Method and device for measuring physical parameters of unconsolidated sand

Abstract

The application provides a method and device for measuring physical parameters of loose sandstone, and the method for measuring physical parameters of loose sandstone comprises the following steps: scanning a pre-prepared loose sandstone core by using nuclear magnetic resonance T2 spectrum to obtain a first nuclear magnetic T2 spectrum; wherein, the loose sandstone core is covered with a protective film; after removing the protective film, the loose sandstone core is saturated by absorbing moisture, and is scanned by using nuclear magnetic resonance T2 spectrum to obtain a second nuclear magnetic T2 spectrum; the loose sandstone core after displacement is scanned by using nuclear magnetic resonance T2 spectrum to obtain a third nuclear magnetic T2 spectrum; and the physical parameters of the loose sandstone core are determined according to the nuclear magnetic T2 spectrum of each calibration core with different water contents, the first nuclear magnetic T2 spectrum, the second nuclear magnetic T2 spectrum and the third nuclear magnetic T2 spectrum. The application can non-destructively detect the physical parameters of loose sandstone, and can more accurately obtain the physical parameters of loose sandstone.

Description

Technical Field

[0001] This application belongs to the field of oil and gas field development technology, especially the field of core physical property measurement technology, and specifically relates to a method and device for measuring the physical property parameters of loose sandstone. Background Technology

[0002] Loose sandstone has a loose structure, and samples are easily dispersed. Laboratory experiments usually require standard core samples with a diameter of 25 mm and a length of 3.5-5 cm. Obtaining standard core samples from loose sandstone is relatively difficult, and the samples are easily damaged during sampling, transportation, and experiments. Therefore, conventional laboratory methods are currently insufficient for processing and measuring loose sandstone.

[0003] Current research is mostly targeted at core samples from different regions and with different lithologies. For example, measurement methods are used for shale and dense sandstone, but these methods are difficult to apply to loose sandstone. Summary of the Invention

[0004] One object of the present invention is to provide a method for measuring the physical properties of loose sandstone, which is to provide a method for non-destructive testing of the physical properties of loose sandstone and to obtain the physical properties of loose sandstone more accurately.

[0005] Another object of the present invention is to provide a measuring device for the physical properties of loose sandstone. A further object of the present invention is to provide an electronic device comprising a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the above-described method for measuring the physical properties of loose sandstone. A further object of the present invention is to provide a readable medium storing a computer program thereon, the computer program being executed by a processor to implement the steps of the above-described method for measuring the physical properties of loose sandstone.

[0006] To address the technical problems in the background section of this application, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for measuring the physical properties of loose sandstone, comprising:

[0008] The pre-prepared loose sandstone core was subjected to nuclear magnetic resonance T2 spectrum scanning to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core was covered with a protective film;

[0009] The loose sandstone core after the protective film was removed was saturated with moisture and subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a second nuclear magnetic resonance T2 spectrum.

[0010] The displaced loose sandstone core was subjected to nuclear magnetic resonance T2 spectrum scanning to obtain the third nuclear magnetic resonance T2 spectrum.

[0011] The physical properties of the loose sandstone core were determined based on the T2 NMR spectra of multiple calibration cores with different water contents, the first T2 NMR spectrum, the second T2 NMR spectrum, and the third T2 NMR spectrum.

[0012] In some embodiments of the present invention, the physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

[0013] In some embodiments of the present invention, determining the physical property parameters of the loose sandstone core based on the respective NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum includes:

[0014] The pore size distribution, gas saturation, and water saturation of the loose sandstone core are determined based on the NMR T2 spectra of the multiple calibration cores with different water contents and the first NMR T2 spectrum.

[0015] The porosity of the loose sandstone core was determined based on the T2 NMR spectra of the multiple calibration cores with different water contents and the second T2 NMR spectrum.

[0016] The dynamic fluid saturation and bound fluid saturation of the loose sandstone core are determined based on the NMR T2 spectra of the multiple calibration cores with different water contents, the second NMR T2 spectra, and the third NMR T2 spectra.

[0017] The T2 cutoff value of the porous sandstone core was determined based on the second nuclear magnetic resonance T2 spectrum;

[0018] The permeability of the loose sandstone core was determined based on its porosity, mobile fluid saturation, and bound fluid saturation.

[0019] In some embodiments of the present invention, the step of saturating the loose sandstone core after the protective film has been removed with moisture absorption includes:

[0020] The loose sandstone core after the protective film was removed was saturated with moisture for a first preset time, and then nuclear magnetic resonance T2 spectrum scan was performed to obtain a fourth nuclear magnetic resonance T2 spectrum.

[0021] Perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%:

[0022] The loose sandstone core, after being saturated with moisture, is subjected to moisture absorption and saturation again for a second preset time, and then subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a fifth nuclear magnetic resonance T2 spectrum; wherein, the first preset time is not less than the second preset time.

[0023] In some embodiments of the present invention, the step of displacing the loose sandstone core includes:

[0024] The porous sandstone core is encapsulated with non-magnetic polytetrafluoroethylene (PTFE) end caps and heat shrink tubing; wherein the PTFE end caps are provided with flow channels and through holes.

[0025] The encapsulated loose sandstone core was placed into a core holder and subjected to low-pressure gas drive.

[0026] Secondly, the present invention provides a measuring device for the physical properties of loose sandstone, the device comprising:

[0027] The first T2 spectrum acquisition module is used to perform nuclear magnetic resonance T2 spectrum scanning on a pre-prepared loose sandstone core to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film.

[0028] The second T2 spectrum acquisition module is used to saturate the loose sandstone core after the protective film has been removed with moisture and perform nuclear magnetic resonance T2 spectrum scanning to obtain the second nuclear magnetic resonance T2 spectrum.

[0029] The third T2 spectrum acquisition module is used to perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic resonance T2 spectrum.

[0030] The physical property parameter determination module is used to determine the physical property parameters of the loose sandstone core based on the respective NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0031] In some embodiments of the present invention, the physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

[0032] In some embodiments of the present invention, the physical property parameter determination module includes:

[0033] The first unit for determining physical property parameters is used to determine the pore size distribution, gas saturation and water saturation of the loose sandstone core based on the nuclear magnetic resonance T2 spectra of the multiple calibration cores with different water contents and the first nuclear magnetic resonance T2 spectra.

[0034] The second unit for determining physical property parameters is used to determine the porosity of the loose sandstone core based on the NMR T2 spectra of the multiple calibration cores with different water contents and the second NMR T2 spectra.

[0035] The third unit for determining physical property parameters is used to determine the dynamic fluid saturation and bound fluid saturation of the loose sandstone core based on the nuclear magnetic resonance T2 spectra of the multiple calibration cores with different water contents, the second nuclear magnetic resonance T2 spectra, and the third nuclear magnetic resonance T2 spectra.

[0036] The fourth unit for determining physical property parameters is used to determine the T2 cutoff value of the loose sandstone core based on the second nuclear magnetic resonance T2 spectrum;

[0037] The fifth unit for determining physical property parameters is used to determine the permeability of the loose sandstone core based on its porosity, mobile fluid saturation, and bound fluid saturation.

[0038] In some embodiments of the present invention, the second T2 spectrum acquisition module includes:

[0039] The fourth T2 spectrum acquisition unit is used to saturate the loose sandstone core after the protective film is removed with moisture for a first preset time, and perform nuclear magnetic resonance T2 spectrum scanning to obtain the fourth nuclear magnetic resonance T2 spectrum.

[0040] A cyclic operation unit is used to perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%:

[0041] The fifth NMR T2 spectrum acquisition unit is used to re-saturate the loose sandstone core after it has been saturated with moisture to a second preset time, and then perform NMR T2 spectrum scanning to obtain the fifth NMR T2 spectrum; wherein the first preset time is not less than the second preset time.

[0042] In some embodiments of the present invention, a measuring device for the physical properties of loose sandstone further includes:

[0043] A core displacement module is used to displace the loose sandstone core; the core displacement module includes:

[0044] A core encapsulation unit is used to encapsulate the loose sandstone core using a non-magnetic polytetrafluoroethylene (PTFE) end cap and a heat shrink tubing; wherein the PTFE end cap is provided with a flow guide groove and a through hole;

[0045] The core low-pressure gas drive unit is used to place the encapsulated loose sandstone core into the core holder and perform low-pressure gas drive.

[0046] Thirdly, the present invention provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of a method for measuring the physical properties of loose sandstone.

[0047] Fourthly, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of a method for measuring the physical properties of loose sandstone.

[0048] Fifthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for measuring the physical properties of loose sandstone.

[0049] As described above, embodiments of the present invention provide a method and apparatus for measuring the physical properties of loose sandstone. The method for measuring the physical properties of loose sandstone includes: firstly, performing nuclear magnetic resonance (NMR) T2 spectrum scanning on a pre-prepared loose sandstone core to obtain a first NMR T2 spectrum; wherein the loose sandstone core is covered with a protective film; next, saturating the loose sandstone core after removing the protective film with moisture absorption and performing NMR T2 spectrum scanning to obtain a second NMR T2 spectrum; performing NMR T2 spectrum scanning on the displaced loose sandstone core to obtain a third NMR T2 spectrum; finally, determining the physical properties of the loose sandstone core based on the respective NMR T2 spectra, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum of multiple calibration cores with different water contents.

[0050] This invention can obtain the physical properties of loose sandstone cores, including porosity, permeability, pore size distribution, T2 cutoff value, and saturation of movable / bound fluids. This invention uses low-field nuclear magnetic resonance technology that can perform non-destructive testing on samples. The samples do not need to be dried, and online moisture absorption saturation is used without damaging the core. A gas-driven method with PTFE end caps and heat shrink tubing is used to obtain the various physical properties of loose sandstone samples. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a flowchart illustrating the method for measuring the physical properties of loose sandstone in an embodiment of the present invention. Figure 1 ;

[0053] Figure 2This is a flowchart illustrating step 400 of the method for measuring the physical properties of loose sandstone in an embodiment of the present invention;

[0054] Figure 3 This is a flowchart illustrating step 200 of the method for measuring the physical properties of loose sandstone in an embodiment of the present invention;

[0055] Figure 4 This is a flowchart illustrating the method for measuring the physical properties of loose sandstone in an embodiment of the present invention. Figure 2 ;

[0056] Figure 5 This is a flowchart illustrating step 500 of the method for measuring the physical properties of loose sandstone in an embodiment of the present invention.

[0057] Figure 6 This is a flowchart illustrating the method for measuring the physical properties of loose sandstone in a specific embodiment of the present invention.

[0058] Figure 7 A mind map illustrating the method for measuring the physical properties of loose sandstone in a specific embodiment of the present invention;

[0059] Figure 8 This is a schematic diagram of the T2 spectrum of sample 2-1 in a specific embodiment of the present invention;

[0060] Figure 9 This is a schematic diagram of the T2 spectra of samples 2-4 in a specific embodiment of the present invention;

[0061] Figure 10 This is a schematic diagram of the T2 spectra of samples 2-8 in a specific embodiment of the present invention;

[0062] Figure 11 This is a schematic diagram of the nuclear magnetic resonance calibration results in a specific embodiment of the present invention;

[0063] Figure 12 In a specific embodiment of the present invention, sample pore radius distribution 2-1 Figure 1 ;

[0064] Figure 13 In a specific embodiment of the present invention, sample pore radius distribution 2-1 Figure 2 ;

[0065] Figure 14 This is a histogram of the pore radius distribution of sample 2-1 in a specific embodiment of the present invention;

[0066] Figure 15 This is a cumulative distribution diagram of the pore radius of sample 2-1 in a specific embodiment of the present invention;

[0067] Figure 16The pore radius distribution of samples 2-4 in the specific embodiments of the present invention Figure 1 ;

[0068] Figure 17 The pore radius distribution of samples 2-4 in the specific embodiments of the present invention Figure 2 ;

[0069] Figure 18 The following are histograms showing the pore radius distribution of samples 2-4 in a specific embodiment of the present invention;

[0070] Figure 19 This is a cumulative distribution diagram of the pore radius of samples 2-4 in a specific embodiment of the present invention;

[0071] Figure 20 The pore radius distribution of samples 2-8 in the specific embodiments of the present invention Figure 1 ;

[0072] Figure 21 The pore radius distribution of samples 2-8 in the specific embodiments of the present invention Figure 2 ;

[0073] Figure 22 The following is a histogram showing the pore radius distribution of samples 2-8 in a specific embodiment of the present invention;

[0074] Figure 23 This is a cumulative distribution diagram of the pore radius of samples 2-8 in a specific embodiment of the present invention;

[0075] Figure 24 This is a diagram showing the calculation of the T2 cutoff value for sample 2-1 in a specific embodiment of the present invention;

[0076] Figure 25 This is a graph showing the calculation of the T2 cutoff value for samples 2-4 in a specific embodiment of the present invention;

[0077] Figure 26 This is a graph showing the calculation of T2 cutoff values ​​for samples 2-8 in a specific embodiment of the present invention;

[0078] Figure 27 A cube representing the measuring device for the physical properties of loose sandstone in an embodiment of the present invention. Figure 1 ;

[0079] Figure 28 This is a block diagram of the physical property parameter determination module 40 in an embodiment of the present invention;

[0080] Figure 29 This is a block diagram of the second T2 spectrum acquisition module 20 in an embodiment of the present invention;

[0081] Figure 30 A cube representing the measuring device for the physical properties of loose sandstone in an embodiment of the present invention. Figure 2 ;

[0082] Figure 31 This is a block diagram of the core displacement module 50 in an embodiment of the present invention;

[0083] Figure 32 This is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. Detailed Implementation

[0084] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0085] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] It should be noted that the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Without conflict, the embodiments and features in the embodiments of this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0087] The acquisition, storage, use, and processing of data in this application comply with relevant laws and regulations.

[0088] Core physical property parameter measurement, including parameters such as porosity, permeability, and saturation, is of great significance for oil exploration and development. Obtaining these parameters can guide oil geological exploration in accurately determining the location of oil and gas reservoirs, providing more reasonable construction plans, and enabling a more accurate evaluation of local oil and gas reserves. Furthermore, the analysis of core physical property parameters is indispensable for formulating subsequent development plans, identifying target layers, and determining how to develop them. Core physical property parameters are key parameters that directly reflect oil and gas reservoirs and are a necessary process in oil and gas field exploration and development.

[0089] Loose sandstone cores refer to sandstone cores with low cementation, weak intergranular bonding, high porosity, and good permeability. They are characterized by low mechanical strength and susceptibility to breakage. They generally exhibit the following characteristics: High porosity: Porosity is typically above 20%, providing a large reservoir space. High permeability: High permeability facilitates fluid flow. Low mechanical strength: Poor cementation makes them susceptible to damage from external forces. Strong heterogeneity: Uneven pore structure and permeability distribution. Therefore, measuring the physical properties of loose sandstone cores presents the following technical challenges:

[0090] Core integrity: Cores are easily damaged during core collection and preservation, affecting experimental results.

[0091] Experimental difficulty: The loose sandstone core is fragile, and the experimental operation is complicated.

[0092] Heterogeneity: Heterogeneity leads to insufficient representativeness of experimental results.

[0093] For the reasons stated above, embodiments of the present invention provide a specific implementation method for measuring the physical properties of loose sandstone, see below. Figure 1 The specific methods for measuring the physical properties of loose sandstone include the following:

[0094] Step 100: Perform nuclear magnetic resonance T2 spectrum scanning on the pre-prepared loose sandstone core to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film;

[0095] Step 200: The loose sandstone core after the protective film has been removed is saturated with moisture and subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a second nuclear magnetic resonance T2 spectrum;

[0096] Step 300: Perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic resonance T2 spectrum;

[0097] Step 400: Determine the physical property parameters of the loose sandstone core based on the NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0098] As described above, the present invention provides a method for measuring the physical properties of loose sandstone, comprising: firstly, performing nuclear magnetic resonance T2 spectroscopy scanning on a pre-prepared loose sandstone core to obtain a first NMR T2 spectrum; wherein the loose sandstone core is covered with a protective film; nextly, saturating the loose sandstone core after removing the protective film with moisture absorption, and performing NMR T2 spectroscopy scanning to obtain a second NMR T2 spectrum; performing NMR T2 spectroscopy scanning on the displaced loose sandstone core to obtain a third NMR T2 spectrum; finally, determining the physical properties of the loose sandstone core based on the respective NMR T2 spectra, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum of multiple calibration cores with different water contents.

[0099] This invention can obtain the physical properties of loose sandstone cores, including porosity, permeability, pore size distribution, T2 cutoff value, and saturation of movable / bound fluids. This invention uses low-field nuclear magnetic resonance technology that can perform non-destructive testing on samples. The samples do not need to be dried, and online moisture absorption saturation is used without damaging the core. A gas-driven method with PTFE end caps and heat shrink tubing is used to obtain the various physical properties of loose sandstone samples.

[0100] For step 100, precisely because of the brittle nature of loose sandstone, nuclear magnetic resonance (NMR) T2 spectroscopy is used to measure its physical properties. Specifically, using NMR T2 spectroscopy to measure the physical properties of the rock core has the following advantages:

[0101] Beneficial effects:

[0102] Non-destructive testing: without damaging the sample structure.

[0103] High resolution: capable of distinguishing pores of different sizes.

[0104] Rapid measurement: Short experimental time and high efficiency.

[0105] Multifunctionality: It can simultaneously analyze pore structure and fluid distribution.

[0106] Nuclear magnetic resonance T2 spectroscopy is based on the nuclear magnetic resonance phenomenon and analyzes the properties of fluids in a sample by measuring the relaxation time of hydrogen nuclei (protons) in a magnetic field. The T2 relaxation time (transverse relaxation time) reflects the motion and interaction of fluid molecules in the pores.

[0107] T2 relaxation time: Fluid molecules are affected by the pore surface and the fluid interior in the pore. The smaller the T2 value, the higher the degree of restriction of molecular motion.

[0108] T2 spectrum: The T2 spectrum is obtained by measuring the signal intensity corresponding to different relaxation times, which reflects the distribution of pores of different sizes in the sample.

[0109] T2 NMR spectroscopy scanning uses a low-field NMR spectrometer, whose main components include:

[0110] Magnet: generates a uniform static magnetic field.

[0111] Radio frequency coil: transmits and receives radio frequency pulse signals.

[0112] Control system: controls experimental parameters (such as pulse sequence, echo time, etc.).

[0113] Data processing system: Analyzes the acquired signals and generates T2 spectra.

[0114] The general experimental steps include:

[0115] 1. Sample preparation: Clean, dry and saturate the core sample with fluid (such as water or oil).

[0116] 2. Place the sample: Place the sample in the measurement area of ​​the nuclear magnetic resonance spectrometer.

[0117] 3. Parameter settings: Set parameters such as echo time (TE), waiting time (TW), and echo number (NE).

[0118] 4. Signal Acquisition: Echo signals were acquired using the CPMG pulse sequence (Carr-Purcell-Meiboom-Gill).

[0119] 5. Data processing: Invert the acquired signal to obtain the T2 spectrum.

[0120] The horizontal axis of the T2 spectrum represents the relaxation time (T2 value), and the vertical axis represents the signal intensity. The peak value and distribution of the T2 spectrum reflect the distribution of pores of different sizes in the sample.

[0121] Short T2 value: corresponds to fluids confined to small pores or surfaces.

[0122] T2 value: corresponds to large pores or free fluid.

[0123] Peak area: reflects the contribution ratio of pores of different sizes.

[0124] For step 200, specifically, the loose sandstone core is placed on a permeable stone and put into a constant temperature and humidity chamber at room temperature and 98% humidity to achieve moisture absorption saturation.

[0125] For step 300, the displaced loose sandstone core can be directly placed in a test tube for nuclear magnetic resonance scanning to obtain the nuclear magnetic resonance T2 spectrum of the displaced sample, i.e., the third nuclear magnetic resonance T2 spectrum.

[0126] For the multiple calibration cores with different water contents in step 400, five standard samples with different water contents need to be selected for calibration to obtain a linear relationship between water content and nuclear magnetic resonance signal intensity, with a linearity requirement higher than 0.999. After calibration, nuclear magnetic resonance data processing is performed to obtain the required physical property parameters.

[0127] In some embodiments of the present invention, the physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

[0128] Gas saturation refers to the proportion of gas in the pore space of a rock core, usually expressed as the gas-saturated portion of porosity. It reflects the gas storage capacity of a rock formation and is crucial for the exploration and exploitation of gas reservoirs. A higher gas saturation indicates abundant gas resources within the rock formation.

[0129] Water saturation refers to the proportion of water phase in the pore space of a rock core. It represents the water content in the rock formation and directly affects the reservoir's production efficiency. For oil and gas reservoirs, lower water saturation usually means higher oil and gas production potential.

[0130] Porosity is the ratio of pore volume to total rock volume, usually expressed as a percentage. It determines a rock's ability to store fluids. Higher porosity means a rock has a greater liquid storage capacity.

[0131] Pore ​​size distribution describes the size, shape, and distribution of pores in a rock within the total porosity. It is crucial for understanding reservoir fluid permeability and flow characteristics. Small pores are often associated with low permeability, while large pores may provide better fluid flow pathways. By analyzing pore size distribution, reservoir properties and fluid behavior can be predicted.

[0132] Permeability is a measure of how easily fluids flow through rocks, representing the ability of fluids to permeate the rock's pore system. Permeability is a key parameter describing the fluid flow capacity of rock formations. High permeability generally indicates smooth fluid flow and a reservoir with good exploitation potential.

[0133] The T2 cutoff value refers to a specific value of the T2 relaxation time in nuclear magnetic resonance (NMR) experiments, and is commonly used to distinguish different types of pore water. Longer T2 times indicate larger pores and more free fluid, while shorter T2 times typically correspond to smaller pores and bound water. The magnitude of the T2 cutoff value helps differentiate the ratio of mobile to bound fluid.

[0134] Movable fluid saturation refers to the proportion of pore space in a rock core that is capable of flowing under a pressure gradient. It typically refers to recoverable fluids in oil and gas reservoirs, distinguishing between freely flowing fluids and bound fluids.

[0135] Bound fluid saturation refers to the proportion of pore space occupied by fluids (such as water) that are bound within the micropores of a rock core. These fluids are typically difficult to flow and are commonly found in the micropores of reservoirs. Bound fluid saturation reflects fluids in the formation that cannot be effectively extracted, usually water that has been adsorbed or physically bound in the reservoir. The presence of bound water can limit the actual production of the reservoir.

[0136] In some embodiments of the present invention, see Figure 2 Step 400 includes:

[0137] Step 401: Determine the pore size distribution, gas saturation, and water saturation of the loose sandstone core based on the NMR T2 spectra of the multiple calibration cores with different water contents and the first NMR T2 spectrum.

[0138] First, the calibration line was determined based on the T2 NMR spectra of multiple calibration cores with different water contents:

[0139] Y = KX + B, where Y is the NMR signal quantity au; K is the slope of the calibrated line; X is the fluid quantity, g; and B is the intercept of the calibrated line.

[0140] Aperture distribution:

[0141] Lateral relaxation time of hydrogen nuclei in the pores of loose sandstone core:

[0142]

[0143] In the formula, T2 is the transverse relaxation time, in milliseconds; T 2B ρ is the volumetric (free) relaxation time of the fluid, ms; D is the diffusion coefficient, μm² / ms; G is the magnetic field gradient, gauss / cm; T E ρ is the echo interval, in milliseconds (ms); S is the surface area of ​​the pores; V is the volume of the pores; ρ is the transverse surface relaxation intensity of the rock, in μm / ms. γ is the gyromagnetic ratio, which is the ratio between the magnetic moment and angular momentum of the spin nuclear.

[0144] T 2B The value is in the 2-3s range, which is much larger than T2, i.e., T... 2B >>T2, therefore 1 / T in the formula 2B It can be ignored; when the magnetic field is very uniform (corresponding to a very small G), and T E When the value is sufficiently small, the third term on the right-hand side of the equation can also be ignored, therefore:

[0145]

[0146] The relationship between T2 and aperture rc is obtained as follows:

[0147]

[0148] In the formula: Fs is called the geometric shape factor, and for spherical pores, Fs = 3;

[0149] Right now:

[0150] r c =ρ2×T2×3,

[0151] For the loose sandstone sample, ρ2 = 50 μm / s.

[0152] Step 402: Determine the porosity of the loose sandstone core based on the NMR T2 spectra of the multiple calibration cores with different water contents and the second NMR T2 spectrum;

[0153] First, determine the pore volume of the loose sandstone core:

[0154] Pore ​​volume V1=(A1-B) / K;

[0155] In the above formula, A1: peak area of ​​the T2 NMR spectrum of the hygroscopic sample (au). V1: pore volume (cm³). 3 .

[0156] Next, the porosity of the loose sandstone core was calculated:

[0157] Porosity Φ = V1 / V0 * 100, where V0 is the sample volume in cm³. 3 .

[0158] Fluid saturation:

[0159] Movable fluid saturation FFI = (A1-A2) / A1*100, where A2 is the peak area of ​​the T2 NMR spectrum of the displaced sample.

[0160] Bound fluid saturation BVI-100-FFI;

[0161] Gas saturation Sg = (A1 - A3) / A1 * 100, where A3 is the peak area of ​​the T2 NMR spectrum of the fresh sample.

[0162] Water saturation Sw = 100 - Sg.

[0163] Step 403: Determine the dynamic fluid saturation and bound fluid saturation of the loose sandstone core based on the NMR T2 spectra of the multiple calibration cores with different water contents, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0164] It is understandable that fluid saturation includes both movable fluid saturation and bound fluid saturation:

[0165] Movable fluid saturation FFI = (A1-A2) / A1*100, where A2 is the peak area of ​​the T2 NMR spectrum of the displaced sample.

[0166] Bound fluid saturation BVI-100-FFI;

[0167] Gas saturation Sg = (A1 - A3) / A1 * 100, where A3 is the peak area of ​​the fresh sample's NMR T2 spectrum.

[0168] Water saturation Sw = 100 - Sg.

[0169] Step 404: Determine the T2 cutoff value of the porous sandstone core based on the second NMR T2 spectrum;

[0170] Specifically, on the saturated T2 spectrum curve, starting from the first relaxation time point, the signal is accumulated. When the accumulated result is greater than or equal to the peak area of ​​the NMR T2 spectrum of the displaced sample, the corresponding relaxation time point is the T2 cutoff value, in ms.

[0171] Step 405: Determine the permeability of the loose sandstone core based on its porosity, mobile fluid saturation, and bound fluid saturation.

[0172] Specifically, the permeability is calculated using the porosity Φ and the saturation of movable and bound fluids, based on the hygroscopic saturated core sample. The model parameter Cn1 is set to 50.

[0173]

[0174] In the formula: K: permeability, in millidarcy mD; Cn1: model parameters, obtained by statistical analysis of laboratory measurement data of rock samples from the corresponding region.

[0175] In some embodiments of the present invention, see Figure 3 Step 200, which involves saturating the loose sandstone core after the protective film has been removed, includes:

[0176] Step 201: After removing the protective film, the loose sandstone core is saturated with moisture for a first preset time, and nuclear magnetic resonance T2 spectrum scan is performed to obtain the fourth nuclear magnetic resonance T2 spectrum;

[0177] Step 202: Perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%:

[0178] Step 203: After the loose sandstone core has been saturated with moisture, it is saturated with moisture again for a second preset time, and nuclear magnetic resonance T2 spectrum is scanned to obtain a fifth nuclear magnetic resonance T2 spectrum; wherein, the first preset time is not less than the second preset time.

[0179] In steps 201 to 203, the loose sandstone core is saturated with moisture for 24 hours. The sample is then removed, covered with raw material tape (protective film), and subjected to nuclear magnetic resonance T2 spectrum scanning. After scanning, the sample continues to absorb moisture for 2 hours, and nuclear magnetic resonance T2 spectrum scanning is performed again. If the peak area deviation between the two T2 spectrum scans is <1%, the sample is considered to have completed moisture saturation; otherwise, the loose sandstone core is further subjected to moisture absorption for 2 hours, and nuclear magnetic resonance T2 spectrum scanning is performed again, until the peak area deviation between the two T2 spectrum scans is <1%.

[0180] In some embodiments of the present invention, see Figure 4 A method for measuring the physical properties of loose sandstone, further comprising:

[0181] Step 500: Displace the loose sandstone core; then, see... Figure 5 Step 500 includes:

[0182] Step 501: Encapsulate the loose sandstone core with a non-magnetic PTFE end cap and heat shrink tubing; wherein the PTFE end cap is provided with a flow guide groove and a through hole;

[0183] The loose sandstone core is protected using non-magnetic special PTFE end caps and heat shrink tubing. The end caps are designed with flow channels and through holes.

[0184] Step 502: Place the encapsulated loose sandstone core into the core holder and perform low-pressure gas drive.

[0185] Place the loose sandstone core into the core holder and perform low-pressure gas driving. The pressure setting is 0.1-0.5 MPa, and the specific pressure setting value is selected according to the core condition.

[0186] As described above, the present invention provides a method for measuring the physical properties of loose sandstone, comprising: firstly, performing nuclear magnetic resonance T2 spectroscopy scanning on a pre-prepared loose sandstone core to obtain a first NMR T2 spectrum; wherein the loose sandstone core is covered with a protective film; nextly, saturating the loose sandstone core after removing the protective film with moisture absorption, and performing NMR T2 spectroscopy scanning to obtain a second NMR T2 spectrum; performing NMR T2 spectroscopy scanning on the displaced loose sandstone core to obtain a third NMR T2 spectrum; finally, determining the physical properties of the loose sandstone core based on the respective NMR T2 spectra, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum of multiple calibration cores with different water contents.

[0187] This invention can obtain the physical properties of loose sandstone cores, including porosity, permeability, pore size distribution, T2 cutoff value, and saturation of movable / bound fluids. This invention uses low-field nuclear magnetic resonance technology that can perform non-destructive testing on samples. The samples do not need to be dried, and online moisture absorption saturation is used without damaging the core. A gas-driven method with PTFE end caps and heat shrink tubing is used to obtain the various physical properties of loose sandstone samples.

[0188] To further illustrate the solution, in one specific embodiment, the present invention also provides a specific implementation of a method for measuring the physical properties of loose sandstone, which specifically includes the following:

[0189] First, let's introduce the equipment used in this invention:

[0190] 1. Low-field nuclear magnetic resonance equipment.

[0191] The equipment frequency is higher than 12MHz, the shortest echo time is no more than 0.15ms, the number of echoes is no less than 10,000, and the cumulative count is no less than 16 times.

[0192] 2. Wire cutting equipment.

[0193] CNC wire cutting equipment uses diamond wire for cutting and can automatically cut and extract standard rock core samples.

[0194] 3. 0.001 g electronic analytical balance.

[0195] 4. Constant temperature and humidity chamber.

[0196] Used for sample moisture saturation, with a temperature control range of 5-30℃ and a humidity control range of 30%-99%.

[0197] 5. Core holder.

[0198] A 25mm standard core holder for core gas drive experiments, equipped with a nitrogen cylinder and pressure regulating valve.

[0199] 6. Core protection end caps

[0200] The core end cap has a diameter of 25mm and a thickness of 2mm, and is designed with a flow channel and a fluid passage.

[0201] 7. Nuclear magnetic resonance standard.

[0202] Low-field nuclear magnetic resonance standards with water contents of 0.1g, 0.2g, 0.4g, 0.6g, and 0.8g.

[0203] See Figure 6 as well as Figure 7 The specific implementation method of the method for measuring the physical properties of loose sandstone provided by the present invention includes the following steps:

[0204] S1: Preparation of loose sandstone core.

[0205] The loose sandstone core was cut into standard cores using wire cutting, and the cores were protected with raw material tape.

[0206] S2: Measure the T2 NMR spectrum of a fresh sample.

[0207] The prepared loose sandstone core sample, with the raw material tape on the outside not needing to be removed, is placed in an NMR test tube and then placed in the NMR sample chamber for NMR T2 spectrum scanning.

[0208] S3: Core saturated with moisture.

[0209] Remove the raw material from the core, place the core on permeable stone, and put it in a constant temperature and humidity chamber at room temperature and 98% humidity to allow it to absorb moisture to saturation.

[0210] S4: Measure the T2 NMR spectrum of a hygroscopically saturated sample.

[0211] After the sample is saturated with moisture for 24 hours, it is taken out, covered with raw material tape, and subjected to nuclear magnetic resonance T2 spectrum scanning. After scanning, the sample continues to absorb moisture for 2 hours, and nuclear magnetic resonance T2 spectrum scanning is performed again. The peak area deviation of the T2 spectrum between the two scans is <1%, and the sample is saturated with moisture.

[0212] S5: Use end caps and heat shrink tubing to protect the loose sandstone core.

[0213] The loose sandstone core is protected using non-magnetic special PTFE end caps and heat shrink tubing. The end caps are designed with flow channels and through holes.

[0214] S6: Conduct a gas-driven water experiment.

[0215] Place the loose sandstone core into the core holder and perform low-pressure gas drive. The pressure is set to 0.1-0.5 MPa, depending on the condition of the core.

[0216] S7: Measure the nuclear magnetic resonance T2 spectrum of the displacement sample.

[0217] After displacement, the core sample can be directly placed in a test tube for nuclear magnetic resonance scanning to obtain the nuclear magnetic resonance T2 spectrum of the displacement sample.

[0218] S8: Determine NMR calibration.

[0219] Nuclear magnetic resonance (NMR) calibration was performed using five standard samples with different water contents. The linear relationship between water content and NMR signal intensity was obtained, with a linearity requirement higher than 0.999. Following calibration, NMR data processing was performed to obtain the desired physical property parameters.

[0220] Measurement results of physical properties of loose sandstone: The method of this invention was applied to loose sandstone core samples from an oilfield. Specific information is as follows:

[0221] A total of 3 standard core samples of loose sandstone were tested. The experimental procedures were as follows:

[0222] 1. Measurement of T2 NMR spectra of fresh samples ( Figure 8 , Figure 9 , Figure 10 ).

[0223] The prepared loose sandstone core sample, with the raw material tape on the outside not needing to be removed, is placed in an NMR test tube and then placed in the NMR sample chamber for NMR T2 spectrum scanning.

[0224] 2. Core saturated with moisture.

[0225] Remove the raw material from the core, place the core on permeable stone, and put it in a constant temperature and humidity chamber at room temperature and 98% humidity to allow it to absorb moisture to saturation.

[0226] 3. Measurement of T2 NMR spectrum of hygroscopically saturated samples ( Figure 8 , Figure 9 , Figure 10 ).

[0227] After the sample is saturated with moisture for 24 hours, it is taken out, covered with raw material tape, and subjected to nuclear magnetic resonance T2 spectrum scanning. After scanning, the sample continues to absorb moisture for 2 hours, and nuclear magnetic resonance T2 spectrum scanning is performed again. The peak area deviation of the T2 spectrum between the two scans is <1%, and the sample is saturated with moisture.

[0228] 4. End caps and heat shrink tubing protection.

[0229] The samples were protected using non-magnetic PTFE end caps and heat shrink tubing. The end caps were designed with flow channels and through holes.

[0230] 5. Gas-driven water experiment.

[0231] Place the sample into the core holder and perform low-pressure gas driving. The pressure is set to 0.1-0.5 MPa, depending on the core condition.

[0232] 6. T2 spectral measurement of displacement sample nuclear magnetic resonance (NMR) Figure 8 , Figure 9 , Figure 10 ).

[0233] After displacement, the core sample can be directly placed in a test tube for nuclear magnetic resonance scanning to obtain the nuclear magnetic resonance T2 spectrum of the displacement sample.

[0234] 7. Nuclear magnetic resonance calibration (NMR) Figure 11 ).

[0235] Nuclear magnetic resonance (NMR) calibration was performed using five standard samples with different water contents. The linear relationship between water content and NMR signal intensity was obtained, with a linearity requirement higher than 0.999. Following calibration, NMR data processing was performed to obtain the desired physical properties (pore size distribution diagram is shown below). Figures 12 to 23 See the T2 cutoff value chart. Figure 24 , Figure 25 as well as Figure 26 The calculated physical properties are shown in Table 1.

[0236] Table 1

[0237]

[0238] As described above, the specific embodiments of the present invention provide a method for measuring the physical properties of loose sandstone, comprising: firstly, performing nuclear magnetic resonance T2 spectroscopy scanning on a pre-prepared loose sandstone core to obtain a first NMR T2 spectrum; wherein the loose sandstone core is covered with a protective film; nextly, saturating the loose sandstone core after removing the protective film with moisture absorption, and performing NMR T2 spectroscopy scanning to obtain a second NMR T2 spectrum; performing NMR T2 spectroscopy scanning on the displaced loose sandstone core to obtain a third NMR T2 spectrum; finally, determining the physical properties of the loose sandstone core based on the respective NMR T2 spectra, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum of multiple calibration cores with different water contents.

[0239] This invention can obtain the physical properties of loose sandstone cores, including porosity, permeability, pore size distribution, T2 cutoff value, and saturation of movable / bound fluids. This invention uses low-field nuclear magnetic resonance technology that can perform non-destructive testing on samples. The samples do not need to be dried, and online moisture absorption saturation is used without damaging the core. A gas-driven method with PTFE end caps and heat shrink tubing is used to obtain the various physical properties of loose sandstone samples.

[0240] Based on the same inventive concept, this application also provides a measuring device for the physical properties of loose sandstone, which can be used to implement the method described in the above embodiments, as shown in the following embodiments. Since the principle of the measuring device for the physical properties of loose sandstone is similar to that of the method for measuring the physical properties of loose sandstone, the implementation of the measuring device for the physical properties of loose sandstone can refer to the implementation of the method for measuring the physical properties of loose sandstone, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0241] This invention provides a specific embodiment of a device for measuring the physical properties of loose sandstone, capable of implementing a method for measuring the physical properties of loose sandstone. See also... Figure 27 A device for measuring the physical properties of loose sandstone includes:

[0242] The first T2 spectrum acquisition module 10 is used to perform nuclear magnetic resonance T2 spectrum scanning on a pre-prepared loose sandstone core to obtain a first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film.

[0243] The second T2 spectrum acquisition module 20 is used to saturate the loose sandstone core after the protective film is removed with moisture and perform nuclear magnetic resonance T2 spectrum scanning to obtain the second nuclear magnetic resonance T2 spectrum.

[0244] The third T2 spectrum acquisition module 30 is used to perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic T2 spectrum.

[0245] The physical property parameter determination module 40 is used to determine the physical property parameters of the loose sandstone core based on the NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0246] In some embodiments of the present invention, the physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

[0247] In some embodiments of the present invention, see Figure 28 The physical property parameter determination module 40 includes:

[0248] The first unit 40a for determining physical property parameters is used to determine the pore size distribution, gas saturation and water saturation of the loose sandstone core based on the nuclear magnetic resonance T2 spectra of the multiple calibration cores with different water contents and the first nuclear magnetic resonance T2 spectra.

[0249] The second unit 40b for determining physical property parameters is used to determine the porosity of the loose sandstone core based on the nuclear magnetic T2 spectra of the multiple calibration cores with different water contents and the second nuclear magnetic T2 spectra.

[0250] The third unit 40c for determining physical property parameters is used to determine the dynamic fluid saturation and bound fluid saturation of the loose sandstone core based on the nuclear magnetic T2 spectra of the multiple calibration cores with different water contents, the second nuclear magnetic T2 spectra, and the third nuclear magnetic T2 spectra.

[0251] The fourth unit, 40d, is used to determine the T2 cutoff value of the loose sandstone core based on the second nuclear magnetic resonance T2 spectrum.

[0252] The fifth unit 40e, which determines physical property parameters, is used to determine the permeability of the loose sandstone core based on its porosity, mobile fluid saturation, and bound fluid saturation.

[0253] In some embodiments of the present invention, see Figure 29 The second T2 spectrum acquisition module 20 includes:

[0254] The fourth T2 spectrum acquisition unit 20a is used to saturate the loose sandstone core after the protective film is removed with moisture to a first preset time, and perform nuclear magnetic resonance T2 spectrum scanning to obtain the fourth nuclear magnetic resonance T2 spectrum.

[0255] The cyclic operation unit 20b is used to perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%:

[0256] The fifth nuclear magnetic resonance T2 spectrum acquisition unit 20c is used to re-saturate the loose sandstone core after it has been saturated with moisture to a second preset time, and to perform nuclear magnetic resonance T2 spectrum scanning to obtain the fifth nuclear magnetic resonance T2 spectrum; wherein, the first preset time is not less than the second preset time.

[0257] In some embodiments of the present invention, see Figure 30 A device for measuring the physical properties of loose sandstone, further comprising:

[0258] Core displacement module 50 is used to displace the loose sandstone core; see also Figure 31 The core displacement module 50 includes:

[0259] The core encapsulation unit 50a is used to encapsulate the loose sandstone core through a non-magnetic polytetrafluoroethylene end cap and a heat shrink tubing; wherein the polytetrafluoroethylene end cap is provided with a flow guide groove and a through hole;

[0260] The core low-pressure gas drive unit 50b is used to place the encapsulated loose sandstone core into the core holder and perform low-pressure gas drive.

[0261] As described above, embodiments of the present invention provide a measuring device for the physical properties of loose sandstone, comprising: a first T2 spectrum acquisition module, used to perform nuclear magnetic resonance T2 spectrum scanning on a pre-prepared loose sandstone core to obtain a first NMR T2 spectrum; wherein the loose sandstone core is covered with a protective film; a second T2 spectrum acquisition module, used to perform moisture saturation on the loose sandstone core after removing the protective film and then perform NMR T2 spectrum scanning to obtain a second NMR T2 spectrum; a third T2 spectrum acquisition module, used to perform NMR T2 spectrum scanning on the displaced loose sandstone core to obtain a third NMR T2 spectrum; and a physical property parameter determination module, used to determine the physical property parameters of the loose sandstone core based on the respective NMR T2 spectra, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum of multiple calibration cores with different water contents.

[0262] This invention can obtain the physical properties of loose sandstone cores, including porosity, permeability, pore size distribution, T2 cutoff value, and saturation of movable / bound fluids. This invention uses low-field nuclear magnetic resonance technology that can perform non-destructive testing on samples. The samples do not need to be dried, and online moisture absorption saturation is used without damaging the core. A gas-driven method with PTFE end caps and heat shrink tubing is used to obtain the various physical properties of loose sandstone samples.

[0263] This application also provides a specific implementation of an electronic device capable of performing all steps in the method for measuring the physical properties of loose sandstone described in the above embodiments. See [link to implementation details]. Figure 32 The electronic devices specifically include the following:

[0264] Processor 1201, memory 1202, communications interface 1203, and bus 1204;

[0265] The processor 1201, memory 1202, and communication interface 1203 communicate with each other via bus 1204; the communication interface 1203 is used to realize information transmission between server-side devices and client-side devices and other related devices.

[0266] The processor 1201 is used to call the computer program in the memory 1202. When the processor executes the computer program, it implements all the steps in the method for measuring the physical properties of loose sandstone in the above embodiment. For example, when the processor executes the computer program, it implements the following steps:

[0267] Step 100: Perform nuclear magnetic resonance T2 spectrum scanning on the pre-prepared loose sandstone core to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film;

[0268] Step 200: The loose sandstone core after the protective film has been removed is saturated with moisture and subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a second nuclear magnetic resonance T2 spectrum;

[0269] Step 300: Perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic resonance T2 spectrum;

[0270] Step 400: Determine the physical property parameters of the loose sandstone core based on the NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0271] Embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the method for measuring the physical properties of loose sandstone in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the method for measuring the physical properties of loose sandstone in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0272] Step 100: Perform nuclear magnetic resonance T2 spectrum scanning on the pre-prepared loose sandstone core to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film;

[0273] Step 200: The loose sandstone core after the protective film has been removed is saturated with moisture and subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a second nuclear magnetic resonance T2 spectrum;

[0274] Step 300: Perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic resonance T2 spectrum;

[0275] Step 400: Determine the physical property parameters of the loose sandstone core based on the NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

[0276] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, hardware + program embodiments are relatively simple in description because they are fundamentally similar to method embodiments; relevant parts can be referred to the descriptions in the method embodiments.

[0277] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0278] While this application provides method operation steps as shown in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or client product execution, the method can be executed sequentially as shown in the embodiments or drawings, or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0279] For ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing the embodiments of this specification, the functions of each module can be implemented in one or more software and / or hardware components, or a module that performs the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.

[0280] Those skilled in the art will also know that, besides implementing the controller using purely computer-readable program code, the same functions can be achieved by logically programming the method steps, making the controller function as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers (PLCs), and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the devices within it used to implement various functions can also be considered structures within that hardware component. Alternatively, the devices used to implement various functions can be considered as both software modules implementing the method and structures within a hardware component.

[0281] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0282] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0283] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, system embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0284] The above description is merely an embodiment of the present specification and is not intended to limit the embodiments of the present specification. For those skilled in the art, various modifications and variations can be made to the embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the embodiments of the present specification should be included within the scope of the claims of the embodiments of the present specification.

Claims

1. A method for measuring the physical properties of loose sandstone, characterized in that, include: The pre-prepared loose sandstone core was subjected to nuclear magnetic resonance T2 spectrum scanning to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core was covered with a protective film; The loose sandstone core after the protective film was removed was saturated with moisture and subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a second nuclear magnetic resonance T2 spectrum. The displaced loose sandstone core was subjected to nuclear magnetic resonance T2 spectrum scanning to obtain the third nuclear magnetic resonance T2 spectrum. The physical properties of the loose sandstone core were determined based on the T2 NMR spectra of multiple calibration cores with different water contents, the first T2 NMR spectrum, the second T2 NMR spectrum, and the third T2 NMR spectrum.

2. The measurement method according to claim 1, characterized in that, The physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

3. The measurement method according to claim 2, characterized in that, The determination of the physical properties of the loose sandstone core based on the NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum includes: The pore size distribution, gas saturation, and water saturation of the loose sandstone core are determined based on the NMR T2 spectra of the multiple calibration cores with different water contents and the first NMR T2 spectrum. The porosity of the loose sandstone core was determined based on the T2 NMR spectra of the multiple calibration cores with different water contents and the second T2 NMR spectrum. The dynamic fluid saturation and bound fluid saturation of the loose sandstone core are determined based on the NMR T2 spectra of the multiple calibration cores with different water contents, the second NMR T2 spectra, and the third NMR T2 spectra. The T2 cutoff value of the porous sandstone core was determined based on the second nuclear magnetic resonance T2 spectrum; The permeability of the loose sandstone core was determined based on its porosity, mobile fluid saturation, and bound fluid saturation.

4. The measurement method according to claim 1, characterized in that, The process of saturating the loose sandstone core after the protective film has been removed with moisture absorption includes: The loose sandstone core after the protective film was removed was saturated with moisture for a first preset time, and then nuclear magnetic resonance T2 spectrum scan was performed to obtain a fourth nuclear magnetic resonance T2 spectrum. Perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%: The loose sandstone core, after being saturated with moisture, is subjected to moisture absorption and saturation again for a second preset time, and then subjected to nuclear magnetic resonance T2 spectrum scanning to obtain a fifth nuclear magnetic resonance T2 spectrum; wherein, the first preset time is not less than the second preset time.

5. The measurement method according to claim 1, characterized in that, The steps for displacing the loose sandstone core include: The porous sandstone core is encapsulated with non-magnetic polytetrafluoroethylene (PTFE) end caps and heat shrink tubing; wherein the PTFE end caps are provided with flow channels and through holes. The encapsulated loose sandstone core was placed into a core holder and subjected to low-pressure gas drive.

6. A measuring device for physical properties of loose sandstone, characterized in that, include: The first T2 spectrum acquisition module is used to perform nuclear magnetic resonance T2 spectrum scanning on a pre-prepared loose sandstone core to obtain the first nuclear magnetic resonance T2 spectrum; wherein, the loose sandstone core is covered with a protective film. The second T2 spectrum acquisition module is used to saturate the loose sandstone core after the protective film has been removed with moisture and perform nuclear magnetic resonance T2 spectrum scanning to obtain the second nuclear magnetic resonance T2 spectrum. The third T2 spectrum acquisition module is used to perform nuclear magnetic resonance T2 spectrum scanning on the displaced loose sandstone core to obtain the third nuclear magnetic resonance T2 spectrum. The physical property parameter determination module is used to determine the physical property parameters of the loose sandstone core based on the respective NMR T2 spectra of multiple calibration cores with different water contents, the first NMR T2 spectrum, the second NMR T2 spectrum, and the third NMR T2 spectrum.

7. The measuring device according to claim 6, characterized in that, The physical properties include: gas saturation, water saturation, porosity, pore size distribution, permeability, T2 cutoff value, mobile fluid saturation, and bound fluid saturation.

8. The measuring device according to claim 7, characterized in that, The physical property parameter determination module includes: The first unit for determining physical property parameters is used to determine the pore size distribution, gas saturation and water saturation of the loose sandstone core based on the nuclear magnetic resonance T2 spectra of the multiple calibration cores with different water contents and the first nuclear magnetic resonance T2 spectra. The second unit for determining physical property parameters is used to determine the porosity of the loose sandstone core based on the NMR T2 spectra of the multiple calibration cores with different water contents and the second NMR T2 spectra. The third unit for determining physical property parameters is used to determine the dynamic fluid saturation and bound fluid saturation of the loose sandstone core based on the nuclear magnetic resonance T2 spectra of the multiple calibration cores with different water contents, the second nuclear magnetic resonance T2 spectra, and the third nuclear magnetic resonance T2 spectra. The fourth unit for determining physical property parameters is used to determine the T2 cutoff value of the loose sandstone core based on the second nuclear magnetic resonance T2 spectrum; The fifth unit for determining physical property parameters is used to determine the permeability of the loose sandstone core based on its porosity, mobile fluid saturation, and bound fluid saturation.

9. The measuring device according to claim 6, characterized in that, The second T2 spectrum acquisition module includes: The fourth T2 spectrum acquisition unit is used to saturate the loose sandstone core after the protective film is removed with moisture for a first preset time, and perform nuclear magnetic resonance T2 spectrum scanning to obtain the fourth nuclear magnetic resonance T2 spectrum. A cyclic operation unit is used to perform the following cyclic operation until the peak area deviation between the fourth NMR T2 spectrum and the current fifth NMR T2 spectrum of the loose sandstone core is <1%: The fifth NMR T2 spectrum acquisition unit is used to re-saturate the loose sandstone core after it has been saturated with moisture to a second preset time, and then perform NMR T2 spectrum scanning to obtain the fifth NMR T2 spectrum; wherein the first preset time is not less than the second preset time.

10. The measuring device according to claim 6, characterized in that, Also includes: The core displacement module is used to displace the loose sandstone core. The core displacement module includes: A core encapsulation unit is used to encapsulate the loose sandstone core using a non-magnetic polytetrafluoroethylene (PTFE) end cap and a heat shrink tubing; wherein the PTFE end cap is provided with a flow guide groove and a through hole; The core low-pressure gas drive unit is used to place the encapsulated loose sandstone core into the core holder and perform low-pressure gas drive.

11. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the method for measuring the physical properties of loose sandstone as described in any one of claims 1 to 5.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for measuring the physical properties of loose sandstone as described in any one of claims 1 to 5.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method for measuring the physical properties of loose sandstone as described in any one of claims 1 to 5.

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