Method for testing the boundary between the laminated shale matrix seepage zone and the liquid supply zone

Abstract

This invention provides a method for testing the boundary between the seepage zone and the fluid supply zone of a laminated shale matrix, comprising: Step 1, selecting a laminated shale sample and measuring its air permeability; Step 2, saturating the shale sample with a fluid under high pressure to obtain the shale pore volume and porosity; Step 3, calculating the shale pore volume V. p Step 4: Perform nuclear magnetic resonance (NMR) experiments on the saturated shale sample to obtain the T2 spectrum and thus the shale pore structure. Step 5: Calculate the permeability of each pore and accumulate them to obtain the total permeability of the shale matrix. Step 6: Determine the boundary between the matrix permeation zone and the matrix fluid supply zone, and calculate the pore volume and porosity corresponding to the matrix permeation zone. This method for testing the boundary between the permeation zone and the fluid supply zone of the layered shale matrix can quantitatively characterize the pores that play a role in permeation, providing effective technical support for shale oilfield permeability calculation, permeation mechanism understanding, and production capacity prediction.

Description

Technical Field

[0001] This invention relates to the field of shale oil exploration and development technology, and in particular to a method for testing the boundary between the seepage zone and the fluid supply zone of a layered shale matrix. Background Technology

[0002] Laminated shale exhibits diverse reservoir spaces, featuring various pore types, bedding fractures, and tectonic fractures. A key characteristic distinguishing laminated shale from tight sandstone is the presence of numerous nanopores and micron-sized microfractures within the matrix. The simultaneous existence of these two large reservoir space types in the matrix results in two zones during seepage: the matrix seepage zone and the matrix fluid supply zone. The matrix seepage zone, supplying fluid, determines the seepage capacity of the shale matrix, while the matrix fluid supply zone provides fluid to the matrix seepage zone, forming the flow pattern of the shale oil matrix. Accurately defining the boundaries between the matrix seepage zone and the matrix fluid supply zone in laminated shale, quantitatively characterizing the pore volume of the matrix seepage zone, and clarifying which factors control flow and supply fluid to matrix microfractures during shale oil matrix flow are crucial for optimizing shale oil production rates, development methods, and production capacity prediction.

[0003] Chinese patent application 201710702054.6 discloses a multi-field coupled seepage multifunctional experimental device, comprising a device body, a stress field control system, a temperature field control system, a fluid loading control system, and a fluid seepage measurement system. It also discloses the use of a multi-field coupled state of temperature field, stress field, pore pressure field, and seepage field to conduct seepage experiments on tight gas, shale gas, tight oil, shale oil, natural gas hydrate, and geothermal energy. The beneficial effects of this invention are: it not only meets the temperature and pressure requirements of tight gas, shale gas, tight oil, and shale oil, but more importantly, it meets the low-temperature requirement for natural gas hydrate flow testing while also meeting the high-temperature requirement for geothermal extraction; it simulates a real geological environment and can complete seepage experiments on the extraction of unconventional energy sources such as tight gas, shale gas, tight oil, shale oil, natural gas hydrate, and hot dry rock using the same equipment. While this method realizes a multi-field coupled seepage multifunctional experimental device, it cannot distinguish between the seepage zone and the fluid supply zone in layered shale.

[0004] Chinese patent application 201910137987.4 discloses a numerical simulation method and apparatus for shale oil flow, belonging to the field of unconventional oil and gas field development engineering technology. The numerical simulation method and apparatus provided by this invention describes the flow characteristics of shale oil production processes in different occurrence states by establishing a reaction model, including the seepage of free crude oil, the adsorption and desorption behavior of adsorbed miscible crude oil in organic matter, and the influence of capillary forces on the occurrence state of dissolved gas. Combined with indoor physical simulation experiments, parameters such as chemical reaction equations, reaction rates, and reaction orders are determined (and each parameter is calibrated). Finally, using reservoir numerical simulation methods, a numerical simulation model considering the complex flow mechanism of shale oil is established, thereby simulating the seepage characteristics of unconventional shale oil. This method can simulate the seepage characteristics of unconventional shale oil, but it cannot distinguish between the seepage zone and the supply zone in layered shale.

[0005] Chinese patent application 201410536314.3 discloses a method for evaluating and predicting the production capacity of shale gas wells, comprising the following steps: obtaining the differential equation expression of a single-phase seepage mathematical model; solving the differential equation and expressing it in pressure form to obtain the seepage velocity and production formulas; determining the production capacity equation by fitting production data; refining the previously derived production formula to obtain the production capacity formula for staged fracturing of shale gas horizontal wells; from the shale gas production formula, it is known that the boundary pressure pe needs to be known; due to the influence of adsorption and desorption of shale gas, the deviation coefficient needs to be corrected to obtain the formation pressure of the shale gas reservoir. This prediction method, considering the desorption and diffusion characteristics of shale gas, derives the production capacity equations for both vertical and horizontal shale wells, thereby establishing a shale gas production capacity evaluation method, obtaining accurate production capacity prediction, and improving economic efficiency.

[0006] The above-mentioned existing technologies are all quite different from the present invention and have failed to solve the technical problem we want to solve. Therefore, we have invented a new method for testing the boundary between the seepage zone and the liquid supply zone of a layered shale matrix. Summary of the Invention

[0007] The purpose of this invention is to provide a method for defining the liquid supply zone and seepage zone of a shale matrix based on the pore structure of the shale matrix, and a test method for the boundary between the seepage zone and liquid supply zone of a layered shale matrix to effectively understand the flow pattern, flow characteristics and productivity contribution of the shale matrix.

[0008] The objective of this invention can be achieved through the following technical measures: a method for testing the boundary between the seepage zone and the liquid supply zone of a laminated shale matrix, the method comprising:

[0009] Step 1: Select a layered shale sample and measure its air permeability.

[0010] Step 2: Saturate the shale sample with fluid under high pressure to obtain the shale pore volume and porosity;

[0011] Step 3, calculate the shale pore volume V p and porosity φ;

[0012] Step 4: Perform nuclear magnetic resonance experiments on the saturated shale sample to obtain the T2 spectrum and thus the shale pore structure;

[0013] Step 5: Calculate the seepage capacity of each pore and sum them up to obtain the total seepage capacity of the shale matrix.

[0014] Step 6: Determine the boundary between the matrix seepage zone and the matrix supply zone, and calculate the pore volume and porosity corresponding to the matrix seepage zone.

[0015] The objective of this invention can also be achieved through the following technical measures:

[0016] In step 1, a layered shale sample from a certain study block is selected, and the air permeability value K of the shale sample after oil washing is measured using a gas permeability meter.

[0017] Step 1 also includes weighing the shale sample after oil washing using an electronic balance to obtain the dry weight m of the shale core sample. g .

[0018] In step 2, the shale sample is evacuated at a vacuum level of -0.1 MPa for 4 hours, and then subjected to high-pressure saturated kerosene at 30 MPa for 24 hours.

[0019] Step 2 also includes weighing the high-pressure saturated shale sample in air to obtain the wet shale sample weight m. s The saturated sample was completely immersed in kerosene and weighed to obtain the mass m1.

[0020] In step 3, the shale pore volume V is calculated. p The formula for calculating porosity φ is:

[0021] V p =(m s -m g ) / ρ o

[0022] φ=V p / (m s -m l ) / ρ o ×100

[0023] In the formula: V p The pore volume of shale is expressed in cm³. 3φ represents porosity, in percent; ρ o Density of kerosene, g / cm³ 3 ;m s The weight of the wet shale sample is in grams (g); m g is the weight of the dry shale core sample, in g; m1 is the weight of the saturated shale sample completely immersed in kerosene, in g.

[0024] Step 4 also includes converting the nuclear magnetic resonance T2 spectrum into a shale pore structure distribution map based on the nuclear magnetic relaxation time and pore diameter conversion coefficient C, and the signal quantity F corresponding to the pore volume of each pore diameter Di. Di ;

[0025] D i =C×T2

[0026] In the formula: C is the conversion coefficient between NMR relaxation time and pore diameter, which is 10 here; Di is the pore diameter, nm; F Di T1 represents the signal quantity corresponding to the pore volume corresponding to the pore diameter Di; T2 represents the transverse relaxation time of the nuclear magnetic resonance imaging (NMR), in milliseconds.

[0027] In step 5, the seepage capacity of each pore is calculated based on the pore diameter and pore volume ratio of the shale, and the total seepage capacity of the shale matrix is ​​obtained by accumulating and superimposing the results.

[0028] In step 5, the seepage capacity S of each pore is calculated based on the shale pore diameter and pore volume ratio. Di The total permeability value of the shale matrix and the total permeability value S of pores with a pore diameter Di < 1 μm are obtained by cumulative superposition. Di＜1μm ;

[0029]

[0030] S=∑S Di

[0031] S Di＜1μm =∑S Di＜1μm

[0032] In the formula, S represents the total permeability of the shale matrix, which is dimensionless; S Di＜1μm F represents the pore flow capacity corresponding to pore diameters less than 1 micrometer in the shale matrix, dimensionless; Di This is the signal quantity corresponding to the pore volume corresponding to the pore diameter Di.

[0033] In step 6, the seepage capacity of pores with pore diameter Di < 1 μm is accumulated from the largest pore diameter to the smallest pore diameter. When the cumulative contribution rate of seepage capacity reaches 99%, the corresponding pore diameter D is... T This marks the boundary between the matrix seepage zone and the matrix supply zone.

[0034] In step 6, the formula for calculating the cumulative contribution rate of seepage capacity is:

[0035]

[0036] Where: M is the cumulative contribution rate of seepage capacity, %; D T The boundary between the matrix seepage zone and the matrix supply zone is defined in nm.

[0037] In step 6, the porosity φ corresponding to the matrix seepage zone is calculated. Di and pore volume V Di The formula is:

[0038]

[0039] V Di =φ Di ×V p

[0040] Where: φ Di V represents the porosity corresponding to the matrix seepage zone, in %; Di The pore volume corresponding to the matrix seepage zone is in cm. 3 Dmax is the maximum pore diameter, in nm.

[0041] The present invention discloses a method for testing the boundary between the seepage zone and the liquid supply zone of a laminated shale matrix. When determining the boundary between the seepage zone and the liquid supply zone of the laminated shale matrix, the air permeability of the washed-oil laminated shale core is measured. Then, the laminated shale is saturated with fluid under high pressure to obtain the shale pore volume and porosity. Next, the saturated shale sample is subjected to nuclear magnetic resonance (NMR) experiments to obtain T2 spectra and thus the shale pore structure. The seepage capacity of each pore is calculated based on the pore diameter and pore volume ratio. These values ​​are accumulated to obtain the total seepage capacity of the shale matrix and the seepage capacity of the shale matrix with pores smaller than 1 μm. The seepage capacity is then accumulated from pores smaller than 1 μm towards smaller pore diameters. When the accumulated seepage capacity reaches 99%, the corresponding pore diameter is considered the boundary between the matrix seepage zone and the matrix liquid supply zone. The pore volume and porosity corresponding to the matrix seepage zone are then calculated. Compared with existing technologies, the present invention has the following advantages:

[0042] This method, when determining the seepage capacity of shale matrix, divides the interconnected pores of shale into two parts based on their primary role in shale flow: a matrix seepage zone and a matrix fluid supply zone. The boundaries between these two zones are determined through experimental techniques such as high-pressure saturation and nuclear magnetic resonance (NMR), as well as theoretical calculations. This allows for the quantitative characterization of the pores in the layered shale matrix that play a seepage role, yielding the pore volume occupied by the shale matrix seepage zone. This invention provides effective technical support for calculating the seepage capacity of shale oilfields, understanding seepage mechanisms, and predicting production capacity. Attached Figure Description

[0043] Figure 1 This is a flowchart of a specific embodiment of the method for testing the boundary between the seepage zone and the liquid supply zone in a layered shale matrix according to the present invention;

[0044] Figure 2 This is a T2 spectrum of laminated shale under saturation state in a specific embodiment of the present invention;

[0045] Figure 3 This is a diagram of the pore structure of layered shale obtained in a specific embodiment of the present invention. Detailed Implementation

[0046] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0047] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0048] The method for testing the boundary between the seepage zone and the liquid supply zone of a layered shale matrix in this invention includes: selecting a rock sample from a research block, measuring the air permeability of the washed-oil layered shale core, saturating the layered shale with fluid under high pressure to obtain the shale pore volume and porosity, then performing nuclear magnetic resonance experiments on the saturated shale sample to obtain the T2 spectrum and thus the shale pore structure, calculating the seepage capacity of each pore based on the pore diameter and pore volume ratio, and accumulating these values ​​to obtain the total seepage capacity of the shale matrix. The seepage capacity is then accumulated from pores with diameters less than 1 μm towards smaller pore diameters. When the cumulative contribution rate of the seepage capacity reaches 99%, the corresponding pore diameter is considered the boundary between the matrix seepage zone and the matrix liquid supply zone. The pore volume and porosity corresponding to the matrix seepage zone are then calculated.

[0049] Preferably, a shale sample from a specific study block is selected, and the air permeability value K of the shale is measured using a gas permeability meter.

[0050] Preferably, the columnar shale core after oil washing is weighed using an electronic balance to obtain the dry weight m of the shale core sample. g .

[0051] Preferably, the shale sample is evacuated at a vacuum level of -0.1 MPa for 4 hours, and then subjected to high-pressure saturated kerosene at 30 MPa for 24 hours.

[0052] Preferably, the shale sample that has been saturated under high pressure is weighed in air to obtain the wet weight m of the shale sample. s The saturated sample was completely immersed in kerosene and weighed to obtain the mass m. l .

[0053] Preferably, the shale pore volume V is calculated. p And porosity φ, its calculation formula is:

[0054] V p =(m s -m g ) / ρ o

[0055] φ=V p / (m s -m l ) / ρ o ×100

[0056] In the formula: V p The pore volume of shale is expressed in cm³. 3 φ represents porosity, in percent; ρ o Density of kerosene, g / cm³ 3 ;m s The weight of the wet shale sample is in grams (g); m g is the weight of the dry shale core sample, in g; m1 is the weight of the saturated shale sample completely immersed in kerosene, in g.

[0057] Preferably, nuclear magnetic resonance experiments are performed on saturated shale samples to obtain the T2 spectrum of the core under saturated conditions.

[0058] Preferably, based on the conversion coefficient C between nuclear magnetic resonance relaxation time and pore diameter, the nuclear magnetic resonance T2 spectrum is converted into a shale pore structure distribution map, and the signal quantity F corresponding to the pore volume of each pore diameter Di is determined. Di .

[0059] D i =C×T2

[0060] In the formula: C is the conversion coefficient between NMR relaxation time and pore diameter, which is 10 here; Di is the pore diameter, nm; F Di T1 represents the signal quantity corresponding to the pore volume corresponding to the pore diameter Di; T2 represents the transverse relaxation time of the nuclear magnetic resonance imaging (NMR), in milliseconds.

[0061] Preferably, the seepage capacity S of each pore is calculated based on the pore diameter and pore volume ratio of the shale.Di The total permeability value of the shale matrix and the total permeability value S of pores with a pore diameter Di < 1 μm are obtained by cumulative superposition. Di＜1μm .

[0062]

[0063] S=∑S Di

[0064] S Di＜1μm =∑S Di＜1μm

[0065] In the formula, S represents the total permeability of the shale matrix, which is dimensionless; S Di＜1μm This represents the pore permeability value corresponding to pore diameters less than 1 micrometer in the shale matrix, and is dimensionless.

[0066] Preferably, the seepage capacity of pores with a pore diameter Di < 1 μm is accumulated from the largest pore diameter to the smallest pore diameter. When the cumulative contribution rate of seepage capacity reaches 99%, the corresponding pore diameter D is... T This marks the boundary between the matrix seepage zone and the matrix supply zone.

[0067]

[0068] Where: M is the cumulative contribution rate of seepage capacity, %; D T The boundary between the matrix seepage zone and the matrix supply zone is defined in nm.

[0069] Preferably, the porosity φ corresponding to the matrix seepage zone is calculated. Di and pore volume V Di

[0070]

[0071] V Di =φ Di ×V p

[0072] Where: φ Di V represents the porosity corresponding to the matrix seepage zone, in %; Di The pore volume corresponding to the matrix seepage zone is in cm. 3 Dmax is the maximum pore diameter, in nm.

[0073] The following are several specific embodiments of the application of the present invention.

[0074] Example 1

[0075] In a specific embodiment 1 of the present invention, such as Figure 1 As shown, the method for testing the boundary between the seepage zone and the supply zone of the layered shale matrix includes the following steps:

[0076] Step 101: Select a shale sample from a certain study block and measure the air permeability value K of the shale using a gas permeability meter. K = 10.7 mD.

[0077] Step 201: Weigh the columnar shale core using an electronic balance to obtain the dry weight m of the shale core sample. g m g =21.200g.

[0078] Step 301: Vacuum the shale sample at a vacuum level of -0.1 MPa for 4 hours, then saturate the shale sample with high-pressure kerosene at 30 MPa for 24 hours.

[0079] Step 401: Weigh the high-pressure saturated shale sample in air to obtain the wet shale sample weight m. s =21.720g, the saturated sample was completely immersed in kerosene and weighed to obtain the mass m. l =13.386g.

[0080] Step 501, calculate the shale pore volume V p And porosity φ, its calculation formula is:

[0081] V p =(m s -m g ) / ρ o =(21.720-21.200) / 0.8088=0.642cm 3

[0082] φ=V p / [(m s -m l ) / ρ o ] = 0.642 / [(21.720 - 13.386) / 0.8088] = 8.37% Where: V p The pore volume of shale is expressed in cm³. 3 φ represents porosity, in percent; ρ o Density of kerosene, g / cm³ 3 ;m s The weight of the wet shale sample is in grams (g); m g The dry weight of the shale core sample is in grams (g); m l The weight, in grams, is the weight of a saturated shale sample completely immersed in kerosene.

[0083] Step 601: Perform nuclear magnetic resonance experiments on the saturated shale sample to obtain the T2 spectrum under saturated core conditions, see... Figure 2 The total nuclear magnetic resonance signal obtained from the shale core was F = 1938.58.

[0084] Step 701: Based on the conversion coefficient C between nuclear magnetic resonance relaxation time and pore diameter, convert the nuclear magnetic resonance T2 spectrum into a shale pore structure distribution map, see... Figure 3 The signal quantity F corresponding to the pore volume for each pore diameter Di Di .

[0085] D i =C×T2

[0086] In the formula: C is the conversion coefficient between NMR relaxation time and pore diameter, which is 10 here; Di is the pore diameter, nm; F Di T1 represents the signal quantity corresponding to the pore volume corresponding to the pore diameter Di; T2 represents the transverse relaxation time of the nuclear magnetic resonance imaging (NMR), in milliseconds.

[0087] Step 801: Calculate the seepage capacity S of each pore based on the pore diameter and pore volume ratio of the shale. Di The total seepage capacity of the shale matrix, obtained by cumulative superposition, is S = 4.60 × 10⁻⁶. 9 S Di＜1μm =1.14×10 8 .

[0088]

[0089] S=∑S Di =4.60×10 9

[0090] S Di＜1μm =∑S Di＜1μm =1.14×10 8

[0091] Step 901: Accumulate the seepage capacity from large pore diameter to small pore diameter. When the cumulative contribution rate of seepage capacity reaches 99%, the corresponding pore diameter D is... T D marks the boundary between the matrix seepage zone and the matrix supply zone. T =100nm.

[0092]

[0093] Where: M is the cumulative contribution rate of seepage capacity, %; D T The boundary between the matrix seepage zone and the matrix supply zone is defined in nm.

[0094] Calculate the porosity φ corresponding to the matrix seepage zone Di and pore volume V Di

[0095]

[0096] V Di =φDi ×V p =4.61% × 0.642 = 0.0296cm 3

[0097] Where: φ Di V represents the porosity corresponding to the matrix seepage zone, in %; Di The pore volume corresponding to the matrix seepage zone is in cm. 3 Dmax is the maximum pore diameter, in nm.

[0098] In a specific embodiment of the present invention, the boundary between the seepage zone and the liquid supply zone of the layered shale matrix is ​​100 nm, and the porosity of the matrix seepage zone is 4.61%.

[0099] Example 2

[0100] like Figure 1 As shown, the method for testing the boundary between the seepage zone and the supply zone of the layered shale matrix includes the following steps:

[0101] Step 101: Select a shale sample from a certain study block and measure the air permeability value K of the shale using a gas permeability meter. K = 0.852 mD.

[0102] Step 201: Weigh the columnar shale core using an electronic balance to obtain the dry weight m of the shale core sample. g m g =29.960g.

[0103] Step 301: Vacuum the shale sample at a vacuum level of -0.1 MPa for 4 hours, then saturate the shale sample with high-pressure kerosene at 30 MPa for 24 hours.

[0104] Step 401: Weigh the high-pressure saturated shale sample in air to obtain the wet shale sample weight m. s =30.401g. The saturated sample was completely immersed in kerosene and weighed to obtain the mass m. l =20.703g.

[0105] Step 501, calculate the shale pore volume V p And porosity φ, its calculation formula is:

[0106] V p =(m s -m g ) / ρ o =(30.401-29.960) / 0.8088=0.546cm 3

[0107] φ=V p / [(m s -m l ) / ρ o ]=0.546 / [(30.401-20.703) / 0.8088]=4.55% Where: V p The pore volume of shale is expressed in cm³. 3 φ represents porosity, in percent; ρ o Density of kerosene, g / cm³ 3 ;m s The weight of the wet shale sample is in grams (g); m g The dry weight of the shale core sample is in grams (g); m l The weight, in grams, is the weight of a saturated shale sample completely immersed in kerosene.

[0108] Step 601: Perform nuclear magnetic resonance experiments on the saturated shale sample to obtain the T2 spectrum of the core under saturation, and obtain the total nuclear magnetic signal of the shale core F = 6129.89.

[0109] Step 701: Based on the conversion coefficient C between nuclear magnetic resonance relaxation time and pore diameter, convert the nuclear magnetic resonance T2 spectrum into a shale pore structure distribution map, and determine the signal quantity F corresponding to the pore volume of each pore diameter Di. Di .

[0110] D i =C×T2

[0111] In the formula: C is the conversion coefficient between NMR relaxation time and pore diameter, which is 10 here; Di is the pore diameter, nm; F Di T1 represents the signal quantity corresponding to the pore volume corresponding to the pore diameter Di; T2 represents the transverse relaxation time of the nuclear magnetic resonance imaging (NMR), in milliseconds.

[0112] Step 801: Calculate the seepage capacity S of each pore based on the pore diameter and pore volume ratio of the shale. Di The total seepage capacity of the shale matrix, obtained by cumulative superposition, is S = 2.55 × 10⁻⁶. 10 S Di＜1μm =1.63×10 8 .

[0113]

[0114] S=∑S Di =2.55×10 10

[0115] S Di＜1μm =∑S Di＜1μm =1.63×10 8

[0116] Step 901: Accumulate the seepage capacity from large pore diameter to small pore diameter. When the cumulative contribution rate of seepage capacity reaches 99%, the corresponding pore diameter D is... T D marks the boundary between the matrix seepage zone and the matrix supply zone. T =77.43nm.

[0117]

[0118] Where: M is the cumulative contribution rate of seepage capacity, %; D T The boundary between the matrix seepage zone and the matrix supply zone is defined in nm.

[0119] Calculate the porosity φ corresponding to the matrix seepage zone Di and pore volume V Di

[0120]

[0121] V Di =φ Di ×V p =1.27% × 0.546 = 0.0069cm 3

[0122] Where: φ Di V represents the porosity corresponding to the matrix seepage zone, in %; Di The pore volume corresponding to the matrix seepage zone is in cm. 3 Dmax is the maximum pore diameter, in nm.

[0123] In a specific embodiment of the present invention, the boundary between the seepage zone and the liquid supply zone of the layered shale matrix is ​​77.43 nm, and the porosity of the matrix seepage zone is 1.27%.

[0124] Example 3

[0125] like Figure 1 As shown, the method for testing the boundary between the seepage zone and the supply zone of the layered shale matrix includes the following steps:

[0126] Step 101: Select a shale sample from a certain study block and measure the air permeability value K of the shale using a gas permeability meter. K = 0.156 mD.

[0127] Step 201: Weigh the columnar shale core using an electronic balance to obtain the dry weight m of the shale core sample. g m g =29.264g.

[0128] Step 301: Vacuum the shale sample at a vacuum level of -0.1 MPa for 4 hours, then saturate the shale sample with high-pressure kerosene at 30 MPa for 24 hours.

[0129] Step 401: Weigh the high-pressure saturated shale sample in air to obtain the wet shale sample weight m. s =29.729g. The saturated sample was completely immersed in kerosene and weighed to obtain the mass m. l =17.461g.

[0130] Step 501, calculate the shale pore volume V p And porosity φ, its calculation formula is:

[0131] V p =(m s -m g ) / ρ o =(29.729-29.264) / 0.8088=0.575cm 3

[0132] φ=V p / [(m s -m l ) / ρ o ]=0.575 / [(29.729-17.461) / 0.8088]=3.79% Where: V p The pore volume of shale is expressed in cm³. 3 φ represents porosity, in percent; ρ o Density of kerosene, g / cm³ 3 ;m s The weight of the wet shale sample is in grams (g); m g The dry weight of the shale core sample is in grams (g); m l The weight, in grams, is the weight of a saturated shale sample completely immersed in kerosene.

[0133] Step 601: Perform nuclear magnetic resonance experiments on the saturated shale sample to obtain the T2 spectrum of the core under saturation, and obtain the total nuclear magnetic signal of the shale core F = 6897.69.

[0134] Step 701: Based on the conversion coefficient C between nuclear magnetic resonance relaxation time and pore diameter, convert the nuclear magnetic resonance T2 spectrum into a shale pore structure distribution map, and determine the signal quantity F corresponding to the pore volume of each pore diameter Di. Di .

[0135] D i =C×T2

[0136] In the formula: C is the conversion coefficient between NMR relaxation time and pore diameter, which is 10 here; Di is the pore diameter, nm; F Di T1 represents the signal quantity corresponding to the pore volume corresponding to the pore diameter Di; T2 represents the transverse relaxation time of the nuclear magnetic resonance imaging (NMR), in milliseconds.

[0137] Step 801: Calculate the seepage capacity S of each pore based on the pore diameter and pore volume ratio of the shale. Di The total seepage capacity of the shale matrix, obtained by cumulative superposition, is S = 2.69 × 10⁻⁶. 9 S Di＜1μm =8.19×10 7 .

[0138]

[0139] S=∑S Di =2.69×10 9

[0140] S Di＜1μm =∑S Di＜1μm =8.19×10 7

[0141] Step 901: Accumulate the seepage capacity from large pore diameter to small pore diameter. When the cumulative contribution rate of seepage capacity reaches 99%, the corresponding pore diameter D is... T D marks the boundary between the matrix seepage zone and the matrix supply zone. T =59.95nm.

[0142]

[0143] Where: M is the cumulative contribution rate of seepage capacity, %; D T The boundary between the matrix seepage zone and the matrix supply zone is defined in nm.

[0144] Calculate the porosity φ corresponding to the matrix seepage zone Di and pore volume V Di

[0145]

[0146] V Di =φ Di ×V p =0.55% × 0.575 = 0.0032cm 3

[0147] Where: φ Di V represents the porosity corresponding to the matrix seepage zone, in %; Di The pore volume corresponding to the matrix seepage zone is in cm. 3 Dmax is the maximum pore diameter, in nm.

[0148] In a specific embodiment of the present invention, the boundary between the seepage zone and the liquid supply zone of the layered shale matrix is ​​59.95 nm, and the porosity of the matrix seepage zone is 0.55%.

[0149] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0150] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A method for testing the boundaries of a laminated shale matrix flow zone and a liquid supply zone, characterized by, The method comprises the following steps: Step 1, selecting a laminated shale sample to measure the air permeability value; Step 2, saturating the shale sample with fluid under high pressure to obtain the pore volume and porosity of the shale; Step 3, Calculate Shale Pore Volume and porosity ; Step 4, performing nuclear magnetic resonance experiment on the saturated shale sample to obtain the T2 spectrum and the pore structure of the shale; Step 5, calculating the percolation capacity of each pore and obtaining the total percolation capacity of the shale matrix; Step 6, determining the boundary between the matrix percolation zone and the matrix liquid supply zone, and calculating the pore volume and porosity corresponding to the matrix percolation zone; Step 4 further comprises converting the nuclear magnetic resonance T2 spectrum into a shale pore structure distribution map according to the conversion coefficient C between the nuclear magnetic relaxation time and the pore diameter; ； In the formula, C is the conversion coefficient between the nuclear magnetic relaxation time and the pore diameter, which is 10 here; Di is the pore diameter, nm; T2 is the nuclear magnetic transverse relaxation time, ms; In step 5, the percolation ability of each pore is calculated according to the shale pore diameter and the pore volume proportion , and the total percolation ability value of the shale matrix and the total value of the percolation ability of pores with a pore diameter Di < 1 μm are obtained by cumulative superposition ; ； ； ； In the formula, S is the total permeability value of the shale matrix, dimensionless; is the pore permeability value corresponding to the pore diameter less than 1 micron in the shale matrix, dimensionless; is the signal quantity corresponding to the pore volume corresponding to the pore diameter Di. In step 6, the pore flow capacity from the large pore diameter to the small pore diameter is accumulated for the pores having a pore diameter Di < 1 μm, and when the pore flow capacity accumulation contribution rate reaches 99%, the corresponding pore diameter is the boundary between the matrix flow region and the matrix liquid supply region.

2. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 1, wherein, In step 1, a laminated shale sample of a certain research block is selected, and the air permeability value K of the shale sample after oil washing is measured by using a gas permeameter.

3. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 2, wherein, Step 1 also includes weighing the shale sample after the oil wash using an electronic balance to obtain the dry shale core sample weight m g .

4. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 1, wherein, In step 2, the shale sample is vacuumized, and the vacuum degree is-0.1 MPa for 4 hours, and then the shale sample is saturated with high-pressure kerosene, and the high-pressure kerosene is saturated at 30 MPa for 24 hours.

5. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 4, wherein, Step 2 also includes weighing the high pressure saturated shale sample in air to obtain the shale wet sample weight m s Weighing the saturated shale sample fully immersed in kerosene to obtain the shale core wet sample weight m l .

6. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 1, wherein, In step 3, the shale pore volume is calculated and porosity The formula for the calculation is: ； = / [(m s－ m l ) / ]×100; wherein: is the shale pore volume, cm 3 ; is the porosity, %; is the kerosene density, g / cm 3 ; m s is the shale core wet sample weight, g;m g is the shale core dry sample weight, g;m l is the shale core wet sample weight, g.

7. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 1, wherein, In step 6, the calculation formula of the percolation capacity cumulative contribution rate is: ； In the formula: is the cumulative contribution rate of the flow capacity, is the boundary between the matrix flow region and the matrix liquid supply region, nm.

8. The laminated shale matrix flow zone and liquid supply zone delineation test method of claim 7, wherein, In step 6, the porosity corresponding to the matrix flow region is calculated and the pore volume is calculated as follows: ； ； In the formula: is the porosity corresponding to the matrix flow region; is the pore volume corresponding to the matrix flow region, cm 3 ; Dmax is the maximum pore diameter, nm; is the shale pore volume, cm 3 .

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