A method, device, equipment, storage medium and computer program for determining a lower limit of reservoir physical properties

Abstract

The present disclosure relates to the technical field of well logging methods and techniques, and particularly relates to a method and device for determining a lower limit of reservoir physical properties, equipment, a storage medium and a computer program. The method comprises: obtaining a core sample and a reservoir sample to be determined; performing data measurement on the core sample by using a preset phase permeability experiment to obtain sample basic data and dynamic porosity; making a scatter plot by using the sample basic data and the dynamic porosity; performing linear fitting on the scatter plot to obtain a porosity lower limit and a permeability lower limit of the core sample; performing reservoir classification on the reservoir sample to be determined by using the porosity lower limit and the permeability lower limit of the core sample to obtain an effective reservoir; performing data verification on the effective reservoir to obtain a verification result; and if the verification result is passed, performing conversion processing on the lower limit of reservoir physical properties of the core sample to obtain the lower limit of reservoir physical properties of the reservoir sample to be determined.

Description

Technical Field

[0001] This disclosure relates to the field of logging methods and technologies, and in particular to a method, apparatus, equipment, storage medium, and computer program for determining the lower limit of reservoir properties. Background Technology

[0002] The lower limit of reservoir physical properties refers to the minimum physical properties of rocks required for the effective storage and flow of oil and gas in oil and gas reservoirs. It includes parameters such as the lower limit of porosity and the lower limit of permeability. Determining these lower limits is crucial for the exploration, development, and assessment of oil and gas resources. By measuring and analyzing rock samples, combined with various experiments and models, determining the lower limits of reservoir physical properties can help identify which reservoirs have economic exploitation value, providing a key basis for the rational development of oil and gas fields and avoiding resource waste and ineffective development.

[0003] In existing technologies, to obtain the lower limit of reservoir properties, the following methods are commonly used: 1) Core porosity-permeability cross-plot method, which determines the lower limit of properties by using the inflection point where the curve changes drastically; 2) Empirical statistical method, which determines the lower limit of properties based on the proportion of energy loss by using the cumulative frequency and cumulative energy storage diagram of porosity and permeability; 3) Mercury intrusion porosimetry method, which draws a cross-plot of porosity, permeability and displacement pressure, and determines the lower limit of properties by the inflection point of the curve.

[0004] However, traditional methods have significant uncertainties in determining the lower limits of physical properties of low-porosity and low-permeability carbonate reservoirs. Traditional dynamic analysis methods also fail to fully utilize the relative permeability curves of core samples to accurately determine the lower limits of reservoir physical properties. Both methods result in significant uncertainties in determining the lower limits of physical properties of low-porosity and low-permeability carbonate reservoirs. Summary of the Invention

[0005] This disclosure provides a method, apparatus, device, storage medium, and computer program for determining the lower limit of reservoir properties, in order to address the problem of significant uncertainty in determining the lower limit of properties of low-porosity, low-permeability carbonate reservoirs.

[0006] In a first aspect, this disclosure provides a method for determining the lower limit of reservoir properties, including: obtaining a core sample and a reservoir sample to be determined, and using a preset relative permeability experiment to measure the data of the core sample to obtain basic sample data and dynamic porosity;

[0007] A scatter plot was created using the basic sample data and the dynamic porosity.

[0008] Linear fitting was performed on the scatter plot to obtain the lower limits of porosity and permeability of the core sample;

[0009] The lower limits of porosity and permeability of the core samples are used to divide the reservoir samples to be determined into effective reservoirs.

[0010] The effective reservoir was verified using data, and the verification results were obtained.

[0011] If the verification result is successful, the lower limit of reservoir properties of the core sample is converted to obtain the lower limit of reservoir properties of the reservoir sample to be determined.

[0012] In some embodiments, the step of measuring data from the core sample using a preset relative permeability experiment to obtain basic sample data and dynamic porosity includes:

[0013] Measure the core volume, core length, and core cross-sectional area of ​​the core sample;

[0014] The injection volume of formation water was obtained by measuring the injection rate of the core sample.

[0015] The formation water flow rate was obtained by measuring the flow rate of the water-saturated core.

[0016] The viscosity of the water-saturated core was measured to obtain the core viscosity.

[0017] The permeability of the core sample was calculated based on the formation water flow, core viscosity, core length, and core cross-sectional area.

[0018] The porosity of the core sample is calculated based on the core volume and the injected formation water volume.

[0019] The injection volume and overflow volume of simulated oil were measured after the core sample was injected with formation water to obtain the overflow volume of formation water and the injection volume of simulated oil.

[0020] The remaining formation water volume of the core sample is calculated based on the injected formation water volume and the overflow formation water volume.

[0021] The bound water saturation of the core sample is calculated based on the remaining formation water volume and the injected formation water volume.

[0022] The volume of spilled simulated oil was obtained by measuring the amount of oil that overflowed after the core sample was injected with simulated oil and then injected with formation water.

[0023] The remaining simulated oil volume is calculated based on the injected simulated oil volume and the overflow simulated oil volume.

[0024] The residual oil saturation is calculated based on the remaining simulated oil volume and the injected formation water volume.

[0025] The porosity and permeability are combined into basic sample data;

[0026] The dynamic porosity is calculated based on the porosity, bound water saturation, and residual oil saturation.

[0027] In some embodiments, the step of creating a scatter plot using the sample baseline data and the dynamic porosity includes:

[0028] A porosity scatter plot is established using the porosity of the basic sample data and the dynamic porosity as coordinates.

[0029] The porosity scatter points are plotted to obtain a porosity scatter plot.

[0030] A permeability scatter plot is established using the permeability and dynamic porosity of the sample's basic data as coordinates.

[0031] The permeability scatter points are plotted to obtain a permeability scatter plot;

[0032] The porosity scatter plot and the permeability scatter plot are combined into a scatter plot.

[0033] In some embodiments, the linear fitting of the scatter plot to obtain the lower limits of porosity and permeability of the core sample includes:

[0034] A porosity straight line is obtained by linearly fitting the porosity scatter points in the porosity scatter plot of the scatter plot cross plot.

[0035] The lower limit of porosity is obtained by setting the dynamic porosity coordinates of the porosity line to zero.

[0036] A linear fit is performed on the permeability scatter points in the permeability scatter plot of the scatter plot to obtain a permeability straight line.

[0037] By setting the dynamic porosity coordinate of the permeability line to zero, the lower limit of permeability is obtained.

[0038] In some embodiments, the step of using the lower limit of porosity and the lower limit of permeability of the core sample to delineate the reservoir to be determined, thereby obtaining effective reservoirs, includes:

[0039] Data surveys were conducted on the reservoir sample to be identified to obtain the conventional porosity and conventional permeability of the reservoir sample.

[0040] By using the lower limit of porosity to screen reservoirs with conventional porosity, reservoirs with porosity higher than the lower limit of porosity are obtained.

[0041] By using the lower permeability limit to screen reservoirs with conventional permeability, reservoirs with permeability higher than the lower permeability limit are obtained.

[0042] The effective reservoir is obtained by performing an intersection operation on the reservoirs that are above the lower limit of porosity and the reservoirs that are above the lower limit of permeability.

[0043] In some embodiments, the step of performing data verification on the effective reservoir to obtain verification results includes:

[0044] The effective reservoirs are used to classify the reservoir samples to be determined, thereby obtaining ineffective reservoirs;

[0045] The effective reservoir is verified by perforation through a pre-set perforation, and the verification result of the effective reservoir is obtained.

[0046] If the effective reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is increased to obtain an increased lower limit of reservoir properties.

[0047] The reservoir sample to be determined is divided into reservoirs by increasing the lower limit of reservoir properties to obtain additional effective reservoirs, and the reservoir sample to be determined is classified by increasing the effective reservoirs to obtain additional ineffective reservoirs.

[0048] If the valid reservoir verification result is passed, then the invalid reservoir is verified by performing invalid perforation through a preset perforation to obtain the invalid reservoir verification result;

[0049] If the invalid reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is reduced to obtain a lower limit of reservoir physical properties.

[0050] The reservoir sample to be determined is divided into reservoirs by using the method of reducing the lower limit of reservoir properties to obtain the effective reservoirs;

[0051] The reservoir samples to be determined are screened by reducing the effective reservoirs to obtain reduced ineffective reservoirs, and the reservoir samples to be determined are classified by reducing the ineffective reservoirs to obtain reduced effective reservoirs.

[0052] If the invalid reservoir verification result is passed, the verification result is passed, and the lower limit of the reservoir properties of the reservoir sample to be determined is obtained.

[0053] Secondly, this disclosure provides a device for determining the lower limit of reservoir properties, including: a sample measurement module for acquiring core samples and reservoir samples to be determined, and using a preset relative permeability experiment to measure data of the core samples to obtain basic sample data and dynamic porosity;

[0054] The scatter plotting module is used to generate scatter plots using the sample basic data and the dynamic porosity.

[0055] The linear fitting module is used to perform linear fitting on the scatter plot to obtain the lower limit of porosity and lower limit of permeability of the core sample.

[0056] The reservoir delineation module is used to delineate the reservoir sample to be determined using the lower limit of porosity and the lower limit of permeability of the core sample, so as to obtain effective reservoirs.

[0057] The data verification module is used to verify the data of the effective reservoir and obtain the verification results;

[0058] The lower limit determination module is used to convert the lower limit of reservoir properties of the core sample into the lower limit of reservoir properties of the sample to be determined if the verification result is passed.

[0059] Thirdly, this disclosure provides a computer device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method for determining the lower limit of reservoir properties as described in the above aspects.

[0060] Fourthly, this disclosure provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for determining the lower limit of reservoir properties described above.

[0061] Fifthly, this disclosure provides a computer program product, including a computer program / instructions, which, when executed by a processor, implements the steps of the method for determining the lower limit of reservoir properties as described above.

[0062] This disclosure provides a method, apparatus, equipment, storage medium, and computer program for determining the lower limit of reservoir properties. It utilizes a pre-set relative permeability experiment to obtain basic data such as static porosity and permeability. By simulating the alternating injection process of oil and formation water, it calculates bound water saturation and residual oil saturation, and further obtains dynamic porosity. By establishing porosity and permeability scatter plots, it can visually present the overall distribution of porosity and dynamic porosity data for all core samples. The lower limit of porosity is obtained through linear fitting, simplifying the reservoir evaluation process and improving work efficiency. It avoids unnecessary investment and development in areas that do not meet the lower limit requirements, thereby rationally allocating resources and improving efficiency. The economic benefits and success rate of exploration and development; determining the effective reservoirs of the reservoir samples to be identified through data comparison can improve the efficiency and success rate of oil and gas exploration and development; verifying the lower limit of reservoir properties through perforation, if the verification of an effective reservoir fails, the lower limit of properties can be raised and reclassified; if it passes, the invalid reservoir is verified, and if it fails, the lower limit of properties can be lowered and reclassified, until the verification result is successful. This repeated verification and adjustment can effectively avoid inaccurate reservoir assessment due to a single judgment error, improve the scientificity and reliability of reservoir classification, and provide a more realistic reservoir property basis for subsequent oil and gas development. This scheme makes full use of the relative permeability curves of the core to accurately determine the lower limit of reservoir properties, which is helpful in determining the lower limit of properties of low-porosity and low-permeability carbonate rock reservoirs. Attached Figure Description

[0063] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0064] Figure 1 A flowchart illustrating a method for determining the lower limit of reservoir properties provided in this embodiment of the disclosure;

[0065] Figure 2 A correlation diagram of dynamic porosity and porosity in an oilfield provided as an embodiment of this disclosure for a method to determine the lower limit of reservoir properties;

[0066] Figure 3 A correlation diagram of dynamic porosity and permeability in an oilfield provided as an embodiment of this disclosure for a method to determine the lower limit of reservoir properties;

[0067] Figure 4 This is a functional block diagram of a device for determining the lower limit of reservoir properties provided in an embodiment of this disclosure.

[0068] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0069] To enable those skilled in the art to better understand the technical solutions of this disclosure, and to fully understand and implement the process of how this disclosure applies technical means to solve technical problems and achieve corresponding technical effects, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. The embodiments of this disclosure and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort should fall within the protection scope of this disclosure.

[0070] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0071] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0072] The embodiments are not copies or restates of the claims. Their purpose is to help examiners understand the technical solution and its effects by describing the application scenario. Especially for overly abstract technical solutions, specific embodiments are needed to help examiners quickly and correctly understand the technical solution. The application scenarios for the embodiments can be various, but they are all typical. For example, ordinary application scenarios, complex application scenarios, etc. Specific data should be attached when necessary to illustrate the technical effects.

[0073] Example 1

[0074] Figure 1 This is a flowchart illustrating a method for determining the lower limit of reservoir properties, provided as an embodiment of this disclosure. Figure 1 As shown, a method for determining the lower limit of reservoir properties includes:

[0075] S1. Obtain core samples and reservoir samples to be determined, and use a preset relative permeability experiment to measure the data of the core samples to obtain basic sample data and dynamic porosity.

[0076] In this embodiment of the invention, the core sample is a key sample used for preliminary experiments and analysis. Basic data and dynamic porosity that reflect reservoir characteristics are obtained through a pre-set relative permeability experiment, which facilitates subsequent data analysis. The reservoir sample to be determined is the reservoir for which the lower limit of reservoir properties needs to be determined. The relative permeability experiment refers to the determination of basic sample data such as permeability, porosity, bound water saturation, and residual oil saturation, as well as dynamic porosity, based on the characteristics of mutual permeation of different fluids (usually oil and water) in the rock.

[0077] In this embodiment of the invention, the step of using a preset relative permeability experiment to measure data from the core sample to obtain basic sample data and dynamic porosity includes:

[0078] Measure the core volume, core length, and core cross-sectional area of ​​the core sample;

[0079] The injection volume of formation water was obtained by measuring the injection rate of the core sample.

[0080] The formation water flow rate was obtained by measuring the flow rate of the water-saturated core.

[0081] The viscosity of the water-saturated core was measured to obtain the core viscosity.

[0082] The permeability of the core sample was calculated based on the formation water flow, core viscosity, core length, and core cross-sectional area.

[0083] The porosity of the core sample is calculated based on the core volume and the injected formation water volume.

[0084] The injection volume and overflow volume of simulated oil were measured after the core sample was injected with formation water to obtain the overflow volume of formation water and the injection volume of simulated oil.

[0085] The remaining formation water volume of the core sample is calculated based on the injected formation water volume and the overflow formation water volume.

[0086] The bound water saturation of the core sample is calculated based on the remaining formation water volume and the injected formation water volume.

[0087] The volume of spilled simulated oil was obtained by measuring the amount of oil that overflowed after the core sample was injected with simulated oil and then injected with formation water.

[0088] The remaining simulated oil volume is calculated based on the injected simulated oil volume and the overflow simulated oil volume.

[0089] The residual oil saturation is calculated based on the remaining simulated oil volume and the injected formation water volume.

[0090] The porosity and permeability are combined into basic sample data;

[0091] The dynamic porosity is calculated based on the porosity, bound water saturation, and residual oil saturation.

[0092] In this embodiment of the invention, the injection of formation water is mainly achieved by simulating the fluid injection process under formation conditions to obtain various physical properties of the core sample under different fluid states; the basic physical dimensions of the core sample are measured, including core volume, core length, and core cross-sectional area; formation water is injected, and the injection volume is recorded to obtain the injected formation water volume; flow rate measurement is based on fluid mechanics principles; under water-saturated core conditions, the formation water flow rate is determined by measuring the volume of formation water flowing through the core per unit time; the flow rate reflects the core's ability to allow fluid to pass through, and this ability is influenced by a combination of factors such as the core pore structure and fluid properties; viscosity determination is based on the principle of internal friction of fluids. For formation water or simulated oil in the core sample, its viscosity reflects the magnitude of internal frictional resistance between fluid molecules. Under certain temperature and pressure conditions, when the fluid flows, frictional forces that hinder relative motion are generated between adjacent fluid layers. The viscosity of the fluid is determined by measuring the magnitude of this frictional force.

[0093] In this embodiment of the invention, the permeability calculation is based on Darcy's law, which describes the relationship between the flow rate of fluid through a porous medium and the permeability of the medium, the viscosity of the fluid, the pressure difference across the medium, and the geometry (length and cross-sectional area) of the medium under laminar flow conditions; it can be achieved using the following formula:

[0094] Q = (kAΔP) / (μL)

[0095] Where Q is the formation water flow rate, k is the permeability, A is the cross-sectional area of ​​the core, and L is the length of the core. The permeability can be obtained by substituting the known values ​​into the formula. Porosity is the ratio of the pore volume in a rock to the total volume of the rock. When formation water is injected into a core sample, assuming that the formation water can fill the pore part of the core (under ideal conditions), then the volume of the injected formation water is approximately equal to the pore volume in the core sample. By comparing this pore volume with the total volume of the core (i.e., the core volume), the porosity can be obtained. It reflects the degree of development of the pore space inside the core sample. That is, porosity is equal to the volume of injected formation water divided by the core volume.

[0096] In this embodiment of the invention, injecting simulated oil after injecting formation water refers to simulating the actual situation of oil-water coexistence in an oil reservoir. In the reservoir environment, formation water and oil coexist, and their distribution and mutual displacement process in rock pores are crucial for understanding the characteristics of the reservoir. By first injecting formation water to saturate the core and then injecting simulated oil, the displacement process of oil on water in the reservoir can be simulated, thereby studying the distribution changes, saturation changes, and interactions of oil and water in the core pores. After the formation water injection is completed and the core is saturated with formation water, simulated oil is injected into the core sample, and the volume of overflowing formation water and injected simulated oil are recorded simultaneously. In the actual reservoir environment, the displacement process of oil and water is mutual. The oil-water displacement process has already been simulated, and the injection of formation water after the injection of simulated oil is to simulate the water-oil displacement process. This reverse displacement process can better reflect the actual situation of the water-driven oil displacement stage during reservoir development, helping us understand the ease with which oil is displaced by water in the core pores and the distribution of remaining oil.

[0097] In this embodiment of the invention, bound water saturation is used to measure the proportion of pore space occupied by oil-bound water that cannot be displaced in the pores of a core sample under reservoir conditions. During the process of injecting formation water followed by simulated oil, the relative content of the water bound by oil in the pore space is determined by comparing the total volume of injected formation water with the volume of formation water remaining after the injection of simulated oil. The bound water saturation is equal to the remaining formation water volume divided by the injected formation water volume.

[0098] In this embodiment of the invention, the overflow simulated oil volume is the amount of oil displaced during water flooding by injecting formation water. For example, if the injected simulated oil volume is V1 and the overflow simulated oil volume is V2, then the remaining simulated oil volume V3 = V1 - V2. Residual oil saturation refers to the proportion of the remaining oil volume in the core pores to the total pore volume after a certain displacement process (in this case, water flooding). Residual oil saturation is equal to the remaining simulated oil volume divided by the injected formation water volume. The collection of data can more comprehensively depict the basic physical properties of the core sample, providing a basis for subsequent comprehensive analysis of reservoir characteristics. The calculation of dynamic porosity is based on the dynamic changes in the pore space of the core sample during the oil-water displacement process, and can be achieved using the following formula:

[0099] Φd = por × (1 - Swi - Sor)

[0100] Where por is porosity, Swi is bound water saturation, and Sor is residual oil saturation.

[0101] In detail, the fluid injection process under simulated formation conditions is used to obtain various physical parameters of the core sample under different fluid states. First, the core volume, core length, and core cross-sectional area of ​​the core sample are measured. Then, the injection volume of formation water is measured to obtain the injected formation water volume. Formation water is injected, and the injection volume is recorded simultaneously to obtain the injected formation water volume. With the core saturated with water, the formation water flow rate is determined by measuring the volume of formation water flowing through the core per unit time. Based on the principle of internal fluid friction, the friction force of the formation water in the core sample is measured, and the viscosity of the fluid is determined by measuring the magnitude of the friction force. The permeability is calculated using the formula: Q = (kAΔP) / (μL), where Q is the formation water flow rate, k is the permeability, A is the core cross-sectional area, and L is the core length. The permeability is calculated based on the core volume and the injected formation water volume. The porosity of the core sample is described; after the formation water injection is completed and the core is saturated with formation water, simulated oil is injected into the core sample, and the volume of overflowing formation water and injected simulated oil are recorded simultaneously; the remaining formation water volume of the core sample is calculated based on the injected formation water volume and the overflowing formation water volume; the bound water saturation is calculated by dividing the remaining formation water volume by the injected formation water volume; the amount of oil overflowing from the injected formation water after the simulated oil injection is measured to obtain the overflowing simulated oil volume; the remaining simulated oil volume is calculated by subtracting the overflowing simulated oil volume from the injected simulated oil volume; the residual oil saturation is calculated by dividing the remaining simulated oil volume by the injected formation water volume; the porosity and permeability are combined into basic sample data; the dynamic porosity is calculated using the formula Φd=por×(1-Swi-Sor), where por is the porosity, Swi is the bound water saturation, and Sor is the residual oil saturation.

[0102] In this embodiment of the invention, a preset phase permeation experiment is used to obtain basic data such as static porosity and permeability. By simulating the alternating injection process of oil and formation water, the saturation of bound water and residual oil is calculated, and the dynamic porosity is further obtained.

[0103] S2. Use the sample basic data and the dynamic porosity to create a scatter plot.

[0104] like Figure 2 , Figure 3As shown in the figure; in this embodiment of the invention, the scatter plot is based on the principle of data visualization and correlation analysis; by plotting the data of different parameters in the form of coordinate points on the same plane, the possible relationships between these parameters are intuitively displayed; in this context, the basic data of the sample (such as porosity and permeability) and dynamic porosity are used as coordinate axis variables to plot the data points corresponding to the core sample, so as to observe their distribution patterns and explore whether there is any inherent correlation or trend between these parameters, thereby providing an intuitive graphical basis for subsequently determining the lower limit of porosity and the lower limit of permeability.

[0105] In this embodiment of the invention, the step of creating a scatter plot using the sample's basic data and the dynamic porosity includes:

[0106] A porosity scatter plot is established using the porosity of the basic sample data and the dynamic porosity as coordinates.

[0107] The porosity scatter points are plotted to obtain a porosity scatter plot.

[0108] A permeability scatter plot is established using the permeability and dynamic porosity of the sample's basic data as coordinates.

[0109] The permeability scatter points are plotted to obtain a permeability scatter plot;

[0110] The porosity scatter plot and the permeability scatter plot are combined into a scatter plot.

[0111] In this embodiment of the invention, the porosity scatter plot is established using porosity and dynamic porosity as coordinates, based on the principle of correlation analysis between variables. Porosity reflects the static pore space ratio of the core sample, while dynamic porosity reflects the actual dynamic changes in pore space during oil-water alternation. Using these two parameters as coordinates, the specific position of each core sample in these two dimensions can be intuitively displayed. The distribution of numerous scatter plots reveals the intrinsic relationship between porosity and dynamic porosity, such as whether there is a linear relationship or other trends. Porosity data can be used as the abscissa value, and dynamic porosity data as the ordinate value. Similarly, permeability scatter plots are established using the permeability of the sample's basic data and the dynamic porosity as coordinates, with permeability data as the abscissa value and dynamic porosity data as the ordinate value.

[0112] In this embodiment of the invention, scatter plotting refers to drawing porosity scatter plots established based on porosity and dynamic porosity, and permeability scatter plots established based on permeability and dynamic porosity, respectively, in different planar coordinate systems; in order to facilitate the analysis and interpretation of the interrelationships between various parameters and their comprehensive impact on reservoir properties.

[0113] In detail, a porosity scatter plot is established using the porosity and dynamic porosity as coordinates, and then a porosity scatter plot is established through scatter plotting. Similarly, a permeability scatter plot is established for subsequent use.

[0114] In this embodiment of the invention, by establishing porosity scatter plots and permeability scatter plots, the overall distribution of porosity and dynamic porosity data of all core samples can be presented in a visual manner.

[0115] S3. Perform linear fitting on the scatter plot to obtain the lower limit of porosity and lower limit of permeability of the core sample.

[0116] In this embodiment of the invention, the linear fitting refers to using the least squares method to find a straight line that minimizes the sum of the squares of the vertical distances from each data point on the scatter plot to that line. The equation of the straight line is obtained through calculation, simplifying the data relationships and approximating the complex data distribution in the scatter plot with a simple linear relationship. This provides a clear calculation basis for the previously difficult-to-determine lower limits of porosity and permeability, and facilitates the determination of the lower limits of physical properties. The porosity and permeability values ​​corresponding to the points determined by the intersection of the fitted straight line with the coordinate axes or other specific rules are the lower limits of porosity and permeability of the core sample.

[0117] In this embodiment of the invention, the step of performing linear fitting on the scatter plot to obtain the lower limit of porosity and lower limit of permeability of the core sample includes:

[0118] A porosity straight line is obtained by linearly fitting the porosity scatter points in the porosity scatter plot of the scatter plot cross plot.

[0119] The lower limit of porosity is obtained by setting the dynamic porosity coordinates of the porosity line to zero.

[0120] A linear fit is performed on the permeability scatter points in the permeability scatter plot of the scatter plot to obtain a permeability straight line.

[0121] By setting the dynamic porosity coordinate of the permeability line to zero, the lower limit of permeability is obtained.

[0122] In this embodiment of the invention, the linear fitting refers to using the least squares method to find a straight line. When the dynamic porosity coordinate of the fitted line is set to zero, it is based on a physical assumption and data relationship derivation. Zero dynamic porosity means that in extreme cases, there is almost no pore space in the core sample that can effectively participate in oil-water flow and exchange. At this time, the corresponding porosity or permeability value can be regarded as a critical state. That is, when the porosity or permeability is lower than this value, the core sample is difficult to achieve effective oil-water flow under actual reservoir conditions. Therefore, determining the porosity or permeability at this time as the lower limit value is a definition of the critical value of the key physical property parameters of the core sample based on the essence of the reservoir fluid flow capacity, thereby obtaining the lower limit of permeability and the lower limit of porosity.

[0123] In detail, the least squares method is used to linearly fit the porosity scatter points in the porosity scatter plot of the scatter plot to obtain a porosity straight line. By setting the dynamic porosity coordinates of the porosity straight line to zero, the lower limit of porosity is obtained, and similarly, the lower limit of permeability is obtained.

[0124] In this embodiment of the invention, the lower limit of porosity is obtained by linear fitting, which simplifies the operation process of reservoir evaluation and improves work efficiency; it avoids unnecessary investment and development in areas that do not meet the requirements of the lower limit of physical properties, thereby rationally allocating resources and improving the economic benefits and success rate of exploration and development.

[0125] S4. Using the lower limit of porosity and lower limit of permeability of the core sample, the reservoir sample to be determined is divided into reservoirs to obtain effective reservoirs.

[0126] In this embodiment of the invention, reservoir classification is based on two key thresholds: the lower limit of porosity and the lower limit of permeability determined from core samples. The core principle is that only when the porosity and permeability of the reservoir sample to be classified reach or exceed the lower limit values ​​determined by the core samples does the reservoir possess sufficient storage space and fluid conduction capacity, enabling it to effectively store and transport oil and gas during actual oil and gas extraction, thus being classified as an effective reservoir. Reservoirs below these lower limits have poor storage and seepage performance, making it difficult to achieve economical and effective oil and gas extraction, and are therefore excluded from the range of effective reservoirs, referred to as ineffective reservoirs.

[0127] In this embodiment of the invention, the step of using the lower limit of porosity and the lower limit of permeability of the core sample to delineate the reservoir to be determined, thereby obtaining effective reservoirs, includes:

[0128] Data surveys were conducted on the reservoir sample to be identified to obtain the conventional porosity and conventional permeability of the reservoir sample.

[0129] By using the lower limit of porosity to screen reservoirs with conventional porosity, reservoirs with porosity higher than the lower limit of porosity are obtained.

[0130] By using the lower permeability limit to screen reservoirs with conventional permeability, reservoirs with permeability higher than the lower permeability limit are obtained.

[0131] The effective reservoir is obtained by performing an intersection operation on the reservoirs that are above the lower limit of porosity and the reservoirs that are above the lower limit of permeability.

[0132] In this embodiment of the invention, the principle of data exploration is based on the accurate measurement and evaluation of reservoir properties to obtain key parameters that reflect the storage capacity and fluid conductivity of the reservoir sample to be determined. Porosity reflects the size of the pore space in the rock, while permeability reflects the ease with which fluid flows in the porous medium. By measuring these parameters, they can be compared with the lower limits of porosity and permeability previously determined based on core samples, thereby determining whether the reservoir possesses the conditions for an effective reservoir. Reservoir screening is based on the principle of comparison, using the lower limits of porosity and permeability determined by core samples as benchmarks. Its core is that only when the porosity and permeability of the reservoir sample to be determined reach or exceed the corresponding lower limits... To effectively store and transport oil and gas, sufficient storage space and fluid conductivity are required. Therefore, by comparing the conventional porosity of each reservoir sample to the lower limit of porosity and the conventional permeability to the lower limit of permeability, the samples that meet the criteria are screened out as potential effective reservoirs. The principle of intersection operation is based on logical judgment: only reservoirs that simultaneously meet the requirements of both the lower limit of porosity and the lower limit of permeability can be identified as effective reservoirs. Because in oil and gas reservoirs, porosity represents the size of the storage space and permeability represents the ability of fluids to pass through, both of which are indispensable for the effectiveness of the reservoir, it is necessary to find reservoirs that are higher than both the lower limit of porosity and the lower limit of permeability. This is the core logic of intersection operation.

[0133] In detail, the principle of data exploration is used to measure and evaluate the reservoir samples to be identified, obtain the porosity and permeability of the reservoir samples, screen the reservoir samples by comparing the data, and obtain reservoirs with porosity and permeability above the lower limit. Then, the common part of the reservoirs with porosity and permeability above the lower limit is obtained by intersection operation, thereby obtaining the effective reservoirs.

[0134] In this embodiment of the invention, determining the effective reservoir of the reservoir sample to be determined by data comparison can improve the efficiency and success rate of oil and gas exploration and development.

[0135] S5. Perform data verification on the effective reservoir to obtain the verification results;

[0136] If the verification result is successful, the lower limit of reservoir properties of the core sample is converted to obtain the lower limit of reservoir properties of the reservoir sample to be determined.

[0137] In this embodiment of the invention, data verification is based on the principles of comparison and reliability testing. By comparing the actual data of the effective reservoir with the standard data or model on which the preset verification rules are based, the validity of the effective reservoir data is checked to see if it meets the requirements in terms of physical rationality, consistency of statistical regularity, and conformity with known reservoir characteristics. This ensures that the effective reservoir and its lower limit of physical properties determined based on the previous steps have high credibility and accuracy, and avoids erroneous conclusions caused by experimental errors, data anomalies, or limitations of analysis methods.

[0138] In this embodiment of the invention, the step of performing data verification on the effective reservoir to obtain verification results includes:

[0139] The effective reservoirs are used to classify the reservoir samples to be determined, thereby obtaining ineffective reservoirs;

[0140] The effective reservoir is verified by perforation through a pre-set perforation, and the verification result of the effective reservoir is obtained.

[0141] If the effective reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is increased to obtain an increased lower limit of reservoir properties.

[0142] The reservoir sample to be determined is divided into reservoirs by increasing the lower limit of reservoir properties to obtain additional effective reservoirs, and the reservoir sample to be determined is classified by increasing the effective reservoirs to obtain additional ineffective reservoirs.

[0143] If the valid reservoir verification result is passed, then the invalid reservoir is verified by performing invalid perforation through a preset perforation to obtain the invalid reservoir verification result;

[0144] If the invalid reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is reduced to obtain a lower limit of reservoir physical properties.

[0145] The reservoir sample to be determined is divided into reservoirs by using the method of reducing the lower limit of reservoir properties to obtain the effective reservoirs;

[0146] The reservoir samples to be determined are screened by reducing the effective reservoirs to obtain reduced ineffective reservoirs, and the reservoir samples to be determined are classified by reducing the ineffective reservoirs to obtain reduced effective reservoirs.

[0147] If the invalid reservoir verification result is passed, the verification result is passed, and the lower limit of the reservoir properties of the reservoir sample to be determined is obtained.

[0148] In this embodiment of the invention, the perforation is an important means of connecting the reservoir and the wellbore in oil and gas extraction, allowing oil and gas to flow into the wellbore. From the perspective of reservoir properties, an effective reservoir should have suitable porosity and permeability to ensure that oil and gas can flow smoothly between the reservoir and the wellbore after perforation. By simulating the perforation operation in actual extraction and observing the subsequent fluid flow, it is verified whether the effective reservoir can effectively produce oil and gas under actual extraction conditions, that is, whether it meets the expected performance of the effective reservoir in terms of seepage.

[0149] In detail, the reservoir samples to be determined are classified into effective and ineffective reservoirs through reservoir classification. First, the effective reservoirs are verified by perforation through a preset perforation to obtain the effective reservoir verification result. If the effective reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is increased to obtain an increased reservoir property lower limit. The increased reservoir property lower limit is used to classify the reservoir samples to be determined into reservoirs to obtain increased effective reservoirs, and the increased effective reservoirs are used to classify the reservoir samples to be determined into reservoirs to obtain increased ineffective reservoirs. If the effective reservoir verification result passes, the ineffective reservoirs are further classified by perforation through a preset perforation. Invalid drilling verification is performed to obtain invalid reservoir verification results. If the invalid reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is reduced to obtain a reduced reservoir property lower limit. The reservoir sample to be determined is divided into reservoirs using the reduced reservoir property lower limit to obtain a reduced effective reservoir. The reservoir sample to be determined is screened using the reduced effective reservoir to obtain a reduced invalid reservoir, and the reservoir sample to be determined is classified using the reduced invalid reservoir to obtain a reduced effective reservoir. If the invalid reservoir verification result passes, the verification result passes, and the reservoir property lower limit of the reservoir sample to be determined is obtained.

[0150] In this embodiment of the invention, the lower limit of reservoir properties is verified by perforation. If the verification of a valid reservoir fails, the lower limit of properties can be raised and the reservoir can be reclassified. If the verification passes, the invalid reservoir is verified. If the verification fails, the lower limit of properties can be lowered and the reservoir can be reclassified. This process is repeated until the verification result is satisfactory. This repeated verification and adjustment can effectively avoid inaccurate reservoir assessment due to a single judgment error, improve the scientificity and reliability of reservoir classification, and provide a more realistic reservoir property basis for subsequent oil and gas development. This scheme makes full use of the relative permeability curve of the core to accurately determine the lower limit of reservoir properties, which is helpful in determining the lower limit of properties of low-porosity and low-permeability carbonate rock reservoirs.

[0151] Example 2

[0152] like Figure 4 As shown in the figure, this embodiment also provides a functional module diagram of an analysis device for determining the lower limit of reservoir properties.

[0153] The reservoir property lower limit determination device 100 described in this embodiment can be installed in an electronic device. Depending on the functions implemented, the reservoir property lower limit determination device 100 may include a sample measurement module 101, a scatter plotting module 102, a linear fitting module 103, a reservoir delineation module 104, and a data verification module 105. The module described in this invention can also be called a unit, which refers to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and are stored in the memory of the electronic device.

[0154] In this embodiment, the functions of each module / unit are as follows:

[0155] The sample measurement module 101 is used to acquire core samples and reservoir samples to be determined, and to measure the data of the core samples using a preset relative permeability experiment to obtain basic sample data and dynamic porosity.

[0156] The scatter plotting module 102 is used to generate a scatter plot using the sample basic data and the dynamic porosity.

[0157] The linear fitting module 103 is used to perform linear fitting on the scatter plot to obtain the lower limit of porosity and lower limit of permeability of the core sample.

[0158] The reservoir delineation module 104 is used to delineate the reservoir sample to be determined using the lower limit of porosity and the lower limit of permeability of the core sample, so as to obtain effective reservoirs.

[0159] The data verification module 105 is used to verify the effective reservoir data and obtain the verification result.

[0160] If the verification result is successful, the lower limit of reservoir properties of the core sample is converted to obtain the lower limit of reservoir properties of the reservoir sample to be determined.

[0161] In detail, each module in the reservoir property lower limit analysis device 100 described in this embodiment of the invention uses the same technical means as the reservoir property lower limit analysis method described in Embodiment 1, and can produce the same technical effect, which will not be repeated here.

[0162] Example 3

[0163] Based on the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the method for determining the lower limit of reservoir properties described in the above embodiments.

[0164] In some embodiments of this example, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that, when the computer program is executed by a processor, it implements the steps of the method for determining the lower limit of reservoir properties described in the above embodiments.

[0165] In some embodiments of this example, a computer program product is provided, including a computer program / instructions, characterized in that the computer program, when executed by a processor, implements the steps of the method described in the above embodiments.

[0166] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the method for determining the lower limit of reservoir properties in the above embodiments.

[0167] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0168] Computer-readable storage media may also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.

[0169] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).

[0170] The processor can communicate with external devices via the I / O bus through wired or wireless networks.

[0171] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0172] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus and method for determining the lower limit of reservoir properties can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0173] It should be noted that, in this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0174] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. A method for determining the lower limit of reservoir properties, characterized in that, The method includes: Core samples and reservoir samples to be determined are obtained. Data are measured on the core samples using a pre-set relative permeability experiment to obtain basic sample data and dynamic porosity. A scatter plot was created using the basic sample data and the dynamic porosity. Linear fitting was performed on the scatter plot to obtain the lower limits of porosity and permeability of the core sample; The lower limits of porosity and permeability of the core samples are used to divide the reservoir samples to be determined into effective reservoirs. The effective reservoir was verified using data, and the verification results were obtained. If the verification result is successful, the lower limit of reservoir properties of the core sample is converted to obtain the lower limit of reservoir properties of the reservoir sample to be determined.

2. The method for determining the lower limit of reservoir properties according to claim 1, characterized in that, The process of measuring data from the core sample using a pre-set relative permeability experiment to obtain basic sample data and dynamic porosity includes: Measure the core volume, core length, and core cross-sectional area of ​​the core sample; The injection volume of formation water was obtained by measuring the injection rate of the core sample. The formation water flow rate was obtained by measuring the flow rate of the water-saturated core. The viscosity of the water-saturated core was measured to obtain the core viscosity. The permeability of the core sample was calculated based on the formation water flow, core viscosity, core length, and core cross-sectional area. The porosity of the core sample is calculated based on the core volume and the injected formation water volume. The injection volume and overflow volume of simulated oil were measured after the core sample was injected with formation water to obtain the overflow volume of formation water and the injection volume of simulated oil. The remaining formation water volume of the core sample is calculated based on the injected formation water volume and the overflow formation water volume. The bound water saturation of the core sample is calculated based on the remaining formation water volume and the injected formation water volume. The volume of spilled simulated oil was obtained by measuring the amount of oil that overflowed after the core sample was injected with simulated oil and then injected with formation water. The remaining simulated oil volume is calculated based on the injected simulated oil volume and the overflow simulated oil volume. The residual oil saturation is calculated based on the remaining simulated oil volume and the injected formation water volume. The porosity and permeability are combined into basic sample data; The dynamic porosity is calculated based on the porosity, bound water saturation, and residual oil saturation.

3. The method for determining the lower limit of reservoir properties according to claim 1, characterized in that, The step of creating a scatter plot using the sample baseline data and the dynamic porosity includes: A porosity scatter plot is established using the porosity of the basic sample data and the dynamic porosity as coordinates. The porosity scatter points are plotted to obtain a porosity scatter plot. A permeability scatter plot is established using the permeability and dynamic porosity of the sample's basic data as coordinates. The permeability scatter points are plotted to obtain a permeability scatter plot; The porosity scatter plot and the permeability scatter plot are combined into a scatter plot.

4. The method for determining the lower limit of reservoir properties according to claim 1, characterized in that, The linear fitting of the scatter plot to obtain the lower limits of porosity and permeability of the core sample includes: A porosity straight line is obtained by linearly fitting the porosity scatter points in the porosity scatter plot of the scatter plot cross plot. The lower limit of porosity is obtained by setting the dynamic porosity coordinates of the porosity line to zero. A linear fit is performed on the permeability scatter points in the permeability scatter plot of the scatter plot to obtain a permeability straight line. By setting the dynamic porosity coordinate of the permeability line to zero, the lower limit of permeability is obtained.

5. The method for determining the lower limit of reservoir properties according to claim 1, characterized in that, The process of using the lower limits of porosity and permeability of the core samples to delineate reservoirs and obtain effective reservoirs includes: Data surveys were conducted on the reservoir sample to be identified to obtain the conventional porosity and conventional permeability of the reservoir sample. By using the lower limit of porosity to screen reservoirs with conventional porosity, reservoirs with porosity higher than the lower limit of porosity are obtained. By using the lower permeability limit to screen reservoirs with conventional permeability, reservoirs with permeability higher than the lower permeability limit are obtained. The effective reservoir is obtained by performing an intersection operation on the reservoirs that are above the lower limit of porosity and the reservoirs that are above the lower limit of permeability.

6. The method for determining the lower limit of reservoir properties according to claim 1, characterized in that, The step of verifying the effective reservoir data to obtain the verification results includes: The effective reservoirs are used to classify the reservoir samples to be determined, thereby obtaining ineffective reservoirs; The effective reservoir is verified by perforation through a pre-set perforation, and the verification result of the effective reservoir is obtained. If the effective reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is increased to obtain an increased lower limit of reservoir properties. The reservoir sample to be determined is divided into reservoirs by increasing the lower limit of reservoir properties to obtain additional effective reservoirs, and the reservoir sample to be determined is classified by increasing the effective reservoirs to obtain additional ineffective reservoirs. If the valid reservoir verification result is passed, then the invalid reservoir is verified by performing invalid perforation through a preset perforation to obtain the invalid reservoir verification result; If the invalid reservoir verification result fails, the lower limit of porosity or the lower limit of permeability is reduced to obtain a lower limit of reservoir physical properties. The reservoir sample to be determined is divided into reservoirs by using the method of reducing the lower limit of reservoir properties to obtain the effective reservoirs; The reservoir samples to be determined are screened by reducing the effective reservoirs to obtain reduced ineffective reservoirs, and the reservoir samples to be determined are classified by reducing the ineffective reservoirs to obtain reduced effective reservoirs. If the invalid reservoir verification result is passed, the verification result is passed, and the lower limit of the reservoir properties of the reservoir sample to be determined is obtained.

7. A device for determining the lower limit of reservoir properties, characterized in that, include: The sample measurement module is used to acquire core samples and reservoir samples to be determined, and to measure the data of the core samples using a preset relative permeability experiment to obtain basic sample data and dynamic porosity. The scatter plotting module is used to generate scatter plots using the sample basic data and the dynamic porosity. The linear fitting module is used to perform linear fitting on the scatter plot to obtain the lower limit of porosity and lower limit of permeability of the core sample. The reservoir delineation module is used to delineate the reservoir sample to be determined using the lower limit of porosity and the lower limit of permeability of the core sample, so as to obtain effective reservoirs. The data verification module is used to verify the data of the effective reservoir and obtain the verification results; If the verification result is passed, the lower limit of reservoir properties of the core sample is converted to obtain the lower limit of reservoir properties of the reservoir sample to be determined.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method for determining the lower limit of reservoir properties as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method for determining the lower limit of reservoir properties as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method for determining the lower limit of reservoir properties as described in any one of claims 1 to 6.

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