INFILTRATION POINT DETECTION

Abstract

A method of detecting one or more potential infiltration points in ground based on cone penetration testing, CPT, data, obtained from CPT measurements throughout a depth interval, and hydraulic profiling tool, HPT, data, obtained from HPT measurements throughout the depth interval, and determining a vertical profile indicating the potential infiltration points and potential matrix failure processes. Unlocking insights from Geo-Data, the present invention further relates to improvements in sustainability and environmental developments: together we create a safe and liveable world.

Claims

1. A method of detecting one or more infiltration points in ground, the method comprising: providing Cone Penetration Testing (CPT) data, obtained from CPT measurements throughout a depth interval of the ground; providing Hydraulic Profiling Tool (HPT) data, obtained from HPT measurements throughout the depth interval; determining the one or more infiltration points from analysis of the CPT data in combination with the HPT data.

2. The method according to claim 1, comprising: from the CPT data, determining initial effective vertical stress, vi, and/or initial effective horizontal stress, hi, over the depth interval, from the HPT data, determining a corrected overpressure over the depth interval; and from the initial effective vertical stress and/or the initial effective horizontal stress in combination with the corrected overpressure, determining ground disruption parameters, the ground disruption parameters predicting onset of one or more types of ground disruption at the corrected overpressure over the depth interval.

3. The method according to claim 2, wherein the one or more infiltration points are determined as one or more locations at which no ground disruption has been predicted.

4. The method according to claim 2, further comprising determining a vertical infiltration profile over the depth interval, the vertical infiltration profile indicating potential infiltration locations representing the one or more infiltration points along the depth interval and potential ground disruption along the depth interval.

5. The method according to claim 4, further comprising determining an ideal well depth from the vertical infiltration profile.

6. The method according to claim 5, further comprising: from the determined ideal well depth, and values of an absolute permeability along the depth interval, determining a transmissivity over the depth interval.

7. The method according to claim 1, further comprising determining a maximum injection pressure profile as function of the depth interval.

8. The method according to claim 7, wherein the maximum injection pressure profile is calculated from CPT data.

9. The method according to claim 7, further comprising determining a maximum well injection capacity from the maximum injection pressure profile.

10. The method according to claim 1, wherein the CPT data and the HPT data are obtained simultaneously during CPT-HPT probing.

11. The method according to claim 1, wherein one or both of the CPT data and the HPT data are obtained from previous measurements and/or previously known data.

12. The method according to claim 1, further comprising providing mini pumping test (MPT), measurement data, obtained by one or more pressure testing series performed at one or more depths along the depth interval.

13. The method according to claim 12, further comprising determining, from the MPT measurement data, a specific absolute permeability over the depth interval, and determining, from the specific absolute permeability and from relative permeability determined from the HPT data, a cohesive strength and an absolute permeability over the depth interval.

14. System for determination of one or more infiltration points in ground along a depth interval in the ground, the system comprising: a probe equipped with an opening for injecting fluid at a set fluid injection flow rate and at least one pressure sensor for measuring a pressure response in the ground; and a processor, configured to: provide Cone Penetration Testing (CPT) data, obtained from CPT measurements throughout a depth interval of the ground; provide Hydraulic Profiling Tool (HPT) data, obtained from HPT measurements throughout the depth interval; and determine the one or more infiltration points from analysis of the CPT data in combination with the HPT data.

15. (canceled)

16. The system according to claim 14, wherein the processor is further configured to: from the CPT data, determining initial effective vertical stress, vi, and/or initial effective horizontal stress, hi, over the depth interval, from the HPT data, determining a corrected overpressure over the depth interval; and from the initial effective vertical stress and/or the initial effective horizontal stress in combination with the corrected overpressure, determining ground disruption parameters, the ground disruption parameters predicting onset of one or more types of ground disruption at the corrected overpressure over the depth interval.

17. The system according to claim 16, wherein the one or more infiltration points are determined as one or more locations at which no ground disruption has been predicted.

18. The system according to claim 16, wherein the processor is further configured to: determine a vertical infiltration profile over the depth interval, the vertical infiltration profile indicating potential infiltration locations representing the one or more infiltration points along the depth interval and potential ground disruption along the depth interval.

19. The system according to claim 18, wherein the processor is further configured to: determine an ideal well depth from the vertical infiltration profile.

20. The system according to claim 19, wherein the processor is further configured to: from the determined ideal well depth, and values of an absolute permeability along the depth interval, determining a transmissivity over the depth interval.

21. A non-transitory computer readable medium storing instructions, which when executed by a processor of a system configured to determine of one or more infiltration points in ground along a depth interval in the ground, causes the system to: configured a probe, the probe equipped with an opening for injecting fluid at a set fluid injection flow rate and at least one pressure sensor for measuring a pressure response in the ground; provide Cone Penetration Testing (CPT) data, obtained from CPT measurements throughout the depth interval of the ground; provide Hydraulic Profiling Tool (HPT) data, obtained from HPT measurements throughout the depth interval; and determine the one or more infiltration points from analysis of the CPT data in combination with the HPT data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Further features and advantages of the invention will become apparent from the description of the invention by way of non-limiting and non-exclusive embodiments. These embodiments are not to be construed as limiting the scope of protection. The person skilled in the art will realize that other alternatives and equivalent embodiments of the invention can be conceived and reduced to practice without departing from the scope of the present invention. Embodiments of the invention will be described with reference to the figures of the accompanying drawings, in which like or same reference symbols denote like, same or corresponding parts, and in which:

[0082] FIGS. 1A and 1B show a flow charts of methods performing probing of the ground, which are known in the art and which may be used for the present invention;

[0083] FIG. 2 shows a schematic side view of an embodiment of a system which may be used for probing;

[0084] FIGS. 3a, 3b and 3c show schematic side views of a probe which may be used for gathering measurement data;

[0085] FIG. 4 shows a graph indicating critical limits of increase in water pressure caused by injection as a function of initial effective vertical stress and the onset of ground disruption;

[0086] FIG. 5 shows a graph illustrating the combination of HPT and CPT measurement data according to embodiments of the invention; and

[0087] FIG. 6 shows a flow chart of a method according to embodiments of the invention, including combined analysis of CPT and HPT measurement data.

DESCRIPTION OF EMBODIMENTS

[0088] FIG. 1A shows a flow chart of a method, which can be used for determining soil properties by use of a probe comprising at least a liquid injection port and a pressure transducer. The probe is pushed into a soil for carrying out one or more pumping tests at predetermined depths. During a pumping test an infiltration liquid, such as water, is pumped though the liquid injection port of the probe. The pressure response resulting from the injection of water through the liquid injection port in the soil is measured by means of the pressure transducer arranged on the probe. The pressure response can be measured for each of the one or more pumping tests. The soil testing system can be used for measuring soil parameters while the probe is penetrated into the soil. This may be referred to as MPT, mini pumping tests.

[0089] FIG. 1B shows a flow chart of a method wherein the pumping test is combined with a hydraulic profiling tool, HPT, and/or cone penetrometer, CPT, test. The probe is pushed into a soil while an infiltration liquid is pumped though the liquid injection port of the probe. During advancement of the probe through the soil the pressure response of the soil/groundwater system against liquid injection can be determined. This may be referred to as HPT measurements or hydraulic profiling tool measurement. Also, during advancement, mechanical resistance and/or friction experienced by the probe can be determined. This may be measured, e.g., using force sensors or strain gauges provided on the probe. This is referred to as CPT, cone penetration testing.

[0090] The probe is halted at one or more predetermined depths. At each predetermined depth, one or more pumping tests, e.g. as described with reference to FIG. 1A, are performed while the probe is halted at the predetermined depth. During a pumping test an infiltration liquid is pumped though the liquid injection port of the probe. The pressure response resulting from the injection of liquid through the liquid injection port in the soil is measured by means of the pressure transducer arranged on the probe. The pressure response can be measured for each of the one or more pumping tests.

[0091] FIG. 2 shows a schematic side view of an embodiment of a system 1, which can be employed during soil penetration tests, e.g. as described above with reference to FIG. 1A and 1B, for subsurface characterization of a soil 2. The system 1 comprises a probe 9 comprising at least a liquid injection port and a pressure transducer. The probe 9 is arranged for penetration of the soil 2. The system further comprises a data acquisition system arranged for sampling measurement signals from the probe, a controller or processor arranged to control the system to push the probe 9 into the soil 2 and carry out one or more pumping tests, and measure by means of a pressure transducer, for each of the one or more pumping tests, a pressure response in the soil, resulting from the injection of liquid through the liquid injection port. The system 1 can comprise a truck 3. The truck 3 according to this embodiment has wheels. However, tracks or a combination of wheels and tracks can also be arranged. Other arrangements are also possible, e.g. the system 1 may be movable by another transportation unit. The truck 3 may further comprise a plurality of stabilizers to provide support and to improve stability during the penetration tests. The system 1 can further comprise a rod 7 which is coupled to the probe 9, and means for forcibly penetrating the probe 9 into the soil 2 by pushing the rod 7, wherein a depth of penetration L and a penetration rate of the probe 9 can be controlled by the controller. The rod 7 is used to push the probe 9 into the soil, and can include a plurality of sub-elements, such as a plurality of rod sections connected to each other. Other solutions are possible for pushing the probe 9 into the soil. The pushing force for penetration of the probe into the soil 2 can be supplied by a hydraulic pushing arrangement, arranged in the truck 3. The weight of the truck 3 can provide the reaction force for pushing against the rod 7 which is connected to the probe 9 which is forcibly penetrated into the soil 2. Other solutions for providing the reaction force are possible. Further, the system comprises a pump arranged to provide liquid, such as water, to the probe, so as to enable the injection of liquid into the soil through the liquid injection port arranged on the probe.

[0092] The system 1 further comprises a digital computer, including one or more processors, which can be coupled to the probe 9 and its sensors, e.g. force sensor and pressure sensors, to receive measurement data from the sensors. The data acquisition system can be arranged to receive electrical signals from the sensors of the probe 9. Also, the digital computer can be coupled to the data acquisition system so as to receive the acquired electrical signals or signals representative for the acquired electrical signals. The digital computer can be arranged for processing the electrical signals to provide an analysis of the measurement results so as to determine and/or calculate soil parameters and characteristics.

[0093] Further, the system can comprise an interface, such as a monitor, coupled to the digital computer for displaying a soil analysis, performed by the one or more processors, which can include the determined soil parameters, such as e.g. permeability and storativity. The analysis may be performed for different depths of penetration L. The results from a measurement campaign may be combined to provide a general overview of the soil parameters over an area or volume.

[0094] The digital computer can be arranged in a measurement unit in the truck 3 or at a remote unit. The measured data may be received by a digital computer through a wired connection or wireless connection. In case of wireless data communication, a wireless connection device may be arranged to transfer signals through mobile data transfer protocols such as 3G, 4G, 5G, etc. However, other wireless protocols such as WiFi (e.g., a wireless communication conforming to the IEEE 802.11 standard or other transmission protocol) or LoRa may also be employed to obtain a wireless communication. A combination of wireless protocols is possible.

[0095] The system 1 may be implemented in or may take the form of a vehicle. Alternatively, the system may be implemented in or take the form of other vehicles, such as cars, recreational vehicles, trucks, agricultural vehicles, construction vehicles and robotic vehicles. It also perceivable that a plurality of systems 1 are included in a vehicle.

[0096] FIGS. 3a and 3b show embodiments of the probe 9 comprising a liquid injection port 11 and a pressure transducer 13. FIG. 3a shows a schematic side view of the probe 9 having a substantially elongated tubular shape comprising a tip 17 facing in a longitudinal penetration direction 19 of the probe 9 and arranged for penetrating the soil 2. In this embodiment, the tip 17 of the tubular probe 9 has a conical shape, however, other shapes are possible. The liquid injection port 11 and the pressure transducer 13 of the probe 9 are arranged at a distance D from each other with respect to a longitudinal penetration direction of the probe 9. FIG. 3b shows a schematic side view of the probe 9 coupled with rod 7 for being pushed into the soil 2. At a certain depth of penetration L into the soil 2, the one or more pumping tests can be conducted, during which the infiltration liquid is pumped through the liquid injection port 11 of the probe 9 in the liquid infiltration flow direction 15 out of the probe 9. By means of the pressure transducer 13, for the one or more pumping tests, a pressure response in the soil 2 resulting from the injection of a liquid through the liquid injection port 11 can be measured. The one or more pumping tests can be carried out at a predefined/chosen substantially fixed depth of soil penetration L of the probe 9. Liquid, such as water, can be injected into the soil 2 through the water injection port 11 at a certain water injection flow rate Q which can be adjusted and controlled. The one or more pumping tests can be carried out at a substantially constant water injection flow rate Q, while in case of a plurality of pumping tests, successive pumping tests at a certain depth of penetration L can be carried out at different water injection flow rates Q.

[0097] The probe 9 may be a hydraulic profiling tool, HPT, probe 9, which may also be used to carry out a cone penetration test, CPT in a hydraulic profiling tool cone penetration test, HPT-CPT. Herein the HPT probe 9 is pushed into the ground or soil 2 at a constant rate while water is injected at a constant flow rate into the soil through a water injection port 11 arranged on the HPT probe 9. A HPT-CPT measurement can be used to evaluate hydraulic properties of a site sub-surface. The system 1 can comprise a HPT probe 9 comprising a tip or cone equipped with one or more water pressure sensors at a distance D from a HPT probe 9 water injection port 11, i.e. injection point. During a HPT measurement the HPT probe is advanced through the soil while injecting water via the injection port 11 at a constant flow rate. During advancement a pressure response of the soil/groundwater system against water injection is determined. During a CPT measurement the probe 9 is advanced through the soil. During advancement mechanical tip resistance, and optionally sleeve resistance, may be measured, as also described with reference to FIG. 1A and 1B. A HPT-CPT measurement combines the HPT and the CPT measurement. During a HPT measurement, the HPT probe movement can be stopped at a certain depth of penetration L. After dissipation of water pressures generated as a result of the HPT measurement, the system 1 can carry out one or more pumping tests, MPT, wherein water is injected in the soil 2 through the injection port 11. For instance, four pumping tests can be carried out, wherein four different water injection flow rates Q are used for the different pumping tests. The different water injection flow rates can be used to perform a quality assessment of the measurements afterwards by analyzing the pressure response measured by the pressure transducer 13 of the HPT probe 9. The water injection flow rate through the water injection port 11 of the HPT probe 9 can induce water overpressures, which may depend on the local geohydrological conditions, and which can be sensed/measured by the pressure transducer 13. After finishing a field measurement inverse modelling can be performed on the measured water overpressure. The inverse modelling can be performed using analytical solutions or using geohydrogeological numerical modelling. The HPT-CPT measurement may be continued after performing one or more pumping tests at a certain depth. The probe 9 may e.g. be pushed further into the soil 2. The HPT probe 9 may pushed into the soil 2 at the same constant rate while water is injected at the constant flow rate as before the pumping tests. It will be appreciated that the HPT-CPT measurement may be resumed after pore water pressure of the preceding pumping tests has dissipated. It is possible that after the HPT-CPT measurement is resumed after water injection has been restored to the level of the initial HPT-CPT measurement, and water pressure has come to an equilibrium.

[0098] FIG. 3c shows an embodiment of a probe system 99 comprising a first probe 9 and a second probe 9. Herein, the probe 9may be similar to the probe 9 described with reference to FIG. 2. The first and second probes 9, 9 are laterally spaced from each other, and may be pushed into the ground and used for performing HPT-CPT measurements in a manner as described with reference to FIG. 2. The first probe 9 comprises the liquid injection port 11. The second probe 9comprises the pressure transducer 13. In this example, the probe system 99 comprises further pressure transducers 13, 13. The liquid injection port 11 and the pressure transducer 13 of the probe system 99 are arranged at a distance D from each other with respect to a lateral direction of the probe 9. The one or more pressure transducers in the 3D space around the injection point can be used to derive horizontal and/or vertical permeability and storativity from the measured pressure response on the injected liquid Q. For example, the pressure transducer 13 can be used to determine the horizontal permeability and storativity. The pressure transducer 13 can be used to determine the vertical permeability and storativity. Optionally the horizontal and/or vertical permeability and storativity can be derived using numerical or analytical calculations, for example with an inverse modelling technique.

[0099] FIG. 4 shows a graph indicating critical limits of increase in water pressure caused by injection as a function of initial effective vertical stress and the onset of ground disruption. This graphs provides an indication of the critical limits of water pressure increase, i.e., the maximum allowed increase in water pressure (in m H.sub.2O), caused by the injection, as a function of initial vertical effective stress and the angle of internal friction for the onset of various types of ground disruption. The short dashed lines, 402, indicate predicted onset of matrix failure. The solid lines, 404, indicated the predicted onset of hydraulic fracture. The long-dashed line, 406, indicates the predicted onset of liquefaction. As can be seen, the expected onset, or initialization, of the different types of disruption is dependent on the soil properties of the formation. In particular, soil or ground layers having a higher initial vertical stress, vi, and higher internal friction angle, , can withstand higher overpressure caused by injection than layers of lower initial vertical stress. The initial vertical stress can be determined from CPT measurement data, as discussed above.

[0100] The point at which ground disruption is initiated can be estimated by recording injection flow rate and injection pressure during HPT probe penetration, and/or during searching for infiltration points. For this, the above equations, Eq 1-Eq 5, can be used.

[0101] FIG. 5 shows a graph illustrating how the HPT and CPT measurement data can be analyzed in conjunction, i.e., can be combined to determine various parameters of the ground over a depth interval. In particular, this graphical representation conceptually illustrates how CPT and HPT data can be combined to determine infiltration points and maximum infiltration capacity, and to create a vertical infiltration profile showing injection points and potential matrix failure locations.

[0102] The diagonally running lines indicates the critical limits when the different types of ground disruption is expected, calculated from CPT data as described herein above. The line 502 indicates the threshold for matrix failure, as a function of depth (probe penetration depth) into the ground. That is, line 502 represents the overpressure, caused by liquid injection, at which matrix failure is predicted to occur. The line 504 indicates the threshold for hydraulic fracturing, as a function of depth (probe penetration depth) into the ground. That is, line 504 represents the overpressure at which hydraulic fracturing is predicted to occur. The line 506 indicates the threshold for fluidization, or liquefaction, as a function of depth (probe penetration depth) into the ground. That is, line 506 represents the overpressure at which fluidization, or liquefaction, is predicted to occur. These failure lines have been determined from CPT measurement data, using the equations and theory which were discussed in the Summary section.

[0103] The quickly fluctuating line, 508, represents the overpressure caused by the liquid injection as a function of probe penetration depth, as measured during HPT probing, using a set substantially constant injection flow rate. Where this fluctuating line crosses one or more of lines 502, 504 and/or 506, it may be concluded that ground disruption, i.e., matrix failure, hydraulic fracturing, or fluidization, respectively, would be expected to occur. The respective type of failure expected is indicated in the line, or bar, 510, in the right hand part of the graphic. Locations, or penetration depth ranges, 510, where substantially no, or at least not matrix failure, is predicted, can be considered potential infiltration points.

[0104] Thereby, by graphically illustrating the pressure fluctuations measured during HPT probing in combination with the thresholds for ground disruption, which have been determined from CPT data, information can be deducted regarding the sensitivity of the ground to ground disruption as a result of the increase in water pressure caused by the injection. From this, infiltration points can be detected.

[0105] CPT and HPT measurement data can be processed and analyzed using methods and algorithms, or equations, as known to the skilled person. The curves indicating prediction of the various types of ground disruption (matrix failure, hydraulic fracturing, fluidization, respectively) can be determined, for example using the theory and equations presented in Chapter 13 of Remediation Hydraulics, 2008, Payne et al.

[0106] As can be seen from FIG. 5, at certain penetration depths no ground disruption or variations in disruption appears to occur, at the injection flow rate of the HPT system. These depth ranges, or intervals, represent possible infiltration points. If injection flow rate is increased, detecting these infiltration points becomes increasingly difficult, since the resulting water pressure increases to a point where the thresholds of fluidization/liquefaction are reached. Further, it can also be deducted that if only considering the resulting increase in water pressure caused by the probing only provides limited information, due to the limited increase in water pressure.

[0107] The above analysis confirms the concept of preferred flow paths and highly permeable layers at infiltration points. At an infiltration point the ground is less prone to disruption by an increase in water pressure than the other ground layers, which do not exhibit good permeability and infiltration properties, since the water pressure can be quickly dissipated. However, the detection of an infiltration point is highly dependent on the flow rate and/or pressure at which is probed.

[0108] As an example, in FIG. 5 a vertical line has been included at an injection pressure of 1 bar (100 kPa). If searching for infiltration points using an injection pressure of 1 bar, fluidization is expected to occur down to a depth of 9-10 meter below the ground surface. As can be seen, the diagonal line 506 representing fluidization intersects with the 1 bar line at around 9-10 meters. Therefore, above this depth, it will not be possible to find infiltration points unless working with a lower injection pressure, i.e., an injection pressure below the injection pressure at which fluidization is expected. That is, an injection pressure underneath the diagonal line indicating the onset of fluidization.

[0109] From pressure measurements performed at the depth of an infiltration point, an indication may be provided of the risk of certain ground disrupting processes. The maximum pressure, at which specific ground disruption is expected, can be deducted from the diagonal lines indicating, respectively, matrix failure, hydraulic fracturing, and fluidization.

[0110] The information deducted as described herein above, e.g., the detected infiltration points, can be used in the design or construction of an injection well to be positioned at the probed location. Such well may be designed with an injection filter at one or more of the infiltration points as determined from the above analysis. Additionally or alternatively, one of the infiltration points may be used for extraction and another of the infiltration points may be used for infiltration, or injection. For example, an upper infiltration point, that is, a point at less depth, may be used for extraction, and a lower lying, i.e., at a deeper depth, infiltration point may be used for infiltration/injection.

[0111] FIG. 6 shows a flow chart of an embodiment of the method as described herein, which may be used for deduction of a graphical representation as illustrated in FIG. 5, and/or for deduction of specific parameters and specifications, e.g. of the information discussed herein above.

[0112] At step S602, combined CPT-HPT probing is performed in the field, for example as described in the Summary section above. This may be performed using a system as described with reference to FIG. 2, 3a-3c. During CPT-HPT probing, the CPT-HPT probe 9, 9, 9, is pushed into ground over a depth interval, at substantially constant penetration speed. While pushing, CPT data, e.g. force relating to tip resistance or local friction, is measured. Simultaneously, an injection liquid, generally water, is injected at a set substantially constant flow rate, through the opening 11, and the resulting water pressure in the soil is measured using the one or more pressure sensors 13, 13, 13. At certain, preferably predetermined, depths, the probe is halted, and, preferably once an equilibrium state has been reached, one or more pumping tests is performed at each depth, so called mini pumping tests, MPT. For example, a series of pumping tests may be performed, at stepwise increasing flow rate. Thereby, CPT, HPT and MPT data are provided.

[0113] During these tests and measurements, CPT measurement data, HPT measurement data, and MPT measurement data, are recorded, e.g. by a data acquisition system. These measurement data are subsequently processed and analyzed, as shown in the flow chart.

[0114] In step S604, the CPT measurement data is input into a CPT data processor, e.g. a processor or processing unit of the digital computer of the system. Analogously, in step S606, the HPT measurement data is input into an HPT data processor, or processing unit of the system. Analogously, in step S608, the MPT measurement data is input into an MPT data processor, or processing unit, of the system.

[0115] In step S610, specific absolute permeability of the ground, as function of depth, i.e., the different layers of the ground, is determined from the MPT data. This may be performed as described in WO 2017/222372 A1 and US 2021/0003492 A1.

[0116] In step S612, the groundwater level may be determined from the MPT data.

[0117] In step S614, the HPT data is processed, to determine a corrected overpressure P, i.e., the pressure in the ground resulting from the fluid injection. In this step, the pressures as measured by the one or more pressure sensors 13, 13, 13, i.e., the pressure measured behind the injection screen, may be corrected using the groundwater level determined in step S612. This corrected overpressure may be represented graphically by the fluctuating line 508 shown in FIG. 5.

[0118] Further, in step S614, the relative permeability as a function of depth is determined from the injection flow rate, Q, and the corrected overpressure, P. This may be determined as Q/P.

[0119] In step S616, the relative permeability over the MPT area of influence, i.e., the volume of influence by the MPT, is determined. Herein, the specific absolute permeability determined in step S610 may be taken into account.

[0120] In step S618, the coherence strength C is determined, which links the absolute permeability to the relative permeability. The coherence strength is a constant, which is typical for certain types of ground layers, and depends on the different properties of the ground. In other words, the coherence strength, C, provides an indication of the type, or class, of ground or layer at a certain depth.

[0121] In step S620, the absolute permeability as a function of depth is determined.

[0122] Hence, the HPT and MPT data can be processed and/or analyzed. The above described analyses and processing of the HPT and MPT data, respectively, may include additional steps or details, as will be understood by a person skilled in the art.

[0123] In step S622, the CPT measurement data is processed, to determine the initial vertical stress, vi, and the initial horizontal stress, hi, over the depth interval. The corrected overpressure, as determined in step S614, is taken as input, to determine the effective vertical stress, v, and the effective horizontal stress, h, respectively. These parameters may be determined as described in the Summary section above.

[0124] In step S624, the parameters determined in step S622 may be used to calculate, or determine, ground disruption parameters, also as described herein above. These indicate the (predicted or estimated) onset of different types of ground disruption. In particular, critical pressure limits versus depth of matrix failure, hydraulic fracturing, and fluidization are determined. These may be represented graphically by curves 502, 504 and 506 as illustrated in FIG. 5.

[0125] In step S624, the parameters may be determined, for example, using Mohr's circle analysis of the horizontal and vertical effective stresses. Such analysis may be performed as known to the person skilled in the art, e.g. as described in Chapter 13 of Remediation Hydraulics, F.C. Payne, J.A. Quinman, and S.T. Potter, CRC Press, 2008

[0126] Based on the predictions of the various types of failures or ground disruption, determined in step S624, and the measured overpressure determined in step S614, a vertical infiltration profile is determined in step S626, indicating potential infiltration points and potential failure processes along the depth interval.

[0127] In step S628, an ideal well depth may be detected or determined, from the vertical infiltration profile determined in step S626. This may comprise selecting one or more of the infiltration points detected in step S626 as infiltration, or injection points, to be used in an injection, or extraction, well.

[0128] In step S630, the transmissivity over the well depth is determined. This is determined, basically, as a function of the thickness of the infiltration point, as determined from step S630, multiplied by the absolute permeability at the infiltration point, as determined in step S620.

[0129] In step S632, a profile over the maximum injection pressure as a function of depth is determined. This may be determined from the failure ground disruption parameters determined from step S624. Thereby, the maximum injection pressure, which may be applied at the infiltration points without risking hydraulic failure or fluidization, may be determined. The maximum injection pressure which may be applied may be determined as a certain percentage or ration of the injection pressure at which ground disruption is expected or estimated to occur. For example, the maximum allowable injection pressure may be determined as the pressure at which a certain type of ground disruption is predicted to occur, divided by 1.2.

[0130] In step S634, the maximum well injection capacity may be determined from the maximum injection pressure profile determined in step S632 and the transmissivity determined in step S630.

[0131] Hence, based on analysis of CPT measurement data in combination with HPT data, and in particular also using MPT data, infiltration points, maximum injection pressure, and maximum well injection capacity can be determined.

[0132] These parameters may be used in the design and construction of injection and/or extraction wells, comprising substantially solid, or non-permeable, wall sections, along which, at one or more infiltration points as determined above, injection/extraction filters are positioned.

[0133] As will be understood by the person skilled in the art, the different steps indicated in the flow chart of FIG. 6 are not necessarily performed in the order in which they have been described above, but may be performed in different order and/or simultaneously, i.e., in parallel. Further, depending on which information and/or parameters or specifications are desired, all or only some of the different steps may be performed. That is, in some embodiments, it may not be necessary to perform all steps.

[0134] The method described with respect to FIG. 6, in particular the measurement steps or probing S602, may be performed using one or more of the systems described with reference to FIG. 3A-3C.

[0135] It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The present invention is not limited to the disclosed embodiments but comprises any combination of the disclosed embodiments that can come to an advantage.

[0136] Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the description and claims, the word comprising does not exclude other elements, and the indefinite article a or an does not exclude a plurality. In fact it is to be construed as meaning at least one. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention. Features of the above described embodiments and aspects can be combined unless their combining results in evident technical conflicts.