CN114059981A - Horizontal well repeated fracturing layer selection and fracturing mode selection method - Google Patents
Horizontal well repeated fracturing layer selection and fracturing mode selection method Download PDFInfo
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Abstract
The invention provides a method for selecting a repeated fracturing layer selection and a fracturing mode of a horizontal well, which comprises the following steps of S1: selecting a horizontal well to be tested and a well to be evaluated in an oil reservoir, and logging a liquid production profile of the horizontal well to be tested to obtain logging data; step S2: calculating oil layer geological parameters and rock mechanical parameters of the horizontal well to be measured according to the logging data; step S3: analyzing the effectiveness of the primary fracturing of the horizontal well to be tested; step S4: analyzing main factors influencing the productivity; step S5: fitting a calculation formula of a liquid production profile of a well to be evaluated; step S6: calculating the liquid production contribution percentage and the recovery ratio of each fracturing section of the well to be evaluated; step S7: evaluating the potential of repeated fracturing of each fracturing section of the well to be evaluated; step S8: and evaluating the repeated fracturing mode of each fracturing section of the well to be evaluated. The invention solves the problems of no pertinence and high cost of the fracturing mode in the prior art.
Description
Technical Field
The invention relates to the technical field of oilfield exploitation equipment, in particular to a method for selecting a horizontal well repeated fracturing layer and a fracturing mode.
Background
At present, the ultra-low permeability and compact oil reservoir has the characteristics of deep burial, poor physical properties and low natural productivity. At present, most oil reservoirs are developed on a large scale in a mode of performing volume fracturing on a horizontal well. Affected by reservoir geology and engineering factors, the horizontal well is severely unbalanced in profile exploitation after repeated fracturing, and a liquid production profile test result shows that over 60% of intervals after primary fracturing have low or even no liquid production contribution. Therefore, repeated fracturing is required for wells with undesirable fracturing effects, and repeated fracturing selection is critical to success or failure of repeated fracturing. According to research, the repeated fracturing and layer selection of the horizontal well at present mainly applies a mathematical method (a least square support vector machine method, a BP neural network method and a fuzzy recognition method). The fracturing mode mainly adopts a mode of repeatedly fracturing by temporarily plugging the whole well section, and the mode has higher cost and does not have the selective potential interval.
That is, the fracturing method in the prior art has the problems of no pertinence and high cost.
Disclosure of Invention
The invention mainly aims to provide a horizontal well repeated fracturing layer selection and a fracturing mode selection method, and aims to solve the problems of no pertinence and high cost of a fracturing mode in the prior art.
In order to achieve the aim, the invention provides a method for selecting a repeated fracturing layer selection and a fracturing mode of a horizontal well, which comprises the following steps: step S1: selecting a horizontal well to be tested and a well to be evaluated in an oil reservoir, and logging a liquid production profile of the horizontal well to be tested to obtain logging data; step S2: calculating oil layer geological parameters and rock mechanical parameters of the horizontal well to be measured according to the logging data; step S3: analyzing the effectiveness of the primary fracturing of the horizontal well to be tested; step S4: analyzing main factors influencing the productivity; step S5: fitting a calculation formula of a liquid production profile of a well to be evaluated; step S6: calculating the liquid production contribution percentage and the recovery ratio of each fracturing section of the well to be evaluated; step S7: evaluating the potential of repeated fracturing of each fracturing section of the well to be evaluated; step S8: evaluating the repeated fracturing mode of each fracturing section of the well to be evaluated; in step S3, if the primary fracture is valid, the process continues to step S4, and if the primary fracture is invalid, the process proceeds to step S6.
Further, in step S1, a well with a production time of more than 6 months and a daily fluid production change of less than 0.5 ton is selected as the horizontal well to be tested, and the daily fluid production of the horizontal well to be tested is more than 30 t/d.
Further, in step S2, the reservoir geological parameters include one or more of reservoir porosity POR, permeability PERM, oil saturation So, and reservoir penetration length Lo, and the rock mechanical parameters include one or more of young 'S modulus ime, poisson' S ratio σ, and brittleness index BI, wherein,
the formula for calculating the Young modulus YME is as follows:
the formula for calculating the poisson ratio sigma is as follows:
the brittleness index is calculated by the formula:
BI ═ y (YME + σ)/2 equation (3)
Wherein the unit of Young's modulus YEM is GPa; poisson ratio σ dimensionless; the brittleness index BI is dimensionless; the unit of the rock density ρ is g/cm3(ii) a The unit of the longitudinal wave velocity Vp is m/s; the unit of the shear wave velocity Vs is m/s.
Further, in step S3, the fracturing section with no setting of the bridge plug and the construction pressure much lower than the construction pressure of other well sections is a fracturing ineffective fracturing section, and the contribution of the production fluid of the fracturing ineffective fracturing section is zero, wherein the no setting of the bridge plug mainly shows that the pressure does not rise after ball throwing, and the construction pressure much lower than the construction pressure of other well sections means that the construction pressure is less than 60% of the construction pressure of other well sections.
Further, in step S4, data mining is performed according to the SPSS decision tree algorithm, and main factors affecting productivity are determined, where the main factors include one or more of reservoir geological parameters, rock mechanical parameters, and primary fracturing parameters, the reservoir geological parameters include one or more of reservoir porosity POR, permeability PERM, oil saturation So, and reservoir drilling length Lo, the rock mechanical parameters include one or more of young 'S modulus YME, poisson' S ratio σ, and brittleness index BI, and the primary fracturing parameters include one or more of charging strength Sq and sand charging strength Ss.
Further, in step S5, after fitting a calculation formula of a fluid production profile of the well to be evaluated, calculating the fluid production rate of each fracture section according to a multiple regression method, where the calculation formula of the pseudo fluid production profile of each fracture section is:
qi＝∑ai×f(geoi)+∑bj×f(rockj)+∑ck×f(frack) Formula (4)
Wherein q isiCalculating a liquid production profile of each fracturing section in unit t; geoiOil layer geological parameters affecting oil production; rockjRock mechanics parameters that affect oil production; frackPrimary fracturing parameters that affect oil production; i is the number of oil layer geological parameters influencing oil production; j is the number of rock mechanical parameters influencing oil production; k is the number of primary fracturing parameters that affect oil production, ai、bj、ckRespectively fitting parameters.
Furthermore, the planned oil production profile obtained in the step S5 can reflect the relative oil production contribution of each fracturing section, the actual oil production of each fracturing section can be obtained by comparing the planned oil production profile with the actual oil production, and meanwhile, the calculated oil production predicted by a single well, the geological reserve of each section and the produced liquid of each fracturing section are used for calculating the contribution percentage and the recovery ratio of each section of produced liquid after the primary fracturing; wherein the content of the first and second substances,
the calculation formula of the percentage contribution of the produced fluid of each fracturing section is as follows:
the formula for calculating the recovery ratio of each fracturing segment is as follows:
wherein eta isiThe percentage of the produced fluid of each fracturing section is contributed, and the unit is; q. q.siCalculating a liquid production profile of each fracturing section in unit t; riThe recovery ratio of each fracturing segment is unit percent; q is the predicted oil production per well in units of t; qiAnd the geological reserves of each fracturing section are expressed in t.
Further, dividing the fracturing sections into four types of fracturing sections according to the percentage contribution of the produced fluid and the recovery ratio of each fracturing section calculated in the step S7, wherein the percentage contribution of the first type of fracturing section to the produced oil is high and the recovery ratio is high; the oil contribution percentage of the second type of fracturing section is high, and the recovery ratio is low; the third type of fracturing section has low contribution percentage and low recovery ratio for oil production; the fourth type of fracturing section has low oil production contribution percentage and high recovery ratio, wherein the oil production contribution percentage is higher than 5%; the oil production contribution percentage is less than or equal to 5 percent, so that the oil production contribution percentage is low; the recovery rate is high when the recovery rate is more than 20 percent; the recovery rate is low when the recovery rate is less than or equal to 20 percent.
Further, in step S8, the evaluation of the repeated fracturing is performed according to the classification result of the fracturing segment in step S7, and the first type of fracturing segment is not subjected to the repeated fracturing; the second type of fracturing stage needs to be repeatedly fractured; the third type of fracturing section needs to be subjected to repeated fracturing; the fourth type of fracturing stage does not undergo repeated fracturing.
Further, the second type of fracturing section is subjected to gap filling fracturing on the basis of primary fracturing; the third type of fracturing stage re-fractures the old fractures.
According to the technical scheme of the invention, the method for selecting the repeated fracturing layer selection and the fracturing mode of the horizontal well comprises the following steps: step S1: selecting a horizontal well to be tested and a well to be evaluated in an oil reservoir, and logging a liquid production profile of the horizontal well to be tested to obtain logging data; step S2: calculating oil layer geological parameters and rock mechanical parameters of the horizontal well to be measured according to the logging data; step S3: analyzing the effectiveness of the primary fracturing of the horizontal well to be tested; step S4: analyzing main factors influencing the productivity; step S5: fitting a calculation formula of a liquid production profile of a well to be evaluated; step S6: calculating the liquid production contribution percentage and the recovery ratio of each fracturing section of the well to be evaluated; step S7: evaluating the potential of repeated fracturing of each fracturing section of the well to be evaluated; step S8: evaluating the repeated fracturing mode of each fracturing section of the well to be evaluated; in step S3, if the primary fracture is valid, the process continues to step S4, and if the primary fracture is invalid, the process proceeds to step S6.
Because the properties of all fracturing sections in one oil reservoir are similar, the horizontal well to be tested and the well to be evaluated are selected from the oil reservoir and are used as a contrast to evaluate the well to be evaluated. And analyzing the effectiveness of the primary fracturing of the horizontal well to be tested to obtain main factors influencing the productivity. And then fitting a calculation formula of the liquid production profile of the well to be evaluated according to the main factors influencing the productivity, and calculating the liquid production amount of each fracturing section according to the fitted calculation formula of the liquid production profile of the well to be evaluated. And calculating the liquid production contribution percentage and the recovery ratio of each fracturing section according to the liquid production amount and the actual liquid production amount of each fracturing section. And evaluating the potential of each fracturing section of the well to be evaluated for repeated fracturing and evaluating the mode of each fracturing section for repeated fracturing through the liquid production contribution percentage and the recovery ratio.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 shows a flow diagram of a horizontal well re-fracturing selection and fracturing pattern selection method according to an alternative embodiment of the invention; and
figure 2 shows the oil production contribution percentage and recovery for each fracture zone of an alternative embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
In the present invention, unless specified to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the component itself in a vertical, perpendicular, or gravitational orientation; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.
The invention provides a horizontal well repeated fracturing layer selection method and a fracturing mode selection method, aiming at solving the problems of no pertinence and high cost of a fracturing mode in the prior art.
As shown in fig. 1 to 2, the method for selecting the repeated fracturing layer selection and the fracturing mode of the horizontal well comprises the following steps: step S1: selecting a horizontal well to be tested and a well to be evaluated in an oil reservoir, and logging a liquid production profile of the horizontal well to be tested to obtain logging data; step S2: calculating oil layer geological parameters and rock mechanical parameters of the horizontal well to be measured according to the logging data; step S3: analyzing the effectiveness of the primary fracturing of the horizontal well to be tested; step S4: analyzing main factors influencing the productivity; step S5: fitting a calculation formula of a liquid production profile of a well to be evaluated; step S6: calculating the liquid production contribution percentage and the recovery ratio of each fracturing section of the well to be evaluated; step S7: evaluating the potential of repeated fracturing of each fracturing section of the well to be evaluated; step S8: evaluating the repeated fracturing mode of each fracturing section of the well to be evaluated; in step S3, if the primary fracture is valid, the process continues to step S4, and if the primary fracture is invalid, the process proceeds to step S6.
Because the properties of all fracturing sections in one oil reservoir are similar, the horizontal well to be tested and the well to be evaluated are selected from the oil reservoir and are used as a contrast to evaluate the well to be evaluated. And analyzing the effectiveness of the primary fracturing of the horizontal well to be tested to obtain main factors influencing the productivity. And then fitting a calculation formula of the liquid production profile of the well to be evaluated according to the main factors influencing the productivity, and calculating the liquid production amount of each fracturing section according to the fitted calculation formula of the liquid production profile of the well to be evaluated. And calculating the liquid production contribution percentage and the recovery ratio of each fracturing section according to the liquid production amount and the actual liquid production amount of each fracturing section. And evaluating the potential of each fracturing section of the well to be evaluated for repeated fracturing and evaluating the mode of each fracturing section for repeated fracturing through the liquid production contribution percentage and the recovery ratio.
Specifically, in step S1, a well with a production time of more than 6 months and a daily fluid production change of less than 0.5 ton is selected as the horizontal well to be tested, and the daily fluid production of the horizontal well to be tested is more than 30 t/d. The selected horizontal well to be tested is required to be guaranteed to be representative and to have a liquid production profile testing condition so as to guarantee that the data measured by the horizontal well to be tested is accurate. And further, the evaluation of the well to be evaluated is ensured to be more accurate.
In step S2, the reservoir geological parameters include one or more of reservoir porosity POR, permeability PERM, oil saturation So, and reservoir penetration length Lo, and the petromechanical parameters include one or more of young 'S modulus ime, poisson' S ratio σ, brittleness index BI, wherein,
the formula for calculating the Young modulus YME is as follows:
the formula for calculating the poisson ratio sigma is as follows:
the brittleness index is calculated by the formula:
BI ═ y (YME + σ)/2 equation (3)
Wherein the unit of Young's modulus YEM is GPa; poisson ratio σ dimensionless; the brittleness index BI is dimensionless; the unit of the rock density ρ is g/cm3(ii) a The unit of the longitudinal wave velocity Vp is m/s; the unit of the shear wave velocity Vs is m/s. And analyzing the effectiveness of primary fracturing by calculating parameters such as oil layer porosity POR, permeability PERM, oil saturation So, oil layer drilling length Lo, Young modulus YME, Poisson ratio sigma, brittleness index BI and the like of the horizontal well to be detected.
In step S3, the fracturing section with no setting of the bridge plug and the construction pressure much lower than the construction pressure of other well sections is a fracturing ineffective fracturing section, and the contribution of the produced fluid of the fracturing ineffective fracturing section is zero, wherein the bridge plug has no setting and mainly shows that the pressure after ball throwing does not rise, and the construction pressure much lower than the construction pressure of other well sections means that the construction pressure is less than 60% of the construction pressure of other well sections.
In step S4, data mining is performed according to the SPSS decision tree algorithm, and main factors affecting productivity are determined, where the main factors include one or more of reservoir geological parameters, rock mechanics parameters, and primary fracturing parameters, the reservoir geological parameters include one or more of reservoir porosity POR, permeability PERM, oil saturation So, and reservoir drilling length Lo, the rock mechanics parameters include one or more of young 'S modulus ime, poisson' S ratio σ, and brittleness index BI, and the primary fracturing parameters include one or more of charging strength Sq and sand charging strength Ss. And analyzing the liquid production condition of each fracturing segment by determining the main factors influencing the productivity.
The data mining is to perform data mining on the porosity POR of an oil layer, the permeability PERM, the oil saturation So, the drilling length Lo of the oil layer, the Young modulus YME, the Poisson ratio sigma, the brittleness index BI, the liquid feeding strength Sq and the sand feeding strength Ss, and finally, the main factors influencing productivity are determined according to the weight sorting.
In step S5, after fitting a calculation formula of a fluid production profile of the well to be evaluated, calculating the fluid production rate of each fracture section according to a multiple regression method, wherein the calculation formula of a simulated fluid production profile of each fracture section is as follows:
qi＝∑ai×f(geoi)+∑bj×f(rockj)+∑ck×f(frack) Formula (4)
Wherein q isiCalculating a liquid production profile of each fracturing section in unit t; geoiOil layer geological parameters affecting oil production; rockjRock mechanics parameters that affect oil production; frackPrimary fracturing parameters that affect oil production; i is the number of oil layer geological parameters influencing oil production; j is the number of rock mechanical parameters influencing oil production; k is the number of primary fracturing parameters that affect oil production, ai、bj、ckRespectively fitting parameters. Obtaining a fitting parameter a by the main factors influencing the productivity and the calculated value of the liquid production profile of each fracturing section of the horizontal well to be measuredi、bj、ckAnd further obtaining the calculated value of the fluid production profile of each fracturing section of the well to be evaluated.
The planned oil production profile obtained in the step S5 can reflect the relative oil production contribution of each fracturing section, the actual oil production of each fracturing section can be obtained by comparing the planned oil production profile with the actual oil production, and meanwhile, the contribution percentage and the recovery ratio of each section of produced oil after the initial fracturing are calculated through the calculated predicted oil production of a single well, the geological reserve of each section and the produced oil of each fracturing section; wherein the content of the first and second substances,
the calculation formula of the percentage contribution of the produced fluid of each fracturing section is as follows:
the formula for calculating the recovery ratio of each fracturing segment is as follows:
wherein eta isiThe percentage of the produced fluid of each fracturing section is contributed, and the unit is; q. q.siCalculating a liquid production profile of each fracturing section in unit t; riThe recovery ratio of each fracturing segment is unit percent; q is the predicted oil production per well in units of t; qiAnd the geological reserves of each fracturing section are expressed in t. And measuring the liquid contribution percentage of each fracturing section and the recovery ratio of each fracturing section by using the calculated value of the liquid production profile of each fracturing section of the well to be evaluated.
The oil production of each fracturing segment can be obtained according to the formula (4), but the real oil production cannot be obtained, and the actual oil production needs to be scaled according to the actual oil production, which is measured by an oil production plant. The oil yield can be predicted by methods such as a decreasing method, a modern yield analysis method and the like according to the dynamic data. And each segment of address reserves can be extracted from the geological model.
Dividing the fracturing sections into four types of fracturing sections according to the percentage contribution of the produced fluid and the recovery ratio of each fracturing section calculated in the step S7, wherein the percentage contribution of the first type of fracturing section to the produced oil is high and the recovery ratio is high; the oil contribution percentage of the second type of fracturing section is high, and the recovery ratio is low; the third type of fracturing section has low contribution percentage and low recovery ratio for oil production; the fourth type of fracturing section has low oil production contribution percentage and high recovery ratio, wherein the oil production contribution percentage is higher than 5%; the oil production contribution percentage is less than or equal to 5 percent, so that the oil production contribution percentage is low; the recovery rate is high when the recovery rate is more than 20 percent; the recovery rate is low when the recovery rate is less than or equal to 20 percent.
In step S8, performing an evaluation of the repeated fracturing according to the classification result of the fractured segments in step S7, the first type of fractured segments not performing the repeated fracturing; the second type of fracturing stage needs to be repeatedly fractured; the third type of fracturing section needs to be subjected to repeated fracturing; the fourth type of fracturing stage does not undergo repeated fracturing.
Specifically, the second type of fracturing section is subjected to air-filling fracturing on the basis of primary fracturing; the third type of fracturing stage re-fractures the old fractures. The oil production contribution percentage of the first type of fracturing section is high, the recovery ratio is high, the mobility is good, and repeated fracturing is not performed; the oil contribution percentage of the second type of fracturing section is high but the recovery ratio is low, which indicates that the material foundation is good but the crack control degree is poor, and the repeated fracturing needs the air-filling fracturing on the basis of the initial fracturing; the oil production contribution percentage of the third type of fracturing section is low and the recovery ratio is low, which indicates that the primary fracturing effect is poor and the old fracture needs to be fractured again; the fourth type of fracturing stage has low oil production contribution percentage and high recovery ratio, which indicates that the oil is better in exploitation but poor in material base and is not subjected to repeated fracturing.
A specific example is used to describe the above-mentioned method for selecting a repeated fracturing layer and a fracturing mode of a horizontal well.
(1) Selecting an HW001 horizontal well as a horizontal well to be tested, taking an HW004 well as a well to be evaluated, and testing the liquid production profile of the horizontal well to be tested, wherein the production time of the horizontal well to be tested is 305 days, the production is stable, and the oil production time of the previous day is 45 t;
(2) calculating geological and rock mechanical parameters of oil layers of horizontal wells HW001 and HW004 by using logging data;
(3) analyzing the effectiveness of primary fracturing construction, wherein the 2 nd stage fracturing of the HW001 well is invalid and the fracturing of the HW004 well is normal through analysis;
(4) the main control factor analysis influencing productivity is carried out by using a HW001 well (except for the 2 nd section), and the result shows that the oil layer drilling length Lo (geological parameter), the brittleness index BI (rock mechanical parameter) and the sand adding strength Ss (engineering parameter) are main factors influencing productivity;
(5) calculating a pseudo-fluid production profile, and performing multiple linear regression by using the HW001 fluid production profile and main control factors to obtain a pseudo-fluid production profile calculation formula; then calculating a planned fluid production profile of the HW004 well;
qi＝0.04×BI+3.27×Ss+0.02*Lo-3.81 equation (7)
Wherein: q. q.siIs a section of the pseudo-fluid; BI is a brittleness index; ssThe sand addition strength is shown.
(6) Calculating the contribution percentage and the recovery ratio of 16 sections of oil production in the initial fracturing according to the calculation combination and the predicted recovery ratio of the HW004 planned production profile, and as shown in figure 2;
(7) the repeated fracturing potential evaluation shows that the sections 1-7, 9-11 and 13-15 have large residual potential and have repeated fracturing potential as shown in figure 2;
(8) optimizing a repeated fracturing mode, wherein the contribution of the produced liquid and the recovery ratio of the section 8 are high according to the section classification result, and the repeated fracturing is not considered; the oil production contribution rate of the 3-7, 9-11 and 15 th sections is high but the recovery rate is low, which indicates that the crack control degree is poor and hole repairing and repeated fracturing are needed; the oil production contribution rate and the recovery rate of the 13 th section and the 14 th section are both low, and heavy pressure is needed to the old seam.
The method for selecting the repeated fracturing layer of the horizontal well and optimizing the fracturing mode has the following technical effects:
(1) by analyzing the main control factors influencing the productivity of the horizontal well, the main geological and engineering factors influencing the primary fracturing of the horizontal well can be obtained, and the repeated fracturing parameter optimization can be guided in the later period;
(2) through calculation of the oil production contribution percentage, the relative liquid production condition of each section can be determined, the oil production quantity of each section in any production period can be calculated by combining production data, and the investment of the whole oil reservoir liquid production profile test is reduced;
(3) the primary fracturing section classification combining the section oil production contribution and the section recovery rate reflects the horizontal well oil layer profile exploitation and potential distribution conditions, and the pertinence and measure effect of the horizontal well repeated fracturing can be improved aiming at different exploitation and potential distribution characteristics.
It is to be understood that the above-described embodiments are only a few, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for selecting a horizontal well repeated fracturing layer selection and a fracturing mode is characterized by comprising the following steps:
step S1: selecting a horizontal well to be tested and a well to be evaluated in an oil reservoir, and logging a liquid production profile of the horizontal well to be tested to obtain logging data;
step S2: calculating oil layer geological parameters and rock mechanical parameters of the horizontal well to be measured according to the logging data;
step S3: analyzing the effectiveness of the primary fracturing of the horizontal well to be detected;
step S4: analyzing main factors influencing the productivity;
step S5: fitting a calculation formula of the liquid production profile of the well to be evaluated;
step S6: calculating the liquid production contribution percentage and the recovery ratio of each fracturing section of the well to be evaluated;
step S7: evaluating the potential of repeated fracturing of each fracturing section of the well to be evaluated;
step S8: evaluating the repeated fracturing mode of each fracturing section of the well to be evaluated;
in the step S3, if the primary fracture is valid, the step S4 is continuously executed, and if the primary fracture is invalid, the step S6 is directly executed.
2. The method for selecting the repeated fracturing stratum selection and the fracturing mode of the horizontal well according to claim 1, wherein in the step S1, a well with production time of more than 6 months and daily liquid production change of less than 0.5 ton is selected as the horizontal well to be tested, and the daily liquid production of the horizontal well to be tested is more than 30 t/d.
3. The horizontal well repeated fracturing layer selection and fracturing mode selection method according to claim 1, wherein in the step S2, the reservoir geological parameters comprise one or more of reservoir porosity POR, permeability PERM, oil saturation So and reservoir drilling length Lo, and the rock mechanical parameters comprise one or more of Young 'S modulus YME, Poisson' S ratio σ and brittleness index BI, wherein,
the calculation formula of the Young modulus YME is as follows:
the calculation formula of the Poisson ratio sigma is as follows:
the calculation formula of the brittleness index is as follows:
BI ═ y (YME + σ)/2 equation (3)
Wherein the unit of Young's modulus YEM is GPa; poisson ratio σ dimensionless; the brittleness index BI is dimensionless; the unit of the rock density ρ is g/cm3(ii) a The unit of the longitudinal wave velocity Vp is m/s; the unit of the shear wave velocity Vs is m/s.
4. The method for selecting the horizontal well repeated fracturing stratum selection and the fracturing mode according to claim 1, wherein in the step S3, the fracturing section with no setting of the bridge plug and the construction pressure far lower than the construction pressure of other well sections is a fracturing ineffective fracturing section, and the contribution of the produced fluid of the fracturing ineffective fracturing section is zero, wherein the setting of the bridge plug is mainly shown that the pressure after the ball is thrown does not rise, and the construction pressure far lower than the construction pressure of other well sections means that the construction pressure is lower than 60% of the construction pressure of other well sections.
5. The method for selecting the horizontal well repeated fracturing selection layer and the fracturing mode according to claim 1, wherein in the step S4, data mining is performed according to an SPSS decision tree algorithm to determine the main factors influencing productivity, wherein the main factors include one or more of the oil layer geological parameters, the rock mechanical parameters and the primary fracturing parameters, the oil layer geological parameters include one or more of oil layer porosity POR, permeability PERM, oil saturation So and oil layer drilling length Lo, the rock mechanical parameters include one or more of Young modulus YME, Poisson ratio σ and brittleness index BI, and the primary fracturing parameters include one or more of liquid feeding strength Sq and sand feeding strength Ss.
6. The method for selecting the repeated fracturing layer selection and the fracturing mode of the horizontal well according to claim 1, wherein in the step S5, the liquid production rate of each fracturing section is calculated according to a multiple regression method after fitting a calculation formula of a liquid production profile of a well to be evaluated, and the calculation formula of a planned liquid production profile of each fracturing section is as follows:
qi＝∑ai×f(geoi)+∑bj×f(rockj)+∑ck×f(frack) Formula (4)
Wherein q isiCalculating a liquid production profile of each fracturing section in unit t; geoiOil layer geological parameters affecting oil production; rockjRock mechanics parameters that affect oil production; frackPrimary fracturing parameters that affect oil production; i is the number of the geological parameters of the oil layer influencing the oil production; j is the number of the rock mechanical parameters influencing the oil production; k is the number of the primary fracturing parameters affecting oil production, ai、bj、ckRespectively fitting parameters.
7. The method for selecting the repeated fracturing stratum selection and the fracturing mode of the horizontal well according to claim 6, wherein the planned production profile obtained in the step S5 can reflect the relative oil production contribution of each fracturing section, the actual oil production of each fracturing section can be obtained by comparing the planned production profile with the actual oil production, and meanwhile, the contribution percentage and the recovery ratio of each section of produced fluid after the initial fracturing are calculated through the calculated predicted oil production of the single well, the geological reserve of each section and the produced fluid of each fracturing section; wherein the content of the first and second substances,
the calculation formula of the percentage contribution of the produced fluid of each fracturing section is as follows:
the formula for calculating the recovery ratio of each fracturing segment is as follows:
wherein eta isiThe percentage of the produced fluid of each fracturing section is contributed, and the unit is; q. q.siCalculating a liquid production profile of each fracturing section in unit t; riThe recovery ratio of each fracturing segment is unit percent; q isPredicting oil production per well in unit t; qiAnd the geological reserves of each fracturing section are expressed in t.
8. The method for selecting the repeated fracturing stratum selection and the fracturing mode of the horizontal well according to the claim 6, wherein the fracturing sections are divided into four types of fracturing sections according to the contribution percentage of the produced fluid and the recovery ratio of each fracturing section calculated in the step S7, and the first type of fracturing section has high contribution percentage of the produced oil and high recovery ratio; the oil contribution percentage of the second type of fracturing section is high, and the recovery ratio is low; the third type of fracturing section has low contribution percentage and low recovery ratio for oil production; the fourth type of fracturing section has low oil production contribution percentage and high oil recovery ratio, wherein the oil production contribution percentage is higher than 5%; the oil production contribution percentage is less than or equal to 5 percent, and is low; the recovery rate is higher than 20%; the recovery rate is lower than or equal to 20 percent.
9. The horizontal well repeated fracturing layer selection and fracturing mode selection method according to claim 8, wherein in the step S8, repeated fracturing evaluation is performed according to the classification result of the fracturing section in the step S7, and the first fracturing section is not subjected to repeated fracturing; the second type of fracturing section needs to be subjected to repeated fracturing; the third type of fracturing stage needs to be subjected to repeated fracturing; the fourth type of fracturing stage is not repeatedly fractured.
10. The method for selecting the repeated fracturing stratum and the fracturing mode of the horizontal well according to claim 9,
the second type of fracturing section is subjected to air-filling fracturing on the basis of primary fracturing;
the third type of fracturing stage re-fractures old fractures.
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