Quantitative evaluation method and device for pore throat heterogeneity of tight sandstone reservoir and storage medium

Abstract

The invention discloses a quantitative evaluation method and device for pore throat heterogeneity of a tight sandstone reservoir and a storage medium, and belongs to the technical field of oil exploration, and the quantitative evaluation method comprises the following steps: based on a core mercury injection experiment, obtaining mercury injection experiment data required for pore throat heterogeneity evaluation; processing mercury injection experiment data, calculating to obtain Lg (1-SHg) and LgPc, and drawing a cross plot of the Lg (1-SHg) and the LgPc; fractal intervals corresponding to different pore throats are intercepted through the cross plot; fitting the trend line of each fractal interval to obtain fractal dimensions corresponding to different fractal intervals; obtaining a relative fractal dimension of each fractal interval relative to the whole reservoir; based on the relative fractal dimension, parameters capable of comprehensively representing the anisotropism of the overall pore throat of the reservoir are obtained. The new parameters obtained by the method and used for characterizing the anisotropism of the whole pore throat of the reservoir provide technical support for comprehensively, accurately and quantitatively characterizing the anisotropism of the microscopic pore throat structure of the compact sandstone reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration and development, and in particular to a method, a device and a storage medium for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir. Background Art

[0002] The geological conditions of my country's continental clastic reservoirs are complex. Sand and mud interbeds are frequent under the continental sedimentary background, which also leads to rapid sedimentary phase changes. Under the influence of sedimentation, diagenesis and geological transformation, there are strong heterogeneity characteristics within and between reservoirs. Reservoir heterogeneity is a key issue for the development of low-porosity and low-permeability oil and gas reservoirs. It is generally analyzed using comprehensive geological analysis methods, reservoir geological modeling methods and laboratory analysis methods. There are some defects in the existing relevant technical methods, such as: not considering the geological characteristics and pore throat distribution characteristics, directly calculating through mathematical models, lacking geological principle support; or taking a single evaluation parameter, which is not comprehensive and accurate; or considering the correlation between different parameters based on a certain layer in a certain area and summarizing the empirical model, which limits the promotion of models and methods.

[0003] Compared with conventional reservoirs, tight reservoirs have smaller pore throats and uneven spatial distribution, and their microscopic pore throat structure is more complex. Previous researchers have studied the pore structure of tight reservoirs based on physical properties, pore throat size, and characteristic parameters of capillary pressure curves. Currently, the mercury capillary pressure method is widely used.

[0004] In practice, the characteristic technical parameters of the reservoir pore structure are determined by determining the capillary pressure curve. Its main working principle is to determine the relationship curve between saturation and throat radius through mercury injection, thereby determining the distribution of pore throats and obtaining a series of parameters. At present, reservoir evaluation using pore structure parameters mostly adopts multi-parameter joint evaluation, such as the displacement pressure parameter (P) representing pore size. T ), maximum pore throat radius (r max ), capillary pressure median (Pc 50 ) and the average pore throat radius (r 50 ), etc.; the pore throat sorting coefficient (S p ), pore throat deflection (S kp ), pore throat peak state (K p ), pore throat distribution peak number (N) peak value (X) peak position (R v ) and homogeneity coefficient (α); the mercury removal efficiency (W) representing the connectivity of pore throats e ), minimum unsaturated pore throat volume percentage (S min ), tortuosity (L), pore structure coefficient Pore ​​throat coordination number, curvature coefficient, apparent pore throat volume ratio (V R ) and structural uniformity (α·W e), etc. There are many parameters and the acquisition methods are complicated, so it is difficult to formulate a unified reservoir evaluation plan. In addition, in the storage space of tight sandstone reservoirs, there are certain differences in the distribution of pore throats in different pore throat intervals. Parameters such as pore, throat sorting coefficient, skewness, and tortuosity can only represent the heterogeneity of the test sample point under the average pore throat structure, and cannot fully and accurately reflect the heterogeneity of the microscopic pore structure of the tight sandstone reservoir. In fact, in the quantitative evaluation of microscopic pore structure, many scholars have confirmed through various experiments and methods that the pore structure of sedimentary rocks has fractal characteristics, and fractal theory is an effective means to describe the complexity and heterogeneity of objects. The pore fractal dimension is one of the parameters used to quantitatively describe the size, heterogeneity and connectivity of pore throats. However, the current calculation of the pore fractal dimension is mostly based on a single dimension obtained by single-point analysis of experimental tests. There is no unified characteristic parameter that can accurately evaluate the microscopic heterogeneity of the pore structure. Summary of the invention

[0005] The present invention aims to solve the above-mentioned problems existing in the prior art for evaluating the pore throat heterogeneity of the pore structure of tight sandstone, and proposes a quantitative evaluation method, device and storage medium for the pore throat heterogeneity of tight sandstone reservoirs, which fully considers the differences in pore throat distribution characteristics in different pore throat intervals, optimizes the application of fractal dimension parameters, and provides technical support for comprehensively and accurately quantitatively characterizing the microscopic pore throat structure heterogeneity of tight sandstone reservoirs.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0007] A method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir comprises the following steps:

[0008] Based on the core mercury injection experiment, the mercury injection experimental data required for pore throat heterogeneity evaluation are obtained;

[0009] Process the mercury injection test data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two;

[0010] The fractal intervals corresponding to different pore throats are intercepted using the intersection diagram;

[0011] Fit the trend lines of each fractal interval to obtain the fractal dimensions corresponding to different fractal intervals;

[0012] Obtain the relative fractal dimension of each fractal interval relative to the entire reservoir;

[0013] By superimposing the relative fractal dimensions of each fractal interval, we can obtain the parameters that can comprehensively characterize the overall pore throat heterogeneity of the reservoir.

[0014] Furthermore, the method of intercepting fractal intervals corresponding to different pore throats using the intersection diagram includes: splitting the interval into n+1 small intervals according to n inflection points of the curve in the intersection diagram, and each of the split intervals corresponds to a different level of pore throat size.

[0015] Furthermore, the step of fitting the trend lines of each fractal interval to obtain the fractal dimensions corresponding to different fractal intervals includes:

[0016] Fit the scattered points of each fractal interval to obtain n+1 trend lines, and obtain the trend lines about Lg(1-S Hgn )~LgP cn According to the slope of the linear formula, combined with the fractal dimension principle and the basic principle of conventional mercury injection, the fractal dimension corresponding to different fractal intervals is obtained.

[0017] Furthermore, the method of obtaining the relative fractal dimension of each fractal interval relative to the entire reservoir includes:

[0018] Obtain the amount of mercury injected into the entire reservoir;

[0019] Each inflection point on the curve in the intersection diagram corresponds to a mercury injection pressure and pore throat radius. The pore throat radius is divided into multiple segments according to the fractal interval division method, and the mercury injection amount in each segment is used to represent the pore throat distribution frequency in each segment.

[0020] The mercury injection amount in each interval is normalized to obtain the pore throat distribution frequency corresponding to each interval, that is, the ratio of the pore throat number in each fractal interval to the total pore throat number in the reservoir.

[0021] The relative fractal dimension of each fractal interval relative to the reservoir as a whole is obtained by multiplying the pore-throat distribution frequency with the fractal dimension of each fractal interval.

[0022] Furthermore, the parameter that can comprehensively characterize the overall pore throat heterogeneity of the reservoir is the sum of the relative fractal dimensions of each fractal interval relative to the reservoir as a whole.

[0023] The present invention also provides a device for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir, comprising:

[0024] Parameter acquisition module, used to obtain the mercury injection test data required for pore throat heterogeneity evaluation obtained from the core mercury injection test;

[0025] Data processing module, used to process mercury injection test data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two;

[0026] The fractal dimension acquisition module is used to intercept the fractal intervals corresponding to different pore throats in the intersection diagram, fit the trend lines of each fractal interval, and obtain the fractal dimensions corresponding to different fractal intervals;

[0027] A relative fractal dimension acquisition module is used to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir;

[0028] The characterization parameter acquisition module is used to obtain parameters that can comprehensively characterize the overall pore throat heterogeneity of the reservoir based on the relative fractal dimension.

[0029] Furthermore, the fractal dimension acquisition module divides the interval into n+1 small intervals according to the n inflection points of the curve in the intersection diagram, and each interval after the division corresponds to a pore throat size at a different level.

[0030] Furthermore, the relative fractal dimension acquisition module includes:

[0031] A mercury injection amount acquisition unit is used to acquire the mercury injection amount of the entire reservoir;

[0032] The pore throat radius division unit is used to divide the pore throat radius into multiple sections in the same way as the fractal interval, and the mercury injection amount in each section is used to represent the pore throat distribution frequency in each section;

[0033] The pore throat distribution frequency acquisition unit is used to normalize the interval mercury injection amount to obtain the pore throat distribution frequency corresponding to each interval, that is, the ratio of the number of pore throats in each fractal interval to the total number of pore throats in the reservoir;

[0034] The relative fractal dimension acquisition unit is used to multiply the pore throat distribution frequency with the fractal dimension of each fractal interval to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir.

[0035] The present invention also provides a device for quantitatively evaluating the pore throat heterogeneity of a tight sandstone reservoir, comprising a processor and a memory for storing instructions executable by the processor, wherein the instructions, when executed by the processor, implement the steps in the above-mentioned method for quantitatively evaluating the pore throat heterogeneity of a tight sandstone reservoir.

[0036] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps in the above-mentioned method for quantitatively evaluating pore-throat heterogeneity of a tight sandstone reservoir.

[0037] In summary, the present invention has the following advantages:

[0038] 1. The present invention provides a method for quantitatively characterizing the pore throat heterogeneity of tight sandstone reservoirs based on mercury injection fractal, optimizes the application of fractal dimension parameters, and obtains new parameters for characterizing the overall pore throat heterogeneity of the reservoir through this method, which provides technical support for comprehensive and accurate quantitative characterization of the microscopic pore throat structure heterogeneity of tight sandstone reservoirs;

[0039] 2. Based on the characteristics of complex microscopic pore structure, small pore throat and uneven spatial distribution of tight sandstone reservoir, the present invention subdivides the pore throat of tight sandstone reservoir into several pore throat intervals according to the degree of heterogeneity, fully considering the differences in pore throat distribution in different pore throat intervals, which can make up for the problems of single parameters and failure to consider the comprehensive distribution of pore throats in previous reservoir heterogeneity evaluation;

[0040] 3. The raw data involved in the present invention can be directly obtained through experiments, which is easy to operate and highly feasible. The method can be extended and replicated, and is suitable for characterizing the microscopic pore throat heterogeneity of tight sandstone reservoirs in different regions and layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the Lg(1-S Hg )~Lg P c intersection diagram;

[0042] Figure 2 is the Lg(1-S Hg )~Lg P c intersection diagram;

[0043] Figure 3 is the Lg(1-S) of the QL202 well in Example 2 Hg )~Lg P c intersection diagram;

[0044] Figure 4 is the Lg(1-S) of the QL205 well in Example 2 Hg )~Lg P c intersection diagram;

[0045] Figure 5 is the D of the sample used in Example 2 总 Relationship diagram with its sorting coefficient;

[0046] Figure 6 is the D of the sample used in Example 2 总 Relationship diagram with its permeability. DETAILED DESCRIPTION

[0047] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments and drawings. It should be understood by those skilled in the art that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir, comprising the following steps:

[0050] Step 1: Based on the core mercury injection experiment, the mercury saturation (S Hg ) and its corresponding mercury injection pressure (P c ) and other experimental data;

[0051] Step 2: Process the experimental data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two;

[0052] Step 3: Use Lg(1-S Hg )~Lg P c The intersection diagram intercepts the fractal intervals corresponding to different apertures, and obtains the fractal dimensions corresponding to different intervals;

[0053] The specific implementation steps include:

[0054] S31, according to Lg(1-S Hg )~Lg P c The n inflection points of the curve have coordinates on the intersection diagram (Lg P ci ,Lg(1-S Hgi )), i = 0, 1, 2, 3, ... n, the interval is divided into n + 1 small intervals, each interval corresponds to a different level of pore throat size;

[0055] S32, fit the scattered points of each interval to obtain n+1 trend lines, and obtain the trend lines about Lg(1-S Hgn )~LgP cn The linear formula is:

[0056] Lg(1-S Hgi )=a i LqCy ci +b i ; (1)

[0057] Among them, i=0,1,2,3,…,n,a i is the slope of the ith trend line, b i is the intercept of the ith trend line;

[0058] S33. Pore fractal dimension is one of the comprehensive parameters used to quantitatively describe pore throat size, heterogeneity and connectivity. The ideal fractal dimension is between 2 and 3. The closer it is to 3, the stronger the pore throat heterogeneity, and the closer it is to 2, the stronger the homogeneity.

[0059] Since the pore throats in tight sandstone are very complex, their pore throat distribution usually has multiple fractal intervals, so it can be represented by the fractal dimensions of multiple intervals. According to the fractal dimension principle and the basic principle of conventional mercury injection, we have:

[0060] Lg(1-S Hgi )=(D i -3)LgP ci +b i ; (2)

[0061] Among them, D i is the fractal dimension corresponding to the i-th interval, i = 0, 1, 2, 3, ..., n;

[0062] It can be seen that the absolute fractal dimension of each interval is:

[0063] D i =a i +3; (3)

[0064] Step 4: The heterogeneity of different pore throat intervals can be obtained by using the above formula (3). The n+1 intervals divided in the above step S31 correspond to n+1 ranges of pore throat intervals, and the overall heterogeneity of the reservoir depends on the heterogeneity of n+1 different pore throat intervals. Therefore, the distribution of reservoir pore throats must also be considered to obtain the fractal dimension of each interval relative to the entire reservoir.

[0065] The specific implementation steps include:

[0066] S41. As the mercury injection pressure increases, mercury is injected from large pore throats to small pore throats, and the amount of mercury injected gradually increases. The amount of mercury injected is obtained by the following formula:

[0067]

[0068] Among them, V Hg is the amount of mercury injected (ml), is the porosity of the sample (%), V r is the sample volume (cm 3 );

[0069] S42, according to different pore throat radius (R1, R2...R X ), the maximum mercury injection pressure corresponds to the minimum pore throat radius R X， Therefore, the mercury injection amount can be subdivided into X-1 stages of mercury injection. The subdivided mercury injection amount corresponding to the X-1th to Xth pore throat radius is calculated as follows:

[0070] V Hgx～x-1 =(V Hgx -V Hgx-1 ) / LOG 10 (R X-1 / R X ); (5)

[0071] Among them, V Hgx～x-1 represents the amount of mercury injection (ml) corresponding to the X-1th to Xth pore throat radius, V Hgx Indicates the amount of mercury injection corresponding to the Xth pore throat radius (ml);

[0072] S43, according to step 3 Lg (1-S Hg )-LgP c There are n inflection points on the curve, each of which corresponds to a mercury injection pressure and pore throat radius. Therefore, the pore throat radius can be divided into n+1 sections. The mercury injection amount in the n+1 section can be used to represent the pore throat distribution frequency in the n+1 section. The mercury injection amount in the section is expressed as V Hgi , i = 0, 1, 2, 3, ..., n; the overall distribution frequency of reservoir pore throats is regarded as 1, and the interval mercury injection volume V Hgi Normalization, the normalized interval mercury injection amount corresponds to the pore throat distribution frequency of n+1 intervals, which are expressed as f1, f2, ..., f n+1 , and there is

[0073]

[0074] S44, the ratio of the number of pore throats represented by each fractal interval to the total number of pore throats in the sample is f i , so the fractal dimension D of each interval relative to the whole can be calculated i :

[0075] D i =D i ×f i ; (7)

[0076] Where i = 1, 2, 3, ..., n, D i represents the fractal dimension of the ith interval relative to the total n+1 intervals, that is, the fractal dimension corresponding to the first fractal interval should be D 1 =D1×f1, the fractal dimension corresponding to the n+1th fractal interval should be D n +1 =D n+1 ×f n+1 ;

[0077] Step 5: <7> Based on this, we can obtain the parameter D that can comprehensively characterize the n+1 fractal intervals and the overall pore throat heterogeneity of the reservoir. 总 :

[0078]

[0079] Example 2

[0080] The following is a specific application example to illustrate a method for quantitatively evaluating the pore throat heterogeneity of a tight sandstone reservoir of the present invention. In this embodiment, the samples selected for the study are mainly from sandstones of different sand groups of the Shaximiao Formation in the central Sichuan Basin. Through rock thin sections, scanning electron microscopy, high-pressure mercury injection, pore permeability saturation and other experimental analyses, it is believed that the sandstone reservoir in this area has strong heterogeneity. Therefore, the evaluation of the heterogeneity of the tight sandstone reservoir of the Shaximiao Formation in the Sichuan Basin is taken as an example to illustrate the specific scheme of the present invention:

[0081] The first step is to conduct core mercury injection experiments using the selected sandstone samples to directly obtain the basic data of mercury injection experiments required for pore throat heterogeneity evaluation, mainly including: porosity (%), sample volume (cm 3 ), mercury injection pressure P c (MPa), mercury saturation S Hg (%), pore throat radius r (μm);

[0082] The second step is to preliminarily process the original mercury injection experimental data and draw the Lg(1-S Hg )~Lg P c Intersection diagram. Figures 1 to 4 As shown, according to the original mercury injection pressure P c and mercury saturation S Hg The Lg(1-S Hg )~Lg P c Intersection diagram. The pore throats are divided into different intervals according to the number of inflection points on the intersection diagram. The pore throats in each interval are distributed differently and have different degrees of heterogeneity, that is, they correspond to different pore throat fractal intervals. For example, the intersection curve of Lg(1-SHg)~Lg Pc in Well QL18 has two inflection points, which divides the interval into three intervals, and each interval corresponds to different levels of pore throat size;

[0083] Step 3: Add the QL18 well Lg(1-S Hg )~Lg P c The trend lines of each fractal interval of the cross plot are fitted to obtain the fractal dimensions corresponding to different intervals. Taking the QL18 well as an example, the specific implementation steps include:

[0084] S31, using the scattered points of the three pore throat fractal intervals to obtain three trend lines, fitting the trend lines to obtain the Lg (1-S Hgn )~Lg P cnThe linear formula of , according to the order of mercury saturation from small to large, the fitting trend lines are:

[0085] Lg(1-S Hg1 )=-0.0013LgP c1 -0.0024;

[0086] Lg(1-S Hg2 )=-0.0723LgP c2 -0.0653;

[0087] Lg(1-S Hg3 )=-0.036LgP c3 -0.1469;

[0088] S32. According to the fractal dimension principle and the basic principle of conventional mercury injection, we have:

[0089] Lg(1-S Hgi )=(D i -3)LgP ci +b i ;

[0090] Among them, D i is the fractal dimension corresponding to the i-th interval, i = 0, 1, 2, 3, ..., n;

[0091] It can be seen that the absolute fractal dimensions of the three fractal intervals of the QL18 well sandstone sample are:

[0092] From D1-3=-0.0013, we get D1=2.9987;

[0093] From D2-3=-0.0723, we get D2=2.9277;

[0094] From D3-3=-0.036, we get D3=2.9640;

[0095] Step 4: According to the above steps, the heterogeneity of the three pore throat intervals of the QL18 well sandstone sample is obtained. The overall heterogeneity of the QL18 well reservoir depends on the heterogeneity of the three different pore throat intervals. Therefore, the distribution of the pore throats of the QL18 well sample reservoir needs to be considered to obtain the relative fractal dimension of each interval. The specific implementation steps include:

[0096] S41. With the increase of mercury injection pressure, mercury is injected from large pore throats to small pore throats, and the amount of mercury injection gradually increases. As shown in Table 1, the mercury injection pressure of Well QL18 increases from 0.0043MPa to 200.05026MPa, and the corresponding pore throat radius increases from 171.0159μm to 0.0037μm. The maximum mercury injection pressure corresponds to the minimum pore throat radius. As shown in Table 1, the mercury injection pressure of Well QL18 has gone through 23 stages from low to high. The cumulative mercury injection amount of each stage can be obtained by multiplying the mercury saturation and pore volume of the corresponding stage, where the pore volume can be obtained by multiplying the porosity in the original data of the mercury injection experiment and the sample volume. Therefore, the cumulative mercury injection amount corresponding to different pressures can be calculated.

[0097] Table 1 Mercury injection data processing of QL18 well sample No. 1

[0098]

[0099] The detailed mercury injection amount of the 23 mercury injection stages in S42 and QL18 wells can be calculated by the formula. For example, in the 9th stage of mercury injection in QL18 well (Table 1), the mercury injection pore throat radius increased from 4.5015μm to 3.0088μm, and the cumulative mercury injection amount increased from 0ml to 0.02388ml. The detailed mercury injection amount calculation formula for this stage is: V Hg9～8 =(0.02388-0) / LOG10(4.5015 / 3.0088), and the calculation of the amount of mercury in other stages is similar;

[0100] S43, by the third step Lg (1-S Hg )-LgP c The two inflection points of the curve can divide the pore throat radius into three intervals. The cumulative mercury injection volume of the three intervals is used to represent the distribution frequency of the three pore throat intervals. Therefore, the interval mercury injection volume of the three pore throat intervals of Well QL18 is 0.13646ml, 2.77845ml, and 1.21389ml, respectively. After normalization, the frequency f of the three intervals is 1、 f 2、 f3 (percentage) are 0.03305 (3.3%), 0.67294 (67.3%), and 0.29401 (29.4%) respectively;

[0101] S44. The relative fractal dimension of each interval relative to the whole sample can be calculated by the above steps:

[0102] D 1 =D1×f1=2.9987×3.3%=0.0991;

[0103] D 2 =D2×f2=2.9277×67.3%=1.9702;

[0104] D 3 =D3×f3=2.9640×29.4%=0.8714;

[0105] Step 5: Obtain the parameter D that can comprehensively characterize the overall pore throat heterogeneity of the three fractal intervals of the QL18 well 总 :

[0106] D 总 =D 1 +D 2 +D 3 =2.9407.

[0107] Applying the above steps to sandstone samples from different wells can obtain a series of D 总 (Table 2):

[0108] Table 2 Calculation of fractal dimension between the tight sandstones of Shaximiao Formation in Sichuan Basin

[0109]

[0110] And further prove the reliability of the new parameters adopted by the present invention. Specifically including:

[0111] The mercury injection sorting coefficient can be obtained from the mercury injection experiment. It is a parameter that reflects the concentration of pore distribution. The lower the sorting coefficient, the more uniform the pore distribution. Affected by the heterogeneity of pore throats, the permeability usually changes accordingly. The more complex the pore throat structure, the lower the permeability. Table 2 D of all samples used 总 There is a good positive correlation between the Figure 5 ), and has a negative correlation with permeability ( Figure 6 ). Therefore, D 总 The pore distribution and pore throat heterogeneity can be characterized simultaneously, which indirectly confirms the reliability of the new parameters proposed in the present invention.

[0112] Example 3

[0113] This embodiment provides a device for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir, comprising:

[0114] Parameter acquisition module, used to obtain the mercury injection test data required for pore throat heterogeneity evaluation obtained from the core mercury injection test;

[0115] Data processing module, used to process mercury injection test data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two;

[0116] The fractal dimension acquisition module is used to intercept the fractal intervals corresponding to different pore throats in the intersection diagram, fit the trend lines of each fractal interval, and obtain the fractal dimensions corresponding to different fractal intervals;

[0117] A relative fractal dimension acquisition module is used to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir;

[0118] The characterization parameter acquisition module is used to obtain parameters that can comprehensively characterize the overall pore throat heterogeneity of the reservoir based on the relative fractal dimension.

[0119] Furthermore, the fractal dimension acquisition module is also used to split the interval into n+1 small intervals according to the n inflection points of the curve in the intersection diagram, and each interval after the split corresponds to a pore throat size at a different level.

[0120] Furthermore, the relative fractal dimension acquisition module also includes:

[0121] A mercury injection amount acquisition unit is used to acquire the mercury injection amount of the entire reservoir;

[0122] The pore throat radius division unit is used to divide the pore throat radius into multiple sections in the same way as the fractal interval, and the mercury injection amount in each section is used to represent the pore throat distribution frequency in each section;

[0123] The pore throat distribution frequency acquisition unit is used to normalize the interval mercury injection amount to obtain the pore throat distribution frequency corresponding to each interval, that is, the ratio of the number of pore throats in each fractal interval to the total number of pore throats in the reservoir;

[0124] The relative fractal dimension acquisition unit is used to multiply the pore throat distribution frequency with the fractal dimension of each fractal interval to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir.

[0125] The functions performed by the functional modules and units in this embodiment correspond to the method steps in Embodiment 1.

[0126] Example 4

[0127] This embodiment provides a device for quantitatively evaluating the pore throat heterogeneity of a tight sandstone reservoir. The device can be used to implement a method for quantitatively evaluating the pore throat heterogeneity of a tight sandstone reservoir as described in the above-mentioned embodiment 1 or 2. The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor implements the method steps in the above-mentioned embodiment 1 when executing the computer program.

[0128] Preferably, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments that can complete specific functions, and the instruction segments are used to describe the execution process of the computer program in the device.

[0129] The processor can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or the processor can also be any conventional processor. The processor is the control center of the device, and various parts of the device are connected using various interfaces and lines.

[0130] The memory mainly includes a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function, etc., and the data storage area can store related data, etc. In addition, the memory can be a high-speed random access memory, or a non-volatile memory, such as a plug-in hard disk, a smart memory card, a secure digital card, and a flash memory card, etc., or the memory can also be other volatile solid-state storage devices.

[0131] Example 5

[0132] This embodiment provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, a method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir disclosed in the above-mentioned embodiment 1 or 2 is implemented.

[0133] In this embodiment, computer storage media may be tangible media that may contain or store programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0134] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for quantitatively evaluating pore throat heterogeneity of tight sandstone reservoirs, characterized in that: The steps include: Based on the core mercury injection experiment, the mercury injection experimental data required for pore throat heterogeneity evaluation are obtained; Process the mercury injection test data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two; The fractal intervals corresponding to different pore throats are intercepted using the intersection diagram; Fit the trend lines of each fractal interval to obtain the fractal dimensions corresponding to different fractal intervals; Obtain the relative fractal dimension of each fractal interval relative to the entire reservoir; By superimposing the relative fractal dimensions of each fractal interval, we can obtain the parameters that can comprehensively characterize the overall pore throat heterogeneity of the reservoir.

2. The method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 1, characterized in that: The method of intercepting the fractal intervals corresponding to different pore throats by using the intersection diagram includes: dividing the interval into n+1 small intervals according to n inflection points of the curve in the intersection diagram, and each of the divided intervals corresponds to the pore throat size at different levels.

3. The method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 1, characterized in that: The step of fitting the trend lines of each fractal interval to obtain the fractal dimensions corresponding to different fractal intervals includes: Fit the scattered points of each fractal interval to obtain n+1 trend lines, and obtain the trend lines about Lg(1-S Hgn )~Lg P cn According to the slope of the linear formula, combined with the fractal dimension principle and the basic principle of conventional mercury injection, the fractal dimension corresponding to different fractal intervals is obtained.

4. The method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 1, characterized in that: The method of obtaining the relative fractal dimension of each fractal interval relative to the entire reservoir includes: Obtain the amount of mercury injected into the entire reservoir; Each inflection point on the curve in the intersection diagram corresponds to a mercury injection pressure and pore throat radius. The pore throat radius is divided into multiple segments according to the fractal interval division method, and the mercury injection amount in each segment is used to represent the pore throat distribution frequency in each segment. The mercury injection amount in each interval is normalized to obtain the pore throat distribution frequency corresponding to each interval, that is, the ratio of the pore throat number in each fractal interval to the total pore throat number in the reservoir. The relative fractal dimension of each fractal interval relative to the reservoir as a whole is obtained by multiplying the pore-throat distribution frequency with the fractal dimension of each fractal interval.

5. The method for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 1, characterized in that: The parameter that can comprehensively characterize the overall pore throat heterogeneity of the reservoir is the sum of the relative fractal dimensions of each fractal interval relative to the reservoir as a whole.

6. A device for quantitatively evaluating pore throat heterogeneity of tight sandstone reservoirs, characterized in that: include: Parameter acquisition module, used to obtain the mercury injection test data required for pore throat heterogeneity evaluation obtained from the core mercury injection test; Data processing module, used to process mercury injection experimental data and calculate Lg(1-S Hg ) and LgP c And draw the intersection diagram of the two; The fractal dimension acquisition module is used to intercept the fractal intervals corresponding to different pore throats in the intersection diagram, fit the trend lines of each fractal interval, and obtain the fractal dimensions corresponding to different fractal intervals; A relative fractal dimension acquisition module is used to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir; The characterization parameter acquisition module is used to obtain parameters that can comprehensively characterize the overall pore throat heterogeneity of the reservoir based on the relative fractal dimension.

7. The device for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 6, characterized in that: The fractal dimension acquisition module divides the interval into n+1 small intervals according to the n inflection points of the curve in the intersection diagram, and each interval after the division corresponds to a pore throat size at a different level.

8. The device for quantitatively evaluating pore throat heterogeneity of a tight sandstone reservoir according to claim 6, characterized in that: The relative fractal dimension acquisition module comprises: A mercury injection amount acquisition unit is used to acquire the mercury injection amount of the entire reservoir; The pore throat radius division unit is used to divide the pore throat radius into multiple sections in the same way as the fractal interval, and the mercury injection amount in each section is used to represent the pore throat distribution frequency in each section; The pore throat distribution frequency acquisition unit is used to normalize the interval mercury injection amount to obtain the pore throat distribution frequency corresponding to each interval, that is, the ratio of the number of pore throats in each fractal interval to the total number of pore throats in the reservoir; The relative fractal dimension acquisition unit is used to multiply the pore throat distribution frequency with the fractal dimension of each fractal interval to obtain the relative fractal dimension of each fractal interval relative to the entire reservoir.

9. A device for quantitatively evaluating pore throat heterogeneity of tight sandstone reservoirs, characterized in that: It comprises a processor and a memory for storing processor executable instructions, wherein the instructions, when executed by the processor, implement the steps of the method according to any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

Images