NL2037121B1

NL2037121B1 - A hydraulic profiling tool probe

Info

Publication number: NL2037121B1
Application number: NL2037121A
Authority: NL
Inventors: Tohami Ahmed; Stoop Nick; De Jong Rolf
Original assignee: Fnv Ip Bv
Priority date: 2024-02-26
Filing date: 2024-02-26
Publication date: 2025-09-04
Also published as: WO2025181040A1

Abstract

A probe for determining properties of a subsurface region is disclosed. The probe has an injection outlet conﬁgured to inject liquid into the subsurface region surrounding the probe, a first pressure transducer configured to measure pressure internal to the probe representative of the pressure required to inject the liquid into the subsurface region, a second pressure transducer configured to measure pressure external to the probe at a ﬁrst location, and a third pressure transducer conﬁgured to measure pressure external to the probe at a second location different to the first location. 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.

Description

A HYDRAULIC PROFILING TOOL PROBE

FIELD

[0001] This disclosure relates to a probe, such as a hydraulic profiling tool probe, for determining properties of a subsurface region. More particularly, the disclosure relates to a probe designed to improve hydraulic profiling tool measurements and significantly reduce the failure rate of hydraulic profiling tool measurements and other tests or measurements performed to determine properties of a subsurface region. Unlocking insights from such Geo-Data, the present invention further relates to improvements in sustainability and environmental developments: together we create a safe and liveable world.

BACKGROUND

[0002] There is a general and ongoing need for systems and methods for determining subsurface ground characteristics through the acquisition and analysis of geological data (also referred to as geodata or Geo-Data). In particular, there is a need for systems and methods that can be used to investigate the properties of a subsurface region beneath the surface of the earth to provide information that is useful for engineering purposes or projects and infrastructure planning. Determination of subsurface ground properties during the early planning phase of construction projects reduces uncertainty during the location determination, (foundation) design, and construction phases of a project.

This in turn reduces delays, overspend, and unnecessary use of material resources (e.g., concrete) during construction. A thorough understanding of subsurface characteristics also enables infrastructure projects to be sited and installed appropriately, thereby improving safety.

[0003] The ground or subsurface region represents a significant source of risk for civil engineering projects that hinders project owners/developers from achieving their objectives. Timely geo-data collection add value by reducing uncertainty at all stages of the project lifecycle to avoid or solve engineering challenges and to help manage ground-related risk exposure and better meet project objectives.

[0004] One way of investigating the properties of subsurface region is through the use of a Hydraulic

Profiling Tool (HPT). Measurements using a HPT are carried out as follows. A HPT probe is pushed into the subsurface region while injecting water or another suitable liquid from an injection port provided on the probe. The pressure required to inject the flow of water into the subsurface region is determined using a pressure transducer sensor of the probe. The resulting injection pressure vs injection rate log is an indicator of the permeability of the subsurface region over depth.

[0005] HPT probes of the type described above can provide inconsistent measurements and are even subject to measurement failure. For example, if the injection port becomes obstructed while measurements are being carried out, the HPT measurement could provide inaccurate results or fail entirely.

[0006] HPT probes also have limited functionality meaning that additional measurements using other measurement apparatuses are often required in order to investigate the properties of subsurface region.

[0007] As can be seen above, existing HPT probes are often subject to measurement inaccuracies or even failure. They also offer limited functionality in terms of determining properties of subsurface region.

It would be advantageous to provide a HPT probe which address one or more of these problems, in isolation or in combination.

SUMMARY

[0008] The present disclosure provides probes and systems which address the above-described problems and provide a more accurate, precise and repeatable mechanism for determining properties of a subsurface region, such as hydrogeological and geotechnical properties. For the reasons described above, this enables vital geodata to be obtained more easily, thereby increasing the efficiency and sustainability of infrastructure projects. The disclosed probes and systems are particularly suitable for hydraulic profiling tool measurements and other tests or measurements performed to determine properties of a subsurface region, such as hydrogeological and geotechnical properties.

[0009] According to a first aspect of the present disclosure, there is provided a probe for determining properties of a subsurface region. Example properties include hydrogeological and geotechnical properties. In some example implementations, the probe is a hydraulic profiling tool (HPT) probe. In some example implementations, the probe has an injection outlet configured to inject liquid, such as water, into the subsurface region surrounding the probe. In some example implementations, the probe has a first pressure transducer configured to measure pressure internal to the probe representative of the pressure required to inject the liquid into the subsurface region.

[0010] In some example implementations, the probe has a second pressure transducer configured to measure pressure external to the probe representative of pore water pressure at a first location. In some example implementations, the second pressure transducer may be configured to measure pressure external to the probe representative of pore water pressure in the subsurface region at the first location.

[0011] In some example implementations, the probe has a third pressure transducer configured to measure pressure external to the probe at a second location. In some example implementations, the second location may be different to the first location. In some example implementations, the third pressure transducer may be configured to measure pressure external to the probe representative of pore water pressure in the subsurface region at the second location.

[0012] Advantageously, such a probe can inject liquid into the subsurface region while simultaneously measuring pore water pressure at two or more different locations. The second and third pressure transducers can be used to test for different subsurface parameters. The provision of two external pressure transducers also reduces failure risk and provides the opportunity for a comparison of pressure measurement results, which can be used to detect anomalous results.

[0013] In some example implementations, probe has a tip at a distal end of the probe and the first location at which the second pressure transducer is configured to measure pressure is one of: at the tip of the probe; adjacent to and proximal of the tip of the probe; and removed from and proximal of the tip of the probe. The locations adjacent to and proximal of the tip of the probe and removed from and proximal of the tip of the probe mean that pressure transducer components are less prone to damage than when the location is at the tip of the probe. When the location is at the tip of the probe, this can be advantageous when making measurements in highly stratified (many different soil type layers) and/or over consolidated soil conditions.

[0014] In some example implementations, probe has a tip at a distal end of the probe and the second location at which the third pressure transducer is configured to measure pressure is one of: at the tip of the probe; adjacent to and proximal of the tip of the probe; and removed from and proximal of the tip of the probe.

[0015] Measuring pressure at the tip of the probe provides information on resistance to flow of certain layers, which can help determine what types of clays and silts are present in the subsurface region.

Measuring pressure at a location adjacent to and proximal of the tip of the probe can be helpful for geotechnical calculations. Measuring pressure at a location removed from and proximal of the tip of the probe can improve pumping test results as the pressure is measured closer to the injection outlet, resulting in a more accurate reading.

[0016] In some example implementations, the probe has a fourth pressure transducer configured to measure pressure external to the probe at a third location different to the first location and the second location.

[0017] The provision of a fourth pressure transducer provides further opportunity to compare data sets between the second, third and fourth pressure transducers, meaning they can be used to validate one another and identify any anomalous readings. Failure risk is therefore reduced.

[0018] In some example implementations, the probe has a tip at a distal end of the probe, wherein the third location at which the fourth pressure transducer is configured to measure pressure is one of: at the tip of the probe; adjacent to and proximal of the tip of the probe; and removed from and proximal of the tip of the probe.

[0019] In some example implementations, the probe has an electric conductivity sensor. With the addition of an electric conductivity sensor, the electrical conductivity of the subsurface region surrounding the probe can be determined.

[0020] In some example implementations, the electric conductivity sensor comprises two conductive elements separated by an insulating element. In some example implementations, the electric conductivity sensor comprises four conductive elements. In some example implementations, the four conductive elements are separated by insulating elements. In some example implementations, the conductive elements comprise copper. In some example implementations, the insulating elements comprise a ceramic. In some example implementations, either of both of the conductive elements comprise rings disposed circumferentially around the probe. In some example implementations, the insulating element comprises an insulating ring.

[0021] Such an electric conductivity sensor is able to provide a more accurate determination of electrical conductivity of the subsurface region surrounding the probe. The employment of copper for the two conductive rings in the probe's electric conductivity sensor is advantageous due to copper's high electrical conductivity. This characteristic enables precise detection and measurement of subsurface electrical properties, allowing for the identification of minor conductivity variations with high accuracy.

Additionally, the incorporation of a ceramic material for the insulating ring is beneficial due to its insulating nature. Ceramic's electrical insulation properties substantially prevent the flow of electric current, ensuring electrical paths are confined to the conductive rings. Such an electric conductivity sensor capable of measuring bulk formation electric conductivity and provide a measure of the combined electric conductivity of the formation solids and any contained fluids and dissolved ions in the subsurface region. By adding such an electric conductivity sensor in combination with the hydraulic profiling tool (HPT) functionality of the probe (and optionally CPT functionality), false detects can be identified more easily.

[0022] In some example implementations, the injection outlet comprises a plurality of holes distributed circumferentially around the probe. In some example implementations, each hole is configured to inject liquid into the subsurface region surrounding the probe. In some example implementations, the plurality of holes are uniformly distributed around the probe.

[0023] Advantageously, the risk of blockages is reduced when compared to an injection outlet having a single opening. It is also easier to conduct mini pumping tests involving the use of a second probe for sensing pressure, such as anisotropic mini pumping tests (AMPTS) as the second probe does not need to be aligned with the direction of a single opening of an injection outlet.

[0024] In some example implementations, the injection outlet has a sleeve disposed circumferentially around the probe, wherein the plurality of holes are located in the sleeve.

[0025] Advantageously, if the sleeve gets damaged, it can be more easily be replaced.

[0026] In some example implementations, the probe further has a chamber within the probe. In some example implementations, the chamber has a liquid inlet. In some example implementations, the chamber is in fluid communication with the injection outlet. In some example implementations, the first pressure transducer is configured to measure pressure in the chamber.

[0027] The chamber ensures distribution of liquid at a uniform pressure around the probe. It also facilitates accurate measurement of pressure within the probe by the first pressure transducer internal to the probe representative of the pressure required to inject the liquid into the subsurface region.

[0028] In some example implementations, the probe further has a temperature sensor configured to measure the temperature of liquid before it is injected into the subsurface area surrounding the probe.

[0029] The temperature of the liquid has some influence on the measurements made by the probe. As such, the output of the temperature sensor can be used to account for these influences.

[0030] In some example implementations, the probe has a chamber within the probe. In some example implementations, the chamber has a liquid inlet. In some example implementations, the chamber is in fluid communication with the injection outlet. In some implementations, the first pressure transducer is configured to measure pressure in the chamber. In some example implementations, the temperature sensor is configured to measure the temperature of liquid within the chamber.

[0031] In this manner, the temperature sensor can more accurately measure the temperature of liquid as it is injected into the subsurface area.

[0032] In some example implementations, the probe further has a friction sleeve and/or a tip resistance sensor configured to perform a cone penetration test, CPT, and/or a piezocone penetration test, CPTu.

Such a probe can provide simultaneous and CPT data.

[0033] In some example implementations, the probe has a porous filter element disposed 5 circumferentially around the probe. In some example implementations, the second pressure transducer is in fluid communication with the porous filter element.

[0034] In some example implementations, the probe further has a first housing portion. In some example implementations, the probe further has a second housing portion movable relative to the first housing portion. In some example implementations, the probe further has the first housing portion, and the second housing portion configured such that the porous filter element can be secured between the first housing portion and the second housing portion by moving the first housing portion and the second housing portion towards one another. Advantageously, with this configuration of the probe, the porous filter element can easily be removed and replaced, and a new porous filter element secured in its place.

[0035] In some example implementations, the first housing portion is coupled to the second housing portion via a threaded engagement configured to permit relative movement of the first housing portion and the second housing portion to secure the porous filter element.

[0036] In some example implementations, the first housing portion comprises a first wall. In some example implementations, the second housing portion comprises a second wall. In some example implementations, the first wall and the second wall are configured such that the porous filter element can be secured between the first wall and the second wall by moving the first housing portion towards the second housing portion. Advantageously, with this configuration of the probe, the porous filter element securing of the porous filter element to the probe is improved.

[0037] In some example implementations, the first wall comprises a surface facing and angled towards the second wall and/or wherein the second wall comprises a surface facing and angled towards the first wall. In this manner, the securing of the filter element in the closed position is improved.

[0038] According to a second aspect of the present disclosure, there is provided a system for determining properties of a subsurface region, the system comprising the probe according to the first aspect having any of the above described features and a pressure sensing probe. In some example implementations, the pressure sensing probe comprises at least one pressure transducer configured to measure pressure external to the pressure sensing probe representative of pore water pressure in the subsurface region.

[0039] Such a system is able to derive horizontal and/or vertical permeability and storativity from the measured pressure response to the liquid injected into the subsurface region by the probe and as detected by the pressure transducers on either or both of the probe and the pressure sensing probe.

[0040] In some example implementations, the pressure sensing probe further comprises a friction sleeve and a tip resistance sensor configured to perform a cone penetration test, CPT. In some example implementations, the pressure sensing probe is a second probe according to the first aspect having any of the above described features.

[0041] In some example implementations the system further comprises a flow meter configured to measure a flow rate of liquid being provided to the probe. In some example implementations, the flow meter is located at a surface of the subsurface region.

[0042] According to a third aspect of the present disclosure, there is provided a probe for determining properties of a subsurface region. In some example implementations, the probe may be a hydraulic profiling tool (HPT) probe. In some example implementations, the probe has an injection outlet configured to inject liquid into the subsurface region surrounding the probe. In some example implementations, the probe has a first pressure transducer configured to measure pressure internal to the probe representative of the pressure required to inject the liquid into the subsurface region. In some example implementations, the injection outlet comprises a plurality of holes distributed circumferentially around the probe. In some example implementations, each hole is configured to inject liquid into the subsurface region surrounding the probe. In some example implementations, the plurality of holes are uniformly distributed around the probe.

[0043] In some example implementations, the probe has a second pressure transducer configured to measure pressure external to the probe representative of pore water pressure at a first location. In some example implementations, the second pressure transducer may be configured to measure pressure external to the probe representative of pore water pressure in the subsurface region at the first location.

The probe of the third aspect may have any of the features of the probe of the first aspect as described above.

[0044] In some example implementations, the injection outlet has a sleeve disposed circumferentially around the probe, wherein the plurality of holes are located in the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be provided by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only exemplary implementations of the disclosure and are therefore not to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail by way of example to illustrate aspects of the disclosure and with reference to the accompanying drawings, in which:

[0046] Fig. 1 shows a flow chart of a method performing probing of the ground;

[0047] Fig. 2 shows a flow chart of a method performing probing of the ground;

[0048] Fig. 3 shows a schematic side view of an embodiment of a system which may be used for probing;

[0049] Fig. 4 shows schematic side views of a probe which may be used for gathering measurement data;

[0050] Fig. 5 shows schematic side views of the probe of Fig. 4 which may be used for gathering measurement data;

[0051] Fig. 6 shows schematic side views of system including the probe of Fig. 4 and Fig. 5 which may be used for gathering measurement data;

[0052] Fig. 7 shows a probe.

[0053] Fig. 8 a subsection of the probe of Fig. 7 in the region of the injection outlet; and

[0054] Fig. 9 shows a subsection of the probe of Fig. 7 and Fig. 8 in the region of the fourth pressure transducer.

Throughout the description and the drawings, like reference numerals refer to like features.

DETAILED DESCRIPTION

[0055] The following is a description of certain embodiments of the invention, given by way of example only and with reference to the drawings.

[0056] Various implementations of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only.

A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Thus, the following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. A reference to an implementation in the present disclosure can be a reference to the same implementation or any other implementation.

Such references thus relate to at least one of the implementations herein.

[0057] The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various implementations given in this specification. References to ranges of values or values “between” two values should be interpreted as encompassing the end points of those ranges unless otherwise specified.

[0058] The present disclosure describes improved systems and methods for determining an erosion characteristic of a soil sample. As noted above, the disclosed methods and systems involve providing a sample holder for holding a soil sample. The sample holder presents a face of the soil sample, via an opening in the holder, to a liquid dispenser. The liquid dispenser is configured to dispense liquid pulses at the face of the soil sample in order to induce erosion. A support frame provides support to one or more of the sample holder and liquid dispenser. As a result of this arrangement, a simple setup is provided that enables soil sample erosion to be studied easily and reliably with a high degree of repeatability. The disclosed system and method also enable high levels of precision when carrying out the erosion tests and lend themselves to automation. Ultimately, this results in an increased ability to efficiently and effectively obtain geodata which can be used to support and inform, amongst other things, critical infrastructure projects.

[0059] The term “subsurface region” can refer to any region below the ground surface of the earth.

[0060] The term “HTP probe” can refer to any probe suitable for making a HTP measurement.

[0061] Tuming now to Figure 1, a flow chart of an example method is shown, which can be used for determining soil properties by use of a probe comprising a liquid injection port and a pressure transducer. The probe is pushed into soil of a subsurface region 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 the pumping tests at each of the predetermined depths. The soil testing system can be used for measuring soil parameters while the probe is penetrated into the soil of the subsurface region. This may be referred to as MPT, mini pumping tests. After a pumping test, the probe can continue probing to a further test depth.

[0062] Turning now to Figure 2, a flow chart of an example method is shown where the pumping test is combined with a hydraulic profiling tool (HPT) measurement and/or cone penetrometer test (CPT).

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 a hydraulic profiling tool (HPT) measurement. During advancement, mechanical resistance and/or friction experienced by the probe can be determined in addition to or instead of the HPT measurement.

Mechanical resistance and/or friction may be measured, e.g., using force sensors or strain gauges provided on the probe. This is referred to as CPT, cone penetration testing.

[0063] In more detail, a CPT is a geotechnical investigation method for determining, e.g., soil and groundwater characteristics, where a probe is pushed into the soil to perform a measurement or measurements. Typical parameters measured by such a probe are cone tip resistance and sleeve friction. Pore-water pressure can additionally be measured where the test is a piezocone penetration test (CPTu). The test method comprises pushing an instrumented cone penetrometer, with the tip facing down, into the ground at a controlled rate.

[0064] 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. 1, 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.

[0065] Fig. 3 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 Figs. 1 and 2, for subsurface characterisation of soil 2 of a subsurface region. The system 1 comprises a probe 9, such as a Hydraulic

Profiling Tool (HPT) probe, comprising 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 on the probe, 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.

[0066] The system 1 may comprise a truck 3. The truck 3 may have wheels. However, tracks or a combination of wheels and tracks can be provided instead of wheels. 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 measurements and tests. The system 1 may 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. 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.

[0067] Other implementations 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.

[0068] The system 1 further 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.

[0069] The system 1 further comprises a 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 may be arranged to receive electrical signals from the sensors of the probe 9. The computer may be coupled to the data acquisition system so as to receive the acquired electrical signals or signals representative for the acquired electrical signals. The 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 of the subsurface region.

[0070] Further, the system can comprise an interface, such as a monitor, coupled to the 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 the analysis at different depths of penetration L may be combined to provide a general overview of the soil parameters over an area or volume ofthe subsurface region.

[0071] The 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 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.

[0072] 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 envisaged that a plurality of systems 1 may include in a single vehicle.

[0073] Fig. 4 and 5 show embodiments of the probe 9 comprising a liquid injection port and a pressure transducer 13. Fig. 4 shows a schematic side view of the probe 9 having a substantially elongated tubular shape comprising a tip 17 facing in a penetration direction 19 of the probe 9 and arranged for penetrating the soil 2. In the depicted example implementation, 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.

[0074] Fig. 5 shows a schematic side view of the probe 9 coupled with rod 7 for being pushed into the soil 2. In Fig. 5, the probe 9 has been pushed into a surface 2a of the soil 2 of the subsurface region and is located at a depth of penetration L. In the example implementation depicted in Fig. 5, a pumping test is being conducted, during which an infiltration liquid is being pumped through the liquid injection port 11 of the probe 9 in the liquid infiltration flow direction 15 out of the probe 9 and into the surrounding soil 2 of the subsurface region. By means of the pressure transducer 13, during the pumping test, 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 liquid injection port 11 at a certain water injection flow rate Q which can be adjusted and controlled. The pumping test can be carried out at a substantially constant water injection flow rate

Q. A plurality of pumping tests may be carried out. For example, successive pumping tests at the depth of penetration L may be carried out at different water injection flow rates Q.

[0075] The probe 98 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. The probe 9 may be pushed into the ground or soil 2 at a constant rate while water is injected at a constant flow rate into the soil through the liquid injection port 11 arranged on the probe 9. A HPT-CPT measurement can be used to evaluate hydraulic properties of a subsurface region, such as hydrogeological and geotechnical properties.

[0076] The system 1 may comprise a probe 9 comprising a tip or cone equipped with a water pressure sensor in the form of pressure transducer 13 at a distance D from the liquid injection port 11, i.e. injection point. During a HPT measurement the probe 9 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. 1 and 2.

[0077] A HPT-CPT measurement combines the HPT and the CPT measurement. During a HPT measurement, the probe 9 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 could be carried out, where 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 analysing the pressure response measured by the pressure transducer 13 of the probe 9.

[0078] The water injection flow rate through the liquid injection port 11 of the 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 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.

[0079] 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.

[0080] Fig. 6 shows an embodiment of a probe system 99 comprising a first probe 9’ and a second probe 9”. The system 99 can be used to perform an anisotropic mini pumping test (AMPT). In Fig. 6, the first probe 9" and a second probe 9” have been pushed into the surface 2a of the soil 2 of the subsurface region and are located at a depth of penetration L. In the example implementation depicted in Fig. 6, the first and second probes 9’, 9” are laterally spaced from each other by distance D.

[0081] The first probe 9’ may be a Hydraulic Profiling Tool (HPT) probe and comprises a liquid injection port 11 and a pressure transducer 13”, and may be similar to, or the same as, the probe 9 shown in

Figs. 3, 4 and 5. The liquid injection port 11 of the first probe 9’ is facing in the direction of the second probe 9” and an infiltration liquid is being pumped through the liquid injection port 11 of the first probe 9’ in the liquid infiltration flow direction 15 out of the probe 9 and into the surrounding soil 2 of the subsurface region.

[0082] The second probe 9” comprises a first pressure transducer 13. In the example shown in Fig. 6, the second probe 9” comprises two further pressure transducers 13’, 13’ disposed on the second probe 9" either side of the pressure transducer 13. The first pressure transducer 13 and the two further pressure transducers 13’, 13’ are arranged to detect changes in pressure in the surrounding soil 2 as a result of the infiltration liquid is being pumped through the liquid injection port 11 of the first probe 9’ which is arranged to face the first pressure transducer 13 and the two further pressure transducers 13’, 13.

[0083] The liquid injection port 11 of the first probe 9’ has been positioned at the same depth and the first pressure transducer 13 of the second probe 9” and they are laterally space at the distance D from each other.

[0084] In the example implementation depicted in Fig. 6, the one or more pressure transducers in the 3D space around the injection port 11 can be used to derive horizontal and/or vertical permeability and storativity from the measured pressure response to the injected liquid as the pore water pressure in the subsurface region surrounding the injection port 11 by the injected liquid. 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. The pressure transducers 13’ provide alternative/additional measurement locations.

[0085] Several issues can arise with systems such as probe system 99. For example, in order for the first pressure transducer 13 and the two further pressure transducers 13’, 13’ of the second probe 9” to accurately measure a pressure response to the liquid injected, the liquid injection port 11 of the first probe 9’ must be positioned to face the direction of the second probe. If the liquid injection port 11 faces away from the second probe, the accuracy of the readings of the first pressure transducer 13 and the two further pressure transducers 13’, 13’ of the second probe 9” will be diminished.

[0086] Another issue can arise if the liquid injection port 11 of the first probe 9' becomes obstructed.

This could provide inaccurate readings at the first pressure transducer 13 and the two further pressure transducers 13’, 13’ and any measurement could fail entirely.

[0087] HPT probes, such as probe 9 shown in Figs. 3. 4 and 5 and probe 9’ shown in Fig. 6 also have limited functionality meaning that additional measurements using other measurement apparatuses are often required in order to investigate the properties of subsurface region.

[0088] As can be seen, existing HPT probes are often subject to measurement inaccuracies or even failure. They also offer limited functionality in terms of determining properties of subsurface region.

[0089] To address these issues, a probe 700 as shown in Fig. 7 is provided, which can be used in place of probe 9 shown in Figs. 3. 4 and 5 and probe 9’ shown in Fig. 6. In some example implementations, the probe 700 may be a Hydraulic Profiling Tool (HPT) probe.

[0090] The probe 700 shown in Fig. 7 comprises an injection outlet 702, which is also shown in an enlarged view in Fig. 7. The probe 700 further comprises first pressure transducer 804 (shown in Fig. 8) configured to measure pressure internal to the probe representative of the pressure required to inject the liquid into the subsurface region. The probe 700 further comprises a second pressure transducer 704, a third pressure transducer 706 and a fourth pressure transducer 708, all configured to measure pressure external to the probe 700. The probe 700 further comprises an electric conductivity sensor 710 comprising two conductive rings 712 separate by an insulating ring 714. The probe 700 also has a tip 718 at a distal end of the probe and a friction sleeve 718. A proximal end of the probe may be coupled to a rod (not shown in Fig. 7), such as rod 7 shown in Fig. 3, for pushing the probe 700 into the subsurface region. In some example implementations, alternative means for pushing the probe 700 into the subsurface region may be provided in place of a rod. The probe 700 can be used to determine properties of a subsurface region, such as hydrogeological and geotechnical properties.

[0091] The injection outlet 702 is in the form of a plurality of holes distributed circumferentially around the probe 700, each configured to inject liquid into the subsurface region surrounding the probe 700. In the example implementation depicted in Fig. 7, the holes are uniformly distributed around the probe 700, although this need not be the case. In this manner, the injection outlet 702 simultaneously injects liquid into the subsurface region in all directions circumferentially around the probe 700. This means that, where the probe 700 is used in conjunction with a second probe, such as the second probe 9” shown in

Fig. 6, no aligning of the injection outlet 702 with the second probe 9” is required. This avoids the aforementioned risk of measurement inaccuracies or even failure due to misalignment of the liquid injection port 11 of the first probe 9’ and the second probe 9” shown in Fig. 6.

[0092] The risk of blockages is also reduced for the injection outlet 702 of the probe 700 when compared with probe 9 shown in Figs. 3. 4 and 5 and probe 9’ shown in Fig. 6. Whereas probes 9 and 9’ have a single liquid injection port 11 which is at risk of being blocked, injection outlet 702 has a plurality of holes, meaning that even if one or a subset of the holes becomes blocked or otherwise obstructed, the injection outlet 702 is still able to inject liquid into the surrounding subsurface region, meaning the risk of measurement inaccuracies or failures is reduced.

[0093] In some example implementations, the injection outlet 702 can take the form of a sleeve disposed circumferentially around the probe 700 with the holes located in the sleeve. Such a sleeve can be replaceable, should any damage occur during use of the probe 700.

[0094] In some example implementations, the probe 700 does not have an injection outlet 702 of the type depicted in Fig. 7, rather the probe 700 is provided with a liquid injection port 11 of the type described above in relation to probe 9, shown in Figs. 3, 4 and 5.

[0095] The second pressure transducer 704 is configured to measure pressure at a first location external to the probe 700, in this instance at the tip 716 located at the distal end of the probe 700. The tip 716 of the probe 700 may be the same or substantially similar to the tip 17 of probe 9 as described above. The second pressure transducer 704 may sense pressure at what is conventionally known as the u, location in the tip 716 of the probe 700, as defined in ISO/FDIS22476-1. The second pressure transducer 704 is configured to measure pressure external to the probe 700 representative of pore water pressure in the subsurface region at the first location. In some example implementations, the second pressure transducer 704 comprises a porous filter element located on the tip 716 of the probe 700.

[0096] The third pressure transducer 706 is configured to measure pressure at a second location external to the probe 700, in this instance a location proximal of the tip 716. In the example shown in

Fig. 7, the third pressure transducer 706 is configured to measure pressure at a location adjacent to and proximal of the tip 716. In other words, the third pressure transducer 706 is configured to measure pressure at a location between the tip 716 and the friction sleeve 718. The third pressure transducer 706 may sense pressure at what is conventionally known as the u, location on the probe 700, as defined in ISO/FDIS22476-1. The third pressure transducer 706 is configured to measure pressure external to the probe representative of pore water pressure in the subsurface region at the second location. In some example implementations, the third pressure transducer 706 comprises a porous filter element located on the probe 700, adjacent the tip 716 in a proximal direction.

[0097] The fourth pressure transducer 708 is configured to measure pressure at a third location external to the probe 700, in this instance removed from and proximal of the tip 716 of the probe 700.

In other words, a location more proximal than the third pressure transducer 706. As shown in Fig. 7, the third pressure transducer 706 is configured to measure pressure at a location between the second pressure transducer 704 and the fourth pressure transducer 708. In other words, the fourth pressure transducer 708 is configured to measure pressure at a location on the other side of the friction sleeve 718 to the third pressure transducer 706. The fourth pressure transducer 708 may be configured to measure pressure at what is conventionally known as the u; location on the probe 700, as defined in

ISO/FDIS22476-1. The fourth pressure transducer 708 is configured to measure pressure external to the probe 700 representative of pore water pressure in the subsurface region at the third location. In some example implementations, the fourth pressure transducer 708 comprises a porous filter element located on the probe 700 at a location more proximal than the third pressure transducer 706.

[0098] As liquid is injected into the surrounding subsurface region via injection outlet 702 of the probe 700, pore water pressure build-up in the subsurface region is measured in time at the second pressure transducer 704, third pressure transducer 706 and fourth pressure transducer 708. These measurements enable the determination of the in-situ horizontal permeability and/or storativity. Where the probe 700 is used in conjunction with a second probe, such as probe 9” in Fig. 6, vertical permeability and anisotropy can also be determined. Advantageously, the use of multiple pressure transducers in the probe 700 enables measurements to be cross-checked to confirm accuracy and identify any anomalous results.

[0099] In some example implementations, the probe 700 is provided with only one of the second pressure transducer 704, third pressure transducer 706 and fourth pressure transducer 708.

Alternatively, the probe 700 may be provided with only two of the second pressure transducer 704, third pressure transducer 706 and fourth pressure transducer 708. For example, only the second pressure transducer 704 and third pressure transducer 706 may be provided, only the second pressure transducer 704 and fourth pressure transducer 708 may be provided, or only the third pressure transducer 706 and fourth pressure transducer 708 may be provided. In some example implementations, the probe 700 is provided with one or more further pressure transducers configured to measure pressure at a location external to the probe 700.

[00100] The electric conductivity sensor 710 is configured to measure the electric conductivity of the subsurface region surrounding the probe 700. The electric conductivity sensor 710 facilitates the interpretation of ground layering and identification of subsurface anomalies in the subsurface region.

The electric conductivity sensor 710 is configured to measure the apparent electric conductivity of bulk formation (solids and fluids) located adjacent to the probe 700 as it is advanced into the subsurface region. The electric conductivity measurement also allows the measurement of fluid properties in the subsurface region to facilitate detection of dissolved ions, contaminants and fresh/brackish/saline water interfaces. The electric conductivity sensor 710 is able to measure the formation electric conductivity in the subsurface region, as opposed to a conventional indicative (small scale) sensor which would not be able to provide this information.

[00101] In the example implementation shown in Fig. 7, the electric conductivity sensor 710 comprises two conductive elements in the form of conductive elements 712 separate by an insulating element 714.

In this manner, a dipole array is provided. In some example implementations, the conductive elements 712 may be disposed circumferentially around the probe 700. In some example implementations, the conductive elements 712 may take the form of conductive rings. In some example implementations,

conductive elements and/or insulating element 714 do not completely surround the circumference of the probe 700. In some example implementations, the insulating element 714 comprises an insulating ring.

[00102] In some example implementations, one or more further conductive elements or rings could be provided. For example, four conducting elements or rings could be provided to form a four-pole array, such as a Wenner array for conducting a Wenner probe test.

[00103] In some example implementations, the conductive elements 712 are made of or comprise copper. In another example implementation, the insulating element 714 is made of or comprises a ceramic.

[00104] The electric conductivity sensor 710 is capable of measuring bulk formation electric conductivity and provide a measure of the combined electric conductivity of the formation solids and any contained fluids and dissolved ions in the subsurface region. By adding such an electric conductivity sensor 710 in combination with the HPT functionality of the probe 700 (and optionally CPT) false detects can be identified more easily. For instance, where a contaminant is perched above a clay layer within a sandy layer, a CPT could show sand whereas an electric conductivity measurement will show values that do not correspond to sand.

[00105] The friction sleeve 718 is an optional feature of the probe 700 and can be provided in conjunction with a tip resistance sensor (not shown in Fig. 7) such that the probe 700 is able to perform a cone penetrometer test (CPT), as described above. One or more of second pressure transducer 704, third pressure transducer 706 and fourth pressure transducer 708 may be used in conjunction with the friction sleeve 718 and tip resistance sensor to perform a piezocone penetration test (CPTu).

[00106] Fig. 8 shows a subsection of the probe 700 in the region of the injection outlet 702. A chamber 802 is provided within the probe 700 which is in fluid communication with the injection outlet 702. The first pressure transducer 804 is configured to measure pressure internal to the probe 700 representative of the pressure required to inject the liquid into the subsurface region. In order to do this, the first pressure transducer 804 is configured to measure the pressure within the chamber 802. A liquid inlet 806 is also present for providing liquid to the chamber 802 for subsequent injection into the surrounding subsurface region via the injection outlet 702. A temperature sensor 808 is also provided for measuring the temperature of the liquid before it is injected into the subsurface area surrounding the probe 700.

[00107] The chamber 802 ensures the injection of liquid into the subsurface region via the holes of the injection outlet 702 at a consistent pressure. In some example implementations, the chamber may be uniform or substantially uniform in shape about a longitudinal axis of the probe 700. The holes of the injection outlet 702 may be uniformly distributed about the perimeter of the chamber. Liquid enters the chamber 802 via the liquid inlet 806 and exits the chamber 802 via the holes of the injection outlet 702.

The chamber 802 also facilitates the accurate determination of the pressure of the liquid as it is being injected into the subsurface region. In this manner, the pressure required to inject the liquid into the subsurface region can be more accurately determined than in conventional HPT systems, which take a pressure measurement somewhere in the liquid flow line as no chamber is provided.

[00108] The first pressure transducer 804, in conjunction with the chamber 802, is able to provide an accurate determination of the pressure of the liquid as it is being injected into the subsurface region.

The first pressure transducer 804 may be located within a recess in the chamber.

[00109] The temperature sensor 808 is configured to measure the temperature of the liquid as it is being injected into the subsurface area surrounding the probe 700. This may be achieved by measuring the temperature of the liquid within the chamber 802. In this manner, the temperature of the liquid before it is injected into the subsurface area surrounding the probe 700 can be accurately determined. The temperature of the liquid can have an influence on the measurements made by the probe 700. As such, the output of the temperature sensor 808 can be used to account for these influences.

[00110] Fig. 8 shows a subsection of the probe 700 in the region of the fourth pressure transducer 708.

A porous filter element 902 of the fourth pressure transducer 708 is shown located between a first housing portion 904 of the probe 700 and a second housing portion 906 of the probe 700. The porous filter element 902 may be made of a ceramic material. This applies to any of the porous filter elements described herein.

[00111] The first housing portion 904 and the second housing portion 906 are movable relative to one another. In some example implementations, the first housing portion 904 is coupled to the second housing portion 906 via a threaded engagement (not shown in Fig. 9) configured to permit relative movement of the first housing portion 904 and the second housing portion 906 to secure the porous filter element 902 in place.

[00112] In an alternative arrangement, the first housing portion 904 and the second housing portion 906 may be slidably engaged with one another and a fixing mechanism, such as a screw or pin may be provided to prevent relative movement of the first housing portion 904 and the second housing portion 906 in the closed position to clamp porous filter element 902 in place.

[00113] The first housing portion 904 and the second housing portion 806 may be moved apart from the closed position shown in Fig. 9 to an open position in order that the porous filter element 902 of the fourth pressure transducer 708 can be removed or replaced, for example, should the porous filter element 902 become damaged. In the closed position shown in Fig. 9, the porous filter element 902 is held in place via a clamping force exerted by the first housing portion 904 and the second housing portion 906 on the porous filter element 902. In other words, the first housing portion 904 and the second housing portion 906 are configured such that the porous filter element 902 can be secured between the first housing portion 904 and the second housing portion 906 by moving the first housing portion 904 towards the second housing portion 906.

[00114] In some example implementations, the first housing portion 904 may comprise a first wall 908 and the second housing portion may comprise a second wall 810 configured such that the porous filter element 902 can be secured between the first wall 908 and the second wall 910 by moving the first housing portion 904 towards the second housing portion 906. In some example implementations, the first wall 908 comprises a surface facing and angled towards the second wall 910 and/or the second wall 810 comprises a surface facing and angled towards the first wall 908. In this manner, the securing of the filter element 902 in the closed position is improved.

[00115] The porous filter element of any one of the second pressure transducer 704, third pressure transducer 706 and fourth pressure transducer 708 could be secured to the probe 700 in this manner.

[00116] The probe 700 may be provided as part of a system alongside a pressure sensing probe having at least one pressure transducer configured to measure pressure external to the pressure sensing probe representative of pore water pressure in the subsurface region. Such a probe could be similar to the probe 9” shown in Fig. 6. In some implementations, the pressure sensing probe could further comprises a friction sleeve and a tip resistance sensor configured to perform a cone penetration test (CPT). In some implementations, the system could further include a flow meter at a surface of the subsurface region, wherein the flow meter is configured to measure a flow rate of liquid being provided to the probe 700.

[00117] The above detailed description describes a variety of example arrangements and methods for determining an erosion characteristic of a soil sample. However, the described arrangements and methods are merely exemplary, and it will be appreciated by a person skilled in the art that various modifications can be made without departing from the scope of the appended claims. Some of these modifications have been described, however this list of modifications is not to be considered as exhaustive, and other modifications will be apparent to a person skilled in the art.

[00118] It is to be understood that the above description is intended to be illustrative, and not restrictive.

Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific example implementations, it will be recognized that the disclosure is not limited to the implementations described but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[00119] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist, only some of which have been mentioned above. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments.

It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.

Claims

Conclusions

1. A probe for determining properties of a subterranean zone, the probe comprising: an injection outlet configured to inject fluid into the subterranean zone surrounding the probe; a first pressure transducer configured to measure a pressure internal to the probe representative of the pressure required to inject the fluid into the subterranean zone; a second pressure transducer configured to measure a pressure external to the probe at a first location; and a third pressure transducer configured to measure a pressure external to the probe at a second location different from the first location.

The probe of claim 1, the probe further comprising a tip at a distal end of the probe, wherein the first location at which the second pressure transducer is configured to measure pressure is one of: located at the tip of the probe; adjacent to and proximal to the tip of the probe; and spaced from and proximal to the tip of the probe.

The probe of claim 1 or claim 2, further comprising a fourth pressure transducer configured to measure a pressure external to the probe at a third location different from the first location and the second location.

4. A probe according to any preceding claim, further comprising an electrical conductivity sensor.

5. The probe of claim 4, wherein the electrical conductivity sensor comprises two conductive elements separated by an insulating element.

6. The probe of claim 5, wherein either of the conductive elements comprises rings disposed circumferentially around the probe and/or wherein the insulating element comprises an insulating ring.

7. A probe as claimed in any preceding claim, wherein the injection outlet comprises a plurality of holes distributed circumferentially around the probe, each hole configured to inject fluid into the subsurface zone surrounding the probe.

8. The probe of claim 7, wherein the injection outlet comprises a sleeve disposed circumferentially around the probe, the plurality of holes being located in the sleeve.

9. The probe of any preceding claim, further comprising a chamber within the probe, the chamber comprising a fluid inlet, the chamber being in fluid communication with the injection outlet, the first pressure transducer being configured to measure a pressure in the chamber.

10. A probe as claimed in any preceding claim, further comprising a temperature sensor configured to measure the temperature of fluid before it is injected into the subsurface zone surrounding the probe.

11. The probe of claim 10, further comprising a chamber within the probe, the chamber comprising a fluid inlet, the chamber being in fluid communication with the injection outlet, the temperature sensor being configured to measure the temperature of fluid within the chamber.

12. The probe of any preceding claim further comprising: a porous filter element disposed circumferentially about the probe, the second pressure transducer being in fluid communication with the porous filter element;

a first housing portion; and a second housing portion movable relative to the first housing portion, the first housing portion and the second housing portion being configured such that the porous filter element can be secured between the first housing portion and the second housing portion by moving the first housing portion toward the second housing portion.

The probe of claim 12, wherein the first housing portion comprises a first wall, the second housing portion comprises a second wall, and the first wall and the second wall are configured such that the porous filter element can be secured between the first wall and the second wall by moving the first housing portion toward the second housing portion.

14. The probe of claim 13, wherein the first wall includes a surface facing and angled relative to the second wall and/or wherein the second wall includes a surface facing and angled relative to the first wall.

15. A system for determining properties of a subterranean zone, the system comprising: the probe of any preceding claim, and a pressure sensing probe comprising a pressure transducer configured to measure a pressure external to the pressure sensing probe representative of a pore water pressure within the subterranean zone.