Three-water conductive model parameter calculation method based on nuclear magnetic resonance constrained conventional logging

Abstract

The invention innovatively provides a three-water electric conduction model parameter calculation method based on nuclear magnetic resonance constrained conventional logging, aiming at the technical problems that three-water electric conduction model parameters are too many, and the model parameters can be determined only by using a large amount of rock core experiment data such as mercury injection, rock electricity experiments, clay analysis and cation exchange capacity in the prior art. According to the calculation method, the free fluid porosity, the micro capillary water porosity and the clay water porosity which are obtained through nuclear magnetic resonance logging interpretation are substituted into a formula of a three-water electric conduction model represented by conventional logging parameters and are combined with the porosity, the shale content, the irreducible water saturation and other parameters which are explained through conventional logging; finally, calculation of all model parameters can still be completed under the condition of not depending on experimental data, and during parameter calculation, the calculation precision is improved by adopting the optimization algorithm assistance of multiple groups of data depending on the characteristic that logging data has a big data sample.

Description

Technical Field

[0001] The invention belongs to the technical field of well logging reservoir evaluation in oil and gas reservoirs, and in particular relates to a method for calculating parameters of a three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance. Background Art

[0002] With the deepening of oil and gas exploration, more and more reservoirs show "non-Archie" phenomena, especially complex lithology, low porosity and low resistivity reservoirs. Saturation formulas such as the mud parallel conductive model, WS model, and double water model are gradually proposed in certain specific cases to replace the Archie formula to obtain more accurate calculation results. The three-pore water conductive model (hereinafter referred to as the three-water conductive model) meets the quantitative evaluation of the saturation of more complex clastic reservoirs. The three-water conductive model believes that the conductive medium in the reservoir includes formation water in the free fluid pores (referred to as free water), bound water in the microcapillary pores (referred to as micropore water), and clay water in the clay pores. The conductivity of the free pore formation water and the micropore bound water is the same and both are ion conductive. Clay water is cation exchange conductive and its conductivity is different from that of free water. The total conductivity of the rock is the parallel connection of the three parts of the medium.

[0003] The three-water conductive model well characterizes the contribution of different conductive media to rock conductivity, but there are many parameters that need to be determined in the three-water conductive model, including the resistivity of free water, micropore water and clay water, the volume of free water, micropore water and clay water, and the cementation index corresponding to the three fluids and the saturation index of free water.

[0004] In the prior art, the methods for determining the parameters of the three-water conductive model are divided into two categories. One category completely relies on various experimental data, for example: a method for establishing a three-water component differential parallel conductive water saturation model disclosed in announcement number CN114862113B. Various experimental data include porosity, permeability, relative permeability, mercury injection, nuclear magnetic resonance, cation exchange capacity, particle size analysis, and rock electrical experiment data. This type of method is costly and has great limitations. It is not applicable to areas without rich experimental data, and the results obtained are regional statistical and only applicable to limited research areas, making it difficult to promote and use.

[0005] The other type relies on conventional logging data and certain empirical coefficients to calculate model parameters. For example, porosity is calculated using neutron, density, and acoustic wave curves, mud content is calculated using gamma curves, and clay content is calculated based on empirical formulas to determine clay water volume. This type of method is difficult to meet the current exploration and development needs due to the accuracy limitations of conventional logging itself and the use of empirical formulas in some steps, which results in low accuracy in calculation results. Summary of the invention

[0006] In view of the technical problem that the existing technology has too many parameters in the three-water conductive model and requires a large amount of core experimental data such as mercury injection, rock electrical experiment, clay analysis, cation exchange capacity, etc. to determine the model parameters, a method for calculating the parameters of the three-water conductive model based on conventional logging constrained by nuclear magnetic resonance is proposed. This calculation method adopts a new calculation idea, substitutes the free fluid porosity, microcapillary porosity and clay water porosity obtained by nuclear magnetic resonance logging interpretation into the three-water conductive model formula represented by conventional logging data, and combines it with conventional logging parameters, and finally achieves the calculation of all model parameters without relying on experimental data. At the same time, relying on the characteristics of large data samples of logging data itself, the optimization algorithm of multiple sets of data is used to assist in parameter calculation, which improves the calculation accuracy.

[0007] In order to achieve the above object, the present invention provides a method for calculating parameters of a three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance, which comprises the following steps: Step S1, establishing a three-water conductive model of rock based on the multi-medium parallel conductive theory, and obtaining a calculation formula for the conductivity of completely water-containing rock and oil and gas-containing rock; Step S2: Calculate the free water resistivity for the three-water conductive model of fully water-bearing rock and oil- and gas-bearing rock , micropore water resistivity and clay water resistivity ; Step S3: Calculate the free fluid porosity in the three-water conductive model according to the nuclear magnetic resonance logging response characteristics of the fully water-bearing rock. , Clay water porosity , microcapillary porosity

[0008] Step S4: calculate the water content of the plurality of fully water-bearing rocks based on nuclear magnetic resonance logging. , , , substitute the three-water conductive model to establish the first overdetermined equation group, and apply the optimization algorithm to iteratively solve it to calculate the cementation index of free water , cementation index of micropore water and the cementation index of clay water

[0009] Step S5: Apply nuclear magnetic resonance logging to constrain conventional logging curves, establish a clay water volume coefficient calculation model for the completely water-bearing rock based on conventional logging parameters according to the conductivity of the completely water-bearing rock, and calculate the clay water volume coefficient. ; Step S6: Establish a saturation index calculation model for oil and gas-bearing rocks based on conventional logging parameters according to the electrical conductivity of the oil and gas-bearing rocks, and calculate the free water saturation index according to the saturation data of the oil-bearing core.

[0010] Step S7: Calculate the cementation index according to the saturation index calculation model and calculation , , the clay water volume coefficient and the free water saturation index , using conventional logging curves to calculate water saturation .

[0011] According to an embodiment of the present disclosure, the conductivity of the fully water-containing rock is

[0012] (1) The electrical conductivity of the oil and gas bearing rock It is expressed as: (2) in, is the resistivity of the fully hydrated rock, is the resistivity of the oil and gas bearing rock, , is the free fluid pore water saturation, is the free fluid porosity.

[0013] According to an embodiment of the present disclosure, step S2 includes the following steps: Directly measuring the resistivity of formation water according to formation water sampling or performing mineralization analysis on the formation water and calculating the resistivity of the formation water according to the mineralization; Calculation of clay water conductivity based on the first operation logic According to the clay water conductivity Calculate the clay water resistivity ; Wherein, the formation water resistivity The free water resistivity , the micropore water resistivity The value of is the same, the first operation logic is expressed as:

[0014] in, for Diffusion factor of the ion diffusion layer Compensating ions in clay water The equivalent conductivity of The cation exchange capacity of clay is The pore volume occupied by water in clay.

[0015] According to an embodiment of the present disclosure, step S3 includes the following steps: The completely water-bearing rock is determined according to the test oil and production data, and the clay bound water volume, capillary bound water volume and movable water volume in the nuclear magnetic resonance logging data processing and interpretation result map are used as the clay water porosity in the three-water conductive model. , the microcapillary porosity and the free fluid porosity .

[0016] According to an embodiment of the present disclosure, step S4 includes the following steps: Selecting a plurality of said completely water-bearing rocks, and obtaining clay water porosity, microcapillary porosity and free fluid porosity at a plurality of depth points for each of said completely water-bearing rocks on a nuclear magnetic resonance interpretation result map; Determine the resistivity of the completely water-bearing rock corresponding to each of the depth points according to the resistivity logging curve, and establish N equations to form the first overdetermined equation group; The optimization algorithm of the least square method is used to solve the first overdetermined equations to calculate the cementation index. , , .

[0017] According to an embodiment of the present disclosure, step S5 includes the following steps: The conventional logging parameters of the completely water-bearing rock are calculated according to the conventional logging curve, and the conventional logging parameters at least include: , the total porosity of the formation , Permeability , Irreducible water saturation ; According to the conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; The conventional logging parameters are used to obtain , , The expression formula and the cementation index calculated in step S4 , , , bring in the conductivity expression formula of the completely water-containing rock, and establish the calculation model of the clay water volume coefficient; The clay water volume coefficient is solved by using an optimization algorithm .

[0018] According to an embodiment of the present disclosure, step S5 further includes the following steps: According to the double water model, the cation exchange capacity The volume of clay water per unit pore volume ; Get cation exchange capacity With the mud content The ratio between and is defined as the clay water volume coefficient ; According to the total porosity And based on the clay water volume coefficient The volume of clay water per unit pore volume , the clay water porosity is obtained The expression formula of ; According to the irreducible water saturation , the microcapillary porosity is obtained The expression formula is: According to the total porosity The clay water porosity With the microcapillary porosity , obtain the free fluid porosity .

[0019] According to an embodiment of the present disclosure, the free water saturation index The calculation of includes the following steps: According to the experimental data of oil-bearing cores, the water saturation and resistivity of different oil-bearing cores are obtained; Based on the water saturation, calculate the free fluid pore water saturation ; The different resistivities and free fluid pore water saturation Substitute into the saturation index calculation model to obtain a third overdetermined equation group; Solve the third overdetermined equations according to the optimization algorithm to calculate the free water saturation index .

[0020] According to an embodiment of the present disclosure, the establishment of the saturation index calculation model includes the following steps: Performing depth correction on the oil-bearing cores obtained to obtain a conventional logging curve corresponding to the depth of each oil-bearing core; The conventional logging parameters are calculated based on the conventional logging curve, and the conventional logging parameters at least include: total porosity Clay content , Permeability , Irreducible water saturation ; According to the conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; The conventional logging parameters are used to obtain , , The expression formula and the cementation index calculated in step S4 , , , bring into the calculation formula of the electrical conductivity of the oil and gas bearing rock, and establish a saturation index calculation model.

[0021] According to an embodiment of the present disclosure, the water saturation The calculation of includes the following steps: According to the saturation index calculation model, the free fluid pore water saturation is obtained. The calculation formula of The calculated cementation index , , , the clay water volume coefficient A and the free water saturation index , substitute the The calculation formula of Calculate conventional logging parameters according to the conventional logging curve, and convert the Convert to total pore water saturation and calculate water saturation .

[0022] In another aspect of the present invention, a system for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance is provided to implement the calculation method in the above technical solution, wherein the calculation system comprises: Three water resistivity calculation modules, which calculate the free water resistivity based on the mineralization analysis of the formation water and micropore water resistivity , and calculate the clay water conductivity based on the first operation logic , according to the clay water conductivity Calculate the clay water resistivity ; Three water porosity extraction modules, extracting free fluid porosity based on the nuclear magnetic resonance logging interpretation results of the fully water-bearing rock , Clay water porosity , microcapillary porosity ; Cementation index calculation module, free fluid porosity obtained from NMR logging data , Clay water porosity , microcapillary porosity The first overdetermined equations are formed, and based on the first overdetermined equations, the cementation index of free water is calculated using an optimization algorithm. , cementation index of micropore water and the cementation index of clay water ; Conventional logging parameter calculation module, which calculates conventional logging parameters based on conventional logging curves, including at least: shale content, total porosity, permeability, and irreducible water saturation; The clay water volume coefficient calculation module is based on the conventional logging parameters to represent the free fluid porosity, clay water porosity, and microcapillary porosity. A calculation model for the clay water volume coefficient of fully water-bearing rocks based on conventional logging parameters is established to calculate the clay water volume coefficient in the model. ; Saturation index calculation module, which establishes a saturation index calculation model for oil and gas-bearing rocks based on conventional logging parameters, and calculates the free water saturation index based on the saturation data of oil-bearing cores ; The water saturation calculation module calculates the water saturation using conventional well logging curves according to the saturation index calculation model and the calculated cementation index, the clay water volume coefficient and the free water saturation index. .

[0023] Compared with the prior art, the advantages and positive effects of the present invention are: providing a new idea and method for calculating the parameters of the three-water conductive model, the calculation method fully utilizes the advantage of nuclear magnetic resonance logging that can accurately calculate the free fluid porosity, microcapillary porosity and clay water porosity, uses nuclear magnetic resonance to constrain conventional logging, and uses a large amount of sample data to establish a set of equations and adopts an optimization algorithm to solve them. On the one hand, it avoids the limitation of having to rely on experimental data to determine the model parameters, and on the other hand, it relies on the constraints of nuclear magnetic resonance logging and is supplemented by an optimization algorithm to improve the calculation accuracy of the model parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a flow chart of a method for calculating parameters of a three-water conductive model based on conventional logging constrained by nuclear magnetic resonance according to an embodiment of the present application; Figure 2 It is a three-water conductive model established based on the parallel conductive theory in the implementation mode of this application; Figure 3 It is a result diagram of nuclear magnetic resonance logging interpretation of a certain section of the formation of the well used in the implementation mode of the present application; Figure 4 is a cross plot of core porosity and density logging values ​​according to an embodiment of the present application; Figure 5 is a cross plot of core porosity and neutron porosity logging values ​​according to an embodiment of the present application; Figure 6 It is a cross plot of core porosity and acoustic time difference logging value according to the implementation mode of the present application; Figure 7 It is a core porosity-permeability cross-plot according to an embodiment of the present application; Figure 8 According to the bound water saturation and The intersection diagram of Fig. 9 is a cross-plot of irreducible water saturation and shale content according to an embodiment of the present application; Fig.10 It is a diagram of the calculation results of the three-water conductive model in the implementation mode of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] The terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] There are two main technical problems in the existing calculation method of the parameters of the three-water conductive model. First, the parameters of the three-water model cannot be determined in the absence of experimental data. The three-water conductive model is proposed based on the theory of parallel conductivity of multiple media. There are many parameters that need to be determined in the model, including free fluid porosity, microcapillary porosity, clay water porosity, free water resistivity, micropore water resistivity, clay water resistivity, cementation index of three types of water, and free water saturation index. If the above parameters can be accurately determined, the water saturation calculated using the three-water conductive model is very accurate. However, a large amount of core experimental data is required to determine the above parameters. In addition to conventional porosity and permeability experimental data, mercury injection, nuclear magnetic resonance experiments and clay content analysis data are also required. The cementation index of the three types of water needs to be combined with rock electrical experimental data and nuclear magnetic resonance or cation exchange capacity, and the determination of clay water resistivity requires cation exchange capacity experiments. However, it is difficult for most research blocks to have all the above experimental data at the same time, so the parameters of the three-water conductive model cannot be fully determined.

[0030] Second, the accuracy of the model parameters determined solely by conventional logging data is too low. Conventional logging data reflects a certain physical property or physical parameter of the formation, and only indirectly reflects the geological characteristics of the formation from a certain aspect. Because each logging information is indirect and multi-solution, the accuracy of the geological parameters calculated directly from conventional logging curves is low. For example, the porosity calculated from the sonic, neutron or density curves, and the mud content calculated from the natural gamma curve must be used under specific conditions. Therefore, the error of the three-water conductive model parameters calculated based on these mud contents and porosities is even higher.

[0031] In view of the above two problems, the present invention provides a method for calculating the parameters of the three-water conductive model based on conventional logging constrained by nuclear magnetic resonance. Figure 1 , the calculation method includes the following steps: Step S1, establishing a three-water conductive model of rock based on the multi-medium parallel conductive theory, and obtaining a calculation formula for the conductivity of completely water-containing rock and oil and gas-containing rock; Step S2: Calculate the free water resistivity for the three-water conductive model of fully water-bearing rock and oil- and gas-bearing rock , micropore water resistivity and clay water resistivity ; Step S3: Calculate the free fluid porosity in the three-water conductive model based on the nuclear magnetic resonance logging response characteristics of the fully water-bearing rock. , Clay water porosity , microcapillary porosity

[0032] Step S4: calculate the water content of the plurality of fully water-bearing rocks based on nuclear magnetic resonance logging. , , , substitute the three-water conductive model to establish the first overdetermined equation group, and apply the optimization algorithm to iteratively solve it to calculate the cementation index of free water , cementation index of micropore water and the cementation index of clay water

[0033] Step S5: Apply nuclear magnetic resonance logging to constrain conventional logging curves, establish a clay water volume coefficient calculation model for the completely water-bearing rock based on conventional logging parameters according to the conductivity of the completely water-bearing rock, and calculate the clay water volume coefficient. ; Step S6: Establish a saturation index calculation model for oil and gas-bearing rocks based on conventional logging parameters according to the electrical conductivity of the oil and gas-bearing rocks, and calculate the free water saturation index according to the saturation data of the oil-bearing core.

[0034] Step S7: Calculate the cementation index according to the saturation index calculation model and calculation , The clay water volume coefficient and the free water saturation index , using conventional logging curves to calculate water saturation .

[0035] The present invention provides a new calculation method, which solves the problem that the existing technology must rely on experimental data to determine parameters. At the same time, it fully utilizes the large sample characteristics and optimization algorithm of logging data to ensure the accuracy of the calculation results.

[0036] After searching, the comparative document with publication number CN114862113B can be used as the closest prior art to the present invention. The three-water component differential parallel conductive model described in the comparative document is similar to the three-water conductive model of the present invention, and it divides pore water into free water, weakly bound water and strongly bound water, while the present invention divides it into free water, micropore water and clay water, and the model parameters to be determined also include cementation index and saturation index.

[0037] However, compared with the comparative document, the core invention of the present invention is to use nuclear magnetic resonance logging curves and conventional logging curves instead of experimental data, avoiding the use of a large amount of experimental data (data that needs to be obtained in the laboratory) as in the comparative document, saving huge time and economic costs.

[0038] In the method for establishing the three-water component differential parallel conductive water saturation model disclosed in the comparative document, it is first necessary to select multiple coring wells in the study area, collect core samples located in different geological layers of each coring well, and conduct rock physics experiments on each core sample. What is more important is to conduct multi-stage centrifugation on the cores, and conduct nuclear magnetic resonance experiments on the cores after displacement with different centrifugal forces. The biggest difficulty of this scheme lies in the setting of multi-stage centrifugal force. The centrifugal force required for cores with different porosities and different looseness is different. How to set it is a big difficulty, and the centrifugal force setting in different regions cannot be extended to another region. How large the centrifugal force is, how long does the centrifugation take to displace free water, and how much is the difference between strong centrifugation and weak centrifugation are difficult to quantitatively describe. Then, rock electrical experiments are conducted on the cores after displacement with different centrifugal forces, and the resistivity of the cores is measured to calculate the cementation index and saturation index. These complex core experiments increase time and economic costs.

[0039] The present invention is to solve the technical problem that the above-mentioned comparative documents require complex core experiments, and use logging curves instead of core experiments, because logging curves are continuous and cover the entire well section, and the measurement cost is low, and the saturation of all wells can be calculated according to the model obtained by the present invention.

[0040] Specifically, this embodiment combines conventional logging with nuclear magnetic resonance logging. On the one hand, the free fluid porosity, microcapillary porosity and clay water porosity obtained by nuclear magnetic resonance logging interpretation are substituted into the three-water conductive model formula represented by conventional logging data, and the three-water model parameters are calculated by combining them with the porosity, mud content, bound water saturation and other parameters interpreted by conventional logging, thereby solving the problem of having to rely on experimental data to calculate model parameters.

[0041] On the other hand, it is well known that at least 8 data points are measured per meter during logging (one data point is measured every 0.125 meters). Therefore, for formations of a certain thickness, the logging data have a large number of samples, which meets the large sample data requirements of the optimization algorithm. Therefore, the optimization algorithm of multiple sets of data is used in the parameter calculation process to obtain the optimal solution, which guarantees the calculation accuracy to a certain extent.

[0042] It should be noted that the main purpose of the present invention is to provide a new idea and method for calculating the parameters of the three-water conductive model. The specific calculation accuracy is affected by the actual data sample size and the accuracy of the data itself.

[0043] Furthermore, in the above step S1, a three-water conductive model of rock is established according to the multiple medium parallel conductive theory. According to the multiple medium parallel conductive theory, it is concluded that the conductive medium of rock is composed of three parts in parallel, namely free fluid water, micropore water and clay bound water (hereinafter referred to as clay water).

[0044] For fully hydrated rock, the conductivity of fully hydrated rock is for: (1) For oil and gas-bearing rocks, only the free fluid pores contain oil and gas. Therefore, the conductivity of oil and gas-bearing rocks is It is expressed as: (2) Free fluid water (free water for short) is water in free fluid pores. It is stored in free fluid pores and can flow and be produced freely under normal formation pressure. In fully water-containing rocks, the volume of free fluid water is equal to the volume of free fluid pores.

[0045] In oil and gas-bearing rocks, part of the free water is replaced by oil and gas; micropore water, also known as capillary bound water, is formation water stored in tiny pore spaces. It cannot flow and be produced under normal formation pressure, and the volume of micropore water is equal to the volume of microcapillary pores; clay water is a part of water with special conductivity formed due to the cation exchange adsorption of clay. It cannot flow freely, and the volume of clay water is equal to the volume of clay pores.

[0046] Total water saturation in oil and gas bearing rocks It is the volume of the three types of water divided by the total pore volume, expressed as: (3) In the above formulas, is the resistivity of fully hydrated rock, is the resistivity of oil and gas bearing rock, , , They are free water resistivity, micropore water resistivity and clay water resistivity respectively; , , They are free fluid porosity, microcapillary porosity and clay water porosity, which are equal to the free water volume, micropore water volume and clay water volume in a unit volume of fully hydrated rock. , , They are the pore structure indices of free fluid pores, microcapillary pores and clay pores, also known as cementation index. , is the free fluid pore water saturation, Free water pores.

[0047] It should be noted that the resistivity of free water in rocks is the same as that of microporous water, and both belong to ionic conductivity. The resistivity is calculated mainly by directly measuring the formation water sample or analyzing the mineralization of the formation water, and calculating the formation water resistivity based on the mineralization. Among them, the value of the formation water resistivity is the same as that of the free water resistivity and the microporous water resistivity.

[0048] Furthermore, clay water resistivity can be calculated based on formation water salinity and formation temperature; Specifically, in the above step S2, the free water resistivity is calculated , micropore water resistivity and clay water resistivity The following steps are involved: Directly measure the formation water resistivity based on formation water sampling or analyze the mineralization of the formation water and calculate the formation water resistivity based on the mineralization; Calculation of clay water conductivity based on the first operation logic , the water conductivity of clay Take the reciprocal to calculate the clay water resistivity ; Among them, the formation water resistivity Free water resistivity , micropore water resistivity The first operation logic is expressed as: (4) in, is the water conductivity of clay, its unit is (S / m), for Diffusion factor of the ion diffusion layer Compensating ions in clay water The equivalent conductivity of a substance, its unit is (S / m)(mmol / L). The cation exchange capacity of clay is The pore volume occupied by clay water is related only to the formation temperature.

[0049] It is understandable that for a specific formation, the formation water salinity and formation temperature are basically constant, so and It can be considered as a constant. It can be calculated according to the following formula (5): According to the following formula (6), It is calculated according to the following formula (7).

[0050] (5) (6) (7) in, is the mineralization of formation water when the thickness of the clay surface diffusion layer is the minimum thickness, is the actual formation water mineralization, is the formation temperature in degrees Celsius (℃).

[0051] For example, formation water is used as The formation water is Water type: 6 water samples were collected, and the water analysis data are shown in Table 1. The average total mineralization of the water samples was 31248.5 mg / L, the average formation depth of the water samples was 2470 meters, the ground temperature was 18°C, and the geothermal gradient was 3.41°C / 100 meters. The formation water resistivity was calculated to be 0.075 (Ω·m) based on the conversion calculation software of formation water mineralization and formation water resistivity.

[0052] Table 1 Ion content and mineralization of water samples Unit: mg / L

[0053] In this embodiment, is the mineralization of the formation water when the thickness of the clay surface diffusion layer is the minimum thickness and is 0.35 mol / cm 3 , calculated according to NaCl solution, the equivalent mineralization is 20475 mg / L, is the actual formation water mineralization. According to the analytical data in Table 1, The average value of the equivalent NaCl mineralization is 30386 mg / L. ,therefore .

[0054] and Only the ground temperature Regarding the formation temperature The calculation is based on the stratum depth and the geothermal gradient. In this embodiment, the ground temperature is 18℃, and the geothermal gradient is 3.41℃ / 100m. , where H is the sampling depth point in meters.

[0055] In step S3, the free fluid porosity in the three-water conductive model is calculated based on the nuclear magnetic resonance logging response characteristics of fully water-bearing rocks. , Clay water porosity , microcapillary porosity The specific steps include: The fully water-bearing rock is determined based on the test oil and production data. In the fully water-bearing rock, the clay bound water volume, capillary bound water volume and movable water volume read from the NMR logging data processing and interpretation results are used as the clay water porosity in the three-water conductive model. , microcapillary porosity and free fluid porosity .

[0056] In this embodiment, the clay water porosity can be accurately calculated by making full use of nuclear magnetic resonance logging. , microcapillary porosity and free fluid porosity .

[0057] Specifically, refer to Figure 3 The NMR logging interpretation results are shown in the figure, in which the first data track is the depth track, the second data track is the lithology (logging) curve, the third data track is the NMR standard T2 spectrum, the fourth data track is the interval porosity distribution, the fifth data track is the permeability analysis, which is the resistivity logging value at different detection depths and the permeability calculated by NMR, the sixth data track is the saturation analysis, which is the water saturation and total porosity, effective porosity and capillary bound water porosity calculated by NMR logging, the seventh data track is the MRIAN analysis, which is the clay bound water volume, capillary bound water volume and movable water volume obtained after curve filling based on the calculation results of the sixth track, as well as the hydrocarbon volume calculated by the difference spectrum method, and the eighth data track is the interpretation conclusion of the NMR logging.

[0058] The clay water porosity read in the present invention is , microcapillary porosity and free fluid porosity These are the data for the seventh track in the figure, which are the clay bound water volume, capillary bound water volume and movable water volume of the seventh track.

[0059] Reading data for fully hydrated rock, Figure 3 Layers 93, 95, 96 and 97 are fully water-bearing rocks as verified by trial mining, and nuclear magnetic resonance fluid analysis also shows them to be fully water-bearing rocks.

[0060] Read depth, rock resistivity, clay water porosity at different depths within a fully water-bearing rock layer , microcapillary porosity and free fluid porosity At the same time, the formation temperature can be calculated according to step S2 , Clay water conductivity , see Table 2 below, which is a partial data example of the data points calculated by NMR logging of fully water-containing rocks.

[0061] Table 2. Calculated data points of NMR logging for fully water-bearing rocks (partial)

[0062] Furthermore, step S4 specifically includes the following steps: Select multiple fully water-bearing rocks, and obtain the clay water porosity, microcapillary porosity and free fluid porosity at multiple depth points for each fully water-bearing rock on the nuclear magnetic resonance interpretation result map; Determine the resistivity of the completely water-bearing rock corresponding to each depth point according to the resistivity logging curve, substitute it into the three-water conductive model, establish N equations, and form the first overdetermined equation group; The optimization algorithm of the least square method is used to solve the first overdetermined equations to calculate the cementation index. , , .

[0063] Specifically, N fully water-bearing rocks are selected, and the clay water porosity, microcapillary porosity and free fluid porosity values ​​at multiple depth points are obtained for each fully water-bearing rock on the NMR interpretation result map. At the same time, the resistivity corresponding to the N depth points is determined according to the resistivity logging curve. , , … In this way, the first overdetermined equation group is established as shown in formula (8).

[0064] Among them, the overdetermined system of equations has a unique least squares solution. The unknowns in the system of equations are solved by programming based on the least squares method. , , .

[0065] (8) For example, in this embodiment, the data in Table 2 are substituted into the calculation formula of the conductivity of completely water-bearing rock shown in formula (1), and the first overdetermined equation group in the form of formula (8) is obtained. The first overdetermined equation group is solved by the optimization algorithm of the least square method. Specifically, the solution can be solved by the method of Matlab programming, and finally the result is calculated. , , .

[0066] In this embodiment, based on the free fluid porosity, microcapillary porosity and clay water porosity calculated by nuclear magnetic resonance logging, combined with the resistivity of fully water-bearing rocks in conventional logging data, a large amount of sample data is used to establish a set of equations and an optimization method is used to solve the parameters of the three-water conductive model. , , , avoiding the limitation of having to rely on experimental data to determine model parameters.

[0067] Further, step S5 may include the following steps: Calculate the conventional logging parameters of fully water-bearing rock based on the conventional logging curve. The conventional logging parameters include at least: shale content , the total porosity of the formation , Permeability , Irreducible water saturation ; According to conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; Based on conventional logging parameters , , The expression formula and the cementation index calculated in step S4 , , , bring in the conductivity expression formula of the completely water-containing rock, and establish a clay water volume coefficient calculation model; The clay water volume coefficient is solved by using an optimization algorithm .

[0068] In this embodiment, nuclear magnetic resonance logging is used as a constraint condition, and the free fluid porosity, microcapillary porosity and clay water porosity obtained by nuclear magnetic resonance logging interpretation are substituted into the three-water conductivity model formula based on conventional logging parameter data, and combined with the porosity, mud content, bound water saturation and other parameters interpreted by conventional logging. At the same time, relying on the characteristics of the logging data itself as a large data sample, the optimization algorithm of multiple groups of data is used in parameter calculation to assist in improving the calculation accuracy, thereby avoiding the limitation of having to rely on experimental data to determine the model parameters.

[0069] Furthermore, step S5 further includes the following steps: According to the double water model, the cation exchange capacity The volume of clay water per unit pore volume ; Get cation exchange capacity With the mud content The ratio between and is defined as the clay water volume coefficient ; According to the total porosity And based on the clay water volume coefficient The volume of clay water per unit pore volume , the clay water porosity is obtained The expression formula of ; According to the irreducible water saturation , the microcapillary porosity is obtained The expression formula is: According to the total porosity The clay water porosity With the microcapillary porosity , obtain the free fluid porosity .

[0070] Specifically, the mud content can be calculated based on the natural gamma curve or the natural potential curve, and the calculation formula is: (9) In the formula, It can be a mud index, which can be calculated according to the following formula (10) or (11).

[0071] (10) (11) in, 、 are the natural potential and natural gamma logging values, 、 They are the natural potential and natural gamma of pure sandstone, 、 They are respectively the natural potential and natural gamma of pure mudstone, and c is the formation coefficient. For old formations, c=2, and for new formations, c=3.7.

[0072] In some embodiments, the total porosity It can be calculated based on the three-porosity logging values. First, it is necessary to perform cross-plot analysis based on the core measured porosity and the acoustic wave time difference, density and neutron porosity logging values ​​to determine the logging curve with the best correlation with the core porosity, and then use the fitting formula to calculate the porosity.

[0073] In this embodiment, the intersection diagram of the core porosity and the three porosity curves is as follows: Figure 4~Figure 6 It can be seen that the core porosity is more correlated with density and neutron porosity. Therefore, the porosity is calculated by combining density and neutron porosity, and the total porosity is obtained by multiple regression analysis. The calculation formula is: (12) in, Density logging value, unit: g / cm 3 , is the neutron porosity logging value, in %.

[0074] The above formula (12) is a fitting formula obtained based on the specific core and logging data in the embodiment. This application does not impose any restrictions on the formula for calculating porosity. In some other embodiments, other calculation formulas can be obtained based on the available core data.

[0075] In some embodiments, reference Figure 7 , permeability The calculation of can be obtained based on the porosity-permeability cross-plot of the core. The calculation formula is: (13) In formula (13), is the permeability, in units of , is the total porosity, and the unit in this formula is %. The calculation of permeability is not limited in this application, and in some other embodiments, other calculation formulas for permeability can also be obtained based on core data.

[0076] It is understandable that bound water saturation , generally related to the mud content Directly proportional to the rock properties and inversely proportional to the rock properties.

[0077] In some embodiments, cross-plot analysis can be performed based on the irreducible water saturation of the core obtained from the mercury injection experiment, and parameters such as shale content, porosity, and permeability ( Figure 8 , Fig. 9 ), the bound water saturation can be obtained The calculation formula is: (14) In the above formula (14), is the bound water saturation, in %, is the mud content, and the formula uses decimal units. is the permeability, in units of , is the total porosity of the formation, which is calculated using decimals in this formula.

[0078] It is understandable that the calculation of irreducible water saturation is not limited in the present application, and in other embodiments, other calculation formulas for irreducible water saturation can be obtained based on other data.

[0079] Step S5 also includes: calculating the free fluid porosity in the fully water-bearing rock according to conventional logging parameters , Clay water porosity , microcapillary porosity The calculation formula for .

[0080] Specifically, according to the clay water volume formula in the double water conductive model, the clay water volume per unit pore volume is expressed as: (15) In the formula, , The meaning is the same as in formula (4). The calculation method refers to formula (5) and formula (6). is the cation exchange capacity, related to the mud content is proportional to, where .

[0081] For the total porosity The strata, clay water porosity It can be expressed as: (16) in, is the total porosity of the formation, which can be calculated according to conventional logging curves such as neutron, density or sonic time difference as disclosed in the above embodiments. is the mud content, which can be calculated using the natural potential or natural gamma curve disclosed in the above embodiments. is the unknown variable to be solved in formula (16) and can be named the clay water volume coefficient.

[0082] It should be noted that both clay water and micropore water in the formation are bound water. The volume of micropore water can be calculated by subtracting the volume of clay water from the total bound water volume of the rock.

[0083] Therefore, the microcapillary porosity It is expressed as: (17) Among them, the formation bound water saturation It can be obtained by calculation through core data as disclosed in the aforementioned embodiments.

[0084] It should be noted that the core data mentioned in this article basically only include the most basic experiments such as porosity and permeability, and they are not necessary conditions and can also be calculated using well logging curves.

[0085] Free fluid porosity It is equal to the total rock porosity minus the porosity of all bound water (including clay water and micropore water): (18) Further, the data obtained based on conventional logging parameters in step S5 are , , The calculation formula of and the calculated value in step S4 according to the nuclear magnetic resonance and optimization algorithm , , , substitute the conductivity formula of fully water-containing rock (three-water conductive model), realize the constraint of nuclear magnetic resonance on conventional logging, and obtain the calculation model of clay water volume coefficient based on conventional logging: (19) In this embodiment, according to the idea of ​​conventional logging constrained by nuclear magnetic resonance, a set of data points identical to those in formula (8) is taken to calculate the total porosity, permeability, shale content and irreducible water saturation at each depth point according to the corresponding depth.

[0086] According to step S2, , and clay water resistivity and formation water resistivity , using the data points of the same well section and depth as in step S3, the data in Table 3 are obtained.

[0087] The data points in Table 3 and the data points calculated in step S4 based on the nuclear magnetic logging data are , , Substituting into formula (19), we get the clay water volume coefficient calculation model equation group expressed by conventional logging parameters, and calculate the coefficient using the least squares method: In this embodiment, the solution is realized by Matlab programming, and the .

[0088] Table 3 Conventional logging parameters for fully water-bearing rocks (partial)

[0089] In some embodiments, the free water saturation index in step S6 is The calculation of includes the following steps: According to the experimental data of oil-bearing cores, the water saturation and resistivity of different oil-bearing cores are obtained; Calculate the free fluid pore water saturation based on the water saturation ; The different resistivities and free fluid pore water saturation Substitute it into the saturation index calculation model to obtain a third overdetermined equation group; The third set of overdetermined equations is solved using an optimization algorithm to calculate the free water saturation index .

[0090] It is understandable that the water saturation of oil-bearing cores is the total water saturation. If the core is a closed core, the experimentally measured water saturation and core resistivity are directly used. If the core is a non-closed core, the experimentally measured water saturation must be volatilized and the core resistivity is taken according to the conventional logging curve.

[0091] In this embodiment, the oil saturation and water saturation of the core are volatilized and then the core depth is returned to obtain the conventional logging curve values ​​such as natural gamma, three-porosity, resistivity, etc. corresponding to each core. The corresponding conventional logging parameters are calculated according to the method in step 5, and the free fluid pore water saturation is calculated according to formula (3) using the total water saturation of the core to obtain the data in Table 4.

[0092] Furthermore, in the above step S6, the establishment of the saturation index calculation model includes the following steps: Perform depth correction on the oil-bearing cores obtained to obtain conventional logging curves corresponding to the depth of each oil-bearing core; Conventional logging parameters are calculated based on the conventional logging curve. The conventional logging parameters include at least: total porosity Clay content , Permeability , Irreducible water saturation ; According to conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; Based on conventional logging parameters , , The expression formula of and the cementation index calculated in step S4 , , and the clay water volume coefficient calculated in step S5 , put it into the calculation formula of the conductivity of oil and gas-bearing rocks, and establish the saturation index calculation model of the following formula (20): (20) Specifically, by substituting the data in Table 4 into the saturation index calculation model represented by formula (20), the third overdetermined equation group of the three-water conductivity model of oil-bearing rocks can be obtained. The free water saturation index is calculated using the least squares optimization algorithm. In this embodiment, the solution is obtained by Matlab programming. .

[0093] Table 4 Conventional logging data of oil-bearing cores (partial)

[0094] Step S7 may obtain a calculation formula for water saturation according to the various models established in steps S1 to S6 and the various parameters calculated, and may include the following steps: According to the saturation index calculation model, the free fluid pore water saturation is obtained The calculation formula of The calculated cementation index , , , clay water volume coefficient and free water saturation index , substitute The calculation formula of Calculate conventional logging parameters according to the conventional logging curve, and convert the Convert to total pore water saturation and calculate water saturation .

[0095] Specifically, according to the saturation index calculation model, the free fluid pore water saturation is obtained The calculation formula is: (twenty one) The free fluid pore water saturation is calculated according to formula (21) using conventional logging parameters. , and based on conventional logging parameters, it is converted into the water saturation of total pores according to the following formula (22): : (twenty two) Specifically, the values ​​calculated in steps S4 to S6 are , , , and And conventional logging parameters calculated from conventional logging curves: total porosity Clay content , Irreducible water saturation Substituting the resistivity logging value into formula (21), the free fluid pore water saturation of all reservoirs in the entire well can be calculated.

[0096] According to formula (22), the free fluid pore water saturation Convert to total pore water saturation , thereby realizing the identification of oil and gas layers and the quantitative calculation of oil and gas reserves.

[0097] In this embodiment, the total water saturation is calculated according to the above method, and the oil saturation is obtained based on this, and then a curve is drawn, such as Fig.10 shown. Fig.10 The first channel is the lithology logging curve (including natural potential SP, natural gamma GR and wellbore curve ), the second is the porosity logging curve (including density curve and acoustic time difference curve AC), the third is the array induction curve, the fourth is the depth channel, the fifth is the logging lithology profile, the sixth is the mud content and porosity calculated based on conventional logging, the seventh is the interpretation result of nuclear magnetic resonance logging, the green filling is the clay water volume, the gray with oblique lines is the microcapillary water volume, the blue filling is the movable water volume, the eighth is the total water saturation and oil saturation calculated based on the three-water conductive model, the blue filling indicates the movable water saturation in the total pores, and the red filling indicates the oil saturation in the total pores. The ninth track is the test layer, and the several test layers in the figure are all oil and water in the same layer. The thirteenth track is the clay water, micropore water and free water volume calculated based on the three-water conductive model, and the filling type is the same as the seventh track.

[0098] Continue to refer Fig.10 , the 10th track is the total water saturation interpreted by NMR logging, the 11th track is the water saturation calculated using the parallel conductivity formula for argillaceous sandstone, and the 12th track is the water saturation calculated using the Archie formula. The Archie formula is the most commonly used formula for calculating water saturation in conventional argillaceous sandstone reservoirs, and the formula is as follows: (twenty three) In formula (23), is water saturation, in decimal units, which can be converted to %; is the formation water resistivity, in ohm·meter (Ω·m); is the formation resistivity (resistivity of oil and gas-bearing rock), in ohm-meter (Ω·m); a and b are lithology coefficients, which are generally taken as 1; m is the cementation index, and n is the saturation index. m and n are obtained based on rock electrical data or take the empirical coefficient of 2.

[0099] For strata with more mud, the parallel conductivity formula of muddy sandstone is often used to calculate water saturation. The formula is as follows: (twenty four) In formula (24), is water saturation, in decimal units, which can be converted to %; is the formation water resistivity, in ohm-meter; Formation resistivity, in ohm-meter; a and b are lithology coefficients, generally taken as 1; m is the cementation index, n is the saturation index, m and n are obtained based on rock electrical data or take the empirical coefficient of 2; is the mud content, which is calculated in decimal units; is the resistivity of mud, in ohm-meter.

[0100] from Fig.10 It can be seen that for several test layers in this layer section, the oil saturation calculated by the three-water conductive model is distributed in the range of 30%-80%, and the water saturation is distributed in the range of 20%-70%. At the same time, there is a certain amount of movable water, which belongs to the same layer of oil and water, which is consistent with the test results.

[0101] Specifically, according to the data in Tracks 8, 10, 11, and 12 in the figure, it can be seen that the water saturation calculated by this method (Track 8 The curve) is more consistent with the water saturation interpreted by nuclear magnetic resonance (track 10). As the most advanced and high-precision logging method, the interpretation results of nuclear magnetic resonance are considered to be the most consistent with the actual formation. However, the calculation results of the existing Archie formula and the parallel conductivity formula of argillaceous sandstone are less consistent with the nuclear magnetic water saturation than the calculation results of this method.

[0102] Fig.10 The saturation calculation results of the oil-bearing layer in the middle are shown in Table 5, where "relative error 1" represents the water saturation calculated by the three-water conductive model of this method. NMR water saturation The relative error of (water saturation interpreted by NMR) is calculated as (water saturation of three-water model - water saturation of NMR) / water saturation of NMR * 100%. "Relative error 2" is the water saturation calculated by Archie's formula. NMR water saturation The relative error is calculated in the same way as above. “Relative error 3” is the water saturation calculated by the parallel conductive formula for argillaceous sandstone. NMR water saturation The relative error of , it can also be seen from the data in Table 5 that the overall relative error of the calculation results of this method is the smallest.

[0103] Table 5 Calculation results analysis data table (partial)

[0104] It should be noted that the main purpose of the present invention is to provide an innovative idea and a specific method. In the absence of experimental data, water saturation is calculated with the assistance of nuclear magnetic resonance and optimization algorithm. The accuracy of the calculation result depends on the data situation. When the optimization algorithm is used to solve the model parameters, the accuracy of the calculation result is closely related to the selected data points and the amount of data.

[0105] The method for calculating the parameters of the three-water conductive model based on conventional logging constrained by nuclear magnetic resonance provided by the present invention makes full use of the advantage of nuclear magnetic resonance logging that can accurately calculate the free fluid porosity, microcapillary porosity and clay water porosity, adopts conventional logging constrained by nuclear magnetic resonance, and uses a large amount of sample data to establish a set of equations and adopts an optimization method to solve them, on the one hand, avoiding the limitation of having to completely rely on experimental data to determine the model parameters, and on the other hand, relying on the constraints of nuclear magnetic resonance logging and the optimization algorithm, improving the calculation accuracy of the model parameters, thereby more accurately calculating the water saturation of the reservoir. The present invention effectively solves the limitation that the parameters of the three-water conductive model must currently be determined by relying on a large amount of experimental data such as mercury injection, rock electrical experiments, clay analysis, cation exchange capacity, etc., and can still obtain more accurate model parameters in the absence of experimental data, thereby improving the calculation accuracy of the water saturation of complex reservoirs.

[0106] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for calculating parameters of three-water conductive model based on conventional logging constrained by nuclear magnetic resonance, characterized in that: The following steps are involved: Step S1, establishing a three-water conductive model of rock based on the multi-medium parallel conductive theory, and obtaining a calculation formula for the conductivity of completely water-containing rock and oil and gas-containing rock; Step S2: Calculate the free water resistivity for the three-water conductive model of fully water-bearing rock and oil- and gas-bearing rock , micropore water resistivity and clay water resistivity ; Step S3: Calculate the free fluid porosity in the three-water conductive model based on the nuclear magnetic resonance logging response characteristics of the fully water-bearing rock. , Clay water porosity , microcapillary porosity ; Step S4: calculate the water content of the plurality of fully water-bearing rocks based on nuclear magnetic resonance logging. , , , substitute the three-water conductive model to establish the first overdetermined equation group, and apply the optimization algorithm to iteratively solve it to calculate the cementation index of free water , cementation index of micropore water and the cementation index of clay water ; Step S5: Apply nuclear magnetic resonance logging to constrain conventional logging curves, establish a clay water volume coefficient calculation model for the completely water-bearing rock based on conventional logging parameters according to the conductivity of the completely water-bearing rock, and calculate the clay water volume coefficient. ; Step S6: Establish a saturation index calculation model for oil and gas-bearing rocks based on conventional logging parameters according to the electrical conductivity of the oil and gas-bearing rocks, and calculate the free water saturation index according to the saturation data of the oil-bearing core. ; Step S7: Calculate the cementation index according to the saturation index calculation model and calculation , , , the clay water volume coefficient and the free water saturation index , using conventional logging curves to calculate water saturation .

2. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The conductivity of the fully hydrated rock for: （1） The electrical conductivity of the oil and gas bearing rock It is expressed as: （2） in, is the resistivity of the fully hydrated rock, is the resistivity of the oil and gas bearing rock, , is the free fluid pore water saturation, Free water pores.

3. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The step S2 comprises the following steps: Directly measuring the resistivity of formation water according to formation water sampling or performing mineralization analysis on the formation water and calculating the resistivity of the formation water according to the mineralization; Calculation of clay water conductivity based on the first operation logic , and according to the clay water conductivity Calculate the clay water resistivity ; Wherein, the formation water resistivity The free water resistivity , the micropore water resistivity The value of is the same, the first operation logic is expressed as: in, for The diffusion factor of the ion diffusion layer, Compensating ions for clay water The equivalent conductivity of The cation exchange capacity of clay is The pore volume occupied by water in clay.

4. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The step S3 comprises the following steps: The completely water-bearing rock is determined according to the test oil and production data, and the clay bound water volume, capillary bound water volume and movable water volume in the nuclear magnetic resonance logging data processing and interpretation result map are used as the clay water porosity in the three-water conductive model. , the microcapillary porosity and the free fluid porosity .

5. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The step S4 comprises the following steps: Selecting a plurality of said completely water-bearing rocks, and obtaining clay water porosity, microcapillary porosity and free fluid porosity at a plurality of depth points for each of said completely water-bearing rocks on a nuclear magnetic resonance interpretation result map; Determine the resistivity of the completely water-bearing rock corresponding to each of the depth points according to the resistivity logging curve, and establish N equations to form the first overdetermined equation group; The optimization algorithm of the least square method is used to solve the first overdetermined equations to calculate the cementation index. , , .

6. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The step S5 comprises the following steps: The conventional logging parameters of the completely water-bearing rock are calculated according to the conventional logging curve, and the conventional logging parameters at least include: , the total porosity of the formation , Permeability , Irreducible water saturation ; According to the conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; The conventional logging parameters are used to obtain , , The expression formula and the cementation index calculated in step S4 , , , bring in the conductivity expression formula of the completely water-containing rock, and establish the calculation model of the clay water volume coefficient; The clay water volume coefficient is solved by using an optimization algorithm .

7. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 6, characterized in that: The step S5 further comprises the following steps: Get cation exchange capacity With the mud content The ratio between the two is defined as the clay water volume coefficient ; According to the total porosity And based on the clay water volume coefficient The volume of clay water per unit pore volume , the clay water porosity is obtained The expression formula of ; According to the irreducible water saturation , the microcapillary porosity is obtained The expression formula is: According to the total porosity , the clay water porosity With the microcapillary porosity , obtain the free fluid porosity .

8. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The free water saturation index The calculation of includes the following steps: According to the experimental data of oil-bearing cores, the water saturation and resistivity of different oil-bearing cores are obtained; Based on the water saturation, calculate the free fluid pore water saturation ; The different resistivities and free fluid pore water saturation Substitute into the saturation index calculation model to obtain a third overdetermined equation group; The free water saturation index is calculated by solving the third overdetermined equations according to the optimization algorithm. .

9. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 7, characterized in that: The establishment of the saturation index calculation model comprises the following steps: Performing depth correction on the oil-bearing cores obtained to obtain a conventional logging curve corresponding to the depth of each oil-bearing core; The conventional logging parameters are calculated based on the conventional logging curve, and the conventional logging parameters at least include: total porosity , mud content , Permeability , Irreducible water saturation ; According to the conventional logging parameters, the free fluid porosity in the three-water conductive model is obtained. , Clay water porosity , microcapillary porosity The expression formula of ; The conventional logging parameters are used to obtain , , The expression formula and the cementation index calculated in step S4 , , , bring into the calculation formula of the electrical conductivity of the oil and gas bearing rock, and establish a saturation index calculation model.

10. The method for calculating parameters of the three-water conductive model based on conventional well logging constrained by nuclear magnetic resonance according to claim 1, characterized in that: The water saturation The calculation of includes the following steps: According to the saturation index calculation model, the free fluid pore water saturation is obtained. The calculation formula of The calculated cementation index , , , the clay water volume coefficient and the free water saturation index , substitute the The calculation formula of Calculate conventional logging parameters according to the conventional logging curve, and convert the Convert to total pore water saturation and calculate water saturation .

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