Method for quantification of porous media by means of analytical particles and use thereof

Abstract

The invention relates to a quantitative method for porous media and to analytical particles specially designed for this purpose and to their use, for example in order to determine the water permeability of rocks as a prerequisite for developing standards for groundwater movement or material properties of porous materials or rock layers, or for monitoring chemical, biological and / or biotechnological reactors, tanks, reservoirs and water pipe systems, or in medical in vivo methods.

Description

[0001] The present invention relates to a method for quantifying porous media and specially designed analytical particles (hereinafter also referred to as "particles"), and to their use, for example, for determining the water permeability of rocks as a prerequisite for developing standards for groundwater movement or material characteristics of porous materials or rock layers, or for monitoring chemical, biological and / or biotechnological reactors, or for use in medical in vivo methods.

[0002] Tracer systems in hydrology are known from the prior art. The basis for hydrogeology according to the definition of DIN 4049-1 and / or DIN 4039-3 is the knowledge of the underground structure. This is based on geological maps, drilling results and three-dimensional models of the underground geology. Tools and methods for analyzing and monitoring groundwater are remote sensing, geophysical methods, drilling, groundwater measuring points, pumping tests, laboratory tests and water chemical analysis. Groundwater in fractured rock or porous materials can flow in a laminar manner, but also in a turbulent manner.

[0003] Since the flow paths and their properties in rock masses or porous materials are rarely fully understood, it is difficult to estimate their share in the total groundwater flow. In general, however, the influence of turbulence on hydraulic permeability and flow rate is considered to be small. Therefore, fractured aquifers are mainly described in a simplified manner using continuum models and with motions that are exclusively laminar. In hydraulic methods, for example in the case of long-term pumping tests, a known signal (positive or negative pressure changes) acts on a virtually unknown system called an aquifer.

[0004] During the test, the reaction of the system (pressure drop, pressure increase or water level drop, water level increase) is recorded per unit time. After the signal ends, the return of the system to its equilibrium state can also be measured. In long-term pumping or injection tests, the changes in water level or pressure transmitted to the aquifer are monitored over a longer period of time. According to STOBER (1993), statements about the flow behavior or aquifer model can only be made in long-term pumping tests. For all other hydraulic tests, the evaluation model is implicitly specified.

[0005] Packer test through a packer (wellbore), a general term for hydraulic tests in a wellbore or a well, which are carried out in the section located above or below the packer and hydraulically separated in the case of a single packer test, and also in the section extending between the two packers in the case of a double packer test. The single packer test is carried out in a partially opened wellbore placed below the water level. A thinner casing is passed through the packer, through which a filling test, a slug test or an oscillation test valid for the lower wellbore section can be carried out to determine the hydraulic parameters of the aquifer. The double packer test is carried out in an uncased wellbore, and the section between the two packers can be tested using the tests listed above.

[0006] The reliability of the results depends on the tightness of the packer, the properties of the wellbore and the surrounding rock mass, or may be reduced by leakage in the rock mass and / or lateral leakage. For rock-mechanical analysis, hydraulic tests through single or double isolated borehole sections are used, in which water is pressed in at different pressures to determine the kf value of the solid rock, for example underground in a dam (Lexicon der Geowissenschaften, Spektrum Verlag). The permeability K is used in geotechnical engineering to quantify the permeability of soils and rocks to liquids and gases (for example groundwater, oil or natural gas). The permeability kf value described here is also closely related to it. The permeability coefficient (or hydraulic conductivity) also quantifies the permeability of the soil or rock, however, the density and viscosity of the fluid are also taken into account here (Bernward Wilhelm G. Coldewey: Hydrogeologie: Einführung in die Allgemeine und Angewandte Hydrogeologie. 6. Auflage. Elsevier Spektrum Akademischer Verlag, Munich 2005).

[0007] Tracer methods are also used in hydrology, with or without pumping tests. Tracers are man-made or natural substances (tracer substances) which, after introduction into a hydrological system, enable a wide variety of analyses.

[0008] Electrolyte tracers (NaCl, MgCl2): The tracer substance is placed at an upstream measuring station (measuring point) or in a pit (sunken section). The resistance measurement is carried out in the well. In doing so, the increase in the ion concentration entering the groundwater is measured over time. The dilution can also be measured at the input water level station.

[0009] Spore drift, microparticles: Lycopodium spores can be colored with up to five different colors. Therefore, different pits colored with spores of different colors can be used simultaneously as input points. Due to their density of 1.1, the spores remain floating for a long time. Their size is about 33 micrometers [μm]. The spores are captured using a plankton net, which usually has to be emptied every day. Evaluation is carried out microscopically by counting. Microparticles such as polystyrene beads with a size of 0.05 to 90 micrometers [μm] are available. They are colored with fluorescent colors and can be used like colored spores. Purpose of analysis: The advantages of this method are that it does not affect the quality of the water or the appearance of the water, and the possibility of being able to distinguish different pits due to the color of the spores.

[0010] The disadvantage is that only qualitative statements can be made about flow paths and flow rates. The spore or particle size restricts drift to open junctions with minimum opening widths and karst cavities. Porous sediments, rocks or materials with smaller pore sizes hinder spores or polystyrene beads.

[0011] Activation-analytical tracer method: For feeding into the pit, non-radioactive substances are added to the permeate water and only the water sample taken is subjected to neutron bombardment to activate the elements in the reactor. Bromine, such as ammonium bromide (NH4Br), lanthanum or indium are possible tracer substances. In the case of indium, tracer quantities in the range of several hundred grams can be expected ( 1974). The advantage of this method is that it uses non-toxic, non-radioactive substances and only relatively small amounts need to be used. As a result, no special safety measures are required during the test process. As with other tracer methods, the evaluation is performed using a concentration / time diagram. This allows the interstitial velocity of the groundwater to be determined between the location where the tracer was introduced and the location where the tracer was measured.

[0012] Single borehole dilution method with radioactive tracers: The decrease in the concentration of a previously added tracer is measured in the borehole zone blocked by a packer. The dilution rate can be derived from the decrease in concentration over time in the packer interval. The dilution rate is empirically related to the current filtration rate. The measurement results must be corrected for the borehole configuration (type of filter tube, slit width, etc.). If radioactive materials are used as tracers, the direction of horizontal groundwater flow can be determined by determining the radioactive radiation after the tracer has flowed into the aquifer by means of angle-dependent measurements. However, radioactive tracers are problematic in drinking water supplies.

[0013] Single-well dilution method with sodium fluorescein as tracer measurement method: The Institute of Hydraulic Engineering at the University of Stuttgart (MARSCHALL 1993) developed a light-guided fluorimeter for in-situ concentration measurements. This allows the use of fluorescent dyes such as sodium fluorescein. The detection limit of these substances (10 -5 -10 -6 mg / l) is much lower than the conductivity measurement with NaCl tracer (0.1-1 mg / l). -7 Horizontal filter velocity in m / s.

[0014] The use of dyes as tracers is also described. Tracer substances are placed in upstream water level stations (measuring points) or sinkholes (sinkholes) as dyes for analyzing water flow and flow direction. The Danube sinkhole was already cleared in 1877 using fluorescein as a tracer molecule.

[0015] Groundwater velocity is significantly affected by interrelated rock properties such as rock mass permeability (water permeability in natural rock structures, rock fractures, and effective flow cavity volume). However, at the outset of site selection, data on these variables are neither completely available nor collected with sufficient evidence for all locations under consideration.

[0016] Disadvantages are the low horizontal depth (range) of penetration into rock formations or porous materials. Only storage coefficients can be estimated. Statements about aquifer models, aquifer margins and anisotropy can only be made to a limited extent with special evaluation methods. The accuracy of the measurement results depends primarily on the quality of the data acquisition and not on the tracer used itself. Especially in the case of low permeabilities, precise pressure and volume measurements are essential.

[0017] In-situ measurements of parameters such as pressure, temperature in stone cracks, rocks, geological formations, porous materials or in boreholes are difficult or impossible due to the difficulty of access and may only be suitable for very small measuring probes. Small electrical or optical sensors and measuring devices that can measure in such locations and under such conditions can only be manufactured with great effort and expense and are difficult to introduce into the rock and connect to external measuring electronics.

[0018] Conventional determinations using measuring probes, sensors and detection electronics are generally excluded because, on the one hand, they must be supplied with energy and, on the other hand, the data must be read out. Both require supplying power and signal lines, which would require separate boreholes, which would not only require huge technical and financial expenditures, but would also tamper with the measured parameters and flow conditions (e.g. water in these rock formations). The use of prior art tracers only results in passive measurements of parameters such as flow velocity, dilution or permeability.

[0019] There is no quantification of parameters such as pressure, temperature or other physical and / or chemical parameters recorded as they pass through rocks and / or formations or porous materials, or what physical, chemical and biochemical conditions they are exposed to on the way.

[0020] Based on this, the object of the present invention is to provide a new method for quantifying porous media, by which the above-mentioned disadvantages of conventional methods can be avoided.

[0021] This object is achieved by a method for quantifying a porous medium with at least one particle or a mixture of particles, wherein the particles have a reference function and at least one reporting function for recording a physical, chemical or biochemical parameter of the porous medium, the method comprising the following steps:

[0022] introducing particles and / or a mixture of particles into a fluid,

[0023] causing a fluid with particles and / or a mixture of particles to flow through and / or permeate the porous medium, wherein when a threshold value of a parameter to be recorded is exceeded or fallen below, at least one reporting function of the particles changes, while a reference function of the particles remains unchanged, and

[0024] After leaving the porous medium, the particles and / or the physically, chemically or biochemically altered particles of the particle mixture are subjected to at least one subsequent analysis of a reporter function and a reference function, wherein the reference function serves to identify the particles.

[0025] The particles according to the invention are submillimeter, millimeter or nanometer sized and comprise at least one reference function and at least one reporter function for recording a physical, chemical or biochemical parameter of the porous medium.

[0026] The particles preferably have a diameter of 100 μm to 0.5 nm, particularly preferably a diameter of 10 μm to 5 nm or very particularly preferably a diameter of 5 μm to 50 nm.

[0027] The base body of the particles is preferably composed of silver, gold, copper or other metals, silica, polystyrene, olefins, waxes or mixtures thereof.

[0028] At least one reporter function is preferably comprised in the particle and / or on the surface of the particle.

[0029] According to the invention, the reporter functions alone or in combination with one another comprise at least one fluorescent marker, a luminescent marker, a marker for a plasma property, a pH indicator, a temperature indicator, a radiation indicator.

[0030] The alteration of at least one reporter function is preferably irreversible.

[0031] The change in at least one reporter function preferably increases continuously with the dose of radiation (radiation exposure) or oxidative stress experienced.

[0032] The reference function of the particle is preferably in the form of a geometrical and / or tactile detection site or in the form of a fluorescent marker, a luminescent marker or a marker for plasmon properties.

[0033] The particles preferably further have an additional functionality which allows the residence time of the particles in the porous medium to be determined based on time-dependent disintegration or time-dependent property changes.

[0034] The particles preferably further have an additional magnetic function.

[0035] The particles preferably have a further reporting function which changes when a threshold value of a second parameter to be recorded, which is different from the first parameter, is exceeded or fallen below.

[0036] The porous medium is preferably a liquid or gas filled space.

[0037] It is further preferred that the porous medium comprises rock, rock formations and / or porous materials or layers made of such porous materials.

[0038] Analysis of the particles and / or particle mixtures is preferably performed by optical spectroscopy, IR spectroscopy, plasmon resonance, microscopy, dosimetry, nuclear magnetic resonance, electron spin resonance, ENDOR, fluorescence spectroscopy, single molecule fluorescence spectroscopy, atomic fluorescence spectroscopy, luminescence spectroscopy, photoluminescence spectroscopy, chromatography, gas chromatography, liquid chromatography and / or high performance liquid chromatography (HPLC), or with the aid of a subsequent reaction that facilitates detection of a change in reporter function.

[0039] The invention further relates to the use of the method according to the invention for the quantification of rocks, rock formations and / or porous materials or layers of such porous materials in geological analysis, in hydrology, water exploration, mineral deposit exploration, mineral deposit monitoring, fracturing, geothermal energy, leak monitoring, in the monitoring of chemical, biological and / or biotechnical reactors, in the monitoring of water tanks, reservoirs and water supply systems, or in medical in vivo methods.

[0040] The invention furthermore relates to a fluid having at least one particle according to the invention or a mixture of particles according to the invention for use in a medical in vivo method.

[0041] As mentioned above, the particles have a reference function and at least one reporter function for recording a physical, chemical or biochemical parameter. The reference function denotes a reporter function that is unchanged by the physical, chemical or biochemical parameter and is used for detecting one or more particles after they leave the porous medium.

[0042] The reporting function changes once the conditions experienced by the particle as it passes through the medium are such that the condition (a physical quantity such as temperature, pressure, light, radiation of a specific intensity or wavelength, etc., or a chemical quantity such as pH, ionic strength, concentration of a specific anion or cation, a specific solubility product, concentration of a specific chemical such as a specific molecule, ion or free radical) exceeds or falls below a specific threshold (or limit or critical value).

[0043] According to the invention, the final analysis of the particles and / or the particle mixture for the reporting function takes place after they have passed through the porous medium, i.e. after flowing and / or permeating through the porous medium (hereinafter also collectively referred to as "passage"), and after having left the porous medium. Here, "leaving" does not mean that the entire particle must be spatially separated from the medium. On the contrary, "after leaving the porous medium" is to be understood as meaning that the analysis of the particles and / or the particle mixture takes place at a location different from the location where the physical, chemical or biochemical parameters of the medium to be examined are to be recorded.

[0044] As a result, according to the invention, information about a parameter is obtained from particles in situ (eg in a rock, in a geological formation or in a chemical reactor) and analyzed ex situ after passing through these locations.

[0045] Therefore, the particles are analytical particles (tracers), preferably micrometers and / or nanoparticles. These have a reference function (also referred to as a recognition function) in the form of a label, which is independent of the physical, chemical, and biochemical parameters experienced, and which can detect particles after they pass through or penetrate through the medium. The particles also have at least one reporting function (i.e. another labeling function, also referred to as a reporting function or a story-telling function), which changes, preferably irreversibly, depending on the physical, chemical and biochemical parameters experienced. The reporting function comprises preferably by means of a quantitatively and / or qualitatively analyzable signal of a substance and / or liquid for the reporting function, to detect and / or quantitatively and / or qualitatively record the physical or chemical and biochemical parameters experienced during passing through or penetrating through the medium.

[0046] With the aid of the method according to the invention, areas and locations which are otherwise difficult or inaccessible and have no visual contact with an observer, preferably within geological formations, i.e. not on the Earth's surface, or within reactors or within the human or animal body, can be analyzed.

[0047] The reporting function may be contained within the particle or disposed on its surface.

[0048] According to the present invention, any measures can be taken to implement the reporting function. However, the reporting function preferably includes at least one of a fluorescent marker, a luminescent marker, a marker for plasma properties, a pH indicator, a temperature indicator or a radiation indicator. These can exist alone or in combination. The reporting function can be shielded from the outside with a semi-permeable membrane or a permeable membrane as an isolation layer or a variable layer, and / or shielding a subsequent or previous reference function.

[0049] The reporter function may preferably include a chemical tag or biomarker that detects the presence of a specific chemical or biological substance.

[0050] Alternatively or in combination, a quantitative and / or qualitative change of the particle itself is used as a reporting function. For this purpose, the reporting function or the particle itself undergoes a change due to the manipulation of the surrounding physical, chemical or biochemical parameters. The change occurs when passing through the porous medium. The particle or particle mixture does not exist in the natural ecosystem, but is introduced as part of the method according to the invention.

[0051] As mentioned above, particles are introduced into the fluid. Generally, the fluid passing through the porous medium can be not only a liquid, but also a gas, a gel or a liquid-gas mixture, an emulsion, a mist (a droplet carrying a gas) or an aerosol. Therefore, the fluid can be water, oil, an oil-water mixture, a generated or natural airflow, a liquid-gas mixture, steam and also a mist.

[0052] Particles, especially nanoparticles, with reference and reporting functions can be in any component of such mixed fluids. They can be in one component or in more than one component, such as in both the droplets and the gas phase of the mist, or in only one of the two.

[0053] The fluid may also contain additives and / or detergents.The gas stream preferably consists of air, industrial gases or noble gases or mixtures thereof.

[0054] The analysis of the particles and / or particle mixtures is preferably carried out by optical spectroscopy, IR spectroscopy, plasmon resonance, microscopy, dosimetry, nuclear magnetic resonance, electron spin resonance, ENDOR, fluorescence spectroscopy, single molecule fluorescence spectroscopy, atomic fluorescence spectroscopy, luminescence spectroscopy, photoluminescence spectroscopy, chromatography, gas chromatography, liquid chromatography and / or high performance liquid chromatography (HPLC).

[0055] A variation of the method according to the invention is to remove the particles or the fluid with the particles and to carry out a subsequent reaction that promotes a change in the detection reporting function. One way of detecting is, for example, to use a test strip similar to that commonly used in medicine and pharmacy, on which the corresponding detection reagent is located. When the reporting function of the particles changes when passing through the porous medium, the test strip will, for example, change color.

[0056] The method according to the invention is used to quantify rocks, rock formations and / or porous materials or layers of porous materials in geological analysis of rocks, rock formations and / or porous materials or layers of porous materials, in hydrology, water exploration, mineral deposit exploration, mineral deposit monitoring, fracturing, geothermal energy, leak monitoring, in monitoring of chemical, biological and / or biotechnical reactors, in monitoring of water tanks, reservoirs and water supply systems, or in medical in vivo methods.

[0057] In particular, the method according to the invention is suitable for the hydrological and / or geological analysis of rocks, rock formations and / or porous materials or layers of such porous materials.

[0058] According to the invention, the following parameters are recorded by means of a reporter function by direct or indirect detection of the physical, chemical or biochemical parameters of the individual particles according to the invention:

[0059] Physical conditions, such as pressure, temperature, radiation, or also chemical conditions, such as pH as a measure of the acidic or alkaline character of an aqueous solution, or the ion concentration of a chemical compound or element.

[0060] The concentration, type and / or presence of gases such as oxygen, nitrogen, gaseous compounds of elements of the periodic table (periodic table of elements), or gaseous hydrocarbons.

[0061] For example, the concentration, type and / or presence of elements of the periodic table of chemical elements such as alkali metals, non-metals, metals, semi-metals, noble gases, lanthanides or actinides, their salts, ions or covalent compounds thereof.

[0062] The concentration, type and / or presence of organic or organic-inorganic macromolecules, such as fats or oils, their salts or ionic compounds.

[0063] For example, the concentration, type and / or presence of biomolecules such as humic acid, protein, nucleic acid or RNA.

[0064] Physical, chemical or biochemical parameters on individual particles are recorded in situ while flowing through and / or permeating porous media.

[0065] Permeation or diffusion is understood to mean a process of penetration, passage or traversing, in which a substance as a permeant (particles according to the invention) penetrates, passes or traverses a solid as a porous medium. The driving force is the concentration of the permeant or a pressure gradient or Brownian molecular motion.

[0066] Flow refers to the process of traveling through gaps and / or voids between solid bodies.

[0067] Due to the influence of physical, chemical or biochemical parameters, the particles receive at least one signal, wherein the particles receive and bind this signal at least by means of an analytical reporting function (i.e. an external labeling function and / or filling of an internal cavity) and / or by a change in the shape of the particles themselves (so-called memory effect). For this purpose, unmixed different particles or particles in a mixture of different particles are introduced into a medium with the aid of a liquid or gas stream (e.g. in rock cracks, rocks, geological formations, channels or pores) and the particle volume is changed or its surface, or the particle layer, is changed by the physical, chemical and biochemical environmental conditions experienced.

[0068] According to the invention, particles of the millimeter size (5-1 mm), submillimeter size (999 μm to 100 μm), micrometer size (100 μm to 1 μm) or nanometer size (999 nm to 0.4 nm) are used.

[0069] Water, oil or oil-water mixtures with or without additives and detergents can be used, for example, as flowing liquid and / or penetrating liquid, which is used as carrier material or flowing liquid and / or penetrating liquid for the particles according to the invention. Generated or natural gas streams, for example from air, industrial gases or rare gases, can also be used as carrier material for the particles according to the invention. Liquid-gas mixtures or steam, mist (gas phase plus condensed water) are also suitable as fluids.

[0070] The diameter of the particles used is preferably in the micrometer to nanometer range, ie between 0.5 nm and 100 μm, particularly preferably between 10 μm and 5 nm. Particles between 50 nm and 5 μm are preferred. Depending on the geological or hydrological analysis question, the particles are used unmixed or in a mixture.

[0071] Particles that can be easily and cheaply mass-produced and have a narrow size distribution (dispersity) consist of oxides or polymers or waxes. For example, they can be made of silicon oxide or polystyrene or of olefins. In the particles or on their surface, molecules or smaller nanoparticles with desired reference or reporting properties can be introduced, accumulated, detached or attached.

[0072] Another very relevant class of materials is particles made of metals such as silver or gold. By adsorbing for example thiols or dithiols, and also other molecules that change the plasmon properties, the plasmon properties of metal nanoparticles can be significantly changed and thus can be detected, or the signal can be used as a reporter function. In addition, the changes can be detected by the chemical reaction of the thiols or dithiols chemically absorbed on the surface of the metal nanoparticles through the change of the plasmon properties: (i) the intensity of the plasmon absorption, (ii) the width of the corresponding absorption band and (iii) the position of the absorption maximum. Metal nanoparticles combine reporting properties and reference properties in a very advantageous way: the "naked" nanoparticle also shows a plasmon resonance. However, it is changed by adsorbates and chemical absorbers: the resonance develops with an initial resonance spectrum shift and the resonance decreases.

[0073] Therefore, metal nanoparticles, for example made of silver, gold or copper, are preferably used as material for the particles. Adsorbates, chemical absorptions and interactions with the surrounding medium change their plasmon resonance, which can be measured spectrally. These particles are easy to manufacture and are readily commercially available.

[0074] As material for the particles, it is also preferred to use polymer particles, in particular polystyrene latex spheres which are very easy to produce and commercially available, or silicon oxide particles (silica spheres), which are also easy to produce, have a narrow size distribution and are in spherical form, and are also commercially available.

[0075] Particles can have different shapes and forms. For many applications, preferably spherical particles (such as polystyrene latex balls or silica balls), or round, elongated, rounded or rod-shaped particles, such as in micellar form, are designed as hollow structures, filled structures or core-shell particles. It can also be a sheet structure, such as a mineral disk made of mica or lithophore, which can be functionally coated, and-particularly in the field of polymers and biopolymers-there are also structures of irregular shapes. In the case of polymers and biopolymer particles, their (i) folding and (ii) conformation and (iii) their swelling degree can also be used for detection. Many polymers tend to condense in solution, which unwinds under specific conditions such as pH or ion concentration. All three parameters mentioned depend strongly on environmental conditions. However, most of these changes are reversible. When the degree of swelling is increased or the coagulum is loosened, the embedded molecules are released or changed by contact with a fluid (e.g. surrounding water) in such a way that they are irreversibly released and / or changed, and this change can be detected as a reporter property, for example with optical spectroscopy, infrared spectroscopy, ultraviolet spectroscopy or fluorescence spectroscopy.

[0076] In addition to (1.) classical core-shell particles (in which the particles are surrounded by a shell in the form of a coating), such as particles of silicon dioxide, coverings made of polystyrene or other polymers or coverings of particles with layers of wax, paraffin or fats that melt at a certain temperature, it is also possible to use (2.) particles consisting of a core and a molecular layer surrounding the core, preferably without gaps. Examples are the covering of metal micro- or nanoparticles, preferably made of coin metals such as copper, silver, gold, and nanoparticles made of metal alloys with layers of thiols, dithiols and thiol derivatives. However, particles of oxides of metals and metal alloys surrounded by a monomolecular layer, particles of silicon dioxide, aluminum oxide, titanium dioxide and also particles of polymers are also conceivable here. (3.) In addition, it is also possible to use hollow particles of various kinds, in which the inner cavity is completely or partially filled with a) at least one gas, b) a surrounding fluid, such as water, or c) a fluid other than the surrounding fluid, such as oil, fat, silicone oil and / or fatty acid. The aforementioned substances or chemical substances and / or the particles contained therein preferably have a labeling function as a reporter function and / or a reference function. Or d) a porous substance with gas-filled cavities or e) a porous substance with liquid-filled cavities.

[0077] If the shell is rigid and brittle, but the core is compressible, the shell breaks under pressure and the interior is exposed to the surrounding fluid (e.g. water). If an irreversible chemical reaction now occurs between a water-sensitive component inside the particle and the water, this component will change at least one physical or chemical property, which can then be used as a reporting property in the sense of the present invention. In this way, it can be demonstrated that the pressure required to cause the particle to collapse on its way (e.g. through a rock) has been reached. The threshold pressure, i.e. the minimum pressure that must be reached so that the particle breaks or collapses under external pressure, can be set very easily, and customized particles with different threshold pressures can be produced. For a given substance for the shell and a given filler, the pressure that must be reached until the particle collapses increases with increasing shell thickness and decreasing particle size.

[0078] According to the invention, at least one analytical particle (tracer) having a reference function and a reporting function is used. Combinations of several analytical particles with or without a porous separation layer are also possible. For example, a particle mixture consisting of filled particles and particles with a central cavity and a surrounding shell, in each case (i) applied to the shell, (ii) integrated into the shell, or (iii) located in the cavity, the marking function has a reporting function and / or a reference function.

[0079] However, a combination of several identical or different marking functions (as reporter function and / or reference function) with or without a permeable separation layer and with or without a permeable shell is also possible, wherein the marking function or the analytical tracer itself can also represent the shell of the particle. The cavity can optionally contain a gel-like, pasty or gaseous filling (see above). For example, by causing the shell to collapse after reaching (exceeding or falling below) a specific pressure, pH value, temperature, etc., the filling itself can be used as an analytical medium or change the physical properties of the particle, such as weight or buoyancy properties such as static buoyancy.

[0080] However, the three aforementioned material systems are only starting particles for analytical particles with a marking function in the form of a reporter function and a reference function produced according to the invention. The implementation of the reporter function and the reference function for the individual particles occurs by applying an adsorbed or chemically absorbed shell to the particle surface, for example during the particle production process, and / or by introducing the reporter function and the reference function - for example by introducing suitable chemical molecules as marking functions - into the particle interior, or by subsequent diffusion and / or filling of the hollow volume of the particle. The particles can also be produced with two half shells (which can be filled with the respective marking functions), and the two half shells can then be connected in the final connection.

[0081] Two specific exemplary embodiments of particles having a reference function and at least one reporter function will be described in more detail below.

[0082] Core-shell version :

[0083] The particles are surrounded by shells made of different materials or of the same material in different structures. For example, the core may include a reference function and the shell may include a reporting function, or vice versa. The deformation in which the reporting function is in the core and reacts to contact with water is particularly attractive. The shell protects the core from the influence of water. As long as the shell exists and is diffusion-tight to water, the reporting function in the water-sensitive interior (core) remains unchanged. If the core is surrounded by a water-diffusion-tight shell (the shell becomes permeable to water when a specific threshold condition is reached (reaching a specific temperature, exceeding or falling below a specific pH value, performing a specific chemical or biochemical reaction)), this can be detected by a change in the reporting function in the core of the particle via contact with water. This can preferably be done in four different ways:

[0084] First: when a threshold condition is reached, the shell becomes porous.

[0085] Second: when threshold conditions are reached, the shell loses its diffusion tightness to water.

[0086] Third: When threshold conditions are reached, the shell dissolves.

[0087] Fourth: When a threshold condition is reached, the shell detaches from the core.

[0088] Examples are melting of the shell when a certain temperature is reached, or dissolution of the shell when a certain pH value is reached.

[0089] Particle-in-particle deformation :

[0090] In addition to the core-shell version, the present invention can be implemented by deformation of the particles in the particles. For example, smaller particles are introduced into larger particles by precipitation reaction, such as metal nanoparticles in polymer particles. The shape of the particles can be round or spherical. Through the shape of the particles, the properties of the particles for dynamic buoyancy in the fluid or for the flow or penetration of porous media can be affected and adapted.

[0091] According to the present invention, particles can also have further additional functions in addition to the reference function and the reporting function. For these trifunctional particles, nanoparticles with the above diameters are also preferred. This additional function can be a timer function, which makes it possible to determine the time from injection to detection after the particle leaves the porous medium based on the time-dependent disintegration or time-dependent property change. Radioactive decay is just an example. Chemical decomposition, a kind of isomer conversion to another more stable isomer or oxidation with fluorescence property loss are further examples.

[0092] In addition, the additional function can be a magnetic function. Use trifunctional nanoparticles, wherein the third function is its magnetism, preferably its ferromagnetism. This can be achieved, for example, that the particles contain magnetic inclusions in addition to their reporting function and their reference function. Subsequently, this promotes the use of magnets and magnetic fields to concentrate and remove particles from the fluid. For example, after leaving the porous medium, the fluid can flow through a grid or screen that has magnetism and attracts and holds the particles.

[0093] Metal nanoparticles, preferably made of gold or silver, show a plasmon resonance that can be detected with optical spectroscopy or IR spectroscopy. This resonance shifts when specific chemical molecules, preferably thiols, are adsorbed. The presence of metal nanoparticles can always be detected spectrally by the presence of the plasmon resonance as a reference function.

[0094] The question whether a particle encounters a thiol on its way through a porous medium can be determined from the spectral position of the resonance after passing through the medium: when thiol is adsorbed, the spectral position of the plasmon resonance shifts. The proportion of particles that encounter thiol can also be determined in this way. The plasmon spectrum can be decomposed into a non-shifted part and a shifted part.

[0095] The following will describe reversible or partially reversible implementations of reporting functions, with (mostly) irreversible changes in reporting functions due to conditions experienced being preferred. If you have a reporting function that changes due to a particular condition being experienced, and that slowly changes back to its original state when that condition is no longer present, you can infer how long ago that experience occurred, and from that indirectly infer where the condition is prevalent, e.g. in a layer of rock.

[0096] A special embodiment is to use bifunctional molecules as particles with reporter and reference units, also referred to below as "two-in-one" solutions. Here, the reporter and reference units are not separate units, but are combined into one unit.

[0097] Example: Metallic nanoparticles, for example made of gold or silver, show plasmon resonances, which can be detected with optical spectroscopy or IR spectroscopy. This resonance shifts when a specific molecule (for example thiol) is adsorbed. The presence of metallic nanoparticles can always be detected spectroscopically by the presence of a plasmon resonance (reference function). The question whether a particle encountered a thiol on its way through a porous medium can be determined from the spectral position of the resonance after passing through the medium: when a thiol is adsorbed, the spectral position of the plasmon resonance shifts. The proportion of particles that encountered thiols can also be determined in this way: the plasmon spectrum can be decomposed into a non-shifted part and a shifted part. Reversible or partially reversible implementation of the reporting function: Basically, consider a complete and / or partially irreversible change of the reporting function due to the conditions experienced. If you have a reporting function that changes due to a specific condition experienced and that slowly returns to its initial state when this condition no longer exists, you can infer how long ago this experience was and therefore also indirectly infer where the above conditions prevail (for example in a rock formation).

[0098] Departure from the above view is possible in exceptional cases where the particles or molecules are already naturally present in the system and are not introduced as part of the method according to the invention. A practical example of a pH-dependent particle is a particle comprising a molecule or a group of molecules that splits or splits out a specific molecular group above a specific pH value (i.e. when the specific pH value is exceeded). Another example of a pH-dependent particle is a particle comprising a molecule or a group of molecules that splits or splits out a specific molecular group below a specific pH value (i.e. when below the specific pH value) as a reporter function. These reactions are actually completely irreversible, because if the critical pH value is exceeded or dropped again, the groups required for the reverse reaction are no longer available.

[0099] The particles used to detect temperature overshoot are particles with a temperature-independent core that is resistant to higher temperatures and a shell that melts and detaches from the core when a specific temperature (threshold condition) is exceeded. Here, the particles have several marks with characteristic geometric shapes, such as a cone, which change at different softening temperatures when the medium flows through. Whenever a specific temperature is reached, the specific mark softens and changes its shape. It is thus clear what temperature has been reached and what temperature has not yet been reached in the medium. The core can be a metal particle, such as an oxide particle made of silicon dioxide, aluminum oxide or titanium dioxide, or a polymer particle such as polystyrene. The shell can be composed of any substance that is insoluble in water in the solid state and melts at the desired temperature. These can be waxes, paraffins, long-chain olefins or alkanes, or can also be fatty acids, aldehydes or esters. If the melting temperature of the various substances that form the shell is reached, the shell will detach during the flow, or the molecules of the shell will dissolve in water or polar fluids.

[0100] According to the invention, different particles that are sensitive to temperature overshoots at different temperatures can also be combined. For example, 10 different particles are used, whose shells melt at 10°C (degrees Celsius), 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C and 100°C, and each of them uses a different molecule as reference. In this way, detailed conclusions about which temperatures have been exceeded and which have not been exceeded, and what percentage of particles have experienced temperature overshoots on their way through the porous medium, and thus, for example, have lost their shells in the above-mentioned embodiment, can be drawn in steps of 10 degrees.

[0101] A further embodiment is that 10 different particles with shells of 10 different melting points are introduced simultaneously or sequentially, and flow and / or penetration are observed or analyzed chromatographically as a function of time. In this case, for all 10 kinds of particle types, the reference properties are the same. Of course, in a similar manner, the inspection of different properties (such as exceeding and / or being lower than pH value, exceeding temperature and being exposed to oxygen) can be analyzed simultaneously or sequentially. Another embodiment for detecting particles of temperature overshoot in non-aqueous weakly polar or non-polar media is a core with temperature independence of resistance to higher temperatures and a particle of a shell that melts and breaks away from the core when exceeding a specific temperature (threshold condition). The core can be a metal particle, an oxide particle (such as made of silicon dioxide, aluminum oxide or titanium dioxide) or a polymer particle (such as polystyrene), and the shell can be composed of any material that is oil-insoluble in the solid state and melts at a desired temperature. These can be polar molecules, such as polyols and / or long-chain or short-chain carboxylic acids. If the melting temperature of the individual substances forming the shell is reached, the shell will break away during the flow, or the molecules of the shell will dissolve in the oil or non-polar fluid.

[0102] A practical example of pressure-dependent nanoparticles is the so-called "hollow sphere", which is a hollow particle in which there is gas and no liquid and which collapses at a certain hydrostatic pressure. Different collapse pressures can be set depending on the diameter and the wall thickness. The particle volume can be partially or completely filled with a solid, gel-like, pasty or gaseous cavity filler.

[0103] The types of changes in the reporting function will be explained in more detail below. This can be done irreversibly (hereinafter referred to as "threshold deformation") or similarly to a dosimeter.

[0104] Threshold variation: For example, if a certain temperature is reached, the reporting function of a certain particle type changes. If a further temperature is reached, the reporting function of another particle type changes. Thus, it can be demonstrated whether a specific parameter value has been reached, exceeded or fallen below.

[0105] Dosimeter deformation: The degree of change depends on the intensity and exposure time. As an example, the change of the reporting function due to radioactive radiation and UV light is mentioned. The degree of change then depends on the dose, i.e. is proportional to the radiation intensity and the exposure time - this corresponds to the invention of the smallest possible dosimeter in the world, the (micro or nano) particle dosimeter. Similarly, chemical dosimeter deformations can also be thought of. The chemical dose is then the concentration of the chemical or biochemical substance to be detected multiplied by the exposure time. In the simplest case, this can be the dose of oxygen action, i.e. the amount of oxidation caused by oxygen. As an extension of the method, of course, there can also be different oxidizing species that can each cause oxidation of the reporting function of the particles, and the total amount of oxidation can be determined. In non-polar media such as oil, emulsified water droplets or other droplets of polar liquids can be used instead of particles, such as micelles. The droplets or micelles can then contain molecules, molecular groups, or particles or nanoparticles with reference properties and with reporting properties in exactly the same way.

[0106] In the chromatographic analysis of the data, the particles are not injected continuously, but at specific points in time, and come out again after different residence times in different paths through the fractured rock or porous medium, for example, so as to be examined at the exit point as a function of time. The different residence times correspond to different paths through the rock or porous medium (possibly with residence times after "falling" into the pores). The "history report" of the particles after leaving the porous medium as a function of residence time provides information about what percentage of particles are exposed to the desired conditions (e.g., temperatures above 80° C.) as a function of residence time.

[0107] The particles can also optionally be provided with individual characteristic reference functions (identification functions) in the form of markings, for example with geometric and / or tactile shapes similar to fingerprints. Another example is the marking with a fluorescent dye that does not exist in nature and whose absorption or fluorescence spectrum indicates the fingerprint of the presence of the molecule. If the particle contains this fluorescent dye inside or is bound to its surface, it can be identified without doubt. A preferred identification is given by using two fluorescent markers in the particle simultaneously for identification (dual identification function).

[0108] The particles can thus be identified at any time as particles of a specific injection batch. If particles with different markings are brought in at different times or in different locations, you can - if necessary even many years later - identify where these particles came from. If these particles leave again, they carry with them information about the environmental conditions they experienced during their passage or the time they were in the rock due to this change. Such particles can be introduced billions of times. By combining particles modified by different environmental conditions (threshold temperature, pressure, etc.), the different environmental conditions experienced can be interrogated simultaneously. This makes it possible to analyze, for example, that 70% of the particles encountered temperatures above 250°C, and 20% encountered temperatures above 300°C, and 44% encountered pH values ​​below 4.5.

[0109] However, in addition to the reference function, it is also possible to equip the particles with more than one reporter function. An example is a nanoparticle of a fluorescent dye of wavelength 1 which loses its shell when a certain temperature (melting point of the shell encapsulating it) is exceeded and thus serves as reporter function 1. At the same time, the core of the particle encapsulated with a fusible shell (e.g. a wax shell) contains another fluorescent dye which fluoresces at wavelength 2 and is chemically stable under the conditions in the porous medium serving as the reference function. In addition, the particle core also contains a further fluorescent dye which fluoresces at wavelength 3 and irreversibly changes its fluorescence when the pH value falls below or exceeds a threshold value, so that it no longer or does not fluoresce strongly at this wavelength 3, or fluoresces at a new wavelength 4.

[0110] According to a preferred embodiment of the present invention, if particles are used whose reporting function changes when a threshold value is exceeded or fallen below, such a threshold value is a sharp value or a narrow range of values, for example the melting temperature of a wax shell dyed with a fluorescent dye is + / -10°C, preferably + / -5°C, particularly preferably + / -3°C.

[0111] A particularly preferred embodiment of the method according to the invention uses particles which are characterized by the following features:

[0112] 1. A particle having a particle core and an inner shell and an outer shell,

[0113] wherein (1.) the particle core comprises a reference function (e.g. fluorescence, or exhibits a defined electromagnetic resonance, such as photoresonance, when illuminated with electromagnetic radiation, such as light, or the particle core comprises a component exhibiting this phenomenon, such as a fluorescent molecule or quantum dot or metal nanoparticle exhibiting plasmon resonance),

[0114] wherein (2.) at least one component is introduced into the inner shell, the at least one component including a reporter function and being water-soluble or oil-soluble, and

[0115] Wherein (3.) the inner shell is surrounded by an outer shell which is diffusion-tight with respect to the surrounding fluid so that the component introduced into the inner shell (having a reporting function) can neither be separated from the fluid nor chemically changed or modified, swollen, etc. in some other way, wherein the outer shell is characterized in that it is easily diffusible to the fluid or to the component encapsulated in the inner shell, or both, when a threshold value of the parameter to be detected is exceeded or fallen below, or by dissolving the outer shell when a specific threshold value is fallen below or exceeded, thereby releasing the component introduced into the inner shell and having a reporting function.

[0116] 2. The particles according to 1. are characterized in that the particle core is a micron or nanoparticle made of metal (preferably silver, gold, lead, copper, iron, cobalt, metal oxide, or ferromagnetic material such as iron oxide or cobalt oxide) or silicon dioxide or carbon or polystyrene.

[0117] 3. The particle according to 1. or 2., characterized in that the shell is a fusible shell that melts or softens at a specific temperature or within a specific temperature range, or dissolves in the surrounding fluid. Alternatively, a shell that dissolves, softens, swells or easily diffuses when exceeding or falling below a specific pH value or a specific ion concentration can also be used.

[0118] 4. The particles according to 1. to 3., characterized in that the shell consists of a wax or a metal or an organic or inorganic polymer or oligomer that is meltable or softenable or swellable within a specific temperature range.

[0119] 5. The particle according to 1. or 2., characterized in that the outer shell is a shell made of an oil-soluble substance that dissolves when in contact with oil.

[0120] 6. Particles according to 1. or 2., characterized in that the outer shell is a shell made of a polymer brush grafted onto an inner shell, or the outer shell is a coordination polymer.

[0121] 7. Particles according to 1., 2. or 6., characterized in that the outer shell is a shell made of a polyelectrolyte. In a particular embodiment, it can also be grafted onto the inner shell. The outer shell can also be a crosslinked or photocrosslinked polymer.

[0122] 8. The particles according to 1. to 7., characterized in that fluorescent dyes or quantum dots or magnetic nanoparticles are introduced into the particle core.

[0123] 9. The particles according to 8., characterized in that at least one of the fluorescent dyes used is rhodamine or a rhodamine derivative or GFP (green fluorescent protein) or a ruthenium-bipyridine complex and compound (eg Rubpy).

[0124] 10. The particle according to 1. or 7., characterized in that the outer shell is a polymer or polyelectrolyte that is easily diffused above a specific pH value or a specific temperature.

[0125] 11. The particle according to 1., characterized in that the outer shell is a semi-permeable membrane.

[0126] 12. Particles according to 1. to 11., characterized in that, in addition to the particle core, the particles have more than two shells.

[0127] According to the invention, the reference function in the form of a label is preferably embedded in the particle core and cannot be dissolved by the fluid. At least one component with a reporter function introduced into the inner shell can be dissolved by the fluid when it comes into contact with the fluid. As a result, when the fluid that makes it soluble comes into contact with the inner shell, it can be "removed" again.

[0128] The following will be described in more detail for the geological analysis of rocks, rock formations and / or porous materials or layers made of the porous materials, for the method of quantifying rocks, rock formations and / or porous materials or layers made of the porous materials. Rocks are solid, naturally occurring, usually microscopically heterogeneous combinations of minerals, fragments of rocks, glass or residues of organisms. The mixing ratio of these components to each other is largely constant, so that regardless of their detailed composition, when observed with the naked eye, the rock looks uniform. The detectable change in properties is caused by specific physical, chemical or biochemical environmental conditions of the material to be examined. If a particle encounters such environmental conditions (e.g., a temperature of at least 80° C.) on its way through a porous medium or rock, the particle will be irreversibly changed, which is detectable by a change in properties after it has left the porous medium or rock. Now, this change in the properties of the particle is detected after it flows through and / or penetrates the rock, rock formation and / or porous material to be examined or the layer made of the porous material. For example, this can be done in the following way. At the exit point of the fluid, a sample is taken for this purpose and the fluid with particles is checked, or a sample is taken for this purpose and the particles are enriched - for example by centrifugation or ultracentrifugation or by sedimentation - and then checked. Separately from or in combination with sampling, the properties can be checked in real time in the flowing liquid, for example through a glass window in the flow cell of a spectrometer through which the fluid flows. The change in the properties of the particles can affect very different properties: in particular, this can be the absorption of electromagnetic radiation such as light, ultraviolet radiation or infrared radiation or microwave radiation. However, this can also be a change in the magnetism of, for example, ferromagnetic or superparamagnetic particles and nanoparticles, which can occur, for example, by oxidative changes due to the effect of oxygen. However, it can also be a change in dielectric properties, which can also occur, for example, by oxidative changes due to the effect of oxygen, and can also occur by another chemical change in the particles or their surfaces or molecules discussed.

[0129] Depending on the type of particles used, changes in the properties of the particles can also be detected by NMR and ESR (nuclear magnetic resonance or electron spin resonance). Changes in properties can also be detected with the aid of ENDOR (electron nuclear double resonance) using magnetic resonance.

[0130] However, there may also be a change in the fluorescence properties, which may be in different ways: a change in the fluorescence intensity or a change in the fluorescence wavelength or the appearance of a new fluorescence or the appearance of a fluorescence at a different excitation wavelength than before. The latter is particularly preferred for the detection described below. At a certain excitation wavelength, fluorescence appears after flowing through the porous medium, which was not present before flowing through the porous medium, or only with a lower intensity. Alternatively, at a specific excitation wavelength, fluorescence appears before flowing through the porous medium, which is no longer present after flowing through the porous medium, or only with a lower intensity.

[0131] After the particles and / or molecules flow through and / or penetrate the porous medium, they must be checked for changes in the reported properties. In a flow-through method or in-situ method, a fluid with particles and / or molecules flows through a sensor or measuring device that detects both the reported signal and the reference signal. This can be done, for example, by flowing through an optical flow cell in a spectrometer or fluorescence spectrometer.

[0132] In the batch method, samples are taken one or more times and then checked. In the sense of ex situ measurement, a liquid volume is sampled and transferred to a measuring device. By sampling and a subsequent enrichment step, the aim is to keep the particles and / or molecules at a higher concentration before the enriched sample is introduced into the measuring device for measurement, thereby having a stronger measurement signal for the reporter and reference functions. Enrichment methods include centrifugation, ultracentrifugation or enrichment by evaporation of part of the fluid.

[0133] Chemical precipitation reactions are also conceivable, where particles or molecules are precipitated out of a fluid and can then be examined in a highly enriched manner. Here, the application of the method is not limited to flow application variants, where a fluid with particles is injected on one side and comes out on the other side. Methods that pump in and then suck it out at the same point are also conceivable. In the case of a "last-in first-out" chromatography, one would expect that the last injected particles would come out first.

[0134] Another variant is cross diffusion: it analyses (if additionally required) the diffusion across the current direction and obtains information about cross diffusion constants, eddies etc. and cross-connected channels and their extent. In borehole experiments this range is usually used as the radial influence distance from the borehole.

[0135] For a pumping test, for example, the extension of the drawdown funnel corresponds to the extent of the pumping test. The volume of influence can be specified if the drilling depth (for an imperfect well) or the test interval (for a packer test) is considered for the extent of groundwater thickness (for a complete well), or if the vertical flow component is assumed to be negligible.

[0136] In addition to hydraulic parameters, the spatial representativeness that can be achieved by a single inspection method also depends on the inspection time and the size of the inspection area. Typically a method performed with a short test time in a small inspection area will have an impact volume that is several orders of magnitude smaller than a long test with several observation points.

[0137] In a particularly advantageous variant of the method, the particle sends two signals during its examination after leaving the rock, the rock formation and / or the porous material or the layer made of this porous material, which signals can be detected. The first, a signal indicating the presence of the particle and not modified by environmental conditions, and the second, a signal also specific to the particle. However, if certain conditions have been reached during the flow and / or penetration (for example: a temperature of at least 80° C.), it is not sent in the same way from its surroundings or the fluid and is modified by environmental conditions. The former signal has the function of a reference signal, the latter has the function of a reporter signal, which reports with a memory function (memory effect) about the conditions experienced during the passage through the rock, the rock formation and / or the porous material or the layer of this porous material, and reports about the properties and signals experienced. The advantage of the combination of reference signal and reporter signal is that it can be used to directly determine the percentage of particles that have been seen in said conditions.

[0138] Furthermore, the absolute concentration of particles can be determined at any time, but also relative concentrations based on the particle concentrations (number of particles per volume based on the concentration when entering the porous medium) can be determined. In particular, the combination of reference signal and reporter signal can be implemented in very different ways.

[0139] A practical method of advantage is the combination of two molecules or molecular groups, both of which emit fluorescence of two different wavelengths when they are excited, for example, in the blue or ultraviolet spectral range. When certain environmental conditions are reached, one of the two different molecules or molecular groups is stable to the possible environmental conditions in the porous medium, while the other is destroyed or its fluorescence properties are irreversibly changed. If a particle containing two molecules or molecular groups is detected after passing through the porous medium and after reaching the conditions necessary for the change, it indicates that the fluorescence of the former molecule is unchanged, but the latter is not. In this way, it is possible to quantitatively determine what percentage of all particles reach the threshold condition for the change of the second molecule on the way through the porous medium.

[0140] The combination of reference properties and reporter properties for the labeling function within one and the same particle or molecule can be achieved in different ways. Particles carrying two functional groups that show fluorescence are used. This can occur, for example, due to the fact that two corresponding molecules with corresponding fluorescent properties are bound to the particle surface or contained in its volume, or corresponding fluorescent groups of molecules are bound to the particle or particle surface. One group or one molecule is changed or destroyed under threshold conditions, while the other is not.

[0141] Thus, after reaching a corresponding threshold value, e.g. temperature, or after exposure to corresponding conditions, e.g. oxygen, UV radiation, radioactive radiation, the fluorescence of one molecule (=reporting property) changes, but the other (=reference property) does not. Alternatively, we will use a molecule that carries two functional groups that show fluorescence. One group is changed or destroyed under threshold conditions, but the other does not. Thus, after reaching a corresponding threshold value (e.g. temperature) or after exposure to corresponding conditions (oxygen, UV radiation, radioactive radiation, etc.), the fluorescence of the molecule (=reporting property) changes, but the other (=reference property) does not.

[0142] The two variants mentioned above can also be used in combination. For this purpose, the first-mentioned molecule is used and introduced into the other-mentioned particle or bound to its surface (physically or chemically or physicochemically). It is also possible to use particles or molecules which change their reporting properties almost immediately when the corresponding conditions (threshold conditions) are reached.

[0143] Particles or molecules can be used that continuously change their reporting properties as a function of the dose (degree and duration of exposure to, for example, oxygen or ultraviolet light or radioactive radiation). Such particles or molecules can then be used as a kind of microscopic dosimeter. Particles or molecules can be used that reversibly change their reporting properties with a certain decay time of the change after the exposure with the changed properties ends. Example: Temperatures above 80°C reversibly change the fluorescence (reporting property) of the particles. When the exposure at the above temperature ends, the change decays with a decay time (half-life) of 183 seconds. If you wait long enough, there is no change compared to the state before the exposure. The advantage of this deformation is that it also provides information about how long the particles have traveled from the exposure time until they leave the porous medium.

[0144] By varying the flow rate - for example via the applied pressure - both the percentage of particles exposed to exposure and the time from exposure to arrival at the detection location can be determined or estimated. A further embodiment is to introduce two different particles (one with a reference property and one with a reporter property) into a larger particle or attach them to its surface (e.g., physically adsorbed, chemically absorbed, or glued with an adhesive).

[0145] These can be optical properties, but also magnetic properties or magnetic resonance properties, for example, which disappear under the influence of oxygen for one type of nanoparticles but not for other types. In this application example, anaerobic conditions in rocks can be detected directly. The combination of two or three of these methods allows comprehensive conclusions to be drawn about the percentage of particles exposed to the conditions in question, the average dose (degree of exposure or concentration or intensity, integrated over time) and the average running time or residence time of the fluid in the medium. Where appropriate, particle measurements can be carried out continuously in a flowing fluid stream by fluorescence spectroscopy with real-time evaluation of the spectrum. Alerts can then be given virtually in real time - for example when used as drinking water or as a leak warning - and you do not have to limit yourself to random samples, but can observe continuously. Chromatography can also be carried out in this way. This information can be related to the residence time in rocks or porous substances or cave systems.

[0146] The readout can be by fluorescence etc. The particles can be measured in the side stream or enriched by filtration. An attractive variant is the use of magnetic particles which can be directed to specific locations in a directed manner by a magnetic field and which additionally have the advantage of being removed and enriched by a strong magnetic field so that the particles can be collected again for analysis after passing through with the help of magnetism.

[0147] In an advantageous variant of the method, the particles dispersed in a fluid, such as a liquid, are treated with ultrasound before the fluid with the particles is injected through the porous medium. In this way, particles that have partially coagulated to form aggregates are dispersed again into individual particles.

[0148] As mentioned above, the reporter function can be any property or combination of different properties that may or may not change due to the environmental conditions experienced when flowing through the porous medium. Properties that are well suited for detection are changes in chemical or biochemical or spectroscopic properties or other properties caused by the cleavage of molecular groups. However, if only H or H + The reaction is usually reversible if the hydrogen is split off in the form of + Ions are ubiquitous in aqueous media. However, if the functional units are more complex, the splitting reaction will remain irreversible, even if the reaction conditions change again during the passage and there are conditions for a reversible reaction to occur: the splitting groups have long diffused away, or have moved to another location with the flow, and are no longer available for the reverse reaction. If the particles split into such groups due to environmental conditions, then even if the conditions for this situation are given again later, the chemical group or the molecular fragment or ion will never return to the starting point (for reasons of probability) and the reverse reaction will never occur again. As the types of groups to be split, it is important to use groups or substances that are in any case unavailable ("ubiquitous") in the fluid flowing or pumped through the porous medium.

[0149] The radicals to be cleaved can be cleaved into free radicals, cations, anions, molecules or molecular fragments or even particles.

[0150] The cleavage can take place in the form of a chemical reaction at a predetermined breaking point of the molecule, which is destroyed by light absorption, UV radiation, radioactive radiation, pH value, oxidative influences or ionic strength, or by the presence of specific molecules or by oxygen, by ozone, by specific or non-specific chemical or biochemical reactions of oxidants.

[0151] In addition to cleavage, specific molecular functional groups or units can also be blocked or protected. In addition, addition reactions, complexation, etc. can also change the properties of the group in a way that reports a change in properties.

[0152] An important variant is the detection of certain ions via complex formation, which is often accompanied by a pronounced color change and other color reactions, which makes it possible to detect the reaction very simply spectroscopically and thus the presence of the substance that triggers the reaction (e.g. metal ions, metals or metal oxides). Examples are iron detection with thioglycolic acid or with hexacyanoferrate or with thiocyanate.

[0153] A completely different possibility is the precipitation of particles, for example starting from a certain ionic strength. For example, five different particles are sent into the porous medium, all of approximately the same size, but labeled with five different detection functions, and at different ionic strengths or pH values, at which they can no longer disperse in the fluid (for example in an aqueous medium), but precipitate. If all five particles are injected into the porous medium at the same time at the same location, but only two or three species come out at the other end, it can be concluded that other species have precipitated, which provides a direct conclusion about the experienced ionic strength or pH value.

[0154] Magnetic particles are very attractive for the method according to the invention in various aspects: (1) Firstly, at least if magnetic nanoparticles are not commonly found in porous media - the magnetic properties of the particles can be well exploited as a reference or identification property. (2) Furthermore, the magnetic properties only allow the possibility of enrichment after passage through a porous medium. (3) Furthermore, the magnetic properties can also optionally be used as a reporter property: the magnetic properties can be destroyed by various chemical reactions with the particles which are still magnetic before the reaction.

[0155] An attractive approach is to systematically debond or detach when a threshold condition is reached. The central particle contains properties with which it can identify itself. Other substances, such as other (e.g., smaller) particles, are "glued" to its surface via specific interactions or "adhesives" in the broadest sense. These particles contain reporting properties. An example is the use of microparticles with nanoparticles glued to their surface. The adhesive can be a wax or a polymer that softens or melts at a certain temperature so that the adhesive is loosened and a small amount of adhesive is separated from a large number of particles. For example, if a large number of particles are enriched by centrifugation after flowing through a porous medium, they lack reporting properties. A particularly advantageous configuration of this variant is to use magnetic particles for glued-on particles or for central particles. For example, if the central particle is ferromagnetic and the glued-on particles are fluorescent, the central particle can be magnetically enriched after flowing through the medium. If they no longer show fluorescence, the adhesive bond between the central particle and the glued particles is broken on the way through the porous medium: the softening temperature of the glue is significantly exceeded. Thus, bonding and adhesion forces between particles can also be used, which depend on ionic strength, pH value, chemical and biochemical conditions or oxygen attack.

[0156] The following different variants can be used in particular for the cleavage of chemical groups and for selective debonding when subjected to certain conditions: (1) cleavage by light (ultraviolet, infrared, visible light), (2) cleavage by other electromagnetic radiation, such as microwaves, (3) cleavage by other radiation, in particular by radioactive radiation (selected to be used as a minimum dosimeter), (4) cleavage by exceeding or falling below a certain pH value, (5) cleavage by the action of water (“moisture-induced cleavage”) and (6) catalytic cleavage or photocatalytic cleavage (for example in the simultaneous presence of titanium dioxide particles and light).

[0157] The latter variant also shows an example of a further variant of the method, namely checking the possibility of the simultaneous presence of more than one property (property consistency check): the simultaneous presence of light and a photocatalyst, or in another example: the simultaneous presence of oxygen and a minimum temperature for an oxidation reaction.

[0158] Therefore, the method according to the invention is used for the quantification of rocks, rock formations and / or porous materials or layers made of such porous materials in the geological analysis of rocks, rock formations and / or porous materials or layers made of such porous materials, in hydrology, water exploration, mineral deposit exploration, mineral deposit monitoring, fracturing, geothermal energy, leak monitoring and also in the monitoring of chemical, biological and / or biotechnological reactors or in in vivo medical methods.

[0159] Technically, for example, the use of particle moisture sensors should play an important role. The detection of oil in rocks (changes in reported properties due to the presence of (trace amounts of) oil) is technically highly relevant. The same applies to the detection of heavy metals. Here, the porous medium can be, for example, soil around landfills or in the catchment area of ​​drinking water reservoirs.

[0160] Potential applications also lie in ensuring the sealing or location of leaks in landfills, hazardous waste landfills and other accumulation areas. If such tracer particles are introduced at certain locations in the stored cargo, it is possible to precisely determine where the leak occurred when such particles are found, for example, in groundwater or landfill drainage. This is also suitable for long-term monitoring of leaks from car washers, radioactively or chemically contaminated pipe systems or water tanks. Monitoring can be extremely cost-effective and at the same time continuous.

[0161] The method is suitable for non-destructive internal exploration of porous media and control of their properties (to ensure quality and properties during production) and for exploration of deposits of oil, natural gas, mineral resources, geothermal energy, porosity of rocks and inexpensive, non-destructive exploration of rock formations, such as in the field of tunnel construction, to name just a few examples.

[0162] However, the study of the parameters of the interior of rock formations and soil formations is a core issue, for example: geothermal energy, extraction of mineral resources and the study of their deposits, waterways in landfill areas, final deposition of toxic and radioactive waste or hydraulic fracturing. Hydraulic fracturing or short hydraulic fracturing (from the English "to break" to tear apart; German also hydraulic fracturing, hydraulic destruction, hydraulic fracture generation or hydraulic fracturing) is a method of creating, extending and stabilizing fractures in rocks of sediments at depth underground, with the aim of increasing the permeability of the sedimentary rocks. As a result, the gases or liquids contained therein can flow more easily and more reliably to the wellbore and be extracted. In an important application variant, a gaseous fluid is used to generate a gas flow, and particles and / or a mixture of particles are added to the gas flow. This is very relevant, for example, for the exploration of natural gas deposits and their application in flows through rocks.

[0163] The method according to the invention is also particularly suitable for use in chemical and biological / biotechnological reactors as well as water tanks, reservoirs and water pipe systems. In these applications, the interior of chemical and biological / biotechnological reactors as well as the interior of water tanks, reservoirs and water pipe systems should be understood as "porous media".

[0164] For example, as a special use, the check whether a maximum temperature is exceeded in a chemical reactor can be mentioned. This is of great interest, for example, in polymerization reactions, in which thermal decomposition products and carbon are formed when a certain temperature value is exceeded, which adversely affects the color of the resulting polymer - and also the electrical insulation properties. The method according to the invention can be used to determine whether and to what extent such a temperature overshoot occurs. The temperature value exceeded, as well as the degree of the overshoot, can be determined with tracer particles having corresponding threshold values ​​in the reporting function. Specifically, based on their reporting function, what percentage of particles experience an overshoot after leaving the reactor.

[0165] The examination can also be carried out by spectroscopy of the particles directly in the corresponding reaction product leaving the reactor or by subsequent extraction of the particles from the reaction product leaving the reactor, for example by ultracentrifugation, or by extracting ferromagnetic particles using a magnetic field.

[0166] Another possibility is to use the method according to the invention in medical in vivo methods. A fluid containing particles having a reference function and at least one reporter function is injected into the human or animal body, for example to perform diagnostic procedures on the blood, lymphatic system, urinary system, digestive tract, lungs and airways, nose and sinuses.

[0167] Therefore, the present invention also relates to a fluid for use in a medical in vivo method with at least one particle or a mixture of particles having a reference function and at least one reporter function for detecting a physical, chemical or biochemical parameter.

Claims

1. A method for quantifying a porous medium using at least one particle or a mixture of particles, wherein each of the particles has a reference function and at least one reporting function, wherein the at least one reporting function is used to record a physical, chemical or biochemical parameter of the porous medium, the method comprising the following steps: introducing the particles and / or the particle mixture into a fluid, causing a fluid having said particles and / or said mixture of particles to flow through and / or permeate said porous medium, wherein when a threshold value of a parameter to be recorded is exceeded or fallen below, at least one reporting function of said particles changes, while a reference function of said particles remains unchanged, and after leaving the porous medium, subjecting the particles and / or the particle mixture to at least one subsequent analysis of a physically, chemically or biochemically altered reporter function of the particles and of a reference function for identifying the particles, wherein the reference function of the particle is in the form of a fluorescent label, a luminescent label or a label for plasmonics, wherein the at least one reporter function is contained in the particle and / or on the particle surface, the at least one reporter function comprises at least one fluorescent label, luminescent label or label for plasmonics, and wherein the alteration of at least one reporter function is irreversible. The method according to claim 1 , wherein the diameter of the particles is from 100 μm to 0.5 nm. The method according to claim 1 , wherein the diameter of the particles is from 10 μm to 5 nm. The method according to claim 1 , wherein the diameter of the particles is 5 μm to 50 nm.

5. The method according to any one of claims 1 to 4, wherein the matrix of the particles consists of silver, gold, copper or other metals, silicon dioxide, polystyrene, olefins, wax or mixtures thereof.

6. The method according to any one of claims 1 to 4, wherein the change in the at least one reporter function increases continuously with the dose of radiation or oxidative stress experienced.

7. The method according to any one of claims 1 to 4, wherein the particles further have an additional functionality which allows the residence time of the particles in the porous medium to be determined based on time-dependent disintegration or time-dependent property changes.

8. The method according to any one of claims 1 to 4, wherein the particles further have an additional magnetic functionality.

9. The method according to any one of claims 1 to 4, wherein the particles have a further reporting function which changes when a threshold value of a second parameter to be recorded, different from the first parameter, is exceeded or fallen below.

10. The method according to any one of claims 1 to 4, wherein the porous medium is a liquid or gas filled space.

11. The method according to any one of claims 1 to 4, wherein the porous medium comprises a rock, a rock formation and / or a porous material or a layer made of the porous material.

12. The method according to any one of claims 1 to 4, wherein the analysis of the particles and / or the particle mixture is performed by optical spectroscopy, IR spectroscopy, plasmon resonance, microscopy, dosimetry, nuclear magnetic resonance, electron spin resonance, ENDOR, fluorescence spectroscopy, single molecule fluorescence spectroscopy, atomic fluorescence spectroscopy, luminescence spectroscopy, photoluminescence spectroscopy, chromatography, gas chromatography, liquid chromatography and / or high performance liquid chromatography HPLC, or with the aid of a subsequent reaction that facilitates the detection of a change in reporter function.

13. The method according to any one of claims 1 to 4, which is used to quantify rocks, rock formations and / or porous materials or layers of porous materials in geological analysis of rocks, rock formations and / or porous materials or layers of porous materials, in hydrology, water exploration, mineral deposit exploration, mineral deposit monitoring, fracturing, geothermal energy, leak monitoring, in monitoring of chemical, biological and / or biotechnical reactors, in monitoring of water tanks, reservoirs and water supply systems, or in medical in vivo methods.

14. A fluid having at least one particle or a mixture of particles for use in a medical in vivo method, wherein each of the particles has a reference function and at least one reporter function for recording a physical, chemical or biochemical parameter, wherein the reference function is used to identify the particle, wherein the reference function of the particle is in the form of a fluorescent label, a luminescent label or a label for plasmonics, wherein the at least one reporter function is contained in the particle and / or on the particle surface, the at least one reporter function comprises at least one fluorescent label, luminescent label or label for plasmonics, and wherein the alteration of at least one reporter function is irreversible.