Hydraulic fracturing diffusion radius monitoring method based on tracer agent and monitoring system thereof
By using tracer monitoring methods in hydraulic fracturing in coal mines, the concentration and rebate of tracer are monitored in real time, and the ratio of the effective occurrence of tracer and the number of mixed liquid injection times is calculated, which solves the shortcomings in the measurement of hydraulic fracturing diffusion radius in the prior art, and achieves efficient and accurate monitoring and optimization.
Patent Information
- Application Number
- CN202411951262.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-05-06
AI Technical Summary
In the prior art, the measurement of the diffusion radius of hydraulic fracturing mainly depends on theoretical models and empirical formulas, and the lack of real-time and accurate monitoring methods leads to a deviation from the expected results.
Using a tracer-based monitoring method, by mixing the tracer with hydraulic fracturing fluid, injecting it into the fracturing drill, and a monitoring drill is arranged around it. The concentration and return of the tracer are monitored by sensors, and the ratio of the effective occurrence of the tracer and the number of mixed liquid injections is calculated to determine the diffusion radius of hydraulic fracturing.
High sensitivity and real-time monitoring of the diffusion radius of hydraulic fracturing are achieved, which avoids the limitations of the theoretical model, can accurately reflect the crack expansion and diffusion range, and improves the effect and efficiency of hydraulic fracturing.
Smart Images
Figure CN119933673A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of mining engineering, and in particular to a tracer-based hydraulic fracturing diffusion radius monitoring method and a monitoring system thereof. Background Art
[0002] Hydraulic fracturing in coal mines is a technology that uses special equipment to inject high-pressure water into the coal and rock mass underground to cause it to break and form a crack network, thereby reducing the strength of the coal and rock mass or increasing the permeability of the coal seam, thereby effectively controlling the strength of the coal and rock roof or improving the efficiency of coalbed methane extraction. Hydraulic fracturing technology is widely used in coal mining, and is widely used in hard roof control, dynamic pressure tunnel pressure relief, hard top coal weakening, and coal seam fracturing and permeability enhancement. It has the characteristics of high safety, small engineering volume, low cost and strong adaptability. The crack diffusion radius of hydraulic fracturing technology is a key parameter for implementing and evaluating the effect of hydraulic fracturing. Traditional measurement methods mainly rely on theoretical models and empirical formulas, lack of real-time and accurate monitoring methods, resulting in deviations between the hydraulic fracturing effect and expectations. Therefore, it is of great practical significance to develop a new measurement method to accurately determine the crack diffusion radius. Summary of the invention
[0003] The present invention provides a tracer-based hydraulic fracturing diffusion radius monitoring method and a monitoring system thereof, which are used to solve the defect that the measurement of crack diffusion radius in the prior art mainly relies on theoretical models and empirical formulas, lacks real-time and accurate monitoring means, and causes the hydraulic fracturing effect to deviate from the expectation.
[0004] The present invention provides a tracer-based hydraulic fracturing diffusion radius monitoring method, comprising: Mixing the tracer with the hydraulic fracturing fluid to form a mixed solution, injecting the mixed solution into a fracturing pump, and recording the concentration of the tracer in the mixed solution; Arrange monitoring boreholes around the fracturing boreholes, and install sensors in the monitoring boreholes to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring boreholes; injecting the mixed fluid in the fracturing pump into the fracturing borehole; Preliminary judgment of hydraulic fracturing diffusion radius based on the return fluid situation of the monitoring borehole; Within the initially determined hydraulic fracturing diffusion radius, the ratio of the effective occurrence times of the tracer in the monitoring borehole to the injection times of the mixed fluid in the fracturing borehole is calculated, and the hydraulic fracturing diffusion radius is determined by the ratio.
[0005] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the step of arranging monitoring boreholes around the fracturing borehole specifically includes: A plurality of monitoring boreholes are arranged on both sides of the fracturing borehole, and the plurality of monitoring boreholes in the same direction are arranged with gradually increasing distances from the fracturing borehole.
[0006] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the distance between two adjacent monitoring boreholes and / or the distance between the fracturing borehole and the monitoring borehole ranges from 5 to 10 m.
[0007] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the step of preliminarily judging the hydraulic fracturing diffusion radius according to the return fluid situation of the monitoring borehole specifically includes: If there is no return fluid in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in this direction does not reach the distance between the monitoring borehole and the fracturing borehole; If there is fluid return in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in that direction reaches the distance between the monitoring borehole and the fracturing borehole.
[0008] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the step of installing a sensor in the monitoring borehole to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring borehole specifically includes: Set the tracer concentration ratio threshold; When the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed liquid is greater than or equal to the tracer concentration ratio threshold, it is determined that the tracer is effectively present in the corresponding monitoring borehole; When the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed fluid is less than the tracer concentration ratio threshold, it is determined that the tracer is not effectively present in the corresponding monitoring borehole.
[0009] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the tracer concentration ratio threshold is set to 90%.
[0010] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the step of calculating the ratio of the effective occurrence number of the tracer in the monitoring borehole to the injection number of the mixed liquid in the fracturing borehole, and determining the hydraulic fracturing diffusion radius by the ratio specifically includes: Set the frequency ratio; When the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole is greater than or equal to the number ratio, determining that the hydraulic fracturing diffusion radius is greater than or equal to the distance between the monitoring borehole and the fracturing borehole; When the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed fluid in the fracturing borehole is less than the number ratio, it is determined that the hydraulic fracturing diffusion radius is less than the distance between the monitoring borehole and the fracturing borehole.
[0011] According to the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, the number ratio is set to 10%.
[0012] According to the method for monitoring the diffusion radius of hydraulic fracturing based on tracers provided by the present invention, after the step of calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole within the initially determined hydraulic fracturing diffusion radius range, and determining the hydraulic fracturing diffusion radius by the ratio, the method further comprises: The determined hydraulic fracturing diffusion radius is compared with the hydraulic fracturing diffusion radius obtained according to the theoretical model and the empirical formula to verify the accuracy of the determined hydraulic fracturing diffusion radius; Optimizing hydraulic fracturing parameters according to the determined hydraulic fracturing diffusion radius; The tracer type is optimized based on the accuracy of the determined hydraulic fracture spread radius.
[0013] The present invention also provides a monitoring system for the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention, comprising: A pump truck is provided with a fracturing pump, which mixes the tracer with the hydraulic fracturing fluid to form a mixed liquid and injects the mixed liquid into the fracturing pump; A water injection system, one end of which is connected to the fracturing pump and the other end of which extends into the fracturing borehole; Sensors, installed in each monitoring borehole; The processor is electrically connected to the sensor and is used to determine the effective occurrence times of the tracer in the monitoring borehole; calculate the ratio of the effective occurrence times of the tracer in the monitoring borehole to the injection times of the mixed liquid in the fracturing borehole, and determine the hydraulic fracturing diffusion radius through the ratio.
[0014] The present invention provides a method for monitoring the diffusion radius of hydraulic fracturing based on a tracer, which comprises the following steps: mixing a tracer with a hydraulic fracturing fluid to form a mixed liquid, injecting the mixed liquid into a fracturing pump, and recording the concentration of the tracer in the mixed liquid; arranging monitoring boreholes around the fracturing borehole, installing sensors in the monitoring boreholes, monitoring and recording the concentration of the tracer, so as to determine the number of effective occurrences of the tracer in the monitoring borehole; injecting the mixed liquid in the fracturing pump into the fracturing borehole; preliminarily judging the diffusion radius of the hydraulic fracturing according to the return fluid situation of the monitoring borehole; within the range of the preliminarily judged hydraulic fracturing diffusion radius, calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole, and determining the diffusion radius of the hydraulic fracturing according to the ratio. The present invention provides a method for monitoring the diffusion radius of hydraulic fracturing based on a tracer, which applies the tracer technology to the diffusion radius measurement of hydraulic fracturing in coal mines, and has the advantages of high sensitivity and real-time monitoring. The presence and concentration changes of the tracer are monitored through surrounding monitoring boreholes, so that the expansion and diffusion range of the cracks can be accurately reflected, and the limitations of the theoretical model can be avoided. The method can be flexibly adjusted according to different tracer characteristics and underground environments, and has strong applicability.
[0015] The present invention provides a tracer-based hydraulic fracturing diffusion radius monitoring system, which applies the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention to determine the hydraulic fracturing diffusion radius, and therefore has the same advantages as above. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0017] Figure 1 It is a schematic flow chart of a tracer-based hydraulic fracturing diffusion radius monitoring method provided in one of the embodiments of the present invention.
[0018] Figure 2 It is a schematic diagram of the structure of a monitoring system for a tracer-based hydraulic fracturing diffusion radius monitoring method provided in one of the embodiments of the present invention.
[0019] Reference numerals: 1: Fracturing pump; 2: Pressure gauge; 3: Water injection system; 4: Fracturing borehole; 5: Monitoring borehole; 6: Sensor. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0021] In the description of the present embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present embodiment.
[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this embodiment, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0023] In this embodiment, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.
[0024] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0025] Combine the following Figure 1 The present invention describes a method for monitoring the diffusion radius of hydraulic fracturing based on a tracer. The method for monitoring the diffusion radius of hydraulic fracturing based on a tracer specifically comprises the following steps: S1, mixing the tracer with the hydraulic fracturing fluid to form a mixed solution, injecting the mixed solution into the fracturing pump 1, and recording the concentration of the tracer in the mixed solution; S2. Arrange monitoring boreholes 5 around the fracturing borehole 4, and install sensors 6 in the monitoring boreholes to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring boreholes; S3, injecting the mixed liquid in the fracturing pump 1 into the fracturing borehole 4, specifically: injecting the mixed liquid into the fracturing borehole 4 (or the hole wall) through the fracturing pump 1 for multiple times from the bottom of each fracturing borehole 4 to the hole mouth at equal or unequal intervals, the number of times being not less than 3 times; S4. Preliminarily determine the hydraulic fracturing diffusion radius based on the return fluid situation of the monitoring borehole 5; S5. Within the initially determined hydraulic fracturing diffusion radius, calculate the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed fluid in the fracturing borehole, and determine the hydraulic fracturing diffusion radius through the ratio.
[0026] Specifically, a method for determining the diffusion radius of hydraulic fracturing provided by the present invention is to select a suitable tracer, mix the tracer with the hydraulic fracturing fluid to form a mixed liquid, record the concentration of the tracer in the mixed liquid for subsequent calculation and use, and the mixed liquid has the dual effects of the tracer and the hydraulic fracturing fluid. The tracer used in step S1 can be a fluorescent dye, a chemical tracer or other detectable substances. The selection of the above tracer needs to ensure that it can be well integrated with the hydraulic fracturing fluid and injected or infiltrated into the coal rock fissures with the fracturing fluid. Therefore, the selection of the tracer follows the following principles: it does not react with the hydraulic fracturing fluid, has a certain fluidity, and is easily detected by a specific sensor.
[0027] In step S2, the periphery (i.e., both sides) of the fracturing borehole is constructed to form a monitoring borehole, and the mixture of the tracer and the hydraulic fracturing fluid can enter the fracturing borehole and the monitoring borehole. The hydraulic fracturing diffusion radius is mainly determined by monitoring whether there is a return of liquid in the borehole and the ratio of the number of effective tracer appearances to the number of injections of the mixture. Therefore, a sensor that can detect the presence of the tracer (i.e., the tracer concentration) is set in the monitoring borehole. According to the type of tracer selected, a specific sensor is used for monitoring, such as an optical sensor (for fluorescent tracers) or other types of chemical sensors (for chemical tracers).
[0028] In steps S3 to S4, the mixed liquid in the fracturing pump is injected into the fracturing borehole. As the mixed liquid spreads, the return liquid situation of the monitoring borehole is first monitored to preliminarily determine the location range of the hydraulic fracturing diffusion radius. Generally, if there is a return liquid situation in the monitoring borehole, it can be preliminarily determined that the hydraulic fracturing diffusion extends to at least the location of the monitoring borehole, but it is still necessary to monitor the presence of tracers in the return liquid to determine whether the return liquid is the mixed liquid pumped in previously, and further determine in step S5.
[0029] As for the monitoring boreholes without fluid return, since the monitoring boreholes are relatively thin and the monitoring time is long, no fluid return occurs, which can basically determine that the hydraulic fracturing diffusion radius has not reached the monitoring borehole at that location.
[0030] In the subsequent judgment process of the hydraulic fracturing diffusion radius, the judgment should be made by monitoring the tracer concentration of the monitoring borehole outside the monitoring borehole, while the tracer concentration of the monitoring borehole inside the monitoring borehole may no longer be monitored, thereby improving the overall monitoring efficiency.
[0031] Step S5 is a precise determination process after the preliminary determination of the hydraulic fracturing diffusion radius in step S4. Since the range of the hydraulic fracturing diffusion radius can be basically determined according to the preliminary determination in step S4, the tracer concentration of the mixed liquid in each monitoring borehole is monitored by the sensor within the determined range of the hydraulic fracturing diffusion radius to accurately determine the hydraulic fracturing diffusion radius.
[0032] The present invention provides a method for monitoring the diffusion radius of hydraulic fracturing based on a tracer, which comprises the following steps: mixing a tracer with a hydraulic fracturing fluid to form a mixed liquid, injecting the mixed liquid into a fracturing pump, and recording the concentration of the tracer in the mixed liquid; arranging monitoring boreholes around the fracturing borehole, installing sensors in the monitoring boreholes, monitoring and recording the concentration of the tracer, so as to determine the number of effective occurrences of the tracer in the monitoring borehole; injecting the mixed liquid in the fracturing pump into the fracturing borehole; preliminarily judging the diffusion radius of the hydraulic fracturing according to the return fluid situation of the monitoring borehole; within the range of the preliminarily judged hydraulic fracturing diffusion radius, calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole, and determining the diffusion radius of the hydraulic fracturing according to the ratio. The present invention provides a method for monitoring the diffusion radius of hydraulic fracturing based on a tracer, which applies the tracer technology to the diffusion radius measurement of hydraulic fracturing in coal mines, and has the advantages of high sensitivity and real-time monitoring. The presence and concentration changes of the tracer are monitored through surrounding monitoring boreholes, so that the expansion and diffusion range of the cracks can be accurately reflected, and the limitations of the theoretical model can be avoided. The method can be flexibly adjusted according to different tracer characteristics and underground environments, and has strong applicability.
[0033] In one embodiment of the present invention, the step of arranging monitoring boreholes around the fracturing borehole, i.e., step S2, specifically includes: arranging a plurality of monitoring boreholes on both sides of the fracturing borehole, and the plurality of monitoring boreholes in the same direction are arranged with gradually increasing distances from the fracturing borehole. Preferably, two monitoring boreholes are arranged on both sides of the fracturing borehole according to the distances from the fracturing borehole; and a sensor is arranged in each monitoring borehole. Of course, other numbers of monitoring boreholes can be arranged according to actual needs to ensure accurate monitoring.
[0034] In one embodiment of the present invention, the distance between two adjacent monitoring boreholes and / or the distance between the fracturing borehole and the monitoring borehole ranges from 5 to 10 m. Preferably, the distance between the nearest monitoring boreholes on the left and right sides of the fracturing borehole is 5 m, and the distance between two adjacent monitoring boreholes is 10 m. By analogy, multiple monitoring boreholes are arranged on both sides of the fracturing borehole. Furthermore, with the fracturing borehole as the center, multiple monitoring boreholes are arranged on both sides of the fracturing borehole at a preset distance to form an arrangement such as a triangle, square, cross, circle, etc., thereby obtaining a monitoring network of a desired specific shape.
[0035] In one embodiment of the present invention, the step of preliminarily determining the hydraulic fracturing diffusion radius according to the fluid return condition of the monitoring borehole, i.e., step S4, specifically includes the following steps: If there is no return fluid in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in that direction (i.e., the monitoring borehole is in the direction of the fracturing borehole) does not reach the distance between the monitoring borehole and the fracturing borehole; If there is fluid return in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in that direction (i.e., the monitoring borehole is in the direction of the fracturing borehole) reaches the distance between the monitoring borehole and the fracturing borehole.
[0036] Specifically, for monitoring boreholes with fluid return, it is preliminarily determined that the distance greater than or equal to the monitoring borehole and the fracturing borehole is the range of values of the hydraulic fracturing diffusion radius; for monitoring boreholes without fluid return, it is preliminarily determined that the distance less than the monitoring borehole and the fracturing borehole is the range of values of the hydraulic fracturing diffusion radius.
[0037] In one embodiment of the present invention, a sensor is installed in the monitoring borehole to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring borehole, that is, step S2 specifically includes the following steps: S21, setting a tracer concentration ratio threshold; S22, when the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed solution is greater than or equal to the tracer concentration ratio threshold, determining that the tracer is effectively present in the corresponding monitoring borehole; When the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed fluid is less than the tracer concentration ratio threshold, it is determined that the tracer is not effectively present in the corresponding monitoring borehole.
[0038] Preferably, the tracer concentration ratio threshold is set to 90%; of course, the tracer concentration ratio threshold can be adjusted according to actual downhole conditions and tracer types.
[0039] Specifically, taking the tracer concentration in the mixed liquid as 10% and the set tracer concentration ratio threshold as 90% as an example, if the tracer concentration in the monitoring borehole is 9%, then the concentration ratio of the tracer concentration in the mixed liquid is calculated to be equal to the tracer concentration ratio threshold, and therefore, the tracer is determined to be effectively present in the corresponding monitoring borehole, and the effective number is recorded as 1. Similarly, if the tracer concentration in the monitoring borehole is less than 9%, the tracer is not effectively present, and the number is not recorded. In step S5, the hydraulic fracturing diffusion radius is determined by the ratio of the recorded number to the number of injections of the mixed liquid.
[0040] In one embodiment of the present invention, the step of calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole, and determining the hydraulic fracturing diffusion radius by the ratio, i.e., step S5, specifically includes the following steps: S51, setting the number of times ratio; S52, when the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole is greater than or equal to the number ratio, determining that the hydraulic fracturing diffusion radius is greater than or equal to the distance between the monitoring borehole and the fracturing borehole; When the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed fluid in the fracturing borehole is less than the number ratio, it is determined that the hydraulic fracturing diffusion radius is less than the distance between the monitoring borehole and the fracturing borehole.
[0041] Preferably, the set number ratio is 10%; of course, the set number ratio can be adjusted according to actual conditions such as the actual downhole conditions and the tracer type.
[0042] Specifically, taking the set number ratio as 10%, the total number of mixed liquid injections as 18 times, the number of tracer appearances as 8 times, and the number of effective tracer appearances as 6 times as an example, the ratio of the effective number of tracer appearances to the number of mixed liquid injections in the fracturing borehole is calculated to be 6 / 18=33.33%, which is greater than 10%. Therefore, it is determined that the hydraulic fracturing diffusion radius is greater than the distance between the fracturing borehole and the monitoring borehole.
[0043] In one embodiment of the present invention, within the initially determined hydraulic fracturing diffusion radius range, the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole is calculated, and after the step of determining the hydraulic fracturing diffusion radius by the ratio, that is, after step S5, the following steps are also included: S6. Compare the determined hydraulic fracturing diffusion radius with the hydraulic fracturing diffusion radius obtained according to the theoretical model and the empirical formula to verify the accuracy of the determined hydraulic fracturing diffusion radius. In this embodiment, the hydraulic fracturing diffusion radius obtained by the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention is compared with the hydraulic fracturing diffusion radius obtained based on the traditional theoretical model and the empirical formula to verify the accuracy of the detection method.
[0044] In one embodiment of the present invention, after the step of comparing the determined hydraulic fracturing diffusion radius with the hydraulic fracturing diffusion radius obtained according to the theoretical model and the empirical formula to verify the accuracy of the determined hydraulic fracturing diffusion radius, that is, after step S6, the following steps are also included: S71. Optimizing hydraulic fracturing parameters according to the determined hydraulic fracturing diffusion radius; S72. Optimize the tracer type based on the accuracy of the determined hydraulic fracturing diffusion radius.
[0045] In this embodiment, the hydraulic fracturing parameters are optimized by the obtained hydraulic fracturing diffusion radius to improve the effect of subsequent operations; the tracer type is optimized by the accuracy of the obtained hydraulic fracturing diffusion radius, and a suitable tracer is used for subsequent monitoring to improve the effect of subsequent monitoring.
[0046] like Figure 2As shown, the present invention also provides a monitoring system for the tracer-based hydraulic fracturing diffusion radius monitoring method according to an embodiment of the present invention. The monitoring system includes: a pump truck, a water injection system, a sensor and a processor.
[0047] Among them, the pump truck is equipped with a fracturing pump 1, which mixes the tracer with the hydraulic fracturing fluid to form a mixed liquid and injects the mixed liquid into the fracturing pump 1; one end of the water injection system 3 is connected to the fracturing pump, and the other end extends into the fracturing borehole 4; the sensor 6 is arranged in each monitoring borehole 5; the processor is electrically connected to the sensor 6, and is used to determine the effective number of occurrences of the tracer in the monitoring borehole 5; the ratio of the effective number of occurrences of the tracer in the monitoring borehole 5 to the number of injections of the mixed liquid in the fracturing borehole 4 is calculated, and the hydraulic fracturing diffusion radius is determined by the ratio.
[0048] The processor is selected according to the needs.
[0049] Optionally, a pressure gauge 2 is provided on the fracturing pump 1 to monitor the injection pressure of the mixed liquid and adjust the fracturing pump 1 accordingly. The water injection system 3 can use a high-pressure hose, one end of which is connected to the fracturing pump 1 and the other end extends into the fracturing borehole 4.
[0050] The present invention provides a tracer-based hydraulic fracturing diffusion radius monitoring system, which applies the tracer-based hydraulic fracturing diffusion radius monitoring method provided by the present invention to determine the hydraulic fracturing diffusion radius, and therefore has the same advantages as above.
[0051] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed over multiple units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. Those of ordinary skill in the art may understand and implement the present invention without creative effort.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for monitoring the diffusion radius of hydraulic fracturing based on tracers, characterized in that: include: Mixing the tracer with the hydraulic fracturing fluid to form a mixed solution, injecting the mixed solution into a fracturing pump, and recording the concentration of the tracer in the mixed solution; Arrange monitoring boreholes around the fracturing boreholes, and install sensors in the monitoring boreholes to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring boreholes; injecting the mixed fluid in the fracturing pump into the fracturing borehole; Preliminary judgment of hydraulic fracturing diffusion radius based on the return fluid situation of the monitoring borehole; Within the initially determined hydraulic fracturing diffusion radius, the ratio of the effective occurrence times of the tracer in the monitoring borehole to the injection times of the mixed fluid in the fracturing borehole is calculated, and the hydraulic fracturing diffusion radius is determined by the ratio.
2. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 1, characterized in that: The step of arranging monitoring boreholes around the fracturing borehole specifically includes: A plurality of monitoring boreholes are arranged on both sides of the fracturing borehole, and the plurality of monitoring boreholes in the same direction are arranged with gradually increasing distances from the fracturing borehole.
3. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 2, characterized in that: The distance between two adjacent monitoring boreholes and / or the distance between the fracturing borehole and the monitoring borehole ranges from 5 to 10 m.
4. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 1, characterized in that: The step of preliminarily determining the hydraulic fracturing diffusion radius based on the return fluid situation of the monitoring borehole specifically includes: If there is no return fluid in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in this direction does not reach the distance between the monitoring borehole and the fracturing borehole; If there is fluid return in the monitoring borehole, it is preliminarily determined that the hydraulic fracturing diffusion radius in that direction reaches the distance between the monitoring borehole and the fracturing borehole.
5. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 1, characterized in that: The step of installing a sensor in the monitoring borehole to monitor and record the concentration of the tracer to determine the number of effective occurrences of the tracer in the monitoring borehole specifically includes: Set the tracer concentration ratio threshold; When the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed liquid is greater than or equal to the tracer concentration ratio threshold, it is determined that the tracer is effectively present in the corresponding monitoring borehole; When the ratio of the concentration of the tracer in the monitoring borehole to the concentration of the tracer in the mixed fluid is less than the tracer concentration ratio threshold, it is determined that the tracer is not effectively present in the corresponding monitoring borehole.
6. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 5, characterized in that: The tracer concentration ratio threshold is set to 90%.
7. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 1, characterized in that: The step of calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole, and determining the hydraulic fracturing diffusion radius by the ratio specifically comprises: Set the frequency ratio; When the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole is greater than or equal to the number ratio, determining that the hydraulic fracturing diffusion radius is greater than or equal to the distance between the monitoring borehole and the fracturing borehole; When the ratio of the number of effective tracer appearances in the monitoring borehole to the number of injections of the mixed fluid in the fracturing borehole is less than the number ratio, it is determined that the hydraulic fracturing diffusion radius is less than the distance between the monitoring borehole and the fracturing borehole.
8. The tracer-based hydraulic fracturing diffusion radius monitoring method according to claim 7, characterized in that: The frequency ratio is set to 10%.
9. The method for monitoring the diffusion radius of hydraulic fracturing based on tracers according to any one of claims 1 to 8, characterized in that: After calculating the ratio of the number of effective occurrences of the tracer in the monitoring borehole to the number of injections of the mixed liquid in the fracturing borehole within the initially determined hydraulic fracturing diffusion radius, and determining the hydraulic fracturing diffusion radius by the ratio, the method further includes: The determined hydraulic fracturing diffusion radius is compared with the hydraulic fracturing diffusion radius obtained according to the theoretical model and the empirical formula to verify the accuracy of the determined hydraulic fracturing diffusion radius; Optimizing hydraulic fracturing parameters according to the determined hydraulic fracturing diffusion radius; The tracer type is optimized based on the accuracy of the determined hydraulic fracture spread radius.
10. A monitoring system for the tracer-based hydraulic fracturing diffusion radius monitoring method according to any one of claims 1 to 9, characterized in that: include: A pump truck is provided with a fracturing pump (1) therein, which mixes the tracer with the hydraulic fracturing fluid to form a mixed liquid and injects the mixed liquid into the fracturing pump (1); A water injection system (3), one end of which is connected to the fracturing pump (1) and the other end of which extends into the fracturing borehole (4); A sensor (6) is disposed in each monitoring borehole (5); a processor, electrically connected to the sensor (6), for determining the number of effective occurrences of the tracer in the monitoring borehole (5); The ratio of the number of effective tracer appearances in the monitoring borehole (5) to the number of injections of the mixed fluid in the fracturing borehole (4) is calculated, and the hydraulic fracturing diffusion radius is determined by the ratio.