A method, device, equipment and medium for calculating water saturation in well logging

Abstract

The present application discloses a method, device, equipment, and medium for calculating well logging water saturation, relating to the technical field of geological research for oil and gas field exploration and development. The method comprises the following steps: pre-processing a well logging curve of a tight sandstone reservoir with a composite structure of fractures and pores, calculating fracture parameter information based on the processed curve; correcting the deep lateral resistivity value in the processed curve to obtain a corrected resistivity value; calculating a target exchange coefficient and a core resistivity increase rate; determining a well logging cementation index based on the fracture parameter information and the target exchange coefficient, classifying reservoir types, fitting the core water saturation and resistivity increase rate of different reservoir types, and obtaining fitting results; obtaining a well logging saturation index and a well logging lithology coefficient based on the Archie formula and the fitting results, and determining the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient. Thus, the well logging water saturation can be accurately calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of geological research on oil and gas field exploration and development, and in particular to a method, device, equipment and medium for calculating water saturation in well logging. Background Art

[0002] Tight sandstone gas reservoirs are important unconventional gas reservoirs in the world, and accurate evaluation of their reservoir water saturation is crucial for reserve calculation and production capacity prediction. However, the traditional Archie formula is less applicable in unconventional reservoirs such as tight sandstone, mainly because these reservoirs have poor physical properties, strong heterogeneity, diverse pore types, and complex pore structures, which lead to the emergence of "non-Archie" phenomena. To solve this problem, researchers have proposed a variety of methods, such as dual-porosity models, three-porosity medium conductivity models, models based on rock conductivity efficiency theory, and digital core technology. However, existing calculation methods are mainly based on homogeneous media or simple dual-media models, and fail to fully consider the interaction between fractures and different types of pore structures, resulting in large deviations between the calculation results and the actual situation. Summary of the Invention

[0003] In light of this, the present invention aims to provide a method, device, equipment, and medium for calculating water saturation in well logging. These methods fully account for the complex interactions between fractures and different types of pore structures, effectively quantifying the impact of fractures on reservoir pore structure, and thus more accurately describing the actual reservoir conditions. This improves the accuracy of water saturation calculations and provides a solid foundation for more accurate reserve assessment and production capacity forecasting. The specific implementation is as follows:

[0004] In a first aspect, the present application discloses a method for calculating water saturation in well logging, comprising:

[0005] Preprocessing the logging curve of the tight sandstone reservoir with composite fractures and pores to obtain a corresponding processed curve, and calculating fracture parameter information based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity;

[0006] Correcting the deep lateral resistivity value in the processed curve using the parameter information of the crack to obtain a corrected resistivity value;

[0007] Calculating a target exchange coefficient and a resistivity increase rate of the core based on the core of the tight sandstone reservoir with composite fractures and pores; the target exchange coefficient is the exchange coefficient for fluid exchange between the fractures and the matrix;

[0008] Determining a logging cementation index based on the fracture parameter information and the target exchange coefficient, classifying reservoir types using the target exchange coefficient, and fitting the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results;

[0009] The well logging saturation index and the well logging lithology coefficient are obtained according to the Archie formula and the fitting result, and the well logging water saturation is determined based on the corrected resistivity value, the well logging cementation index, the well logging saturation index and the well logging lithology coefficient.

[0010] Optionally, the pre-processing of the logging curve of the tight sandstone reservoir with composite fractures and pores to obtain the corresponding processed curve includes:

[0011] The well logging curve is offset-corrected using the core of the tight sandstone reservoir with composite fractures and pores to obtain a corrected curve; the well logging curve includes any one or a combination of natural gamma ray logging curve, sonic time difference logging curve, deep lateral resistivity logging curve, shallow lateral resistivity logging curve, compensated neutron porosity logging curve and formation microresistivity scanning imaging logging curve;

[0012] visually inspecting the corrected curve to remove erroneous data or spikes from the corrected curve to obtain a removed curve;

[0013] Processing the outliers and / or missing values ​​in the removed curve data to obtain an initial processed curve;

[0014] The data of the initial post-processing curves of different magnitude sequences were converted into the same magnitude sequences conforming to the standard normal distribution by Z-score normalization to obtain post-processing curves.

[0015] Optionally, calculating the parameter information of the crack according to the processed curve includes:

[0016] performing denoising processing on the formation microresistivity scanning imaging logging curve to obtain a denoised curve;

[0017] enhancing the display effect of cracks in the denoised curve based on image enhancement technology to obtain an enhanced curve;

[0018] Cracks are identified based on the enhanced curves, and sinusoidal curve fitting is performed on each identified crack through Hough transform to obtain a plurality of corresponding sinusoidal function curves. Parameter information of the cracks is calculated based on the sinusoidal function curves.

[0019] Optionally, the correcting the deep lateral resistivity value in the processed curve using the parameter information of the fracture to obtain the corrected resistivity value includes:

[0020] measuring an electric current flowing through a core of the porous composite tight sandstone reservoir;

[0021] determining a first product between the current and a cross-sectional area of ​​the core, and determining a second product between a distance between parallel plate electrodes and a voltage across the core;

[0022] determining core resistivity based on a ratio of the second product to the first product;

[0023] Determining the depth of the core of the tight sandstone reservoir with composite fractures and pores to determine the deep lateral resistivity value in the logging curve corresponding to the depth;

[0024] Obtaining a calculation formula for calculating parameter information of the fracture using the core resistivity and the deep lateral resistivity values ​​based on multiple linear regression;

[0025] The deep lateral resistivity value is corrected based on the calculation formula using a resistivity correction formula to obtain the corrected resistivity value; the resistivity correction formula is:

[0026] ;

[0027] in, is the corrected resistivity value; is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

[0028] Optionally, the calculation of the target exchange coefficient and the resistivity increase rate of the core based on the core of the tight sandstone reservoir with composite fractures and pores includes:

[0029] Conducting an imbibition experiment on the core of the tight sandstone reservoir with composite fractures and pores to obtain measurement data; the measurement data includes total porosity and permeability of the core, imbibition volume, imbibition time, contact area, and capillary pressure;

[0030] Performing an outlier elimination operation and a temperature correction operation on the measurement data to obtain corresponding processed data;

[0031] The target exchange coefficient is calculated based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is:

[0032] ;

[0033] Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, and t is the imbibition time. is the capillary pressure, k is the permeability, and n is the total porosity;

[0034] Conducting rock electrical experiments on the core of the fracture and pore composite tight sandstone reservoir to obtain experimentally determined rock water saturation, experimentally determined saturation index, and experimentally determined lithology coefficients;

[0035] Determine a calculation result using the experimentally determined rock water saturation as a base and the experimentally determined saturation index as an index;

[0036] The resistivity increase rate of the core is determined based on the ratio of the experimentally determined lithology coefficient to the calculation result.

[0037] Optionally, determining the logging cementation index according to the fracture parameter information and the target exchange coefficient includes:

[0038] The logging cementation index is determined according to the parameter information of the fracture and the target exchange coefficient using a logging cementation index determination formula; the logging cementation index is:

[0039] ;

[0040] in, is the well logging cementation index; is the total porosity of the core; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma ray logging curve value in the logging curve; is the regression coefficient.

[0041] Optionally, determining the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient includes:

[0042] The well logging water saturation is determined based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient using a well logging water saturation determination formula; the well logging water saturation determination formula is:

[0043] ;

[0044] in, is the water saturation of the well logging; is the well logging cementation index; is the corrected resistivity value; is the total porosity of the core; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

[0045] In a second aspect, the present application discloses a well logging water saturation calculation device, comprising:

[0046] A parameter information calculation module is used to pre-process the logging curve of the tight sandstone reservoir with a composite fracture and pore structure, obtain the corresponding processed curve, and calculate the parameter information of the fracture based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity;

[0047] a resistivity value correction module, configured to correct the deep lateral resistivity value in the processed curve using the parameter information of the crack to obtain a corrected resistivity value;

[0048] a calculation module for calculating a target exchange coefficient and a resistivity increase rate of the core based on the core of the tight sandstone reservoir with composite fractures and pores; the target exchange coefficient is the exchange coefficient for fluid exchange between the fractures and the matrix;

[0049] a fitting module, configured to determine a logging cementation index based on the fracture parameter information and the target exchange coefficient, classify reservoir types using the target exchange coefficient, and perform fitting on the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results;

[0050] The well logging water saturation determination module is used to obtain the well logging saturation index and the well logging lithology coefficient according to the Archie formula and the fitting result, and to determine the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index and the well logging lithology coefficient.

[0051] In a third aspect, the present application discloses an electronic device, comprising:

[0052] memory for storing computer programs;

[0053] The processor is used to execute the computer program to implement the above-mentioned well logging water saturation calculation method.

[0054] In a fourth aspect, the present application discloses a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for calculating water saturation in well logging as described above is implemented.

[0055] The present application first pre-processes the logging curve of the tight sandstone reservoir with a composite of fractures and pores to obtain the corresponding processed curve, and calculates the parameter information of the fracture based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity; the deep lateral resistivity value in the processed curve is corrected using the fracture parameter information to obtain the corrected resistivity value; based on the core of the tight sandstone reservoir with a composite of fractures and pores, the target exchange coefficient and the resistivity increase rate of the core are calculated; the target exchange coefficient is The exchange coefficient for fluid exchange between the fracture and the matrix; determining the logging cementation index based on the parameter information of the fracture and the target exchange coefficient, and using the target exchange coefficient to classify the reservoir type, respectively fitting the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results; obtaining the logging saturation index and the logging lithology coefficient based on the Archie formula and the fitting results, and determining the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient. It can be seen that this application effectively quantifies the impact of fractures on reservoir structure and optimizes resistivity measurement and parameter calculation methods by introducing the exchange coefficient for fluid exchange between the fracture and the matrix and comprehensively analyzing logging curves, formation microresistivity scanning imaging, and core experimental data. By comprehensively considering the impact of fractures on reservoir structure, the problem of poor applicability of the traditional Archie formula in unconventional reservoirs is effectively solved, and the accuracy of water saturation calculation is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0057] Figure 1 This is a flow chart of a method for calculating water saturation in well logging disclosed in this application;

[0058] Figure 2 This is a schematic diagram of a comprehensive characterization of cracks disclosed in this application;

[0059] Figure 3 This is a schematic diagram of the calculation results of the multivariate regression optimization logging cementation index disclosed in this application;

[0060] Figure 4 This is a schematic structural diagram of a well logging water saturation calculation device disclosed in this application;

[0061] Figure 5This is a structural diagram of an electronic device disclosed in this application. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 efforts are within the scope of protection of the present invention.

[0063] Existing calculation methods, primarily based on homogeneous media or simple dual-media models, fail to fully consider the interaction between fractures and different types of pore structures, leading to significant deviations between calculated results and actual conditions. To address these technical issues, this application discloses a well logging water saturation calculation method, apparatus, equipment, and medium. These methods fully account for the complex interactions between fractures and different types of pore structures, effectively quantifying the impact of fractures on reservoir pore structure and thereby more accurately describing the reservoir's actual conditions. This improves the accuracy of water saturation calculations and provides a solid foundation for more accurate reserve assessments and production capacity forecasts.

[0064] See also Figure 1 As shown, an embodiment of the present invention discloses a method for calculating water saturation in well logging, comprising:

[0065] Step S11, pre-processing the logging curve of the tight sandstone reservoir with a composite fracture and pore structure to obtain a corresponding processed curve, and calculating fracture parameter information based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity.

[0066] In this example, due to geological factors and the influence of the logging instrument, the well logging curves exhibit depth offsets. Furthermore, the range of the same logging data varies across different wells, impacting subsequent identification accuracy. To eliminate the influence of the logging instrument itself and ensure data reliability, the well logging curve data requires preprocessing. First, core and logging curve data of a tight sandstone reservoir with a composite of fractures and pores are obtained; then, the logging curve is offset-corrected using the core of the tight sandstone reservoir with a composite of fractures and pores to obtain a corrected curve; the logging curve includes any one or a combination of natural gamma ray logging curve (GR), acoustic time difference logging curve (AC), deep lateral resistivity logging curve (RD), shallow lateral resistivity logging curve (RS), compensated neutron porosity logging curve (CNL) and formation microresistivity scanning imaging logging curve (FMI); the corrected curve is visually inspected to remove erroneous data or spikes from the corrected curve to obtain a removed curve; outliers and / or missing values ​​in the removed curve data are processed to obtain an initial processed curve; and data of the initial processed curve of different order of magnitude sequences are converted into sequences of the same order of magnitude that conform to a standard normal distribution through Z-score normalization to obtain a processed curve.

[0067] After preprocessing the logging curve, the formation microresistivity scanning imaging logging data in the logging curve is used to identify fractures and calculate fracture parameter information, where the parameter information includes fracture tendency, fracture dip angle, , crack length , crack width , crack density and fracture porosity ,like Figure 2 As shown. The formation microresistivity scanning imaging logging curve is subjected to denoising processing to remove the cluttered signals caused by instrument noise, wellbore interference and other factors, thereby improving the signal-to-noise ratio of the data; based on image enhancement techniques such as contrast adjustment and filtering, the display effect of the cracks in the denoised curve is enhanced to obtain the enhanced curve; the enhanced formation microresistivity scanning imaging logging data (enhanced curve) is used to complete the identification of the crack morphology and obtain the identified cracks; the Hough transform method is used to fit the sine curve to each of the identified cracks, converting them into multiple sine function curves, and calculating the crack parameter information based on the sine function curve. Among them, the fracture porosity The calculation formula is:

[0068] ;

[0069] in, is the crack density (number of cracks per meter); is the average crack width per meter; is the average fracture length per meter, and V is the core volume per meter.

[0070] Step S12: Correcting the deep lateral resistivity value in the processed curve using the parameter information of the crack to obtain a corrected resistivity value.

[0071] In this embodiment, the parameter information of the fracture is used to calculate the deep lateral resistivity value in the pre-processed logging curve. For the tight sandstone reservoir with composite fractures and pores, the fractures in the reservoir are relatively developed. When formation water with a certain salinity or drilling mud, mud filtrate and other low-resistivity liquids invade and fill the fractures and pores, it will cause the deep lateral resistivity value of the logging curve to The obvious decrease is consistent with the actual resistivity of the formation There is a large error, so it is necessary to calculate the deep lateral resistivity value in the logging curve of the tight sandstone reservoir with composite fractures and pores. Specifically, the core of the tight sandstone reservoir with a composite of fractures and pores is placed between a pair of parallel plate electrodes with a constant voltage, the current flowing through the core is measured, and the true core resistivity is calculated. , and its calculation formula is:

[0072] ;

[0073] Where U is the voltage across the core, L is the distance between the electrodes, I is the current flowing through the core, and O is the cross-sectional area of ​​the core.

[0074] Read the core depth of the tight sandstone reservoir with composite fractures and pores, and obtain the deep lateral resistivity value in the logging curve at the corresponding depth , using the multivariate linear regression method, the deep lateral resistivity value is obtained Compared with the true core resistivity The calculation formula for the parameter information of the crack is as follows:

[0075] ;

[0076] in, is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

[0077] Finally, the deep lateral resistivity value in the pre-processed logging curve is corrected using a multivariate linear regression formula. , get the corrected resistivity value That is, the deep lateral resistivity value is corrected based on the calculation formula using the resistivity correction formula to obtain the corrected resistivity value. ; The resistivity correction formula is:

[0078] ;

[0079] in, is the corrected resistivity value; is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

[0080] In this way, the present application effectively reduces the measurement error caused by the low-resistivity fluid filling the fracture by considering the fracture parameter information.

[0081] Step S13: Calculating a target exchange coefficient and a resistivity increase rate of the core based on the core of the tight sandstone reservoir with composite fractures and pores; the target exchange coefficient is the exchange coefficient for fluid exchange between the fractures and the matrix.

[0082] In this example, we first used the core of the tight sandstone reservoir with a composite fracture and pore structure to conduct an imbibition experiment, calculated the fracture-matrix fluid exchange coefficient F, and characterized the fluid exchange at different spatial scales. Specifically, we first pre-processed the sample, cleaned the cylindrical core sample, and then The samples were dried to constant weight, and basic parameters such as dry weight and size were measured and recorded. The experimental environment temperature and relative humidity were kept stable, and the total porosity of the core of the composite tight sandstone reservoir with fractures and pores was measured using the helium method. and permeability k. Simulated formation water was prepared according to the density, viscosity, and water type of the formation water in the study area; the experimental environment temperature and relative humidity were kept stable, the sample was suspended below the balance and kept 1-3 mm above the liquid surface, and the imbibition volume Q, imbibition time t, contact area B, and capillary pressure were recorded every 30 seconds from 0 to 2 hours, every 2 minutes from 2 to 5 hours, and every 5 minutes after 5 hours. The data is processed until the imbibition is stable. The measured data is subjected to outlier removal and temperature correction, and the fracture-matrix fluid exchange coefficient F is calculated. That is, the target exchange coefficient is calculated based on the processed data according to the target exchange coefficient determination formula; the target exchange coefficient determination formula is:

[0083] ;

[0084] Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, and t is the imbibition time. is the capillary pressure, k is the permeability, and n is the total porosity.

[0085] It should be noted that each set of experiments mentioned above needs to be repeated 3 times or more to ensure data reliability.

[0086] Afterwards, a rock electrical experiment was conducted on the core of the said fracture and pore composite tight sandstone reservoir to obtain the resistivity increase rate and formation factors of all core samples. A rock electrical experiment was conducted on the core of the said fracture and pore composite tight sandstone reservoir to obtain the experimentally determined rock water saturation, the experimentally determined saturation index and the experimentally determined lithology coefficient; the calculation result with the experimentally determined rock water saturation as the base and the experimentally determined saturation index as the index was determined; the resistivity increase rate of the core was determined according to the ratio of the experimentally determined lithology coefficient to the calculation result. More specifically, the core of the said fracture and pore composite tight sandstone reservoir was subjected to oil and salt washing by solution extraction method, and then dried to constant weight at 105°C, and the dry weight and resistivity of the core were measured. Formation water was configured, and simulated formation water samples were configured according to the mineralization and water type of the formation water in the study area, and the formation water resistivity was measured. Then, the core was immersed in the simulated formation water sample under a pressure of 30 MPa for more than 24 hours, and the wet weight of the core was measured using an electronic balance. At a constant pressure and temperature, the resistivity of the core was measured using a standard resistance detection system when it was 100% water-containing. Use a micro pump to press kerosene into the soaked core. Use a metering tube to determine the amount of water displaced from the core, thereby determining the water saturation of the core. Simultaneously, measure the corresponding resistance. Each time the water saturation of the core changes, measure the resistance of the core until no water is displaced from the core. The electrical parameters can be calculated using Archie's formula, where:

[0087] ;

[0088] ;

[0089] Among them, H is the formation factor; is the formation water resistivity; is the measured resistivity of oil and gas cores; To experimentally determine the lithology coefficient; is the total porosity of the core; is the experimentally determined cementation index; E is the resistance increase rate; To determine the water saturation of rocks for experiments; Determine the saturation index for the experiment.

[0090] Step S14: determining the logging cementation index based on the fracture parameter information and the target exchange coefficient, and using the target exchange coefficient to classify the reservoir type, respectively fitting the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results.

[0091] In this embodiment, the logging cementation index is determined according to the parameter information of the fracture and the target exchange coefficient using a logging cementation index determination formula; the logging cementation index is:

[0092] ;

[0093] in, is the well logging cementation index; is the total porosity of the core; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma ray logging curve value in the logging curve; is the regression coefficient.

[0094] Specifically, the parameter information of the fracture and the fracture-matrix fluid exchange coefficient F are used to calculate the well logging cementation index using a multivariate stepwise regression algorithm. The specific implementation steps are: let a = 1 to obtain the experimental cementation index of all samples The characteristic of this method is that all the pore structure information is concentrated on the cementation index, so that the calculated cementation index can not only reflect the pore structure, but also facilitate the selection when processing well data; the sampling depth of all samples in the study area is corrected for core position; the correlation between the experimental cementation index m1 and the logging curve, porosity, permeability and the fracture-matrix fluid exchange coefficient F is statistically analyzed, and the parameters with a correlation coefficient greater than 0.5 between the two are removed to avoid multicollinearity problems; the parameters with the best correlation coefficient with the logging cementation index are selected from the remaining parameters through the multivariate stepwise regression method. Sensitive parameters with significant influence, among which sensitive parameters refer to the logging cementation index Variables with significant influence are selected as input features of the formula in the multivariate stepwise regression process; the actual application effect of the formula is evaluated and the logging cementation index is calculated through the model Experimental cementation index For comparison, such as Figure 3 As shown, if the absolute coefficient is greater than 0.8, the model is output; if the absolute coefficient is less than the threshold, the model is rebuilt; the logging cementation index is output The explanation formula established by the multivariate stepwise regression algorithm is:

[0095] ;

[0096] It should be noted that the actual sensitive parameters need to be determined based on the specific data and the results of multivariate stepwise regression analysis. The parameters listed above are based on the information commonly contained in geological and well logging data and may vary in actual applications.

[0097] The fracture-matrix fluid exchange coefficient F is then used to classify different reservoir types. The relationship between core water saturation and resistivity increase coefficient is fitted for each reservoir type to obtain corresponding fitting results. The fracture-matrix fluid exchange coefficient F is used to classify reservoir types into three categories: fracture-dominated, intermediate-complex, and pore-dominated, representing the varying degrees of influence of fractures. In a specific embodiment, the fracture-dominated fitting formula is: ; The intermediate composite fitting formula is: The pore-dominated fitting formula is: .

[0098] As can be seen, this application optimizes the calculation of the well logging cementation index through a multivariate stepwise regression model, classifies reservoir types based on the fracture-matrix fluid exchange coefficient, and determines the well logging saturation index and lithology coefficient, respectively. This parameter optimization method significantly improves the accuracy of resistivity measurements and related parameter calculations, laying a more reliable data foundation for subsequent water saturation calculations.

[0099] Step S15: Obtain the logging saturation index and the logging lithology coefficient according to the Archie formula and the fitting result, and determine the logging water saturation based on the corrected resistivity value, the logging cementation index, the logging saturation index and the logging lithology coefficient.

[0100] In this embodiment, the corresponding well logging saturation index is obtained by using the resistivity increase coefficient formula in the Archie formula in the above steps and the fitting results. and logging lithology coefficient Then, the well logging water saturation is determined based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient using a well logging water saturation determination formula; the well logging water saturation determination formula is:

[0101] ;

[0102] in, is the water saturation of the well logging; is the well logging cementation index; is the corrected resistivity value; is the total porosity of the core; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

[0103] In a specific embodiment, the final well logging water saturation calculation formula is:

[0104] ;

[0105] By comparing the water saturation values ​​measured on actual cores, the proposed water saturation model for well logging of tight sandstone reservoirs with composite fractures and pores has smaller relative and absolute errors than traditional methods. It is more applicable to dual-media reservoirs than the Archie formula method, and the average calculation error is reduced by 44.72%, as shown in Table 1:

[0106] Table 1

[0107]

[0108] As can be seen, this application not only utilizes conventional well logging data but also leverages multiple data sources, including core test data and formation microresistivity scanning imaging logging data. Through comprehensive analysis and processing of this data, including well logging preprocessing, fracture identification and parameter extraction, imbibition experiments, and rock electrical experiments, the present invention establishes a more comprehensive and accurate water saturation calculation model. This multi-source data integration approach significantly improves the model's applicability and accuracy, enabling it to better cope with complex geological conditions.

[0109] In summary, the present application first pre-processes the logging curve of the tight sandstone reservoir with a composite of fractures and pores to obtain the corresponding processed curve, and calculates the parameter information of the fracture according to the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity; uses the parameter information of the fracture to correct the deep lateral resistivity value in the processed curve to obtain the corrected resistivity value; calculates the target exchange coefficient and the resistivity increase rate of the core based on the core of the tight sandstone reservoir with a composite of fractures and pores; the target exchange coefficient The number is the exchange coefficient for fluid exchange between the fracture and the matrix; the logging cementation index is determined based on the fracture parameter information and the target exchange coefficient, and the reservoir type is divided using the target exchange coefficient. The core water saturation and the resistivity increase rate of different reservoir types are fitted to obtain corresponding fitting results; the logging saturation index and the logging lithology coefficient are obtained based on the Archie formula and the fitting results, and the logging water saturation is determined based on the corrected resistivity value, the logging cementation index, the logging saturation index, and the logging lithology coefficient. It can be seen that by introducing the exchange coefficient for fluid exchange between the fracture and the matrix, the present application effectively quantifies the impact of fractures on reservoir structure and optimizes resistivity measurement and parameter calculation methods through comprehensive analysis of logging curves, formation microresistivity scanning imaging, and core experimental data. By comprehensively considering the impact of fractures on reservoir structure, the poor applicability of the traditional Archie formula in unconventional reservoirs is effectively resolved, and the accuracy of water saturation calculation is improved.

[0110] See also Figure 4 As shown, an embodiment of the present invention discloses a well logging water saturation calculation device, comprising:

[0111] The parameter information calculation module 11 is used to pre-process the logging curve of the tight sandstone reservoir with a composite fracture and pore structure, obtain the corresponding processed curve, and calculate the parameter information of the fracture based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity;

[0112] a resistivity value correction module 12, configured to correct the deep lateral resistivity value in the processed curve using the parameter information of the fracture to obtain a corrected resistivity value;

[0113] A calculation module 13 is configured to calculate a target exchange coefficient and a resistivity increase rate of the core of the tight sandstone reservoir with a composite fracture and pore structure; the target exchange coefficient is an exchange coefficient for fluid exchange between the fracture and the matrix;

[0114] A fitting module 14 is configured to determine a logging cementation index based on the fracture parameter information and the target exchange coefficient, classify reservoir types using the target exchange coefficient, and perform fitting on the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results.

[0115] The well logging water saturation determination module 15 is used to obtain the well logging saturation index and the well logging lithology coefficient according to the Archie formula and the fitting result, and determine the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index and the well logging lithology coefficient.

[0116] This paper, by introducing the exchange coefficient for fluid exchange between fractures and the matrix and comprehensively analyzing well logging curves, formation microresistivity scanning imaging, and core test data, effectively quantifies the impact of fractures on reservoir structure and optimizes resistivity measurement and parameter calculation methods. By comprehensively considering the impact of fractures on reservoir structure, the paper effectively addresses the poor applicability of the traditional Archie formula in unconventional reservoirs and improves the accuracy of water saturation calculations.

[0117] In some specific embodiments, the parameter information calculation module 11 can be specifically used to use the core of the fracture and pore composite tight sandstone reservoir to perform offset correction on the logging curve to obtain a corrected curve; the logging curve includes any one or a combination of natural gamma ray logging curve, acoustic time difference logging curve, deep lateral resistivity logging curve, shallow lateral resistivity logging curve, compensated neutron porosity logging curve and formation microresistivity scanning imaging logging curve; the corrected curve is visually inspected to remove erroneous data or peaks of the corrected curve to obtain a removed curve; outliers and / or missing values ​​in the removed curve data are processed to obtain an initial processed curve; the data of the initial processed curve of different order of magnitude sequences are converted into the same order of magnitude sequence that conforms to the standard normal distribution through Z-score normalization to obtain a processed curve.

[0118] In some specific embodiments, the parameter information calculation module 11 can be specifically used to denoise the formation microresistivity scanning imaging logging curve to obtain a denoised curve; enhance the display effect of cracks in the denoised curve based on image enhancement technology to obtain an enhanced curve; identify cracks based on the enhanced curve, fit the identified cracks with a sine curve through Hough transform to obtain several corresponding sinusoidal function curves, and calculate the parameter information of the cracks based on the sinusoidal function curves.

[0119] In some specific embodiments, the resistivity value correction module 12 can be specifically used to measure the current flowing through the core of the porous composite tight sandstone reservoir; determine a first product between the current and the cross-sectional area of ​​the core, and determine a second product between the distance between the parallel plate electrodes and the voltage at both ends of the core; determine the core resistivity based on the ratio of the second product to the first product; determine the depth of the core of the porous composite tight sandstone reservoir to determine the deep lateral resistivity value in the logging curve corresponding to the depth; obtain a calculation formula for calculating parameter information of the fracture using the core resistivity and the deep lateral resistivity value based on multiple linear regression; use a resistivity value correction formula to correct the deep lateral resistivity value based on the calculation formula to obtain the corrected resistivity value; the resistivity value correction formula is:

[0120] ;

[0121] in, is the corrected resistivity value; is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

[0122] In some specific embodiments, the calculation module 13 can be specifically used to perform an imbibition experiment on the core of the fracture and pore composite tight sandstone reservoir to obtain measurement data; the measurement data includes the total porosity and permeability of the core, the imbibition volume, the imbibition time, the contact area, and the capillary pressure; the measurement data is subjected to an outlier removal operation and a temperature correction operation to obtain corresponding processed data; the target exchange coefficient is calculated based on the processed data according to a target exchange coefficient determination formula; the target exchange coefficient determination formula is:

[0123] ;

[0124] Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, and t is the imbibition time. is the capillary pressure, k is the permeability, and n is the total porosity;

[0125] A rock electrical experiment is conducted on the core of the fracture and pore composite tight sandstone reservoir to obtain experimentally determined rock water saturation, experimentally determined saturation index and experimentally determined lithology coefficient; a calculation result with the experimentally determined rock water saturation as the base and the experimentally determined saturation index as the exponent is determined; and the resistivity increase rate of the core is determined based on the ratio of the experimentally determined lithology coefficient to the calculation result.

[0126] In some specific embodiments, the fitting module 14 may be specifically configured to determine the logging cementation index according to the fracture parameter information and the target exchange coefficient using a logging cementation index determination formula; the logging cementation index is:

[0127] ;

[0128] in, is the well logging cementation index; is the total porosity of the core; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma ray logging curve value in the logging curve; is the regression coefficient.

[0129] In some specific embodiments, the well logging water saturation determination module 15 can be specifically configured to determine the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient using a well logging water saturation determination formula; the well logging water saturation determination formula is:

[0130] ;

[0131] in, is the water saturation of the well logging; is the well logging cementation index; is the corrected resistivity value; is the total porosity of the core; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

[0132] Furthermore, the embodiment of the present application also discloses an electronic device, Figure 5 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content in the diagram should not be considered as any limitation to the scope of application of the present application.

[0133] Figure 5This is a schematic diagram of the structure of an electronic device 20 provided in an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the relevant steps of the well logging water saturation calculation method disclosed in any of the aforementioned embodiments. Furthermore, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0134] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and the external device. The communication protocol it follows is any communication protocol that can be applied to the technical solution of this application and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world. Its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0135] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or CD, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0136] The operating system 221 is used to manage and control the hardware devices and computer program 222 on the electronic device 20. The operating system 221 can be Windows Server, NetWare, Unix, Linux, etc. In addition to including a computer program capable of implementing the well logging water saturation calculation method performed by the electronic device 20 as disclosed in any of the aforementioned embodiments, the computer program 222 can further include computer programs capable of performing other specific tasks.

[0137] Furthermore, this application discloses a computer-readable storage medium for storing a computer program. When executed by a processor, the computer program implements the aforementioned method for calculating well logging water saturation. The specific steps of this method can be found in the corresponding contents disclosed in the aforementioned embodiments and will not be further described here.

[0138] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0139] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0140] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0141] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0142] The above is a detailed introduction to the technical solution provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for calculating water saturation in well logging, characterized in that: include: Preprocessing the logging curve of the tight sandstone reservoir with composite fractures and pores to obtain a corresponding processed curve, and calculating fracture parameter information based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity; Correcting the deep lateral resistivity value in the processed curve using the parameter information of the crack to obtain a corrected resistivity value; The target exchange coefficient and the resistivity increase rate of the core of the fracture-pore composite tight sandstone reservoir are calculated based on the core; the target exchange coefficient is the exchange coefficient for fluid exchange between the fracture and the matrix; wherein the target exchange coefficient is determined by the formula: ； Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, and t is the imbibition time. is the capillary pressure, k is the permeability, and n is the total porosity; Determining a logging cementation index based on the fracture parameter information and the target exchange coefficient, classifying reservoir types using the target exchange coefficient, and fitting the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results; The well logging saturation index and the well logging lithology coefficient are obtained according to the Archie formula and the fitting result, and the well logging water saturation is determined based on the corrected resistivity value, the well logging cementation index, the well logging saturation index and the well logging lithology coefficient.

2. The method for calculating water saturation in well logging according to claim 1, wherein: The pre-processing of the logging curve of the tight sandstone reservoir with composite fractures and pores to obtain the corresponding processed curve includes: The well logging curve is offset-corrected using the core of the tight sandstone reservoir with composite fractures and pores to obtain a corrected curve; the well logging curve includes any one or a combination of natural gamma ray logging curve, sonic time difference logging curve, deep lateral resistivity logging curve, shallow lateral resistivity logging curve, compensated neutron porosity logging curve and formation microresistivity scanning imaging logging curve; visually inspecting the corrected curve to remove erroneous data or spikes from the corrected curve to obtain a removed curve; Processing the outliers and / or missing values ​​in the removed curve data to obtain an initial processed curve; The data of the initial post-processing curves of different magnitude sequences were converted into the same magnitude sequences conforming to the standard normal distribution by Z-score normalization to obtain post-processing curves.

3. The method for calculating water saturation in well logging according to claim 2, wherein: The calculating of the parameter information of the crack according to the processed curve includes: performing denoising processing on the formation microresistivity scanning imaging logging curve to obtain a denoised curve; enhancing the display effect of cracks in the denoised curve based on image enhancement technology to obtain an enhanced curve; Cracks are identified based on the enhanced curves, and sinusoidal curve fitting is performed on each identified crack through Hough transform to obtain a plurality of corresponding sinusoidal function curves. Parameter information of the cracks is calculated based on the sinusoidal function curves.

4. The method for calculating water saturation in well logging according to claim 1, wherein: The method of correcting the deep lateral resistivity value in the processed curve using the parameter information of the fracture to obtain the corrected resistivity value includes: measuring an electric current flowing through a core of the porous composite tight sandstone reservoir; determining a first product between the current and a cross-sectional area of ​​the core, and determining a second product between a distance between parallel plate electrodes and a voltage across the core; determining core resistivity based on a ratio of the second product to the first product; Determining the depth of the core of the tight sandstone reservoir with composite fractures and pores to determine the deep lateral resistivity value in the logging curve corresponding to the depth; Obtaining a calculation formula for calculating parameter information of the fracture using the core resistivity and the deep lateral resistivity values ​​based on multiple linear regression; The deep lateral resistivity value is corrected based on the calculation formula using a resistivity correction formula to obtain the corrected resistivity value; the resistivity correction formula is: ； in, is the corrected resistivity value; is the deep lateral resistivity value; is the crack inclination; is the crack length; is the crack width; is the fracture porosity; c, d, h, f, g are the multivariate fitting coefficients.

5. The method for calculating water saturation in well logging according to claim 1, wherein: The calculation of the target exchange coefficient and the resistivity increase rate of the core based on the core of the tight sandstone reservoir with composite fractures and pores includes: An imbibition experiment is performed on the core of the tight sandstone reservoir with a composite fracture and pore structure to obtain measurement data; the measurement data includes total porosity and permeability of the core, imbibition volume, imbibition time, contact area, and capillary pressure; Performing an outlier elimination operation and a temperature correction operation on the measurement data to obtain corresponding processed data; Calculating a target exchange coefficient based on the processed data according to a target exchange coefficient determination formula; Conducting rock electrical experiments on the core of the tight sandstone reservoir with composite fractures and pores to obtain experimentally determined rock water saturation, experimentally determined saturation index, and experimentally determined lithology coefficients; Determine a calculation result using the experimentally determined rock water saturation as a base and the experimentally determined saturation index as an index; The resistivity increase rate of the core is determined based on the ratio of the experimentally determined lithology coefficient to the calculation result.

6. The method for calculating water saturation in well logging according to claim 1, wherein: Determining the logging cementation index according to the parameter information of the fracture and the target exchange coefficient includes: The logging cementation index is determined according to the parameter information of the fracture and the target exchange coefficient using a logging cementation index determination formula; the logging cementation index is: ； in, is the well logging cementation index; is the total porosity of the core; is the corrected resistivity value; F is the target exchange coefficient; AC is the acoustic transit time logging curve value in the logging curve; K is the core permeability; GR is the natural gamma ray logging curve value in the logging curve; is the regression coefficient.

7. The method for calculating water saturation in well logging according to any one of claims 1 to 6, characterized in that: The determining of the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient includes: The well logging water saturation is determined based on the corrected resistivity value, the well logging cementation index, the well logging saturation index, and the well logging lithology coefficient using a well logging water saturation determination formula; the well logging water saturation determination formula is: ； in, is the well logging water saturation; is the well logging cementation index; is the corrected resistivity value; is the total porosity of the core; is the formation water resistivity; is the logging lithology coefficient; is the logging saturation index.

8. A well logging water saturation calculation device, characterized in that: include: A parameter information calculation module is used to pre-process the logging curve of the tight sandstone reservoir with a composite fracture and pore structure, obtain the corresponding processed curve, and calculate the parameter information of the fracture based on the processed curve; the parameter information includes fracture tendency, fracture dip, fracture length, fracture width, fracture density and fracture porosity; a resistivity value correction module, configured to correct the deep lateral resistivity value in the processed curve using the parameter information of the crack to obtain a corrected resistivity value; A calculation module is used to calculate a target exchange coefficient and a resistivity increase rate of the core based on the core of the tight sandstone reservoir with a composite fracture and pore structure; the target exchange coefficient is the exchange coefficient for fluid exchange between the fracture and the matrix; wherein the target exchange coefficient is determined by the formula: ； Wherein, F is the target exchange coefficient; Q is the imbibition volume, A is the fluid viscosity, B is the contact area, and t is the imbibition time. is the capillary pressure, k is the permeability, and n is the total porosity; a fitting module, configured to determine a logging cementation index based on the fracture parameter information and the target exchange coefficient, classify reservoir types using the target exchange coefficient, and perform fitting on the core water saturation and the resistivity increase rate of different reservoir types to obtain corresponding fitting results; The well logging water saturation determination module is used to obtain the well logging saturation index and the well logging lithology coefficient according to the Archie formula and the fitting result, and to determine the well logging water saturation based on the corrected resistivity value, the well logging cementation index, the well logging saturation index and the well logging lithology coefficient.

9. An electronic device, characterized in that: include: memory for storing computer programs; A processor, configured to execute a computer program to implement the steps of the method for calculating water saturation in well logging according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that A computer program is stored on a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method for calculating water saturation in well logging according to any one of claims 1 to 7 are implemented.

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