Quantitative evaluation method for shale reservoir exploitation difficulty level and related device

Abstract

The invention discloses a quantitative evaluation method for the mining difficulty degree of a shale reservoir and a related device. The method comprises the following steps: obtaining the percentage of each mineral component in a rock sample of a shale reservoir target evaluation section, and calculating reservoir rock complex factors according to the percentage of each mineral component in the rock sample; recording ringing counting rates of the rock sample in the acoustic emission test process, and calculating acoustic emission influence factors corresponding to the rock sample according to the plurality of ringing counting rates; according to the reservoir rock complex factors and the acoustic emission influence factors, shale reservoir exploitation difficulty coefficients are calculated; according to the obtained shale reservoir exploitation difficulty coefficient, the exploitation difficulty degree of the reservoir target evaluation section where the rock sample is located is evaluated. According to the method, a large number of mine field tests are avoided, the engineering cost is reduced, and the efficiency of evaluating the shale reservoir exploitation difficulty degree is improved.

Description

Technical Field

[0001] The invention relates to the field of petroleum and natural gas engineering, and in particular to a quantitative evaluation method for the difficulty of shale reservoir exploitation and a related device. Background Art

[0002] China's shale oil and gas resources are extremely rich and have great development potential. They are the most strategic oil replacement resources. Fully releasing oil and gas reservoirs and finding favorable reservoir qualities are the basis for selecting wells and sections for horizontal well volume fracturing, and are the key to achieving a breakthrough in single well production. The accurate evaluation of the difficulty of shale reservoir exploitation in engineering projects is largely related to the exploration potential and scale benefits of unconventional oil and gas resources.

[0003] Shale is a sedimentary rock. Due to the differences in sedimentary environment and geological structure, shale reservoirs are usually composed of multiple thin layers of different lithologies. At the same time, reservoir bedding and natural fractures are well developed, which are highly heterogeneous. It is well known that the core factors affecting the difficulty of unconventional shale reservoir exploitation are the oil and gas flow performance in the fractures of the reservoir itself and the complexity of the network formed after fracturing. At present, scholars at home and abroad mainly evaluate the quality of reservoirs based on how to quantify shale brittleness indicators. The factors affecting brittleness include shale mineral composition, lithology, lithofacies, porosity, permeability, mineral crystal form and mineral occurrence.

[0004] In addition to shale brittleness, the external environment of the reservoir is also an important factor affecting the oil and gas flow performance in the reservoir fractures and the complexity of the network formed after fracturing. The two most important parameters reflecting the external environment are the temperature of the reservoir and the confining pressure. For shale reservoirs under different geological conditions, if only the shale brittleness is evaluated without considering the influence of temperature and pressure, the difficulty of shale reservoir exploitation cannot be accurately evaluated. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a quantitative evaluation method and related device for the difficulty of shale reservoir exploitation.

[0006] In a first aspect, an embodiment of the present invention provides a method for quantitatively evaluating the difficulty of shale reservoir exploitation, comprising the following steps:

[0007] Conducting mineral composition testing on rock samples of the target evaluation section of the shale reservoir, and calculating the percentage of each mineral component in the rock samples;

[0008] Calculating the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0009] Performing an acoustic emission test on the rock sample, recording the ringing count rate of the rock sample during the acoustic emission test, and calculating the acoustic emission impact factor corresponding to the rock sample according to a plurality of the ringing count rates;

[0010] Calculating the shale reservoir mining difficulty coefficient according to the reservoir rock complexity factor and the acoustic emission impact factor;

[0011] According to the shale reservoir mining difficulty coefficient, the mining difficulty of the target evaluation section of the reservoir where the rock sample is located is evaluated.

[0012] In one embodiment, the rock sample of the target evaluation section of the shale reservoir is obtained in advance by:

[0013] The shale reservoir target evaluation section is divided into a number of units and continuous coring is carried out on the units, and the coring rocks are made into rock samples of preset sizes.

[0014] In one embodiment, the percentage of each mineral component in the rock sample is calculated in the following manner:

[0015] The rock sample is placed in an oven and dried to constant weight. The dried rock sample is tested to obtain the mass of each mineral in the rock sample, and the mass percentage of each mineral is calculated according to the following formula:

[0016]

[0017] Where: W i is the mass percentage of each mineral in the rock sample; m i is the mass of each mineral in the rock sample; n is the number of mineral types contained in the rock sample.

[0018] In one embodiment, the reservoir rock complexity factor corresponding to the rock sample is calculated according to the percentage of each mineral component in the rock sample, including:

[0019] The reservoir rock complexity factor is calculated according to the following formula:

[0020]

[0021] Wherein: MI is the reservoir rock complexity factor; W0 is the mass percentage of clay minerals in the rock sample.

[0022] In one embodiment, an acoustic emission test is performed on the rock sample, a ringing count rate of the rock sample during the test is recorded, and an acoustic emission impact factor corresponding to the rock sample is calculated according to the ringing count rate, including:

[0023] The acoustic emission test is performed on the rock sample by using a triaxial loading control system and an acoustic emission monitoring system, and the temperature and confining pressure of the rock sample in the test are controlled according to the actual temperature and confining pressure of the target evaluation section of the shale reservoir;

[0024] During the acoustic emission test, the ringing count rate at the start and end of each ringing sampling period is recorded to obtain the ringing count rate at each ringing sampling time;

[0025] According to the change rule of each of the ring count rates, a ring calculation interval is determined, the duration of the ring calculation interval is an integer multiple of the duration of the ring sampling period, and the start time of each ring calculation interval corresponds to each ring sampling time;

[0026] Calculate the difference in ring count rate between the end time and the start time of each ring count rate calculation interval, and calculate the acoustic emission impact factor based on the maximum value of the difference in each ring count rate and the end time of the ring calculation interval where the maximum value of the difference is located.

[0027] In one embodiment, the difference between the ring count rates corresponding to the end time and the start time in each ring calculation interval is calculated, and the acoustic emission impact factor is calculated according to the maximum value of the difference between the ring count rates and the end time of the ring calculation interval where the maximum value of the difference is located, including:

[0028] The acoustic emission impact factor corresponding to the rock sample is calculated according to the following formula:

[0029]

[0030] Where: Z is the acoustic emission impact factor; (N t+T -N t ) max is the maximum value of the difference between the ringing count rate at the end and start of the ringing calculation interval; t is the ringing sampling time, which is equal to the time from the start time 0 of the test to the ringing sampling time; T is the duration of the ringing calculation interval; t x is the end time of the ringing calculation interval where the maximum value is located, and the end time is equal to the duration from the test start time 0 to the end time of the ringing calculation interval where the maximum value is located; a and b are constants used to adjust the calculation result of Z so that it falls within a preset reasonable range.

[0031] In one embodiment, the shale reservoir mining difficulty coefficient is calculated according to the reservoir rock complexity factor and the acoustic emission impact factor, including:

[0032] The shale reservoir mining difficulty coefficient is calculated according to the following formula:

[0033]

[0034] Where: K is the shale reservoir mining difficulty coefficient corresponding to the rock sample; Z max is the preset maximum value of the acoustic emission impact factor, which is a constant; MI maxis the preset maximum value of the reservoir rock complexity factor, which is a constant.

[0035] In a second aspect, an embodiment of the present invention provides a method for determining a shale reservoir mining difficulty coefficient, comprising:

[0036] Obtaining the results of a mineral composition test of a rock sample of a target evaluation section of a shale reservoir, wherein the results of the mineral composition test of the rock sample are the percentages of each mineral component in the rock sample;

[0037] Calculating the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0038] Obtaining a ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculating an acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value;

[0039] The shale reservoir mining difficulty coefficient is calculated based on the reservoir rock complexity factor and the acoustic emission influence factor, and the shale reservoir mining difficulty coefficient is used to characterize the difficulty of mining the shale reservoir.

[0040] In a third aspect, an embodiment of the present invention provides a device for determining a shale reservoir mining difficulty coefficient, comprising:

[0041] An acquisition module, used to acquire the result of the mineral composition test of the rock sample of the target evaluation section of the shale reservoir, wherein the result of the mineral composition test of the rock sample is the percentage of each mineral component in the rock sample;

[0042] A rock complexity factor calculation module, used to calculate the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0043] An acoustic emission impact factor calculation module is used to obtain the ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculate the acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value;

[0044] The shale reservoir mining difficulty coefficient determination module is used to calculate the shale reservoir mining difficulty coefficient according to the reservoir rock complexity factor and the acoustic emission influencing factor. The shale reservoir mining difficulty coefficient is used to characterize the difficulty of mining the shale reservoir.

[0045] In a fourth aspect, an embodiment of the present invention provides a computing device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the aforementioned method for determining the difficulty coefficient of shale reservoir exploitation when executing the program.

[0046] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the aforementioned method for determining the difficulty coefficient of shale reservoir exploitation is implemented.

[0047] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0048] The above-mentioned quantitative evaluation method and related devices for the difficulty of shale reservoir mining provided by the embodiment of the present invention comprehensively consider the two factors of shale reservoir brittleness and external environment, use the reservoir rock complexity factor and the acoustic emission influencing factor, determine the shale reservoir mining difficulty coefficient that can characterize the difficulty of shale reservoir mining, and propose a quantitative evaluation method for the difficulty of shale reservoir mining, which avoids a large number of mine field tests, improves the efficiency of the evaluation of the difficulty of shale reservoir mining, reduces the economic cost, and has good application prospects.

[0049] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0051] Figure 1 It is a flow chart of a quantitative evaluation method for the difficulty of shale reservoir exploitation in an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of the relationship between the ringing sampling period and the ringing calculation interval in an embodiment of the present invention;

[0053] Figure 3a It is a bar chart showing the percentage of each mineral component in the shale sample G1 in the embodiment of the present invention;

[0054] Figure 3b This is a bar chart showing the percentage of each mineral component in the shale sample G2 in an embodiment of the present invention;

[0055] Figure 4a This is a graph showing the correlation between the ringing count rate and time of the shale sample G1 in the acoustic emission test in an embodiment of the present invention;

[0056] Figure 4b This is a graph showing the correlation between the ringing count rate and time of the shale sample G2 in the acoustic emission test in an embodiment of the present invention;

[0057] Figure 5 Flow chart of a method for determining a shale reservoir mining difficulty coefficient in an embodiment of the present invention;

[0058] Figure 6 Schematic diagram of the structure of a device for determining a shale reservoir mining difficulty coefficient in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] This embodiment provides a quantitative evaluation method for the difficulty of shale reservoir exploitation. Although the drawings show exemplary embodiments of the present disclosure, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. Specifically, the following steps are included:

[0060] The embodiment of the present invention provides a method for quantitatively evaluating the difficulty of shale reservoir mining, referring to Figure 1 As shown, the method comprises the following steps:

[0061] S11. Conduct mineral composition testing on rock samples of the target evaluation section of the shale reservoir and calculate the percentage of each mineral component in the rock samples;

[0062] S12. Calculate the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0063] S13, performing an acoustic emission test on the rock sample, recording the ringing count rate of the rock sample during the acoustic emission test, and calculating the acoustic emission influence factor corresponding to the rock sample according to multiple ringing count rates;

[0064] S14. Calculate the difficulty coefficient of shale reservoir mining based on reservoir rock complexity factor and acoustic emission impact factor;

[0065] S15. Based on the shale reservoir mining difficulty coefficient, the mining difficulty of the target evaluation section of the reservoir where the rock sample is located is evaluated.

[0066] In step S11, the rock sample of the target evaluation section of the shale reservoir is obtained in advance by the following method:

[0067] The target evaluation section of the shale reservoir is divided into several units and continuous coring is carried out on several units, and the extracted rocks are made into rock samples of preset sizes.

[0068] For example, a rock sample with a diameter of 2.5 cm and a length of 5 cm is prepared, but the embodiment is not limited to the above dimensions.

[0069] Furthermore, in step S11, the percentage of each mineral component in the rock sample can be obtained by the following method:

[0070] First, the rock sample must be dried, for example, by placing it in a 100°C oven and drying it to constant weight. Then, the dried rock sample is tested using a test instrument to analyze the different mineral components in the rock sample and the mass of each mineral component. Then, the mass percentage of each mineral mass in the total mass of the rock sample is calculated:

[0071]

[0072] Where: W i is the mass percentage of each mineral in the rock sample; m i is the mass of each mineral in the rock sample; n is the number of mineral types contained in the rock sample.

[0073] When performing mineral analysis on the dried rock sample, for example, an X-ray diffractometer may be used to test and obtain the mass of each mineral in the rock sample, but the embodiment of the present invention is not limited to the above method.

[0074] In step S12, according to the percentage of each mineral component in the rock sample obtained in step S11 above, the reservoir rock complexity factor corresponding to the rock sample can be calculated according to the following formula:

[0075]

[0076] Where: MI is the reservoir rock complexity factor; W0 is the mass percentage of clay minerals in the rock sample.

[0077] According to the percentage of each mineral in the rock sample, the complexity of the reservoir rock is calculated, and the composition and morphology of the original microcracks in the reservoir and the complexity of the network formed after fracturing can be determined. The greater the reservoir rock complexity factor, the more developed the original microcracks in the reservoir, the better the oil and gas fluidity in the cracks, and the more complex the fracture network formed by fracturing transformation, indicating that the shale reservoir is easier to exploit.

[0078] Here, the influence of reservoir rock complexity factors on the difficulty of reservoir exploitation is called internal factors.

[0079] In step S13, an acoustic emission test is performed on the rock sample, the ringing count rate of the rock sample during the test is recorded, and the acoustic emission impact factor corresponding to the rock sample is calculated according to the ringing count rate, which can be achieved, for example, in the following manner:

[0080] Using a triaxial loading control system and an acoustic emission monitoring system, an acoustic emission test is conducted on rock samples. The temperature and confining pressure of the rock samples in the test are controlled according to the actual temperature and confining pressure of the target evaluation section of the shale reservoir.

[0081] During the acoustic emission test, the ringing count rate at the start and end of each ringing sampling period is recorded respectively to obtain the ringing count rate at each ringing sampling time;

[0082] According to the change rule of each ringing counting rate, a ringing calculation interval is determined, the duration of the ringing calculation interval is an integer multiple of the duration of the ringing sampling period, and the start time of each ringing calculation interval corresponds to each ringing sampling time;

[0083] Calculate the difference in ring count rate between the end time and the start time of each ring count interval, and calculate the acoustic emission impact factor based on the maximum value of the difference in each ring count rate and the end time of the ring calculation interval where the maximum difference is located.

[0084] In order to understand the ringing sampling period, the ringing calculation interval and the relationship between them in the present invention, a diagram is provided in the embodiment, as shown in FIG. Figure 2 shown.

[0085] The test process starts from 0, t j is the ringing sampling moment, and the duration of each ringing sampling cycle is (t j+1 -t j ), the jth ringing sampling period is [t j , t j+1 ], the duration of each ringing calculation interval is T, and the start time of the ringing calculation interval corresponds to the ringing sampling time one by one.

[0086] For example: in one embodiment, t1=90s, the ringing sampling period is 200s, and the ringing calculation interval is 3 times of the ringing sampling period, which is 600s. Then the ringing sampling moments are 90s, 290s, 490s, 690s..., the start time of the ringing calculation interval is the same as the ringing sampling moment, and the end time of the ringing calculation interval is 690s, 1290s, 1890s... respectively.

[0087] Since the collected ring count rate data fluctuates greatly within a period of time after the start of the acoustic emission test, it is easy to cause distortion of the calculation result. Therefore, the ring count rate data within this period of time, that is, the time range represented by 0 to t1 in the figure, needs to be discarded. The embodiment of the present invention does not limit the value of t1.

[0088] The ringing sampling period duration and the ringing calculation interval duration are empirically determined based on changes in test data, and the embodiments of the present invention do not limit their values.

[0089] Acoustic emission is a phenomenon that occurs when solid materials release stored energy to generate elastic waves when they break. The received acoustic emission signals can be used to study materials and dynamically evaluate the integrity of structures. In the present invention, the acoustic emission monitoring system is synchronized with the triaxial loading control system, and the rock sample failure process can be tracked in real time.

[0090] Furthermore, the difference in the ringing count rate corresponding to the end time and the start time in each ringing calculation interval is calculated, and the acoustic emission impact factor is calculated according to the maximum value of the difference in each ringing count rate and the end time of the ringing calculation interval where the maximum difference is located. The acoustic emission impact factor corresponding to the rock sample is calculated according to the following formula:

[0091]

[0092] Where: Z is the acoustic emission impact factor; (N t+T -N t ) max is the maximum value of the difference between the ringing count rate at the end and start of the ringing calculation interval; t is the ringing sampling time, which is equal to the time from the start time 0 of the test to the ringing sampling time; T is the duration of the ringing calculation interval; t x is the end time of the ringing calculation interval where the maximum value is located, and the end time is equal to the duration from the test start time 0 to the end time of the ringing calculation interval where the maximum value is located; a and b are constants used to adjust the calculation result of Z so that it falls within the preset reasonable range.

[0093] According to the test data obtained from the acoustic emission test, the acoustic emission impact factor is calculated, which can quantitatively express the influence of external factors on the difficulty of reservoir exploitation, namely temperature and confining pressure. The larger the acoustic emission impact factor, the smaller the corresponding reservoir temperature and external confining pressure, the better the oil and gas fluidity in the reservoir fractures, the more complex the fracture network formed during fracturing, and the easier it is to exploit the surface shale reservoir.

[0094] Here, the impact of acoustic emission factors on the difficulty of reservoir exploitation is called external factors.

[0095] Here, the order of implementing step S12 and step S13 is not limited, and the order of implementing them has no effect on the calculation result of the final reservoir exploitation difficulty coefficient.

[0096] In step S14, the shale reservoir mining difficulty coefficient is calculated according to the reservoir rock complexity factor calculated in step S12 and the acoustic emission influence factor calculated in step S13. The shale reservoir mining difficulty coefficient can be calculated according to the following formula:

[0097]

[0098] Where: K is the shale reservoir mining difficulty coefficient corresponding to the rock sample; Z max is the preset maximum value of the acoustic emission impact factor, which is a constant; MI max is the preset maximum value of the reservoir rock complexity factor, which is a constant.

[0099] Z max and MI max, in specific implementation, empirical values ​​can be used.

[0100] In step S15, by comparing the values ​​of the shale reservoir mining difficulty coefficients of different rock samples, the mining difficulty of the target evaluation section of the shale reservoir where the different rock samples are located can be quantitatively compared.

[0101] The influence of internal and external factors on the difficulty of reservoir exploitation is not isolated, but mutually influential, and there is a positive correlation between the two. When the reservoir rock complexity factor is the same, the shale reservoir with a larger acoustic emission factor is relatively easy to exploit; when the acoustic emission factor is the same, the shale reservoir with a larger reservoir rock complexity factor is relatively easy to exploit. By correcting the internal and external factors to express the mutual influence between the two, and then adding the respective correction values, the mining difficulty coefficient is obtained, which is the comprehensive influence of internal and external factors on the difficulty of reservoir exploitation.

[0102] A specific example is used to illustrate the quantitative evaluation method for the difficulty of shale reservoir exploitation.

[0103] The first step is rock sample preparation: the target evaluation section of the shale reservoir is divided into several units, and continuous coring is carried out for each evaluation unit. The rock coring depth is 2000-2500m, and the extracted rock is made into a rock sample with a diameter of 2.5cm and a length of 5cm. There are two rock samples prepared, numbered G1 and G2, and the rock samples are placed in a 100℃ oven to dry to constant weight.

[0104] The second step is the analysis of the mineral composition of the rock samples: using an X-ray diffractometer, the two rock samples G1 and G2 in the first step are tested respectively to obtain the mass of each mineral in the rock samples G1 and G2. The test results show that the minerals in the rock samples G1 and G2 include dolomite, quartz, calcite, feldspar, pyrite and clay. The percentage of each mineral component in the rock sample is calculated according to the following formula:

[0105]

[0106] Where: W i is the percentage of each mineral component in the rock sample; m i is the weight of each mineral in the rock sample; n is the number of mineral types contained in the rock sample.

[0107] The percentage of each mineral in rock samples G1 and G2 is shown in Table 1 below. The percentage of each mineral in rock samples G1 and G2 is shown in the bar chart below. Figure 3a and Figure 3b As shown in FIG3 , the horizontal axis represents the different minerals contained in the rock sample, and the vertical axis represents the mass percentage of the different minerals.

[0108] Table 1

[0109]

[0110] The third step is to calculate the shale reservoir complexity factor: According to the percentage of each mineral in the rock sample obtained in the second step, calculate the reservoir rock complexity factor. The shale reservoir complexity factor corresponding to the rock sample is calculated according to the following formula:

[0111]

[0112] Where: MI is the reservoir rock complexity factor; W0 is the composition percentage of clay minerals.

[0113] According to the percentage of each mineral in Table 1 in the second step, the corresponding reservoir rock complexity factors of rock samples G1 and G2 are calculated as MI G1 =0.94, MI G2 =0.99.

[0114] The fourth step is acoustic emission test: the rock sample is subjected to an acoustic emission test and the ringing count rate of the rock sample during the test is recorded. The acoustic emission test uses a triaxial loading control system and an acoustic emission monitoring system. During the test, the temperature and confining pressure of the rock sample are controlled to simulate the real external environment of the underground shale reservoir.

[0115] During the acoustic emission test, the ringing count rate at the start and end of each ringing sampling period is recorded respectively to obtain the ringing count rate at each ringing sampling time;

[0116] According to the changing rules of each ringing count rate, a ringing calculation interval is determined. The duration of the ringing calculation interval is an integer multiple of the duration of the ringing sampling period. The start time of each ringing calculation interval corresponds to each ringing sampling time.

[0117] In the fourth step, the ringing sampling time starts from the 90th second. This is because the data between 0 and 90 seconds in the test fluctuate greatly. In order to avoid errors in the calculation results, the data of the first period of time in the test are discarded. Preferably, the ringing sampling period of the acoustic emission test is 200 seconds long, and the ringing calculation interval is 600 seconds long. The selection of the ringing sampling period and the ringing calculation interval is selected based on test experience.

[0118] The ringing count rates of rock samples G1 and G2 recorded in the acoustic emission test are shown in Table 2. The correlation between the ringing count rate and time of the acoustic emission test of rock samples G1 and G2 is shown in Table 2. Figure 4a and Figure 4b In Figure 4, the horizontal axis represents the time process of the acoustic emission test, and the coordinate axis represents the ringing count rate recorded at different ringing sampling times.

[0119] Table 2

[0120]

[0121] Step 5: Calculate the acoustic emission impact factor: Calculate the difference in the ringing count rate corresponding to the end time and the start time in each ringing calculation interval, and calculate the acoustic emission impact factor based on the maximum value of the difference in the ringing count rate and the end time of the ringing calculation interval where the maximum difference is located. Calculate the acoustic emission impact factor corresponding to the rock sample according to the following formula:

[0122]

[0123] Where: Z is the acoustic emission impact factor; (N t+T -N t ) max is the maximum value of the difference between the ringing count rate at the end and start of the ringing calculation interval; t is the ringing sampling time, which is equal to the time from the start time 0 of the test to the ringing sampling time; T is the duration of the ringing calculation interval; t x is the end time of the ringing calculation interval where the maximum value is located; a and b are constants used to adjust the calculation result of Z so that it falls within the preset reasonable interval.

[0124] In the calculation of the acoustic emission influence factor, in order to make the calculation result fall within a preset reasonable range, the empirical values ​​of constants a and b in the preset acoustic emission influence factor formula are 6000 and 10 respectively.

[0125] From the fourth step, Table 2 shows that for the G1 rock sample, the ringing calculation interval with the maximum ringing count rate difference is 3290-3890s. For the G2 rock sample, the ringing calculation interval with the maximum ringing count rate difference is 2890-3490s. The acoustic emission influence factors of rock samples G1 and G2 are calculated as Z and Z, respectively. G1 =1.66, Z G2 =1.16.

[0126] It should be noted that the order of calculating the internal factors for evaluating the difficulty of reservoir exploitation, namely the reservoir rock complexity factor, and the order of calculating the external factors for evaluating the difficulty of reservoir exploitation, namely the acoustic emission influencing factor, in steps 2 and 3 is not limited, and their order has no effect on the calculation result of the final reservoir exploitation difficulty coefficient.

[0127] Step 6: Calculate the difficulty coefficient of shale reservoir exploitation: According to the reservoir rock complexity factor and acoustic emission influencing factor, the difficulty coefficient of shale reservoir exploitation is calculated according to the following formula:

[0128]

[0129] Where: K is the shale reservoir mining difficulty coefficient corresponding to the rock sample; Z max is the preset maximum value of the acoustic emission impact factor, which is a constant; MImax is the preset maximum value of the reservoir rock complexity factor, which is a constant.

[0130] MI max Indicates the reservoir rock complexity factor corresponding to the average and uniform distribution of mineral contents in the rock sample. The preset MI max Take it as 16.05. max Indicates that the rock sample is in an exposed state, that is, the corresponding acoustic emission influence factor at normal temperature and pressure. The preset Z max Take it as 1.83. Then, the shale reservoir mining difficulty coefficients corresponding to rock samples G1 and G2 are calculated to be K G1 =0.88, K G2 =0.66. Where K G1 >K G2 This indicates that the target evaluation section of the reservoir where rock sample G1 is located is easier to mine than the target evaluation section where rock sample G2 is located.

[0131] The embodiment of the present invention also provides a method for determining the difficulty coefficient of shale reservoir mining, referring to Figure 5 As shown, the method comprises the steps of:

[0132] S51, obtaining the results of the mineral composition test of the rock sample of the target evaluation section of the shale reservoir, where the results of the mineral composition test of the rock sample are the percentages of each mineral component in the rock sample;

[0133] S52. Calculate the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0134] S53, obtaining the ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculating the acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value;

[0135] S54. The shale reservoir exploitation difficulty coefficient is calculated based on the reservoir rock complexity factor and the acoustic emission influencing factor. The shale reservoir exploitation difficulty coefficient is used to characterize the difficulty of shale reservoir exploitation.

[0136] The implementation of the above steps S51-S54 can refer to the specific implementation of the above steps S11-S15, and the repeated parts will not be repeated.

[0137] The embodiment of the present invention provides a device for determining the difficulty coefficient of shale reservoir mining, referring to Figure 6 As shown, including:

[0138] An acquisition module 61 is used to acquire the results of the mineral composition test of the rock sample of the target evaluation section of the shale reservoir, where the results of the mineral composition test of the rock sample are the percentages of each mineral component in the rock sample;

[0139] A rock complexity factor calculation module 62 is used to calculate the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample;

[0140] The acoustic emission impact factor calculation module 63 is used to obtain the ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculate the acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value;

[0141] The shale reservoir mining difficulty coefficient determination module 64 is used to calculate the shale reservoir mining difficulty coefficient according to the reservoir rock complexity factor and the acoustic emission influence factor. The shale reservoir mining difficulty coefficient is used to characterize the difficulty of mining the shale reservoir.

[0142] An embodiment of the present invention provides a computing device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for determining the difficulty coefficient of shale reservoir exploitation as described above is implemented.

[0143] An embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method for determining the difficulty coefficient of shale reservoir mining as described above is implemented.

[0144] Obviously, those skilled in the art can make various changes to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes.

Claims

1. A quantitative evaluation method for the difficulty of shale reservoir exploitation, characterized in that: include: Conducting mineral composition testing on rock samples of the target evaluation section of the shale reservoir, and calculating the percentage of each mineral component in the rock samples; Calculating the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample; Performing an acoustic emission test on the rock sample, recording the ringing count rate of the rock sample during the acoustic emission test, and calculating the acoustic emission impact factor corresponding to the rock sample according to a plurality of the ringing count rates; Calculating the shale reservoir mining difficulty coefficient according to the reservoir rock complexity factor and the acoustic emission impact factor; According to the shale reservoir mining difficulty coefficient, the mining difficulty of the target evaluation section of the reservoir where the rock sample is located is evaluated.

2. The method according to claim 1, characterized in that The rock sample of the target evaluation section of the shale reservoir is obtained in advance by the following method: The shale reservoir target evaluation section is divided into a number of units and continuous coring is carried out on the units, and the coring rocks are made into rock samples of preset sizes.

3. The method according to claim 1, characterized in that The percentage of each mineral component in the rock sample is calculated in the following way: The rock sample is placed in an oven and dried to constant weight. The dried rock sample is tested to obtain the mass of each mineral in the rock sample, and the mass percentage of each mineral is calculated according to the following formula: Where: W i is the mass percentage of each mineral in the rock sample; m i is the mass of each mineral in the rock sample; n is the number of mineral types contained in the rock sample.

4. The method according to claim 3, characterized in that According to the percentage of each mineral component in the rock sample, the reservoir rock complexity factor corresponding to the rock sample is calculated, including: The reservoir rock complexity factor is calculated according to the following formula: Wherein: MI is the reservoir rock complexity factor; W0 is the mass percentage of clay minerals in the rock sample.

5. The method according to claim 1, characterized in that Performing an acoustic emission test on the rock sample, recording the ringing count rate of the rock sample during the test, and calculating the acoustic emission impact factor corresponding to the rock sample according to the ringing count rate, including: The acoustic emission test is performed on the rock sample by using a triaxial loading control system and an acoustic emission monitoring system, and the temperature and confining pressure of the rock sample in the test are controlled according to the actual temperature and confining pressure of the target evaluation section of the shale reservoir; During the acoustic emission test, the ringing count rate at the start and end of each ringing sampling period is recorded to obtain the ringing count rate at each ringing sampling time; According to the change rule of each of the ring count rates, a ring calculation interval is determined, the duration of the ring calculation interval is an integer multiple of the duration of the ring sampling period, and the start time of each ring calculation interval corresponds to each ring sampling time; Calculate the difference in ringing count rate between the end time and the start time of each ringing calculation interval, and calculate the acoustic emission impact factor based on the maximum value of the difference in each ringing count rate and the end time of the ringing calculation interval where the maximum value of the difference is located.

6. The method according to claim 5, characterized in that Calculating the difference in ring count rates corresponding to the end time and the start time in each ring calculation interval, and calculating the acoustic emission impact factor according to the maximum value of the difference in each ring count rate and the end time of the ring calculation interval where the maximum value of the difference is located, including: The acoustic emission influence factor corresponding to the rock sample is calculated according to the following formula: Where: Z is the acoustic emission impact factor; (N t+T -N t ) max is the maximum value of the difference between the ringing count rate at the end and start of the ringing calculation interval; t is the ringing sampling time, which is equal to the time from the start time 0 of the test to the ringing sampling time; T is the duration of the ringing calculation interval; t x is the end time of the ringing calculation interval where the maximum value is located, and the end time is equal to the duration from the test start time 0 to the end time of the ringing calculation interval where the maximum value is located; a and b are constants used to adjust the calculation result of Z so that it falls within a preset reasonable range.

7. The method according to claim 1, characterized in that The shale reservoir mining difficulty coefficient is calculated based on the reservoir rock complexity factor and the acoustic emission influence factor, including: The shale reservoir mining difficulty coefficient is calculated according to the following formula: Where: K is the shale reservoir mining difficulty coefficient corresponding to the rock sample; Z max is the preset maximum value of the acoustic emission impact factor, which is a constant; MI max is the preset maximum value of the reservoir rock complexity factor, which is a constant.

8. A method for determining the difficulty coefficient of shale reservoir mining, characterized in that: include: Obtaining the results of a mineral composition test of a rock sample of a target evaluation section of a shale reservoir, wherein the results of the mineral composition test of the rock sample are the percentages of each mineral component in the rock sample; Calculating the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample; Obtaining a ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculating an acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value; The shale reservoir mining difficulty coefficient is calculated based on the reservoir rock complexity factor and the acoustic emission influence factor, and the shale reservoir mining difficulty coefficient is used to characterize the difficulty of mining the shale reservoir.

9. A device for determining the difficulty coefficient of shale reservoir mining, characterized in that: include: An acquisition module, used to acquire the result of the mineral composition test of the rock sample of the target evaluation section of the shale reservoir, wherein the result of the mineral composition test of the rock sample is the percentage of each mineral component in the rock sample; A rock complexity factor calculation module, used to calculate the reservoir rock complexity factor corresponding to the rock sample according to the percentage of each mineral component in the rock sample; An acoustic emission impact factor calculation module is used to obtain the ringing count rate change value of each ringing calculation interval obtained during the rock sample acoustic emission test, and calculate the acoustic emission impact factor corresponding to the rock sample according to the ringing count rate change value; The shale reservoir mining difficulty coefficient determination module is used to calculate the shale reservoir mining difficulty coefficient according to the reservoir rock complexity factor and the acoustic emission influencing factor. The shale reservoir mining difficulty coefficient is used to characterize the difficulty of mining the shale reservoir.

10. A computing device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for determining the shale reservoir mining difficulty coefficient as described in claim 8 when executing the program.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the shale reservoir mining difficulty coefficient according to claim 8 is implemented.

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