A method for identifying sweet spots in hydraulic fracturing engineering based on MSE

Abstract

The present invention discloses a method for identifying hydraulic fracturing engineering sweet spots based on MSE, which relates to the technical field of oil and gas exploration, and comprises the following steps: obtaining drilling time data and raw data for calculating mechanical specific energy from well history data, obtaining gamma logging data from logging data, and using Fred E. Dupriest model to calculate mechanical specific energy of formation rocks at different depths; using moving average method to reduce noise of mechanical specific energy, gamma logging data and drilling time data; fusing mechanical specific energy data with gamma logging data to construct MSE+GR model, and drawing MSE / GR curves of formation rocks at different well depths; further fusing MSE+GR model with drilling time data to obtain MSE / (GR*drilling time) value, and drawing MSE / (GR*drilling time) fusion graph of formation rocks at different well depths; verifying identification results through fracturing curve and rock brittleness index, and determining engineering sweet spots. The present invention requires gamma logging data of logging data to quickly and accurately identify engineering sweet spots, and the identification results are verified by pressure curve and rock brittleness analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method for identifying sweet spots in hydraulic fracturing engineering based on MSE. Background Art

[0002] With the continuous growth of energy demand and the increasing difficulty of conventional oil and gas reservoir exploration, the proportion of unconventional oil and gas reservoirs in the exploration field, especially in the secondary exploration of oil fields, is increasing. As an important part of unconventional oil and gas reservoirs, tight sandstone oil and gas is an unconventional oil and gas resource that has been explored and developed in recent years. Due to the small porosity and low permeability between sand particles, the storage and migration capacity of tight sandstone reservoirs for oil and gas is poor, so it is difficult to exploit. With the continuous development of horizontal well technology and multi-stage fracturing technology, the exploitation of tight sandstone oil and gas resources has become more and more promising. The accurate evaluation and mutual matching of geological sweet spots and engineering sweet spots are the key to the large-scale and efficient development of tight oil and gas with horizontal well volume fracturing as the core technology. Therefore, establishing an MSE-based engineering sweet spot identification method is of great guiding significance for accurately and quickly identifying the engineering sweet spots of horizontal well fracturing and promoting the integration of geology and engineering.

[0003] At present, the mainstream "engineering sweet spot" evaluation methods mainly include shale reservoir brittleness, natural fracture prediction methods and other methods. Although these methods have been actually applied on site, there are many problems. For example, the brittleness of shale reservoirs can only be evaluated by selecting appropriate indicators through existing data. If the data is insufficient or not accurate enough, the evaluation results will produce errors; the prediction method of natural fractures has certain errors in prediction accuracy, and some complex geological structures cannot be effectively predicted and analyzed, and the data processing and acquisition costs are high. At present, there is still a lack of a method for accurately and quickly identifying horizontal well engineering sweet spots in the absence of logging data. The present invention, based on the preferred mechanical specific energy calculation model, forms a method for identifying engineering sweet spots in tight sandstone horizontal wells, which realizes accurate and rapid identification of horizontal well engineering sweet spots in the absence of logging data, which is conducive to promoting geological engineering integration. Through the above analysis, the problems and defects of the prior art are: the prior art must rely on complete logging data in the process of identifying horizontal well fracturing engineering sweet spots, and cannot accurately and quickly identify horizontal well fracturing engineering sweet spots in the absence of logging data, which often increases the error of identifying engineering sweet spots and increases fracturing costs in the absence of logging data. Summary of the invention

[0004] In view of the defects of the above-mentioned prior art, the purpose of the present invention is to propose a method for identifying sweet spots in horizontal well fracturing engineering based on MSE, so as to solve the problem of accurately and quickly identifying sweet spots in horizontal well fracturing engineering in the absence of complete logging data and promote the integration of geology and engineering.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:

[0006] A method for identifying sweet spots in hydraulic fracturing projects based on MSE, comprising the following steps:

[0007] S1. Obtaining original data required for calculating mechanical specific energy from drilling history data, obtaining gamma logging data from logging data, and obtaining drilling time data from drilling history data.

[0008] S2. Fred E. Dupriest model is selected as the basic formula for calculating mechanical specific energy, and the original data is substituted into the basic formula to calculate the mechanical specific energy data of rocks in formations at different depths along the well depth direction.

[0009] S3. Use the moving average method to reduce the noise of the mechanical specific energy data, gamma logging data and drilling time data, and obtain the MSE value, GR value or drilling time at different depths along the well depth direction.

[0010] S4. Divide the MSE value by the GR value at the same well depth to obtain the MSE / GR value, and draw the MSE / GR curves of formation rocks at different well depths, so as to fuse the mechanical specific energy data with the gamma logging data to construct the MSE+GR model. The areas in the formation rock MSE / GR curves where the MSE / GR value is not less than 15 are preliminarily identified as engineering sweet spots.

[0011] S5. Divide the MSE / GR value by the drilling time at the same well depth to obtain the MSE / (GR*drilling time) value, and draw a fusion diagram of the MSE data, gamma logging data and drilling time of the formation rocks at different well depths. Then further fuse the MSE+GR model with the drilling time data. In the fusion diagram, the areas where the MSE / (GR*drilling time) value is greater than 5 can preliminarily determine the identification results of the engineering sweet spots.

[0012] S6. The identification results of the engineering sweet spot were preliminarily verified through the fracturing curve. The fracturing curve data were extracted from the fracturing data. The fracturing pressure and the pressure change after the formation rupture were statistically analyzed to determine whether the fracturing data corresponded to the engineering sweet spot. The well sections with a fracturing pressure of not less than 50MPa and a pressure after fracturing of not less than 7.5MPa met the characteristics of the engineering sweet spot.

[0013] If the fracturing data does not correspond to the engineering sweet spot, the cuttings mineral composition and brittleness index analysis and calculation results are used to verify the engineering sweet spot identification results. The well section with a cuttings brittleness index greater than 0.7 can be determined as the engineering sweet spot, verifying that the rock in the identified sweet spot area is hard and brittle and is prone to forming a complex fracture network.

[0014] Furthermore, the original data required for calculating the mechanical specific energy described in S1 include drilling depth, drilling pressure, drill bit size, rotation speed, torque and mechanical rotation speed, and the fracturing curves of each fracturing section along the well depth direction are obtained from the drilling history data.

[0015] Furthermore, S2 uses the calculation formula of Fred E. Dupriest model,

[0016] ;

[0017] In the formula, is the mechanical specific energy; is drilling pressure; is the drill bit area; is the rotation speed; is the torque; Mechanical drilling speed.

[0018] Furthermore, the MSE value of a certain depth obtained after the noise reduction process in S3 refers to the average value of the MSE values ​​at 5 adjacent depths above and below the depth.

[0019] The GR value of a certain depth obtained after the noise reduction process in S3 refers to the average value of the GR values ​​at five adjacent depths above and below the depth.

[0020] The drilling time at a certain depth obtained after the noise reduction process in S3 refers to the average value of the drilling times at 5 adjacent depths above and below the depth.

[0021] Furthermore, the fracturing curve in S6 preliminarily verifies the engineering sweet spot, including the following steps:

[0022] S61. Analyze each fracturing section in combination with the fracturing curve extracted from the fracturing data, and analyze the area with MSE / (GR*drilling time) value greater than 5 as the engineering sweet spot. Identify the area with MSE / GR value not less than 15 within the fracturing section as the engineering sweet spot fracturing section.

[0023] S62: Statistics on the formation fracture pressure and pressure drop after formation fracture in the fracturing curve. 3 / min, the fracturing sections with a fracturing pressure of not less than 50MPa and a pressure drop of not less than 7.5MPa after fracturing are further screened out, which meet the characteristics of engineering sweet spots. If the pressure drop after fracturing is less than 7.5MPa, the fracturing section will not be regarded as an engineering sweet spot.

[0024] Furthermore, a rock cutting sample was taken from each section of the drilling, and the mineral composition of the rock cutting sample was analyzed to obtain the content of quartz minerals, carbonate minerals and clay minerals in the rock cutting sample of each section, and the rock brittleness index of each section was calculated. The calculation formula of the rock brittleness index is as follows:

[0025] ;

[0026] In the formula, is the content of quartz minerals; is the content of carbonate minerals; is the clay mineral content; BI3 is the brittleness index.

[0027] Furthermore, the calculation results of the rock brittleness index of each well section are marked in the above fusion diagram. The well section with a rock brittleness index greater than 0.7 corresponds to the area with an MSE / (GR*drilling time) value greater than 5, which is determined as the engineering sweet spot.

[0028] Compared with the prior art, the beneficial technical effects of the present invention are:

[0029] 1. The present invention can quickly and accurately identify engineering sweet spots with only the gamma logging data in the logging data, without relying on other data in the well data, thereby improving the efficiency of identifying engineering sweet spots and promoting the integration of geology and engineering.

[0030] 2. In the case of incomplete logging data, the present invention proposes a method for identifying the engineering sweet spots of horizontal wells through the MSE+GR model. Gamma logging data can be obtained after drilling is completed. The gamma logging data is combined with the well history data to obtain a fusion map, and the engineering sweet spots are preliminarily determined. Then, combined with the pressure curve, the well section that meets the engineering sweet spots can be quickly judged.

[0031] 3. The present invention proposes for the first time to verify the identification results of the engineering sweet spot through pressure curve and rock brittleness analysis respectively, so as to verify the accuracy of the identification of the engineering sweet spot of the horizontal well. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the MSE and GR diagram of the formation rocks at different depths of the G31-P7 well provided by the present invention.

[0033] Figure 2 It is a drilling time diagram of strata at different well depths of the G31-P7 well provided by the present invention.

[0034] Figure 3 It is the MSE and GR diagram of the formation rock before and after denoising by the moving average method of the G31-P7 well provided by the present invention.

[0035] Figure 4This is the drilling time diagram of the G31-P7 well before and after denoising by the moving average method provided by the present invention.

[0036] Figure 5 This is the MSE / GR diagram of the formation rocks at different well depths of the G31-P7 well provided by the present invention.

[0037] Figure 6 This is a fusion diagram of the formation rock MSE / (GR*drilling time) at different well depths of the G31-P7 well provided by the present invention.

[0038] Figure 7 It is a fracturing curve diagram of the 19th well section of the G31-P7 well provided by the present invention.

[0039] Figure 8 This is a fusion diagram of formation rock MSE / (GR*drilling time) with marked cuttings brittleness index for Well G31-P7 provided by the present invention.

[0040] Fig. 9 It is a flow chart of the method for identifying the sweet spots of hydraulic fracturing engineering based on MSE of the present invention. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with the accompanying drawings:

[0042] Embodiment 1, combination Fig. 9 , a method for identifying sweet spots in hydraulic fracturing engineering based on MSE, comprising the following steps:

[0043] S1. Obtaining original data required for calculating mechanical specific energy from drilling history data, obtaining gamma logging data from logging data, and obtaining drilling time data from drilling history data.

[0044] S2. Fred E. Dupriest model is selected as the basic formula for calculating mechanical specific energy, and the original data is substituted into the basic formula to calculate the mechanical specific energy data of rocks in formations at different depths along the well depth direction.

[0045] The raw data required for calculating the mechanical specific energy include drilling depth, drilling pressure, drill bit size, rotation speed, torque and mechanical rotation speed, and the fracturing curves of each fracturing section along the well depth direction are obtained from the drilling history data.

[0046] The Fred E. Dupriest model is used as the mechanical specific energy calculation model, and the mechanical specific energy calculation formula is:

[0047] ;

[0048] In the formula, is the mechanical specific energy; is drilling pressure; is the drill bit area; is the rotation speed; is the torque; Mechanical drilling speed.

[0049] The calculated MSE and GR data are plotted in the same figure ( Figure 1 As shown in the figure), the corresponding graphs of MSE and GR of different well depths are obtained, and the drilling time curve is obtained by plotting the well depth and drilling time data extracted from the well history data ( Figure 2 as shown).

[0050] S3, using the moving average method to reduce the noise of the mechanical specific energy data, gamma logging data and drilling time data, and respectively obtain the MSE value, GR value or drilling time at different depths along the well depth direction. The corrected mechanical specific energy calculation model is to reduce the noise of the MSE data, and in order to eliminate the influence of abnormal fluctuations and facilitate the observation of the change law of MSE, GR and drilling time, the moving average method is used to weaken the influence of abnormal fluctuations.

[0051] The MSE value of a certain depth obtained after noise reduction processing refers to the average value of the MSE values ​​at the five adjacent depths above and below the depth. The GR value of a certain depth obtained after noise reduction processing refers to the average value of the GR values ​​at the five adjacent depths above and below the depth. The MSE and GR data after noise reduction processing are plotted in the same figure ( Figure 3 The drilling time at a certain depth obtained after noise reduction processing refers to the average value of the drilling time at 5 adjacent depths above and below the depth. The drilling time data after noise reduction processing is plotted to obtain the drilling time curve correction diagram ( Figure 4 as shown).

[0052] Comparing the MSE, GR, drilling time and well depth after moving average denoising with the original data, it can be seen that the data before denoising fluctuates significantly and frequently, making it difficult to observe and identify the engineering sweet spot. However, the data after denoising becomes significantly easier to observe, and the errors caused by other influences are removed, making it easier to proceed to the next step of processing and analysis.

[0053] S4. Divide the MSE value by the GR value at the same well depth to obtain the MSE / GR value, and draw the MSE / GR curve of the formation rock at different well depths ( Figure 5 As shown in the figure, the mechanical specific energy data is integrated with the gamma logging data to construct the MSE+GR model. The area with an MSE / GR value of not less than 15 in the formation rock MSE / GR curve is preliminarily identified as the engineering sweet spot. The greater the mechanical specific energy and the lower the gamma logging curve value, the higher the hardness and brittleness of the formation and the lower the mud content, which makes it easier to maintain the fracture opening and form a complex fracture network.

[0054] S5. Divide the MSE / GR value by the drilling time at the same well depth to get the MSE / (GR*drilling time) value, and draw a fusion diagram of the MSE data, gamma logging data and drilling time of the formation rocks at different well depths. Then further fuse the MSE+GR model with the drilling time data. In the fusion diagram, the area where the MSE / (GR*drilling time) value is greater than 5 is used to preliminarily determine the identification result of the engineering sweet spot. After the MSE+GR model is further fused with the drilling time data, the position of the MSE / GR curve is further lowered, and the horizontal axis can be approximately used as the baseline for identifying the engineering sweet spot. In addition, the influence of some small peaks is eliminated, making the engineering sweet spot easier to identify, such as Figure 6 shown.

[0055] S6. The identification results of the engineering sweet spot were preliminarily verified through the fracturing curve. The fracturing curve data was extracted from the fracturing data. The fracturing pressure and the pressure change after the formation rupture were statistically analyzed to determine whether the fracturing data corresponded to the engineering sweet spot. The well sections with a fracturing pressure of not less than 50MPa and a pressure drop of not less than 7.5MPa after fracturing met the characteristics of the engineering sweet spot.

[0056] The fracturing curve initially verifies the engineering sweet spot, including the following steps:

[0057] S11. Analyze each fracturing section in combination with the fracturing curve extracted from the fracturing data, and analyze the area with MSE / (GR*drilling time) value not less than 15 as the engineering sweet spot. Identify the well section with MSE / GR value not less than 15 within the fracturing section as the engineering sweet spot fracturing section.

[0058] S12: Statistics on the formation fracture pressure and pressure drop after formation fracture in the fracturing curve. 3 / min, the fracturing sections with a fracturing pressure of not less than 50MPa and a pressure drop of not less than 7.5MPa after fracturing are further screened out, which meet the characteristics of engineering sweet spots. The fracturing sections with a pressure drop of less than 7.5MPa after fracturing are not regarded as engineering sweet spots.

[0059] If the fracturing data does not correspond to the engineering sweet spot, the rock cuttings mineral composition and brittleness index analysis and calculation results are used to verify the engineering sweet spot identification results. The section with a rock cuttings brittleness index exceeding 0.7 is determined as the engineering sweet spot. It is verified that the rock in the identified sweet spot area is hard and brittle, and it is easy to form a complex fracture network.

[0060] A rock cutting sample is taken from each section of the well, and the mineral composition of the rock cutting sample is analyzed to obtain the content of quartz minerals, carbonate minerals and clay minerals in the rock cutting sample of each section, and the rock brittleness index of each section is calculated. The calculation formula of the rock brittleness index is as follows:

[0061] ;

[0062] In the formula, is the content of quartz minerals; is the content of carbonate minerals; is the clay mineral content; BI3 is the brittleness index, dimensionless.

[0063] The calculation results of the rock brittleness index of each well section are marked in the above fusion diagram. The well section with a rock brittleness index exceeding 0.7 corresponds to the section with an MSE / (GR*drilling time) value greater than 5, which is determined as the engineering sweet spot.

[0064] Example 2: Traditional engineering sweet spot identification methods often have the disadvantages of cumbersome parameter selection and large errors in identification results, which leads to increased fracturing costs. The present invention is based on the mechanical specific energy theory to accurately and quickly identify engineering sweet spots in tight sandstone horizontal wells when logging data is incomplete, and promotes geological engineering integration.

[0065] Taking Well G31-P7 as an example, the data required for calculating mechanical specific energy were extracted from the field data, the mechanical specific energy was calculated, and the mechanical specific energy was fused with the gamma logging data and drilling time data to obtain the MSE / (GR*drilling time) fusion diagram of Well G31-P7. Well G31-P7 was subjected to 19 fracturing stages, and the MSE / (GR*drilling time) values ​​were significantly higher (greater than 5) as the engineering sweet spot for analysis. The 4th, 6th, 8th, 10th, 12th, 13th, 17th, 18th, and 19th fracturing stages had areas with MSE / GR values ​​not less than 15, which were preliminarily identified as engineering sweet spot fracturing stages. The formation fracture pressure in the fracturing curve and the pressure drop after formation fracture were statistically analyzed, as shown in Table 1.

[0066] Table 1 Formation fracture initiation pressure and pressure drop after fracture in different fracturing stages

[0067]

[0068] Furthermore, it can be seen from Table 1 that, under similar displacement, the initiation pressure of the 2nd, 3rd, 4th, 5th, 7th, 12th, 16th, and 18th fracturing stages is not less than 50 MPa, and the pressure drop after initiation is not less than 7.5 MPa, which meets the characteristics of the engineering sweet spot.

[0069] After combining the MSE / (GR*drilling time) fusion graph, the engineering sweet spot identification analysis can be performed. It can be preliminarily concluded that the MSE / (GR*drilling time) values ​​of well sections 2, 3, 4, 5, 7, 12, 16, 18, and 19 are relatively high (greater than 5). Combined with the analysis of their fracturing curves, it can be seen that: when the displacement is 4.5-5.5m 3 / min fracturing section, 2, 3, 4, 5, 7, 12, 16, 18 well sections were selected. It is roughly consistent with the previous prediction of the engineering sweet spot formation depth. In addition, the fracturing pressure of the above fracturing sections is not less than 50MPa, and the pressure drop after fracturing is not less than 7.5MPa, which meets the characteristics of the engineering sweet spot. However, the pressure drop of the 19th section after fracturing is lower than 7.5MPa, which may be due to the low drilling time during the fracturing process, resulting in a large value, and there is no obvious pressure drop after the rock cracks after drilling for a long time, so the 19th well section is not used as an engineering sweet spot.

[0070] The fracturing data basically correspond to the engineering sweet spot identification results, which preliminarily verifies the effectiveness of the engineering sweet spot identification method proposed above. However, the fracturing data do not completely correspond to the engineering sweet spot identification results. This is because fracturing data is affected by engineering factors in addition to formation factors. Therefore, it is not comprehensive to verify the engineering sweet spot identification method based solely on fracturing data. It is also necessary to further verify the engineering sweet spot identification method through cuttings analysis results.

[0071] The purpose of using the rock brittleness evaluation method to verify the engineering sweet spot identification result is to circumvent the limitations of the fracturing curve data, and the rock cuttings mineral composition and brittleness index analysis calculation results are used to verify the engineering sweet spot identification result.

[0072] For Well G31-P7, the cuttings sampling sections were designed, as shown in Table 2. Among them, there are sections with higher MSE and sections with lower MSE, making the sampling representative.

[0073] Table 2 Cuttings sampling well section design

[0074]

[0075] Furthermore, four rock chip samples were successfully obtained, and the mineral composition of these samples was analyzed. The rock brittleness index (dimensionless) of the four rock chip samples was obtained according to the calculation formula of the rock brittleness index, as shown in Table 3 below. The brittleness index of the four rock chip samples is 5366, 4882, 4888 and 5534 in descending order, among which the first three rock chip brittleness indices are all greater than 0.7, reflecting that the rocks in this area are relatively hard and brittle and can be identified as engineering sweet spots.

[0076] Table 3 Test results of well sections with successful cuttings sampling

[0077]

[0078] The results of the rock cuttings brittleness index analysis are annotated in the fusion diagram of MSE, gamma and drilling time data, as shown below Figure 8 It can be seen that the area with a larger brittleness index in rock chip analysis corresponds to the area with a higher MSE / (GR*drilling time), which verifies that the rock in the sweet spot area identified by the engineering sweet spot identification method is hard and brittle, and is prone to form a complex fracture network.

[0079] Parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0080] Furthermore, the terms “first” and “second” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0081] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0082] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for identifying sweet spots in hydraulic fracturing projects based on MSE, characterized in that: The steps include: S1. Obtaining original data required for calculating mechanical specific energy from drilling history data, obtaining gamma logging data from logging data, and obtaining drilling time data from drilling history data; S2. Selecting Fred E. Dupriest model as the basic formula for calculating mechanical specific energy, substituting the original data into the basic formula to calculate the mechanical specific energy data of the rock formations at different depths along the well depth direction; S3, using the moving average method to perform noise reduction on the mechanical specific energy data, gamma logging data and drilling time data, and obtain the MSE value, GR value or drilling time at different depths along the well depth direction; S4. Divide the MSE value by the GR value at the same well depth to obtain the MSE / GR value, and draw the MSE / GR curve of the formation rock at different well depths, so as to fuse the mechanical specific energy data with the gamma logging data to construct the MSE+GR model. The area where the MSE / GR value in the formation rock MSE / GR curve is not less than 15 is preliminarily identified as the engineering sweet spot; S5. Divide the MSE / GR value by the drilling time at the same well depth to obtain the MSE / (GR*drilling time) value, draw a fusion diagram of the MSE data, gamma logging data and drilling time of the formation rocks at different well depths, and then further fuse the MSE+GR model with the drilling time data. In the area where the MSE / (GR*drilling time) value is greater than 5 in the fusion diagram, preliminarily determine the identification result of the engineering sweet spot; S6. Preliminary verification of the identification results of the engineering sweet spot through the fracturing curve. Extract the fracturing curve data from the fracturing data, and count the fracturing pressure and the pressure change after the formation rupture to determine whether the fracturing data corresponds to the engineering sweet spot. The well section with a fracturing pressure of not less than 50MPa and a pressure after fracturing of not less than 7.5MPa meets the characteristics of the engineering sweet spot. If the fracturing data does not correspond to the engineering sweet spot, the cuttings mineral composition and brittleness index analysis and calculation results are used to verify the engineering sweet spot identification results. The well section with a cuttings brittleness index greater than 0.7 can be determined as the engineering sweet spot, verifying that the rock in the identified sweet spot area is hard and brittle and is prone to forming a complex fracture network.

2. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 1, characterized in that: The original data required for calculating the mechanical specific energy described in S1 include drilling depth, drilling pressure, drill bit size, rotation speed, torque and mechanical rotation speed, and the fracturing curves of each fracturing section along the well depth direction are obtained from the drilling history data.

3. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 2, characterized in that: S2 uses the calculation formula of Fred E. Dupriest model. ； In the formula, is the mechanical specific energy; is drilling pressure; is the drill bit area; is the rotation speed; is the torque; Mechanical drilling speed.

4. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 1, characterized in that: The MSE value of a certain depth obtained after noise reduction processing in S3 refers to the average value of the MSE values ​​at the five adjacent depths above and below the depth; The GR value of a certain depth obtained after the noise reduction process in S3 refers to the average value of the GR values ​​at the five adjacent depths above and below the depth; The drilling time at a certain depth obtained after the noise reduction process in S3 refers to the average value of the drilling times at 5 adjacent depths above and below the depth.

5. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 1, characterized in that: The fracturing curve initially verifies the engineering sweet spot, including the following steps: S61, analyzing each fracturing section in combination with the fracturing curve extracted from the fracturing data, taking the fracturing section with MSE / (GR*drilling time) value greater than 5 as the engineering sweet spot for analysis, and identifying the area within the fracturing section with MSE / GR value not less than 15 as the engineering sweet spot fracturing section; S62: Statistics on the formation fracture pressure and pressure drop after formation fracture in the fracturing curve. 3 / min, the fracturing sections with a fracturing pressure of not less than 50MPa and a pressure drop of not less than 7.5MPa after fracturing are further screened out, which meet the characteristics of engineering sweet spots. If the pressure drop after fracturing is less than 7.5MPa, the fracturing section will not be regarded as an engineering sweet spot.

6. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 1, characterized in that: A rock cutting sample is taken from each section of the well, and the mineral composition of the rock cutting sample is analyzed to obtain the content of quartz minerals, carbonate minerals and clay minerals in the rock cutting sample of each section, and the rock brittleness index of each section is calculated. The calculation formula of the rock brittleness index is as follows: ； In the formula, is the content of quartz minerals; is the content of carbonate minerals; is the clay mineral content; BI3 is the brittleness index.

7. The method for identifying the sweet spots in hydraulic fracturing projects based on MSE according to claim 6, characterized in that: The calculated results of the rock brittleness index of each well section are marked in the above fusion diagram. The well section with a larger rock brittleness index corresponds to the area where the MSE / (GR*drilling time) value is greater than 5, which is determined as the engineering sweet spot.

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