Method and device for automatically picking up turning point information of rock sample mercury injection curve

Abstract

The invention relates to a method and a device for automatically picking up turning point information of a rock sample mercury injection curve. The method comprises the following steps: acquiring rock sample mercury injection curve data; calculating mercury pressure saturation ratio difference values of a plurality of test points in the rock sample mercury injection curve according to the rock sample mercury injection curve data; marking a turning point of the rock sample mercury injection curve according to the mercury pressure saturation ratio difference value; and picking up turning point information of the mercury injection curve according to the turning point. According to the method, errors caused by manual picking of the mercury injection curve turning point information are effectively avoided, and the efficiency of large-data-volume mercury injection curve processing and turning point picking is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development data processing, and particularly to a method and device for automatically picking up the turning point information of a mercury injection curve of a rock sample. Background Art

[0002] The mercury injection curve, that is, the capillary pressure curve of a rock measured by the mercury injection method, reflects the relationship between the mercury injection saturation of a rock sample and the mercury injection pressure. The mercury injection curve consists of a gentle slope section at the lower part and a steep slope section at the upper part. Among them, the gentle slope section reflects the characteristics of large pores in the rock, and the steep slope section reflects the characteristics of micro-pores in the rock. The turning point of the mercury injection curve is the intersection point where the gentle slope section and the steep slope section are connected to each other, representing the boundary between large pores and micro-pores, and reflecting the ease of fluid entering the micro-pores of the rock. The turning point information can be used to study the microscopic pore structure characteristics of reservoir rocks, estimate the storage and seepage capacities of reservoirs, evaluate the quality of reservoirs, etc.

[0003] However, there is still a lack of an automatic picking-up method for the turning point information of the mercury injection curve. Currently, the turning point of the mercury injection curve is mainly calibrated by the graph reading method, that is, by observing the mercury injection curve graph, calibrating the position of the turning point and reading the mercury injection saturation and mercury injection pressure at this point. The current method is not only time-consuming and laborious, but also varies from person to person, and is extremely prone to human errors, which is not conducive to the application of the turning point information.

[0004] Therefore, there is an urgent need in this field for a method for quantitatively and automatically picking up the turning point information of the mercury injection curve. Summary of the Invention

[0005] The present invention provides a method and device for automatically picking up the turning point information of a mercury injection curve of a rock sample to solve the defects of the prior art.

[0006] The present invention provides a method for automatically picking up the turning point information of a mercury injection curve of a rock sample, including:

[0007] S1: Obtain the mercury injection curve data of the rock sample;

[0008] S2: Calculate the difference in the mercury pressure saturation ratio of multiple test points in the mercury injection curve of the rock sample according to the mercury injection curve data of the rock sample;

[0009] S3: Mark the turning point of the mercury injection curve of the rock sample according to the difference in the mercury pressure saturation ratio;

[0010] S4: Pick up the turning point information of the mercury injection curve according to the turning point.

[0011] According to the method for automatically picking up the turning point information of a mercury injection curve of a rock sample provided by the present invention, step S1 further includes:

[0012] S11: Perform a mercury injection test on the rock sample based on the mercury injection method to obtain a relationship curve between the capillary pressure and the mercury saturation of the rock sample;

[0013] S12: Collect mercury injection curve data of the rock sample from the relationship curve.

[0014] According to an automatic picking method for inflection point information of a mercury injection curve of a rock sample provided by the present invention, the mercury injection curve data of the rock sample in step S1 includes:

[0015] Mercury injection pressure data and mercury injection saturation data.

[0016] According to an automatic picking method for inflection point information of a mercury injection curve of a rock sample provided by the present invention, step S2 further includes:

[0017] S21: Calculate the mercury pressure saturation ratio of multiple test points according to the mercury injection curve data of the rock sample;

[0018] S22: Calculate the difference in mercury pressure saturation ratio between two continuously adjacent test points according to the mercury pressure saturation ratio.

[0019] According to an automatic picking method for inflection point information of a mercury injection curve of a rock sample provided by the present invention, the expression of the mercury pressure saturation ratio in step S21 is:

[0020]

[0021] where i is the test point index, E i is the ratio of mercury injection saturation to mercury injection pressure at the i-th test point, S Hg,i is the mercury injection saturation corresponding to the mercury injection pressure at the i-th test point, P c,i is the mercury injection pressure at the i-th test point;

[0022] The expression of the difference in mercury pressure saturation ratio in step S22 is:

[0023] A i = E i+1 - E i ;

[0024] where A i is the difference between the ratio of mercury injection saturation to mercury injection pressure at the (i + 1)-th test point and the ratio of mercury injection saturation to mercury injection pressure at the i-th test point, E i+1 is the ratio of mercury injection saturation to mercury injection pressure at the (i + 1)-th test point.

[0025] According to an automatic picking method for inflection point information of a mercury injection curve of a rock sample provided by the present invention, step S3 specifically includes:

[0026] When the difference in mercury pressure saturation ratio of the current test point is greater than or equal to 0 and the difference in mercury pressure saturation ratio of the next test point is less than or equal to 0, mark the next test point as the inflection point of the mercury injection curve of the rock sample.

[0027] According to an automatic picking method for inflection point information of a mercury injection curve of a rock sample provided by the present invention, the inflection point information in step S4 includes:

[0028] The mercury injection saturation at the inflection point of the mercury injection curve and the mercury injection pressure at the inflection point of the mercury injection curve;

[0029] The expression for the mercury injection saturation at the inflection point of the mercury injection curve is:

[0030] S Hg,tp = S Hg,jtp ;

[0031] where S Hg,tp is the mercury injection saturation at the inflection point of the mercury injection curve, and S Hg,jtp is the mercury injection saturation at the position of the inflection point of the mercury injection curve;

[0032] The expression for the mercury injection pressure at the inflection point of the mercury injection curve is:

[0033] P c,tp = P c,jtp ;

[0034] where P c,tp is the mercury injection pressure at the inflection point of the mercury injection curve, and P c,jtp is the mercury injection pressure at the position of the inflection point of the mercury injection curve.

[0035] The present invention further provides an automatic picking device for inflection point information of a mercury injection curve of a rock sample, including:

[0036] A collection module: used to obtain mercury injection curve data of the rock sample;

[0037] A calculation module: used to calculate the difference in mercury pressure saturation ratios of multiple test points in the mercury injection curve of the rock sample according to the mercury injection curve data of the rock sample;

[0038] A determination module: used to mark the inflection point of the mercury injection curve of the rock sample according to the difference in mercury pressure saturation ratios;

[0039] A picking module: used to pick the inflection point information of the mercury injection curve according to the inflection point.

[0040] The third aspect of the present invention further provides an automatic picking device for inflection point information of a mercury injection curve of a rock sample, including:

[0041] A memory and at least one processor, wherein instructions are stored in the memory;

[0042] At least one of the processors calls the instructions in the memory so that an automatic picking device for inflection point information of a mercury injection curve of a rock sample executes an automatic picking method for inflection point information of a mercury injection curve of a rock sample as described in any one of the above.

[0043] In the fourth aspect of the present invention, there is also provided a computer-readable storage medium, on which instructions are stored, and when the instructions are executed by a processor, a method for automatically picking up the turning point information of a mercury injection curve of a rock sample as described in any one of the above is realized.

[0044] A method, device, equipment and storage medium for automatically picking up the turning point information of a mercury injection curve of a rock sample provided by the present invention can automatically and accurately identify and pick up the turning point information on the curve through precise analysis and processing of the mercury injection curve data of the rock sample, thereby greatly improving the efficiency and accuracy of the analysis of the pore structure characteristics of the rock.

[0045] The present invention first obtains the relationship curve between the capillary pressure and the mercury saturation of the rock sample based on the mercury injection method, and collects the mercury injection pressure data and the mercury injection saturation data; then, by calculating the mercury pressure saturation ratio and its difference of multiple test points, a scientific and reasonable judgment criterion is established, that is, when the difference of the mercury pressure saturation ratio of the current test point changes from positive to negative (or exactly zero), the next test point is marked as the turning point. The objective judgment method based on the mathematical model overcomes the disadvantages of strong subjectivity, poor repeatability and low efficiency in the traditional manual picking method. In addition, the present invention also clearly defines the specific content and calculation method of the turning point information, including the mercury injection saturation and the mercury injection pressure of the turning point, so that the obtained turning point information is more comprehensive and accurate. In practical applications, these turning point information has important guiding significance for the research on the pore distribution characteristics, permeability performance, reservoir evaluation, etc. of the rock. Due to the high degree of automation, the present invention can process a large amount of rock sample data, significantly improve the work efficiency, reduce human errors, and ensure the consistency and reliability of the analysis results. At the same time, the present invention has a wide range of applicability and can be applied to the analysis of different types of rock samples, such as sandstone, carbonate rock, etc., and has important application value in the fields of oil and gas field exploration and development, geological research, materials science, etc.

[0046] Generally speaking, the automatic picking method provided by the present invention is scientific and reasonable, easy to operate, high in efficiency and good in accuracy, provides a new technical means for the turning point analysis of the mercury injection curve of the rock sample, and promotes the development and progress of the research on the physical properties of the rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1Schematic flow chart of a method for automatically picking the inflection point information of a mercury injection curve of a rock sample provided by an embodiment of the present invention;

[0049] Figure 2 Schematic structural diagram of a device for automatically picking the inflection point information of a mercury injection curve of a rock sample provided by an embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the vertex of the Swanson curve provided by an embodiment of the present invention;

[0051] Figure 4 Mercury injection curve graph corresponding to the embodiment provided by an embodiment of the present invention;

[0052] Figure 5 Graph of the automatic picking result of the inflection point of the mercury injection curve corresponding to the embodiment provided by an embodiment of the present invention. Detailed implementation manners

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention, and they should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention. In the description of the present invention, it should be understood that the terms used are only for the purpose of description and cannot be construed as indicating or implying relative importance.

[0054] The embodiments of the present invention will be described below with reference to the drawings.

[0055] As Figure 1 shown, the present invention provides a method for automatically picking the inflection point information of a mercury injection curve of a rock sample, including:

[0056] S1: Obtain the mercury injection curve data of the rock sample.

[0057] Among them, step S1 further includes:

[0058] S11: Conduct a mercury injection test on the rock sample based on the mercury injection method to obtain the relationship curve between the capillary pressure and the mercury saturation of the rock sample.

[0059] In step S11, first, the mercury injection method is used to perform mercury injection tests on rock samples to obtain the relationship curve between capillary pressure and mercury saturation of the rock samples. Specifically, first, rock samples need to be prepared. Usually, core samples are cut into cylinders or cubes of appropriate sizes, and then dried to remove the moisture in the rock samples. Subsequently, the processed rock samples are placed in the sample cell of a mercury injection instrument, evacuated to remove the gas in the rock samples, and then mercury is injected. As the system pressure gradually increases, the amount of mercury injected into the rock samples at each pressure point is recorded. The pressure range usually varies from atmospheric pressure to several hundred megapascals, depending on the properties of the rock samples and the experimental purpose. Based on these recorded data, the relationship curve between capillary pressure and mercury saturation of the rock samples is plotted.

[0060] S12: Collect mercury injection curve data of the rock samples from the relationship curve. The mercury injection curve data of the rock samples includes: mercury injection pressure data and mercury injection saturation data.

[0061] Furthermore, the mercury injection pressure data is the external pressure value applied to mercury, and the mercury injection saturation data represents the ratio of the volume of mercury entering the pores of the rock samples to the total pore volume of the rock samples at a specific pressure, expressed as a percentage. These two sets of data constitute the basic data set of the mercury injection curve of the rock samples, providing a data basis for subsequent inflection point picking.

[0062] S2: Calculate the difference in mercury pressure saturation ratio at multiple test points in the mercury injection curve of the rock samples according to the mercury injection curve data of the rock samples.

[0063] Among them, step S2 further includes:

[0064] S21: Calculate the mercury pressure saturation ratio at multiple test points according to the mercury injection curve data of the rock samples.

[0065] Among them, the expression of the mercury pressure saturation ratio in step S21 is:

[0066]

[0067] where i is the test point index, E i is the ratio of the mercury injection saturation to the mercury injection pressure at the i-th test point, S Hg,i is the mercury injection saturation corresponding to the mercury injection pressure at the i-th test point, and P c,i is the mercury injection pressure at the i-th test point.

[0068] In step S21, first, the mercury pressure saturation ratio at multiple test points needs to be calculated according to the mercury injection curve data of the rock samples. The mercury pressure saturation ratio refers to the ratio of the mercury injection saturation to the mercury injection pressure at the test point. The physical meaning of the mercury pressure saturation ratio is the saturation change per unit pressure, reflecting the absorption ability of the rock samples to mercury at a specific pressure point.

[0069] The specific steps for calculating the mercury pressure saturation ratio are as follows: First, extract the mercury injection pressure and the corresponding mercury injection saturation of each test point from the obtained mercury injection curve data of the rock sample. Then, for each test point, divide its mercury injection saturation by the mercury injection pressure to obtain the mercury pressure saturation ratio of this test point. Repeat the above calculation for all test points to obtain a set of mercury pressure saturation ratio data.

[0070] S22: Calculate the difference in mercury pressure saturation ratio between two consecutive adjacent test points based on the mercury pressure saturation ratio.

[0071] Among them, the expression for the difference in mercury pressure saturation ratio in step S22 is:

[0072] A i =E i+1 -E i ;

[0073] Among them, A i is the difference between the ratio of mercury injection saturation to mercury injection pressure at the (i + 1)-th test point and the ratio of mercury injection saturation to mercury injection pressure at the i-th test point, and E i+1 is the ratio of mercury injection saturation to mercury injection pressure at the (i + 1)-th test point.

[0074] In step S22, calculate the difference in mercury pressure saturation ratio between two consecutive adjacent test points based on the already calculated mercury pressure saturation ratio. The difference in mercury pressure saturation ratio reflects the change in mercury pressure saturation ratio between adjacent test points and is an important basis for identifying the turning point of the mercury injection curve.

[0075] The specific steps for calculating the difference in mercury pressure saturation ratio are as follows: For each test point, calculate the difference between its mercury pressure saturation ratio and the mercury pressure saturation ratio of the next test point. For n test points, n - 1 differences in mercury pressure saturation ratio can be obtained.

[0076] S3: Mark the turning point of the mercury injection curve of the rock sample according to the difference in mercury pressure saturation ratio.

[0077] Furthermore, the sign change of the difference in mercury pressure saturation ratio is the key basis for judging the turning point of the mercury injection curve. When the difference in mercury pressure saturation ratio changes from a positive value to a negative value (or from a negative value to a positive value), it indicates that the mercury injection curve has a turning point here, that is, the pore structure of the rock sample has changed.

[0078] Among them, step S3 specifically includes:

[0079] When the difference in mercury pressure saturation ratio of the current test point is greater than or equal to 0 and the difference in mercury pressure saturation ratio of the next test point is less than or equal to 0, mark the next test point as the turning point of the mercury injection curve of the rock sample.

[0080] Specifically, in step S3, the inflection point positions of the mercury injection curve are marked according to the differences in the mercury injection saturation and the ratio of mercury injection pressure at different test points. Further, as Figure 3 shown, it is a schematic diagram of the vertex of the Swanson curve. When on the left side of the vertex of the Swanson curve, the mercury injection saturation is small and A i is a positive number (A i ≥0); on the right side, the mercury injection saturation is large and A i+1 is a negative number (A i+1 ≤0). At this time, for the determined A i with the above characteristics, the inflection point of the mercury injection curve should be at the position of the (i + 1)-th test point.

[0081] S4: Pick up the inflection point information of the mercury injection curve according to the inflection point.

[0082] Step S4 is the last key step in the automatic picking method of the inflection point information of the mercury injection curve of the rock sample in the present invention. The main purpose is to extract the corresponding inflection point information according to the marked inflection point. The inflection point information refers to the mercury injection saturation and the mercury injection pressure at the inflection point of the mercury injection curve. These information directly reflect the pore structure characteristics of the rock sample and are of great significance for rock physical property evaluation and reservoir analysis.

[0083] Among them, the inflection point information in step S4 includes:

[0084] The mercury injection saturation at the inflection point of the mercury injection curve, the mercury injection pressure at the inflection point of the mercury injection curve;

[0085] The expression of the mercury injection saturation at the inflection point of the mercury injection curve is:

[0086] S Hg,tp = S Hg,jtp ;

[0087] Among them, S Hg,tp is the mercury injection saturation at the inflection point of the mercury injection curve, and S Hg,jtp is the mercury injection saturation at the position of the inflection point of the mercury injection curve;

[0088] The expression of the mercury injection pressure at the inflection point of the mercury injection curve is:

[0089] P c,tp = P c,jtp ;

[0090] Among them, P c,tp is the mercury injection pressure at the inflection point of the mercury injection curve, and P c,jtp is the mercury injection pressure at the position of the inflection point of the mercury injection curve.

[0091] In the mercury injection curve, the turning points usually correspond to the pore distribution boundaries of different types or sizes in the rock sample. By obtaining the specific information of these turning points, the pore structure parameters of the rock sample can be quantitatively described. The mercury saturation at the turning point of the mercury injection curve refers to the mercury saturation value at the turning point position. Similarly, the mercury injection pressure at the turning point of the mercury injection curve refers to the mercury injection pressure value at the turning point position.

[0092] As Figure 2 shown, the present invention also provides an automatic picking device for the turning point information of the mercury injection curve of a rock sample, including:

[0093] A collection module 100: used to obtain the mercury injection curve data of the rock sample;

[0094] A calculation module 200: used to calculate the difference in the mercury pressure saturation ratio of multiple test points in the mercury injection curve of the rock sample according to the mercury injection curve data of the rock sample;

[0095] A determination module 300: used to mark the turning points of the mercury injection curve of the rock sample according to the difference in the mercury pressure saturation ratio;

[0096] A picking module 400: used to pick the turning point information of the mercury injection curve according to the turning points.

[0097] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0098] The present invention also provides an automatic picking device for the turning point information of the mercury injection curve of a rock sample, including:

[0099] A memory and at least one processor, and instructions are stored in the memory;

[0100] At least one of the processors calls the instructions in the memory so that an automatic picking device for the turning point information of the mercury injection curve of a rock sample executes an automatic picking method for the turning point information of the mercury injection curve of a rock sample as described in any one of the above.

[0101] The present invention also provides a computer-readable storage medium, and instructions are stored on the computer-readable storage medium. When the instructions are executed by a processor, an automatic picking method for the turning point information of the mercury injection curve of a rock sample as described in any one of the above is implemented.

[0102] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the above technical solution, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0103] The following describes a method and device for automatically picking the turning point information of a mercury injection curve of a rock sample provided by the present invention in conjunction with specific embodiments.

[0104] In this embodiment, taking Oilfield A with an area of about 2600 km 2 , the main layer is the Chang 63 sand group of the Chang 6 oil formation in the upper Yanchang Formation of the Triassic System, belonging to the gravity flow deposition of the deep lake - semi - deep lake facies. The average porosity of the reservoir is 9.09%, and the average permeability is 0.219×10 -3 μm 2 , belonging to the extra - low porosity - ultra - low permeability reservoir as an example.

[0105] Taking the mercury injection curve of the 16# rock sample (2064.1 m) in Well Bai 221 of the Chang 6 oil formation in Oilfield A as an example, the basic data of the mercury injection experiment of this rock sample is shown in Table 1, the measured mercury injection curve data is shown in Table 2, and the corresponding mercury injection curve is as Figure 4 shown, Figure 4 where the ordinate is the mercury injection pressure P c , with the unit of MPa, and the abscissa is the mercury injection saturation S Hg , with the unit of %.

[0106] Table 1 Basic data table of the mercury injection experiment of the rock sample

[0107] Core Number: 16# <![CDATA[Pore volume (cm 3 ):]]> 1.48 Sample Weight (g): 27.51 Well Number: Bai 221 <![CDATA[Sample volume (cm 3 ):]]> 12.14 Lithology: Sandstone Well Depth (m): 2064.1 Porosity (%): 12.19 Stratigraphic Horizon: <![CDATA[Length 63]]> <![CDATA[Permeability (×10 -3 μm 2 ):]]> 0.216

[0108] Table 2 Data table of the mercury injection curve of the rock sample

[0109] Test Pressure Point Mercury Injection Pressure Mercury Injection Saturation Mercury Withdrawal Pressure Mercury Withdrawal Saturation Serial Number (MPa) (％) (MPa) (％) 1 0.0035 0 2 0.0075 0 3 0.0109 0 4 0.0151 0 5 0.022 0 6 0.0309 0 7 0.044 0 8 0.0626 0 9 0.0838 0 10 0.1068 0 11 0.1377 0 0.1585 61.3829 12 0.237 0 0.2775 63.6555 13 0.3406 0 0.3816 65.6115 14 0.498 0 0.5405 67.7848 15 0.7164 0.8138 0.7623 70.0284 16 1.0335 5.2854 1.064 72.4667 17 1.459 24.1657 1.514 75.0862 18 2.0839 38.0085 2.1411 77.4097 19 2.971 46.4137 3.0173 79.3458 20 4.2272 53.5336 4.2822 81.0612 21 6.014 59.2188 6.0628 82.6573 22 8.5497 65.0701 8.5711 84.1764 23 12.1674 70.9302 12.2235 85.62 24 17.2745 76.1575 17.2939 87.0513 25 24.5409 80.4162 24.6502 88.2665 26 34.8352 84.5203 34.9639 89.1302 27 49.49 87.4704 49.6183 89.2592 28 70.3341 89.1605 70.2943 89.4704 29 99.9604 89.5728 99.9604 89.5728

[0110] Calculated by the method for automatically picking the turning point information of the mercury injection curve of the rock sample provided by the present invention, the automatically picked turning point information of the mercury injection curve is shown in Table 3. The result of automatically picking the turning point of the mercury injection curve in the embodiment of the present invention is as Figure 5 shown, Figure 5 where the ordinate is the mercury injection pressure P c , with the unit of MPa, and the abscissa is the mercury injection saturation S Hg , with the unit of %. From Figure 5It can be seen that through the calculation method of the present invention, the inflection point of the mercury injection curve of the rock sample can be determined efficiently and accurately, and the information of the inflection point of the mercury injection curve of the corresponding rock sample can be automatically picked up.

[0111] Table 3 Automatic picking calculation result table of the information of the inflection point of the mercury injection curve of the rock sample

[0112]

[0113] The mercury injection curve is not only a conventional test item in oilfield mines, but also an important basic data for oil and gas field development and reservoir geology research. The information of the inflection point of the mercury injection curve is an important characteristic parameter of the mercury injection curve and is widely used in the research of oil and gas reservoir geology. However, at present, the picking of the information of the inflection point of the mercury injection curve is still in the stage of manual calibration, which seriously delays the application of the information of the inflection point of the mercury injection curve.

[0114] Therefore, in view of the massive mercury injection curve data accumulated in oilfield mines, through the processing of the mercury injection curve data information, the present invention provides a method, device, equipment and medium for automatically picking up the information of the inflection point of the mercury injection curve of the rock sample, which can realize the automatic quantitative picking function of the information of the inflection point of the mercury injection curve of the rock sample, is suitable for batch processing of the mercury injection curve, and can significantly improve the processing efficiency of the mercury injection curve with a large amount of data and the picking efficiency of its inflection point information. This method is simple and easy to implement, and has strong operability, which can provide data support for carrying out oil and gas reservoir geology research by using the information of the inflection point of the mercury injection curve, and has important theoretical and practical value.

[0115] Based on the processing of the mercury injection curve data information, the present invention can realize the automatic quantitative picking function of the information of the inflection point of the mercury injection curve of the rock sample, without the need to manually calibrate the inflection point of the mercury injection curve by the reading method, thus greatly reducing the workload of the traditional manual calibration of the inflection point of the mercury injection curve and picking up the inflection point information; the present invention effectively avoids the error of manually picking up the information of the inflection point of the mercury injection curve, significantly improves the processing efficiency of the mercury injection curve with a large amount of data and the picking efficiency of its inflection point, and fills the blank of the automatic quantitative picking method of the inflection point of the mercury injection curve; the method of the present invention is simple and easy to implement, and has strong operability. The information of the inflection point of the mercury injection curve picked up can provide data support for carrying out related research on oil and gas reservoirs by using the information of the inflection point of the mercury injection curve, such as studying the microscopic pore structure characteristics of reservoir rocks, estimating the storage and seepage capacity of reservoirs, and evaluating the quality of reservoirs, etc., and has broad application prospects.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic picking method for the inflection point information of the mercury injection curve of rock samples, characterized in that, Including: S1: Obtain mercury injection curve data of rock samples; S2: Calculate the difference in mercury pressure saturation ratios at multiple test points on the mercury injection curve of the rock sample according to the mercury injection curve data of the rock sample; S3: Mark the inflection points of the mercury injection curve of the rock sample according to the difference in mercury pressure saturation ratios; S4: Pick up the inflection point information of the mercury injection curve according to the inflection points.

2. The automatic picking method for the inflection point information of the mercury injection curve of a rock sample according to claim 1, wherein, Step S1 further includes: S11: Conduct mercury injection tests on rock samples based on the mercury injection method to obtain the relationship curve between capillary pressure and mercury saturation in the rock sample; S12: Collect mercury injection curve data of the rock sample from the relationship curve.

3. The automatic picking method for the inflection point information of the mercury injection curve of a rock sample according to claim 1, characterized in that, The mercury injection curve data of the rock sample in step S1 includes: Mercury injection pressure data, mercury injection saturation data.

4. The automatic picking method for the inflection point information of the mercury injection curve of rock samples according to claim 1, characterized in that, Step S2 further includes: S21: Calculate the mercury pressure saturation ratios at multiple test points according to the mercury injection curve data of the rock sample; S22: Calculate the difference in mercury pressure saturation ratios between two consecutive adjacent test points according to the mercury pressure saturation ratios.

5. The automatic picking method for the inflection point information of the mercury injection curve of rock samples according to claim 4, characterized in that, The expression for the mercury pressure saturation ratio in step S21 is: where i is the test point index, and E i is the ratio of mercury intrusion saturation to mercury intrusion pressure at the i-th test point, and S Hg,i is the mercury intrusion saturation corresponding to the mercury intrusion pressure at the i-th test point, and P c,i is the mercury intrusion pressure at the i-th test point; The expression for the difference in mercury pressure saturation ratios in step S22 is: A i = E i+1 - E i ; Among them, A i is the difference between the ratio of mercury intrusion saturation to mercury intrusion pressure at the (i + 1)-th test point and the ratio of mercury intrusion saturation to mercury intrusion pressure at the i-th test point, and E i+1 is the ratio of mercury intrusion saturation to mercury intrusion pressure at the (i + 1)-th test point.

6. A method for automatically picking up the inflection point information of the mercury injection curve of a rock sample according to claim 1, characterized in that Step S3 specifically includes: When the difference in mercury pressure saturation ratios at the current test point is greater than or equal to 0 and the difference in mercury pressure saturation ratios at the next test point is less than or equal to 0, mark the next test point as the inflection point of the mercury injection curve of the rock sample.

7. The automatic picking method for the inflection point information of the mercury injection curve of a rock sample according to claim 1, wherein, The inflection point information in step S4 includes: Mercury injection saturation at the inflection point of the mercury injection curve, mercury injection pressure at the inflection point of the mercury injection curve; The expression for mercury injection saturation at the inflection point of the mercury injection curve is: S Hg,tp = S Hg,jtp ; Among them, S Hg,tp is the mercury intrusion saturation at the turning point of the mercury intrusion curve, and S Hg,jtp is the mercury intrusion saturation at the position of the turning point of the mercury intrusion curve; The expression for mercury injection pressure at the inflection point of the mercury injection curve is: P c,tp = P c,jtp ; Among them, P c,tp is the mercury injection pressure at the turning point of the mercury injection curve, and P c,jtp is the mercury injection pressure at the position of the turning point of the mercury injection curve.

8. An automatic picking device for the turning point information of the mercury injection curve of a rock sample, characterized in that, Including: Acquisition module: used to obtain mercury injection curve data of rock samples; Calculation module: used to calculate the difference in mercury pressure saturation ratios at multiple test points on the mercury injection curve of the rock sample according to the mercury injection curve data of the rock sample; Determination module: used to mark the inflection points of the mercury injection curve of the rock sample according to the difference in mercury pressure saturation ratios; Pick-up module: used to pick up the inflection point information of the mercury injection curve according to the inflection points.

9. An automatic picking device for the turning point information of the mercury injection curve of a rock sample, characterized in that, Including: A memory and at least one processor, wherein instructions are stored in the memory; At least one of the processors calls the instructions in the memory so that a device for automatically picking up the inflection point information of a mercury injection curve of a rock sample executes a method for automatically picking up the inflection point information of a mercury injection curve of a rock sample as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, Instructions are stored on the computer-readable storage medium, and when the instructions are executed by the processor, a method for automatically picking up the inflection point information of a mercury injection curve of a rock sample as described in any one of claims 1-7 is implemented.

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