhibit substantially the same efficiency (optimization) as the operating point for which further optimization has been attempted, although the previously drilled operating point may not form the basis for determining a new set of operating points.

In this way, the drilling may be continuously optimized during the drilling, which optimization is automatically performed by the rig control system during the drilling. This allows not only efficient drilling, for example when drilling is fully automated, but also efficient drilling, for example when drilling is partly manually controlled, so that settings set by an inexperienced driller, for example, can be changed and optimized by the rig control system during drilling, as a result of which drilling will also be efficient when the rig is in the hands of an inexperienced operator. This also allows drilling to continuously take into account changes in rock properties, for example, as drilling progresses.

Fig. 4A illustrates an example of the manner in which control parameter settings, i.e., operating points, may be changed during drilling when drilling is performed in accordance with an embodiment of the present invention. As discussed, the number of dimensions controlled will depend on the number of control parameters that participate in the optimization. According to the present example, the drilling process is optimized in terms of percussion pressure and feed pressure, thus yielding a two-dimensional search space for the settings for optimizing the drilling, wherein, for example, according to the method of fig. 3, point 401 represents the initial operating point from which the optimization starts. Then, the first set of operating points to be drilled are determined as points 401a to 401d according to the above. The operating point 401c is determined as the best operating point of the evaluated operating points 401a to 401d (and operating point 401) and is thus used as the operating point from which the new operating point is selected, according to the present example, one of the operating points coincides with the point 401 and thus does not need to be drilled. However, the operating points 402 b-402 d are drilled, and the operating point 402d is considered better than the operating point 401c, and thus the operating point 402d is used as a new "basis" for next determination of the operating point to be drilled.

The next set of operating points to be drilled includes points 403c and 403d, and also points that substantially coincide with points 401c and 401d, respectively. The operating point 403d is found to be optimal and is thus selected. Similarly, an operating point 404b is selected in a subsequent step. In this case, the frame is also reduced, which may for example be arranged to be performed based on various criteria, such as a relative improvement from one operating point to another. The method then proceeds in such a way that the points 405, 406, 407, 408 etc. are selected so as to converge towards an operating point representing the optimal operating point in relation to the drilling rate given the specific preconditions of the rock being drilled.

Fig. 4 illustrates a solution in which the optimization takes place in different directions in the search space represented by the drawing and also in the opposite direction, see for example 402 d-403 d and back to 404b. In the case of using a gradient instead, assuming starting in point 401, the gradient may be determined in point 402d, for example, it may be advantageous to try to drill further along the line intersecting point 401 and point 402 d.

Fig. 5 illustrates the optimization procedure of fig. 4 in terms of evolution of the drilling rate (y-axis) as a function of the iteration (x-axis) according to fig. 3. As can be seen from the figure, after about 15 iterations, the best operating point (relative to the other operating points) is found. The specific value of the rate of penetration is given only as a parameter value, which is any suitable representation of the rate of penetration.

The present invention may be used with essentially any type of drilling machine that uses hydraulic percussive drilling. Similarly, the present invention is applicable to any other type of percussive drilling technique. The invention can also be applied to underground drilling rigs as well as drilling rigs operating on the ground.

Claims (19)

1. A method for optimizing at least one drilling parameter during an ongoing drilling process, the drilling being performed by a percussion drilling machine (105), the drilling machine (105) being set to drill at an operating point, the operating point of the drilling being determined by setting a plurality of control parameters, characterized in that the method comprises:

Determining a first plurality of drilling machine operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d), said operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) being set by said plurality of control parameters,

performing percussive drilling at each of the first plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d),

evaluating at least one final drilling parameter for each of the plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d),

determining a new plurality of drilling machine operating points (401 a-401d, 402b-402d, 403c-403d, 404a-404 d) to be drilled based on the evaluation, and

drilling the new plurality of drilling machine operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d).

2. The method of claim 1, further comprising:

continuously determining operating points (401 a-401d;402b-402d; 404 c-404 d) during drilling based on an evaluation of the drilled operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d), and

the determined operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) are drilled and evaluated successively.

3. The method of claim 1 or 2, further comprising:

When evaluating at least one drilling parameter for each of a plurality of drilled operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d), a plurality of drilling parameters for each of the plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) are evaluated.

4. A method according to claim 3, further comprising:

the plurality of drilling parameters are assigned different weights and/or priorities in the evaluation.

5. The method of any of claims 1 to 4, further comprising, upon determining the new plurality of drilling machine operating points (401 a-401d;402b-402d;403 c-404 d;404a-404 d):

from a plurality of drilling machine operating points (401 a-401d, 402b-402d, 404 c-404 d, 404a-404 d) being drilled, what are considered to be the plurality of operating points (401 a-401d, 402b-402d, 404 c-404 d, 404a-404 d) drilled; starting to select a new plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) for the drilling machine operating point (401; 401c;402d; 404b; 405-408) of the optimal operating points (401; 401c;402d; 404b; 405-408).

6. The method of any one of claims 1 to 5, further comprising:

The drilling machine operating point (401; 401c;402d; 404b; 405-408) is continuously optimized by determining a new plurality of operating points (401 a-401d;402b-402d; 404 c-404 d) to be drilled at least as long as a better drilling machine operating point (401; 401c;402d; 404b; 405-408) is identified among the new plurality of operating points (401 a-401d;402b-402d; 404 c-404 d).

7. The method of claim 6, further comprising:

when an evaluation of a plurality of drilled operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) does not identify a better operating point (401; 401c;402d; 404b; 402 b; 404b; 405-408) than at least one of the operating points (401 a-401d;402b-402d; 404a-404 d) from which the plurality of drilled operating points (401 a-402 d;402 c-404 d;404a-404 d) is determined, the previous operating point does not form a basis for determining a new set of operating points (401 a-402 d;404b; 404 c-404 d;404 d) from the previously drilled operating points (401; 401c;402d; 404b; 405-408).

8. The method of any of claims 1 to 7, further comprising, prior to evaluating the drilling machine operating point:

performing percussive drilling at the operating point to be evaluated for at least a predetermined number of impacts and/or a predetermined period of time.

9. The method of claim 8, further comprising:

the drilling machine operating point is evaluated while the operating point is being drilled,

determining whether to cease drilling at the evaluated operating point, an

When the evaluation considers that drilling at the current operating point is to be aborted, switching drilling to a previously drilled operating point or to a subsequently to be drilled operating point before completing the predetermined number of shocks and/or drilling periods.

10. The method of any of claims 1 to 9, further comprising:

at least one drilling parameter is determined by measuring a reflected stress wave caused by an incident stress wave generated by at least one impact of the percussion device of the drilling machine (105) on a drill string of the drilling machine.

11. The method of any of claims 1 to 10, further comprising, when drilling is performed at a particular operating point:

Determining a control parameter setting to be used when drilling at the particular operating point;

setting the drilling control parameter to the determined control parameter setting; and

drilling is performed at the specific operating point after setting the control parameters.

12. The method of any one of claims 1 to 11, further comprising:

before determining a plurality of operating points (401 a-401d, 402b-402d, 404 c-404 d;404a-404 d) to drill based on previously drilled operating points (401; 401c;402d, 404 d;404b; 405-408), it is determined whether a difference in control parameter values between the operating points (401 a-401d, 402b-402d; 404 c-404 d;404 c-401 d;404 b-402d; 404 c-404 d) is increased or decreased before generating a new plurality of operating points (401 a-401d;402b-402d; 404a-404 d).

13. The method of any one of claims 1 to 12, further comprising, at the beginning of drilling:

the initial operating point (401) is selected as the operating point previously used as the optimal operating point in the early drilling period, the operating point set by the operator of the drilling machine or the empirically determined operating point (401 a-401d;402b-402d;403c-403d;404a-404 d).

14. The method of any of claims 1 to 13, further comprising:

The drilling is optimized by maximizing at least one drilling parameter and/or minimizing at least one drilling parameter.

15. The method of any of claims 1 to 14, wherein the plurality of control parameters includes two or more from the group of: rotation pressure, percussion pressure, feed pressure, flushing flow.

16. The method of any of claims 1 to 15, further comprising, when determining a plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) to be drilled starting from a drilling machine operating point (401; 401c;402d; 404b; 405-408) that is considered to be the optimal operating point (401 a-401d;402b-402d; 404 c-404 d) of the plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) to be drilled:

a higher and/or lower value of a control parameter associated with the drilling machine operating point (401; 401c;402d;403d;404b; 405-408) considered the optimal operating point is selected.

17. The method of claim 15 or 16, further comprising:

when determining a subsequent plurality of operating points (401 a-401d;402b-402d;403c-403d;404a-404 d) to be drilled, a maximum limit and/or a minimum limit of the at least one drilling parameter is complied with.

18. A system for optimizing at least one drilling parameter during an ongoing drilling process, the drilling being performed by a percussion drilling machine (105), wherein during drilling the drilling machine (105) is set to drill at an operating point, the operating point of the drilling being determined by setting a plurality of control parameters, characterized in that the system comprises:

means for determining a plurality of drilling machine operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d), said operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) being set by said plurality of control parameters,

means for performing percussive drilling at each of the determined plurality of operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d),

means for evaluating at least one final drilling parameter for each of the plurality of drilling machine operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d),

means for determining a new plurality of drilling machine operating points (401 a-401d;402b-402d; 404 c-404 d;404a-404 d) to be drilled based on the evaluation, and

means for drilling the new plurality of drilling machine operating points (401 a-401d;402b-402d;403c-403d;404a-404 d).

19. A rock drilling rig, characterized in that it comprises a system according to claim 18.