Penetration point detection

Abstract

A method is provided that detects one or more potential penetration points in a land based on cone penetration test (CPT) data obtained from CPT measurements of a depth interval and hydraulic profiling tool (HPT) data obtained from HPT measurements of the depth interval, and determines a vertical profile indicative of the potential penetration points and potential matrix failure processes. The invention releases insight from geographic data and also relates to improvements in sustainability and environmental development: we together create a safe and livable world.

Description

Technical Field

[0001] The present invention relates to a method for detecting penetration points in soil. In particular, the present invention relates to a method for determining the vertical penetration profile within a depth interval of the ground, and also to determining the well capacity of the soil at each penetration point. The present invention unlocks insights from geographic data and also relates to improvements in sustainability and environmental development: together we create a safe and livable world. Background Art

[0002] The penetration of liquids into the ground may occur naturally, for example due to rainfall, or may be triggered by human activities. This has various applications, such as freshwater storage, remediation of contaminated soils, return or recycling of water pumped from the ground during construction works, for example during construction works involving lowering of the groundwater table, etc. The importance of freshwater storage and the rapid removal of excess rainwater or water caused by flooding is likely to increase with climate change, resulting in alternating periods of drought and heavy rains.

[0003] However, the ability to penetrate into the ground, ie the extent to which the ground or its soil can receive the infiltrating liquid, depends on various parameters, including the permeability of the ground and the infiltration rate, ie the pressure and / or flow rate of the infiltrating liquid.

[0004] The water permeability of the land, especially the water permeability of different soil layers, affects various properties of the land, such as the land's infiltration capacity. This may vary in different strata and therefore may be different at different depths in the land.

[0005] The penetration point is usually determined by trial and error, for example by using the 'Düsensauginfiltration' (DSI) technique ('jet suction infiltration' in English), which involves pushing an injection probe into the ground while the liquid is at a set pressure, and pushing the probe down into the ground until penetration is observed. However, injecting liquid at too high a pressure or too high a flow rate can cause various types of ground rupture or deformation, such as matrix failure, hydraulic fracturing and / or fluidization / liquefaction, particularly in and around the injection probe orifice and at the penetration point of the ground. This can result in the intended penetration well becoming unsuitable for use and the process having to be repeated at a different location.

[0006] For example, for water body remediation processes, penetration points can traditionally be searched for by measuring injection flow rates and the associated pressure response during well installation. However, this does not predict matrix failure, which can occur during well installation. If matrix failure occurs during well installation, water will not seep into the ground but will rise to the surface, and the remediation process will not be effective. In fact, well installation may have to be restarted at a new location.

[0007] Attempts have been made to predict or estimate various soil parameters related to infiltration, such as infiltration flow rate, infiltration cone volume, etc., from hydraulic permeability values ​​of the land, which are assumed to be previously known or determined from measurements.

[0008] However, the above conventional techniques do not allow estimation or prediction of the location of the penetration point, i.e., the depth at which the penetration point occurs, nor do they allow estimation or prediction of the vertical penetration profile of the land. Therefore, conventional methods cannot predict matrix failure nor correctly estimate well capacity.

[0009] Lack of estimation of penetration points adversely affects accuracy and leads to uncertainty in the design of assets such as oil wells. If matrix failure occurs, the resulting inefficient repair process or new well installation leads to additional time and effort. This results in long-term exposure of personnel to hazardous environments and negatively affects sustainability. Therefore, a method to solve the above problems is needed. Summary of the invention

[0010] It is an object of the present invention to provide a method of detecting or determining the location of penetration points in the ground which method reduces the risk of damage and / or destruction of the ground caused by the measurement process used to detect the penetration points.

[0011] The term "permeability point" as used herein is defined as a location or depth range at a surface within the ground (deeper than the surface) that is more permeable to water than its surroundings and therefore may be subject to a certain amount of pressure.

[0012] The term "infiltration location" as used herein is defined as the point at which one or more vertically arranged infiltration points penetrate the face of the earth.

[0013] The terms land, soil, and subsurface are used interchangeably in this application to refer to the material or substance of the earth's formation.

[0014] The methods described herein are particularly applicable to the design of injection and / or extraction wells. Injection and / or extraction wells may generally be formed by a substantially solid pipe extending through an underground wellbore, interrupted by one or more filter areas located at penetration points, so that liquid can be injected or extracted into or from the underground. Such wells may be used, for example, to receive excess rainwater, store fresh water, store water pumped from a construction site, or water drained from a venue such as a sports field.

[0015] In a cone penetration test (CPT), a probe is pushed into the ground and the tip resistance is measured as the probe is pushed into the ground and through various subsurface layers within a depth interval or penetration depth. This can be measured, for example, by force sensors, strain gauges or piezoelectric elements provided on or in the CPT probe that measure forces related to the tip resistance, local friction at the probe and friction ratio.

[0016] During a hydraulic profiling tool (HPT) measurement, a probe is pushed into the ground, while fluid is injected from one or more openings provided on the probe, and the pressure response of the ground is measured using one or more pressure sensors provided on the probe. The hydraulic profiling tool (HPT) is used to measure the flow rate and pressure required to inject water into the soil. The result is called an HPT log or HPT data. The liquid is usually injected at a preset, substantially constant flow rate. In some applications, one or more additional probes may be provided at a certain lateral distance from the probe, and these additional probes are pushed into the ground substantially simultaneously. The one or more additional probes include one or more additional pressure sensors, whereby soil-related parameters, such as relative water permeability values, can be determined in three dimensions of the permeable volume.

[0017] CPT probing and HPT measurements can be performed using a single probe, which is referred to as a CPT-HPT measurement, and the probe may be referred to as an HPT probe or a CPT-HPT probe.

[0018] Alternatively or additionally, during the CPT-HPT measurement, the probe may be stopped at one or more (set) penetration depths and pressure tests may be performed at these depths. For example, multiple or a series of pressure tests may be performed at each penetration depth with a stepwise increasing flow rate. At each of the one or more penetration depths, a liquid of injection water is injected into the ground and the resulting pressure response of the soil is measured. In addition, the injection flow rate may be measured. This may be referred to as a miniature pumping test (MPT).

[0019] Various parameters may be determined from the HPT and / or MPT measurements, including the water permeability of the soil of the subsurface layer.

[0020] CPT, HPT and MPT measurements can be performed as described in WO 2017 / 222372A1 and US 2021 / 0003492A1.

[0021] In particular, it is an object of the present invention to detect potential penetration points within a subsurface depth interval.

[0022] This is achieved by a method as defined in claim 1 .

[0023] Embodiments of the invention are given in the dependent claims.

[0024] According to a first aspect, there is provided a method of detecting one or more infiltration points in ground, the method comprising:

[0025] - Provide CPT data obtained from CPT measurements within a subsurface depth interval;

[0026] - provide HPT data obtained from HPT measurements within the depth interval; and

[0027] - determining the one or more penetration points by analyzing the CPT data in combination with the HPT data.

[0028] The penetration points can be determined using the DSI technique, which involves pushing an injection probe into the ground until penetration is observed, while simultaneously pumping out the liquid near the water table and injecting the pumped-out liquid into the same borehole at a set pressure and rate, but at a greater depth. That is, at the penetration points, the ground is capable of receiving the liquid injected at the applied injection rate. Furthermore, at these points, no ground rupture should occur during the injection of the liquid.

[0029] Therefore, the method of the present invention is based on the concept of detecting penetration points from a combination or joint analysis of CPT measurement data and HPT measurement data, and achieves that a penetration point can be identified as a certain underground location or part along a depth interval where the ground is able to receive injected liquid without the ground being ruptured or restricted relative to its surrounding environment.

[0030] Here, CPT and HPT data can be obtained according to methods known in the art. For example, CPT and HPT measurement data can be obtained by combined CPT-HPT detection using CPT-HPT probes. Alternatively, one or both sets of measurement data can be provided as previously known data.

[0031] By combining CPT and HPT measurement data, the knowledge of the characteristics of the ground is improved, thereby gaining insight into the potential for damage, thereby optimizing the well installation. In fact, the method of the present invention prevents uncontrolled injection of liquids, such as injection of liquids at too high a pressure or too high a flow rate, and thus prevents various types of ground disruption or deformation, such as matrix damage, hydraulic fracturing and / or fluidization / liquefaction, especially in and around the injection probe orifices and at penetration points of the ground. In addition, the present invention prevents penetration points from being overlooked due to inadvertence.

[0032] By means of the method as described herein, potential penetration points can be detected, for example during injection well design, while reducing the risk of ground rupture or even well explosion, also commonly referred to as a blowout.

[0033] The water permeability of land, especially that of different soil layers, affects various properties of land, such as the likelihood or ability of liquids to penetrate the land.

[0034] However, the permeability of the ground generally varies in different underground layers, which affects the ability of the ground, i.e., the soil, to receive the infiltrating liquid. If the liquid is injected at too high a pressure at a depth where the permeability of the ground does not allow infiltration, the infiltrating liquid is not received by the soil but flows upward through the well to the surface.

[0035] The pressure applied during injection also affects the soil. The increase in groundwater pressure caused by the injection of water reduces the effective stress in the formation, which can cause various types of ground rupture. Typically, during DSI, pressures of 1 bar or the order of 1 bar are used. If the liquid is injected at this pressure beyond the penetration point, i.e. at a depth where the ground cannot receive the injected liquid, ground rupture may occur around the injection point, such as matrix failure, hydraulic fracturing or even fluidization. If this happens during the installation of the infiltration well, the infiltration well will become unusable and a new well may need to be installed.

[0036] As will be discussed in further detail below, various types of ground disruption, such as matrix failure, hydraulic fracturing, and fluidization, can be predicted from CPT data.

[0037] The method may further comprise the following steps:

[0038] - Determine the initial effective vertical stress σ'vi and / or the initial effective horizontal stress σ'hi in the depth interval from the CPT data,

[0039] - Determine the corrected overpressure in the depth interval from the HPT data;

[0040] - determining a ground rupture parameter from the initial effective vertical stress and / or the initial effective horizontal stress in combination with the corrected overpressure, the ground rupture parameter predicting the onset of one or more types of ground rupture at the corrected overpressure within a depth interval.

[0041] Corrected overpressure is the pressure measured during the HPT survey and corrected for the groundwater level. That is, it represents the pressure due to HPT injection.

[0042] The increase in water pressure that occurs in response to injecting water into the ground reduces the effective stress in the formation and may cause ground rupture. Three different types of ground rupture can be distinguished: matrix failure, hydraulic fracturing and fluidization or liquefaction. These processes depend, for example, on the increase in water pressure caused by the injection, the overload (i.e., depth), the effective horizontal stress and the effective vertical stress. These types of ground rupture and the theory behind them are known in the art. For example, Chapter 13 of Remediation Hydraulics by F.C. Payne, J.A. Quinman and S.T. Potter, published by CRC Press in 2008, summarizes the theory behind these phenomena and the equations that define the locations where these damages or ruptures occur.

[0043] Hydraulic fracturing occurs when the horizontal effective stress in the earth matrix is ​​reduced to zero due to injection pressure. During hydraulic fracturing, the water pressure increases by an amount equal to the effective horizontal stress. Hydraulic fracturing can result in preferred flow paths and uncontrolled development of fractures / ruptures.

[0044] Mathematically, the onset of hydraulic fracturing risk can be expressed as:

[0045] σ′h=σ′hi-Δσu=0, [Formula 1]

[0046] or

[0047] σ′hi=Δσu [Formula 2]

[0048] Among them, σ'h is the effective horizontal stress, σ'hi is the initial effective horizontal stress, and Δσu is the water pressure increase caused by water injection.

[0049] According to the present invention, it has been found that the initial effective horizontal stress σ′hi can be obtained from the CPT data, and the pressure increase Δσu due to liquid injection can be obtained from the HPT data.

[0050] Fluidization / liquefaction occurs when the vertical and horizontal effective stresses in the soil matrix are reduced to zero due to the application of injection pressure to a value that exceeds the overload capacity of the matrix. Therefore, fluidization / liquefaction occurs when the increase in water pressure is equal to the effective vertical stress:

[0051] σ′v=σ′vi--Δσu=0, [Formula 3]

[0052] or

[0053] σ′vi=Δσu [Formula 4]

[0054] where σ'v is the effective vertical stress, σ'vi is the initial effective vertical stress, and Δσu is the increase in water pressure due to injection.

[0055] According to the present invention, it has been found that the initial effective vertical stress σ'vi can be obtained from the CPT data and the increase in pressure can be obtained from the HPT data.

[0056] Matrix failure occurs before hydraulic fracturing or fluidization / liquefaction occurs. Matrix failure begins when the horizontal effective stress decreases to a level such that the ratio of vertical effective stress to horizontal effective stress reaches a critical limit. In addition, water injection may lead to short cuts in situations where overloading (depth) is limited and / or the well design is poor.

[0057] Therefore, in other words, matrix failure may occur at a critical limit of the applied water pressure caused by injection, which can be expressed as:

[0058]

[0059] Wherein, Φ is the internal friction angle (in degrees), σ'vi is the initial effective vertical stress, and Δσuf is the critical limit of the water pressure increase caused by water injection. Similarly, according to the present invention, the initial effective vertical stress can be determined from the CPT measurement data.

[0060] As can be seen from the above, by jointly analyzing CPT data and HPT data, ground fracturing of the detected formation, especially the onset of hydraulic fracturing and fluidization or liquefaction, can be predicted.

[0061] From the CPT data, using the equations above, it is possible to determine or estimate the injection pressure as a function of subsurface depth that may cause different types of damage or surface structural failure to occur.

[0062] The one or more penetration points may be identified as one or more locations where ground rupture is not expected to occur.

[0063] The penetration point can be determined from the HPT data, which depends on the flow rate at which the HPT is performed, as a point or portion along a depth interval where the pressure response measured at a depth is below the pressure at which one or more types of ground fracturing are expected to occur. When higher injection rates are used in the HPT, the HPT data may show ground fracturing due to matrix failure even at points where fluidization and hydraulic fracturing are not expected to occur.

[0064] The method may also include determining a vertical penetration profile within the depth interval, the vertical penetration profile indicating potential penetration locations, indicating one or more penetration points along the depth interval, and potential ground fracturing and maximum pressure preventing matrix failure along the depth interval.

[0065] The occurrence or predicted occurrence of fluidization, hydraulic fracturing, and matrix failure determined from the CPT data may be indicated relative to depth intervals.

[0066] The corrected overpressure is determined from the HPT data as a function of the depth interval and used as a predicted ground rupture. As described above, the penetration point can be detected as a location or portion along the depth interval where the corrected overpressure is below the pressure that triggers ground rupture or the corrected overpressure has a low rupture level when matrix failure occurs.

[0067] The method may also include determining an ideal well depth from the vertical permeability profile, and determining the permeability within the well depth range from the determined ideal well depth and the absolute permeability along the depth interval.

[0068] This may also involve using MPT measurement data, i.e., specific absolute permeability determined from one or more series of pumping tests using a CPT-HPT probe stopped at one or more penetration depths. The specific absolute permeability (or specific absolute permeability) determined from the MPT may be combined with the relative permeability value determined from the HPT measurement data to determine the absolute permeability of the land as a function of penetration depth.

[0069] Although it is described herein that HTP data and MPT data are preferably used to determine water permeability, any other known method or combination of methods may be used to determine water permeability.

[0070] The method may further comprise determining a maximum injection pressure profile as a function of depth.The maximum injection pressure profile may be calculated from the CPT data.

[0071] The maximum injection pressure profile can be determined from the CPT measurements and ground fracturing parameters, which are calculated from the CPT measurements and the pressure response obtained during the HPT measurements. The maximum injection pressure is determined as the maximum pressure allowed as a response to the injection without ground fracturing occurring, and in particular, the maximum pressure that can be induced without fluidization or hydraulic fracturing occurring.

[0072] The method may also include determining a maximum well injection capacity from the maximum injection pressure profile.

[0073] The maximum well injection capacity represents the maximum injection capacity of the well, i.e. the maximum flow rate that can be infiltrated without risk of hydraulic fracturing or fluidization of the surrounding soil. The maximum well injection capacity depends on various parameters, in particular the percolation length along one or more infiltration points, the water permeability of the soil within the percolation length, the storability and the maximum pressure that can be applied during infiltration, among others.

[0074] According to the method, CPT data and HPT data are simultaneously acquired during CPT-HPT detection.

[0075] For example, a single probe as described in WO 2017 / 222372 A1 and US 2021 / 0003492 A1 can be used for CPT-HPT detection. Alternatively, two different probes closer to each other can be used.

[0076] Alternatively, one or both of the CPT data and the HPT data may be obtained from previous measurements and / or previously known data.

[0077] In some embodiments, CPT data may be known for a site being considered for placement of an injection well. Such known or previously collected CPT data may be used in conjunction with HPT data obtained from measurements.

[0078] The method may also include providing mini-pumping test (MPT) measurement data obtained by a series or more series of pressure tests at one or more locations along the depth interval. The method may also include determining the specific absolute water permeability within the depth interval from the MPT measurement data, and determining the cohesive strength C and the absolute water permeability K within the depth interval based on the specific absolute water permeability and the relative water permeability Q / P determined from the HPT data. Alternatively, the specific absolute water permeability within the depth interval may be obtained from data other than the MPT measurement data.

[0079] As described above, such MPT data can be obtained by stopping the probe during an HPT or CPT-HPT measurement. Soil parameters such as specific absolute water permeability can be calculated from the MPT measurement data.

[0080] According to a second aspect, there is provided a system for determining one or more ground penetration points along a depth interval, the system comprising:

[0081] - a probe provided with an opening for injecting a fluid at a set injection rate and at least one pressure sensor for measuring a pressure response in the subsurface; and

[0082] - A processor configured to perform the steps of the method according to any one of claims 1-12.

[0083] The probe may be a probe as described in WO 2017 / 222372 A1 and US2021 / 0003492 A1. In some embodiments, the system may further include a second probe comprising one or more additional pressure sensors for measuring the pressure response of the subsurface, also as described in WO 2017 / 222372 A1 and US2021 / 0003492 A1. The system may be based on the system described in WO 2017 / 222372 A1 and US2021 / 0003492 A1, wherein the processor, controller and / or data acquisition system is adapted or configured to perform the method of any one of the embodiments described above.

[0084] Depending on the system, the opening for injecting the fluid may be an injection opening located on at least one side of the probe, or an injection opening extending around the probe, or a combination of both.

[0085] Specifically, the system according to the second aspect may be configured to execute the method in any one of the embodiments described above with respect to the first aspect.

[0086] According to a third aspect, there is provided a computer program product comprising instructions which, when executed by a computer, cause the computer to perform the steps of any one embodiment of the method according to the first aspect.

[0087] The methods, systems, and computer program products described herein can be used in various applications, such as well design (e.g., injection / extraction well design) to indicate one or more locations or depth regions representing penetration points. In addition, a maximum injection pressure profile within an underground depth interval can be determined. The maximum injection pressure represents the injection pressure that can avoid land rupture, that is, the maximum corrected overpressure. In addition, the maximum well capacity can be determined. Therefore, the method including the various steps as described above according to various embodiments can determine the vertical profile of a potential well, indicating one or more potential penetration points and the associated maximum injection pressure, at which no land rupture, such as fluidization / liquefaction, hydraulic fracturing, and matrix failure, is expected to occur when the maximum injection pressure is applied.

[0088] Since CPT and HPT data are usually recorded when the probe penetrates the ground, these data can be represented as a vertical profile of the ground. According to the present invention, a vertical infiltration profile, including the infiltration point and the infiltration capacity at the infiltration point, can be determined by combining the measurement data obtained from the CPT detection and the HPT detection. In particular, the infiltration point can be determined based on the vertical profiles obtained during the CPT and HPT, respectively.

[0089] Although the present disclosure focuses on liquid injection, the methods and related steps disclosed herein, and the related mechanisms used or present in the methods, and the probes and systems can be applied to extraction in a similar manner, after final modifications that can be understood by those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Further features and advantages of the present invention will become apparent through the description of the present invention by means of non-limiting and non-exclusive embodiments. These embodiments should not be construed as limiting the scope of protection. Those skilled in the art will recognize that other alternative and equivalent embodiments of the present invention can be conceived and put into practice without departing from the scope of the present invention. Embodiments of the present invention will be described below with reference to the accompanying drawings, in which similar or identical reference numerals represent similar, identical or corresponding parts, wherein:

[0091] 1A and 1B show flow charts of methods for performing underground detection, which are known in the art and can be used in the present invention;

[0092] FIG2 shows a schematic side view of one embodiment of a system that may be used for detection;

[0093] 3a, 3b and 3c show schematic side views of probes that may be used to collect measurement data;

[0094] Figure 4 shows the critical limit of the water pressure increase caused by injection as a function of the initial effective vertical stress and the point of initiation of ground rupture;

[0095] Figure 5 A graph showing a combination of HPT and CPT measurement data according to an embodiment of the present invention; and

[0096] Figure 6 A flow chart showing a method according to an embodiment of the invention comprising a combined analysis of CPT and HPT measurement data. DETAILED DESCRIPTION

[0097] FIG. 1A shows a flow chart of a method for determining soil properties using a probe including at least one liquid injection port and a pressure sensor. The probe is pushed into the soil for performing one or more pumping tests at a predetermined depth. During the pumping test, a penetrating liquid, such as water, is pumped through the liquid injection port of the probe. The pressure response generated by injecting water through the liquid injection port in the soil is measured by a pressure sensor disposed on the probe. The pressure response can be measured for each of the one or more pumping tests. While the probe is penetrating the soil, soil parameters can be measured using a soil testing system. This can be referred to as a miniature pumping test (MPT).

[0098] Fig. 1B shows a flow chart of a method for combining a pumping test with a hydraulic profiling tool (HPT) and / or a cone penetration tester (CPT) test. The probe is pushed into the soil while the infiltrating liquid is pumped through the liquid injection port of the probe. During the advancement of the probe through the soil, the pressure response of the soil / groundwater system to the injection of the liquid can be determined. This can be referred to as an HPT measurement or a hydraulic profiling tool measurement. In addition, during the advancement, the mechanical resistance and / or friction experienced by the probe can be determined. For example, this can be measured using a force sensor or a strain gauge provided on the probe. This is referred to as a cone penetration test (CPT).

[0099] The probe is stopped at one or more predetermined depths. At each predetermined depth, one or more pumping tests are performed while the probe is stopped at the predetermined depth, for example, as described with reference to FIG. 1A . During the pumping test, the permeating liquid is pumped through the liquid injection port of the probe. The pressure response generated by injecting the liquid through the liquid injection port in the soil is measured by a pressure sensor disposed on the probe. The pressure response can be measured for each of the one or more pumping tests.

[0100] FIG. 2 shows a schematic side view of an embodiment of a system 1 that can be used during a soil penetration test, for example, as described above with reference to FIGS. 1A and 1B , for underground characterization of a soil 2. The system 1 includes a probe 9 that includes at least one liquid injection port and a pressure sensor. The probe 9 is arranged to penetrate the soil 2. The system also includes a data acquisition system arranged to sample a measurement signal from the probe; a controller or processor that is arranged to control the system to push the probe 9 into the soil 2 and perform one or more pumping tests, and, for each of the one or more pumping tests, measure the pressure response in the soil caused by the injection of liquid through the liquid injection port using a pressure sensor. The system 1 can include a trolley 3. The trolley 3 of this embodiment has wheels. However, tracks or a combination of wheels and tracks can also be arranged. Other arrangements are also possible, for example, the system 1 can be moved by another transport unit. The trolley 3 can also include a plurality of stabilizers to provide support and improve stability during the penetration test. System 1 can also include a rod 7 coupled to probe 9 and a device for forcing probe 9 4 into soil 2 by pushing rod 7, wherein the penetration depth L and penetration rate of probe 9 can be controlled by a controller. Rod 7 is used to push probe 9 into soil, and can include multiple sub-elements, such as multiple rod sections connected to each other. Other schemes for pushing probe 9 into soil are also possible. The thrust for the probe to penetrate soil 2 can be provided by a hydraulic propulsion device arranged in trolley 3. The weight of trolley 3 can provide a reaction force to push rod 7, and rod 7 is connected to probe 9 forcibly penetrated into soil 2. Other schemes for providing reaction force are also possible. In addition, described system includes a pump, which is arranged to provide liquid, such as water, to the probe so that liquid can be injected into soil through a liquid injection port arranged on the probe.

[0101] The system 1 further comprises a digital computer comprising one or more processors which can be coupled to the probe 9 and its sensors, such as force sensors 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. Furthermore, the digital computer can be coupled to the data acquisition system to receive the acquired electrical signals or signals representing the acquired electrical signals. The digital computer can be arranged to process the electrical signals to provide an analysis of the measurement results, thereby determining and / or calculating soil parameters and properties.

[0102] In addition, the system may include an interface, such as a monitor, coupled to the digital computer for displaying the soil analysis performed by the one or more processors, which may include determined soil parameters such as water permeability and water storage coefficient. The analysis may be performed for different penetration depths L. The results of the measurement campaigns may be combined to provide an overall overview of soil parameters for a certain area or volume.

[0103] The digital computer can be arranged in the measuring unit in the trolley 3 or at a remote unit. The measured data can be received by the digital computer via a wired connection or a wireless connection. In the case of wireless data communication, a wireless connection device can be arranged to transmit signals via a mobile data transmission protocol such as 3G, 4G, 5G. However, other wireless protocols such as WiFi (e.g. wireless communication in accordance with the IEEE 802.11 standard or other transmission protocols) or LoRa can also be used to obtain wireless communication. A combination of wireless protocols is possible.

[0104] The system 1 may be implemented in a vehicle or may take the form of a vehicle. Alternatively, the system may be implemented in other vehicles or take the form of other vehicles, such as cars, RVs, trucks, agricultural vehicles, construction vehicles, and robotic vehicles. It is also conceivable to include multiple systems 1 in a vehicle.

[0105] 3a and 3b show an embodiment of a probe 9 comprising a liquid injection port 11 and a pressure sensor 13. FIG3a shows a schematic side view of a probe 9 having a substantially elongated tubular shape, comprising a tip 17, which faces the longitudinal penetration direction 19 of the probe 9 and is arranged for penetrating the soil 2. In this embodiment, the tip 17 of the tubular probe 9 has a conical shape, but other shapes are also possible. The liquid injection port 11 of the probe 9 and the pressure sensor 13 are arranged at a distance D from each other relative to the longitudinal penetration direction of the probe 9. FIG3b shows a schematic side view of a probe 9 coupled to a rod 7 so as to push it into the soil 2. At a specific penetration depth L in the soil 2, one or more pumping tests can be performed, during which the infiltrating liquid is pumped out of the probe 9 through the liquid injection port 11 of the probe 9 along the flow direction 15 of the liquid penetration. With the help of the pressure sensor 13, for one or more pumping tests, the pressure response in the soil 2 caused by the injection of liquid through the liquid injection port 11 can be measured. One or more pumping tests may be performed at a predetermined / selected substantially fixed soil penetration depth L of the probe 9. A liquid such as water may be injected into the soil 2 at an adjustable and controllable specific injection flow rate Q through the injection port 11. One or more pumping tests may be performed at a substantially constant injection flow rate Q, and in the case of multiple pumping tests, consecutive pumping tests at a certain penetration depth L may be performed at different injection flow rates Q.

[0106] The probe 9 may be a hydraulic profiling tool (HPT) probe 9, which may also be used to perform a cone penetration test (CPT) in a hydraulic profiling tool-cone penetration test (HPT-CPT). Here, the HPT probe 9 is pushed into the land or soil 2 at a constant rate, while water is injected into the soil at a constant flow rate through a water injection port 11 arranged on the HPT probe 9. HPT-CPT measurements may be used to assess the hydraulic properties of the underground of a site. The system 1 may include an HPT probe 9, which includes a tip or cone equipped with one or more water pressure sensors at a distance D from the water injection port 11 (i.e., the injection point) of the HPT probe 9. During the HPT measurement, the HPT probe advances through the soil while water is injected at a constant flow rate through the injection port 11. During the advancement, the pressure response of the soil / groundwater system to the water injection is determined. During the CPT measurement, the probe 9 advances through the soil. During the advancement, the mechanical tip resistance may be measured, and optionally the casing resistance may be measured, as also described with reference to FIGS. 1A and 1B. HPT-CPT measurement combines HPT measurement with CPT measurement. During the HPT measurement, the movement of the HPT probe can be stopped at a certain penetration depth L. After the water pressure generated by the HPT measurement dissipates, the system 1 can perform one or more pumping tests (MPT), in which water is injected into the soil 2 through the injection port 11. For example, four pumping tests can be performed, in which different pumping tests are performed using four different water injection flow rates Q. Subsequently, the quality assessment of the measurement can be performed by analyzing the pressure response measured by the pressure sensor 13 of the HPT probe 9 using different water injection flow rates. The water injection flow rate through the injection port 11 of the HPT probe 9 can induce water overpressure, which may depend on the local hydrogeological conditions and can be sensed / measured by the pressure sensor 13. After completing the field measurement, the measured water overpressure can be inversely modeled. Inverse modeling can be performed using an analytical solution or using a geohydrological numerical model. After one or more pumping tests are performed at a certain depth, the HPT-CPT measurement can be continued. For example, the probe 9 can be pushed further into the soil 2. While injecting water at the same constant flow rate as before the pumping test, the HPT probe 9 can be pushed into the soil 2 at the same constant rate. It should be understood that the HPT-CPT measurement can be resumed after the pore water pressure of the previous pumping test dissipates. The HPT-CPT measurement can be resumed after the water injection is restored to the level of the initial HPT-CPT measurement and the water pressure reaches equilibrium.

[0107] Figure 3c shows an embodiment of a probe system 99 including a first probe 9' and a second probe 9". Here, the probe 9' may be similar to the probe 9 described with reference to Figure 2. The first probe 9' and the second probe 9" are laterally spaced apart from each other and can be pushed into the ground and used to perform HPT-CPT measurements in the manner described with reference to Figure 2. The first probe 9' includes a liquid injection port 11. The second probe 9" includes a pressure sensor 13. In this example, the probe system 99 includes additional pressure sensors 13', 13". The liquid injection port 11 and the pressure sensor 13 of the probe system 99 are arranged at a distance D from each other relative to the lateral direction of the probe 9'. One or more pressure sensors in the three-dimensional space around the injection point can be used to derive horizontal and / or vertical permeability and storage coefficient from the measured pressure response to the injected liquid Q. For example, the pressure sensor 13 can be used to determine the horizontal permeability and storage coefficient. The pressure sensor 13" may be used to determine vertical permeability and storage coefficient. Alternatively, numerical or analytical calculations, such as using inverse modeling techniques, may be used to derive horizontal and / or vertical permeability and storage coefficient.

[0108] FIG4 shows the critical limit of the water pressure increase caused by injection, which is a function of the initial effective vertical stress and the starting point of the ground rupture. This figure shows the critical limit of the water pressure increase, that is, the maximum allowable water pressure increase caused by injection (in m H2O), which is a function of the initial vertical effective stress and the internal friction angle at the beginning of various types of ground rupture. The short dashed line 402 represents the predicted start of matrix failure. The solid line 404 represents the predicted start of hydraulic fracturing. The long dashed line 406 represents the predicted start of liquefaction. It can be seen that the expected start or start of different types of failure depends on the soil properties of the formation. In particular, soils or formations with higher initial vertical stresses σ'vi and higher internal friction angles Φ can withstand higher injection overpressures than formations with lower initial vertical stresses. As described above, the initial vertical stress can be determined from CPT measurement data.

[0109] The starting point of the ground rupture can be estimated by recording the injection rate and injection pressure during the HPT probe penetration and / or during the search for the penetration point. To this end, the above formulas 1 to 5 can be used.

[0110] Figure 5 The graph of FIG. 1 shows how the HPT and CPT measurement data can be combined for analysis, i.e., how the data can be combined to determine various ground parameters within a depth interval. Specifically, the illustration conceptually shows how the CPT and HPT data can be combined to determine the penetration point and maximum penetration capacity and to produce a vertical penetration profile showing injection points and potential matrix failure locations.

[0111] The lines extending diagonally represent critical limits at which different types of ground failure are expected to occur, calculated from the CPT data as described above. Line 502 represents the threshold for matrix failure as a function of the depth into the ground (probe penetration depth). That is, line 502 represents the overpressure caused by liquid injection at which matrix failure is expected to occur. Line 504 represents the threshold for hydraulic fracturing as a function of the depth into the ground (probe penetration depth). That is, line 504 represents the overpressure at which hydraulic fracturing is expected to occur. Line 506 represents the threshold for fluidization or liquefaction as a function of the depth into the ground (probe penetration depth). That is, line 506 represents the overpressure at which fluidization or liquefaction is expected to occur. These failure lines are determined from the CPT measurement data using the formulas and theory discussed in the "Summary of the Invention" section.

[0112] The fast fluctuation line 508 represents the overpressure caused by the liquid injection, which is a function of the probe penetration depth measured during the HPT survey using a set substantially constant injection rate. At the location where this fluctuation line intersects one or more of the lines 502, 504 and / or 506, it can be concluded that the ground is expected to break, that is, matrix failure, hydraulic fracturing or fluidization, respectively. The corresponding expected failure type is shown in the line or bar 510 on the right side of the figure. Locations or penetration depth ranges 510 where substantially no or at least no matrix failure is expected to occur can be considered potential penetration points.

[0113] Thus, by graphically showing the pressure fluctuations measured during the HPT survey in conjunction with the ground rupture threshold determined from the CPT data, information about the sensitivity of the ground to ground rupture caused by the increase in water pressure resulting from the injection can be inferred. Thus, penetration points can be detected.

[0114] The CPT and HPT measurement data can be processed and analyzed using methods and algorithms or equations known to those skilled in the art. For example, the theory and equations presented in Chapter 13 of Payne et al., Remediation Hydraulics, published in 2008, can be used to determine curves indicating predictions for various types of ground failure (matrix failure, hydraulic fracturing, fluidization, respectively).

[0115] from Figure 5 It can be seen that at certain penetration depths, no ground fracturing or fracturing changes appear to occur at the injection rate of the HPT system. These depth ranges or intervals represent possible penetration points. If the injection rate is increased, then it becomes increasingly difficult to detect these penetration points because the resulting water pressure will increase to the point where the fluidization / liquefaction threshold is reached. Furthermore, it can be inferred that, since the increase in water pressure is limited, only limited information can be provided if only the increase in water pressure caused by the detection is considered.

[0116] The above analysis confirms the concept of preferred flow paths and highly permeable layers at penetration points. The land at penetration points is less susceptible to increased water pressure than other formations because the water pressure can dissipate quickly, while other formations do not exhibit good permeability and infiltration characteristics. However, the detection of penetration points is highly dependent on the flow rate and / or pressure at the time of detection.

[0117] For example, in Figure 5 , contains a vertical line at 1 bar (100 kPa) injection pressure. If an injection pressure of 1 bar is used to find the penetration point, fluidization is expected to occur at a depth of 9-10 meters below the ground. It can be seen that the diagonal line 506 representing fluidization intersects the 1 bar line at about 9-10 meters. Therefore, above this depth, it is impossible to find a penetration point unless working with a lower injection pressure, that is, an injection pressure lower than the injection pressure at which fluidization is expected to occur. In other words, the injection pressure "below" the diagonal line indicates the onset of fluidization.

[0118] From the pressure measurements taken at the depth of the penetration point, an indication of the risk of certain ground fracturing processes can be provided. The maximum pressure at which a particular ground fracturing is expected to occur can be derived from the diagonal lines representing matrix failure, hydraulic fracturing and fluidization respectively.

[0119] The information derived as described above, such as the detected penetration points, can be used in the design or construction of an injection well located at the detection location. Such a well can be designed to have an injection filter at one or more penetration points determined from the above analysis. Additionally or alternatively, one of the penetration points can be used for extraction, while another penetration point can be used for infiltration or injection. For example, a higher penetration point, i.e., a point at a shallower depth, can be used for extraction, while a lower penetration point, i.e., a point at a deeper depth, can be used for infiltration / injection.

[0120] Figure 6 A flowchart of an embodiment of the method described herein is shown, which can be used to derive Figure 5 The graphs shown represent and / or derive specific parameters and specifications of the information as discussed above.

[0121] In step S602, a combined CPT-HPT survey is performed on site, for example as described in the "Summary of the Invention" section above. This can be done using the system described with reference to Figures 2, 3a-3c. During the CPT-HPT survey, the CPT-HPT probe 9, 9', 9" is pushed into a depth interval underground at a substantially constant penetration rate. While pushing, CPT data, such as forces associated with tip resistance or local friction, are measured. At the same time, an injection liquid, typically water, is injected through the opening 11 at a set, substantially constant flow rate, and the water pressure generated in the soil is measured using one or more pressure sensors 13, 13', 13". The probe is stopped at a specific, preferably predetermined depth, and one or more pumping tests, so-called mini-pumping tests (MPT), are preferably performed at each depth when a state of equilibrium is reached. For example, a series of pumping tests can be performed with gradually increasing flow rates. CPT, HPT and MPT data are thereby provided.

[0122] During these tests and measurements, CPT measurement data, HPT measurement data and MPT measurement data are recorded, for example, by a data acquisition system. These measurement data are subsequently processed and analyzed, as shown in the flow chart.

[0123] In step S604, the CPT measurement data is input into a CPT data processor, such as a processor or processing unit of a digital computer of the system. Similarly, in step S606, the HPT measurement data is input into an HPT data processor or processing unit of the system. Similarly, in step S608, the MPT measurement data is input into an MPT data processor or processing unit of the system.

[0124] In step S610, the specific absolute water permeability of the ground as a function of depth, i.e. different strata, is determined from the MPT data. This can be done as described in WO 2017 / 222372 A1 and US 2021 / 0003492 A1.

[0125] In step S612, the groundwater level may be determined from the MPT data.

[0126] In step S614, the HPT data is processed to determine the corrected overpressure P, i.e., the ground pressure caused by the fluid injection. In this step, the groundwater level determined in step S612 can be used to correct the pressure measured by the one or more pressure sensors 13, 13', 13", i.e., the pressure measured after the injection of the screen. Figure 5 The ripple line 508 shown in pictorially represents this corrected overpressure.

[0127] Furthermore, in step S614, the relative water 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.

[0128] In step S616, the relative water permeability of the MPT influence area, ie, the influence volume of the MPT, is determined. Here, the relative absolute water permeability determined in step S610 may be taken into account.

[0129] In step S618, a coherence strength C is determined, which relates the absolute water permeability to the relative water permeability. The coherence strength is a constant that is typical for certain types of formations and depends on different characteristics of the land. In other words, the coherence strength C provides an indication of the type or category of the land or formation at a particular depth.

[0130] In step S620, the absolute water permeability as a function of depth is determined.

[0131] Therefore, the HPT and MPT data may be processed and / or analyzed. It will be appreciated by those skilled in the art that the above analysis and processing of the HPT and MPT data may include additional steps or details, respectively.

[0132] In step S622, the CPT measurement data is processed to determine the initial vertical stress σ'vi and the initial horizontal stress σ'hi within the depth interval. The corrected overpressure determined in step S614 is used as input to determine the effective vertical stress σ'v and the effective horizontal stress σ'h, respectively. These parameters can be determined as described in the "Summary of the Invention" section above.

[0133] In step S624, ground fracturing parameters may be calculated or determined using the parameters determined in step S622, as also described above. These parameters indicate (predict or estimate) the onset of different types of ground fracturing. In particular, critical pressure limits are determined in relation to depth of matrix failure, hydraulic fracturing, and fluidization. Figure 5 As shown, these relationships may be represented by curves 502 , 504 , and 506 .

[0134] In step S624, parameters may be determined, for example using a Mohr circle analysis of horizontal and vertical effective stresses. Such analysis may be performed as known to those skilled in the art, for example, as described in Chapter 13 of Remediation Hydraulics by FC Payne, JA Quinman and ST Potter, published in 2008 by CRC Press.

[0135] Based on the predictions of various types of damage or ground rupture determined in step S624, and the measured overpressure determined in step S614, a vertical penetration profile indicating potential penetration points and potential damage processes along the depth interval is determined in step S626.

[0136] In step S628, the ideal well depth may be detected or determined from the vertical permeability profile determined in step S626. This may include selecting one or more of the permeation points detected in step S626 as the permeation or injection point to be used in the injection well or extraction well.

[0137] In step S630, the permeability within the range of well depths is determined. This value is essentially determined as a function of the thickness of the penetration point determined from step S630 multiplied by the absolute water permeability at the penetration point determined in step S620.

[0138] In step S632, a maximum injection pressure profile as a function of depth is determined. This may be determined based on the ground-breaking parameters determined from step S624. From this, a maximum injection pressure that can be applied at the penetration point without causing hydraulic failure or risk of fluidization may be determined. The maximum injection pressure that can be applied may be determined as a percentage or ratio of the injection pressure at which ground-breaking is expected or estimated to occur. For example, the maximum allowable injection pressure may be determined as the pressure at which a particular type of ground-breaking is expected to occur divided by 1.2.

[0139] 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.

[0140] Therefore, based on the analysis of CPT measurement data combined with HPT data, especially using also MPT data, it is possible to determine the penetration point, the maximum injection pressure and the maximum well injection capacity.

[0141] These parameters may be used in the design and construction of injection and / or extraction wells that include substantially solid or impermeable wall sections along which injection / extraction filters are disposed at one or more penetration points as determined above.

[0142] Those skilled in the art will understand that Figure 6 The different steps indicated in the flowchart are not necessarily executed in the order described above, but may be executed in a different order and / or simultaneously, i.e., in parallel. Furthermore, depending on the desired information and / or parameters or specifications, all steps may be executed or only some different steps may be executed. That is, in some embodiments, it may not be necessary to execute all steps.

[0143] Reference may be performed using one or more of the systems described with reference to FIGS. 3A-3C. Figure 6 The method is described (particularly the measuring step or detection S602).

[0144] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, and that various modifications and variations can be made thereto without departing from the scope of the present invention as defined by the appended claims. Although the present invention is shown and described in detail in the drawings and the specification, such illustration and description are merely illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments, but includes any combination of the disclosed embodiments that can bring advantages.

[0145] By studying the drawings, the description and the appended claims, those skilled in the art will be able to understand and implement changes to the disclosed embodiments when practicing the claimed invention. In the description and the claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude the plurality. In fact, it should be interpreted as meaning "at least one". The specific features described in different dependent claims do not indicate that the combination of these features cannot be used to advantage. Any figure marks in the claims do not constitute a limitation on the scope of the invention. The features of the above-mentioned embodiments and aspects can be combined unless their combination leads to obvious technical conflicts.

Claims

1. A method for detecting one or more infiltration points in soil, the method comprising: - providing cone penetration test (CPT) data (S604) obtained from CPT measurements (S602) within a subsurface depth interval; - providing hydraulic profiling tool (HPT) data (S606) obtained from HPT measurements (S602) within the depth interval; - Determining (S626) the one or more penetration points from the analysis of the HPT data in combination with the CPT data.

2. The method according to claim 1, comprising: - determining (S622) the initial effective vertical stress σ'vi and / or the initial effective horizontal stress σ'hi in the depth interval from the CPT data, - determining (S614) a corrected overpressure within said depth interval from the HPT data; and - determining (S624) a ground rupture parameter from said initial effective vertical stress and / or said initial effective horizontal stress in combination with said corrected overpressure, said ground rupture parameter predicting the onset of one or more types of ground rupture within said depth interval at said corrected overpressure.

3. The method according to claim 2, wherein: The one or more penetration points are determined (S624, S626) as one or more locations where ground rupture is not expected to occur.

4. The method according to any one of claim 2 or claim 3 also includes determining (S626) a vertical permeability profile within the depth interval, the vertical permeability profile indicating potential penetration locations representing the one or more penetration points along the depth interval and potential ground ruptures along the depth interval.

5. The method according to claim 4 also includes determining (S628) an ideal well depth from the vertical permeability profile.

6. The method according to claim 5, further comprising: - Determining (S630) the permeability within the depth interval from the determined ideal well depth and the absolute water permeability along the depth interval (S620).

7. The method according to any of the preceding claims, further comprising determining (S632) a maximum injection pressure profile as a function of the depth interval.

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

9. The method according to claim 7 or claim 8, further comprising determining (S634) a maximum well injection capacity based on the maximum injection pressure profile.

10. The method according to any of the preceding claims, wherein during CPT-HPT detection CPT data and HPT data are simultaneously acquired (S602).

11. A method according to any one of the preceding claims, 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 any of the preceding claims further includes providing (S608) small-scale pumping test (MPT) measurement data, wherein the small-scale pumping test (MPT) measurement data is obtained by a series or more series of pressure tests performed at one or more depths along a depth interval.

13. The method according to claim 12 also includes determining (S610) the specific absolute permeability within the depth interval from the MPT measurement data, and determining (S618) the cohesive strength (C) and the absolute permeability (K) within the depth interval from the specific absolute permeability and the relative permeability (Q / P) determined (S616) from the HPT data.

14. A system for determining one or more penetration points in the ground along a depth interval in the ground, the system comprising: - a probe provided with an opening for injecting a fluid at a set fluid injection rate and at least one pressure sensor for measuring a pressure response in the ground; and - A processor configured to perform the steps of the method according to any one of claims 1-12.

15. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the steps of any one of claims 1 to 12.

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