Composite material and method for detecting ground stress of fractured well

Abstract

The invention relates to the field of geological exploration, and discloses a composite material and method for detecting ground stress of a fractured well, and the composite material comprises metal particles and an elastic material coating the surfaces of the metal particles; the density of the metal particles is 5g / cm < 3 >-10g / cm < 3 >, and the elastic modulus of the elastic material is less than or equal to 0.1 GPa. The crustal stress of the fractured well can be measured by using the composite material and an acoustic logging instrument, and the measuring difficulty of the crustal stress of the fractured well is reduced. The composite material can be input into a stratum along with fracturing fluid and located in the stratum for a long time, and long-acting detection is achieved. By adopting the composite material, the crustal stress of the fractured well can be obtained based on the analysis of the reflected sound waves of the composite material, and the time consumed for detecting the crustal stress of the fractured well is shortened. By adopting the composite material, the crustal stress of the fractured well can be obtained based on the change of reflected sound waves caused by deformation of the composite material, the sound wave response is generally sensitive, and the measurement precision of the crustal stress of the fractured well can be improved.

Description

Technical Field

[0001] The invention relates to the field of geological exploration, and in particular to a composite material for detecting ground stress of a fracturing well and a method for detecting ground stress of a fracturing well. Background Art

[0002] In-situ stress refers to the stress state in underground rocks or formations. In the process of oil and gas production, understanding the in-situ stress is crucial to determine the appropriate fracturing operation and optimize the well pattern design.

[0003] At present, the commonly used measurement methods for the in-situ stress of fracturing wells include direct measurement methods such as hydraulic fracturing, and indirect measurement methods such as casing core stress relief method and strain recovery method. For example, CN109469479B discloses a hydraulic fracturing in-situ stress measurement system and method, which provides a measurement system including a packer, a packer water injection pipeline and a fracturing water injection pipeline to solve the problem of the packer's sealing and pressure relief and automatic recovery of the sealing function. CN110006568A discloses a method and an acquisition system for obtaining three-dimensional in-situ stress using a core, which performs inversion and evolutionary calculation on the generated test data to reasonably match the output parameters, so that the estimated three-dimensional in-situ stress parameters are accurate and the efficiency of obtaining three-dimensional in-situ stress is improved. CN108629463A discloses a method and device for predicting in-situ stress, which determines the in-situ stress of the well point position in the work area at the prediction time based on the in-situ stress of the well point position in the work area at the prediction time, so as to obtain the three-dimensional in-situ stress distribution data of the work area at the prediction time. CN113687411B discloses a method for predicting the orientation of ground stress based on microseismic observations, which obtains the angle of the artificial fractures in each fracturing section by calculating the arctangent value of the slope of each fracturing section, wherein the angle of the artificial fractures in each fracturing section is the orientation of the maximum horizontal principal stress of each fracturing section; thus, the orientation of the horizontal stress of the formation can be predicted more accurately. CN115655133A discloses an optical fiber strain sensing column and a method for measuring ground stress, which uses a winding optical fiber strain sensing column to install a high spatial resolution optical fiber sensor in the formation, so that the different ground stress states at different sensing sections can be calculated based on the strains measured at different sensing points on the optical fiber strain sensing column, thereby achieving real-time measurement of multiple layers of ground stress.

[0004] However, in practical applications, the above measurement methods have the problems of great measurement difficulty, short measurement time, long measurement time and low measurement accuracy. For example, when using the hydraulic fracturing method for measurement, the relevant ground stress measurement device sometimes fails to measure, resulting in great measurement difficulty, affecting the measurement accuracy, and failing to achieve long-term monitoring. When using the strain recovery method for measurement, the operation procedure is complicated, there are many influencing and interfering factors, it takes a long time and the measurement accuracy is low. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of great difficulty, short measurement time, long measurement time and low measurement accuracy in the prior art in measuring the in-situ stress of a fracturing well, and to provide a composite material and method for detecting the in-situ stress of a fracturing well.

[0006] In order to achieve the above-mentioned object, the present invention provides a composite material for detecting ground stress of a fracturing well in a first aspect, the composite material comprising metal particles and an elastic material coated on the surface of the metal particles;

[0007] Wherein, the density of the metal particles is 5g / cm 3 -10g / cm 3 , the elastic modulus of the elastic material is less than or equal to 0.1 GPa.

[0008] In an embodiment of the present application, the ratio of the radius of the metal particles to the coating thickness of the elastic material is 1:1 to 1:2.

[0009] In the embodiment of the present application, the shape of the composite material is spherical or quasi-spherical.

[0010] In the embodiment of the present application, the metal particles are made of iron or copper.

[0011] In an embodiment of the present application, the elastic material includes rubber.

[0012] In the embodiment of the present application, the particle size of the composite material is 20 mesh to 40 mesh.

[0013] The second aspect of the present application provides a method for detecting geostress of a fracturing well, wherein the composite material for detecting geostress of a fracturing well provided in the first aspect of the present application is used to detect geostress of a fracturing well, and the method comprises:

[0014] The composite material is introduced into the formation for fracturing;

[0015] Acoustic waves are emitted to the formation, and the in-situ stress of the fractured well is obtained based on the reflected acoustic waves of the composite material.

[0016] In the embodiment of the present application, the step of inputting the composite material into the formation for fracturing includes:

[0017] In the sand adding stage, the composite material is added to the fracturing fluid to obtain the target fracturing fluid;

[0018] The target fracturing fluid is introduced into the formation for fracturing.

[0019] In an embodiment of the present application, the method of obtaining the in-situ stress of the fracturing well based on the reflected sound wave of the composite material includes:

[0020] Obtaining a corresponding sound wave response curve according to the reflected sound wave;

[0021] Based on the acoustic wave response curve and the standard plate of ground stress, the ground stress of the fracturing well is obtained.

[0022] In the embodiment of the present application, the in-situ stress of the fracturing well is obtained based on the acoustic wave response curve and the in-situ stress standard plate, including:

[0023] comparing the acoustic wave response curve with a standard plate of ground stress;

[0024] Calculate the in-situ stress of fractured wells based on the interpolation method.

[0025] The composite material for detecting the ground stress of a fracturing well provided by the above technical solution comprises metal particles and an elastic material coated on the surface of the metal particles; wherein the density of the metal particles is 5 g / cm 3 -10g / cm 3 , the elastic modulus of the elastic material is less than or equal to 0.1GPa. Since the ground stress of the fractured well can be measured by using the composite material and the acoustic logging instrument, the difficulty of measuring the ground stress of the fractured well is greatly reduced. In addition, since the composite material can be input into the formation with the fracturing fluid and is located in the formation for a long time, after the oil and gas well is produced for a period of time, the ground stress of the fractured well can still be detected by measuring the reflected sound waves of the composite material of the fracturing section; that is, long-term detection can be achieved. In addition, by adopting the composite material provided in the embodiment of the present application, the ground stress of the fractured well can be obtained based on the analysis of the reflected sound waves of the composite material, and the process is relatively simple, thereby greatly shortening the time consumed for the detection of the ground stress of the fractured well. In addition, by adopting the composite material provided in the embodiment of the present application, the ground stress of the fractured well can be obtained based on the change of the reflected sound waves caused by the deformation of the composite material, and the sound wave response is generally more sensitive, so the measurement accuracy of the ground stress of the fractured well can be improved.

[0026] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0028] Figure 1 A schematic diagram of the structure of a composite material for detecting ground stress in a fracturing well according to an embodiment of the present application is shown;

[0029] Figure 2 A photograph schematically shows a composite material for detecting in-situ stress in a fractured well according to an embodiment of the present application.

[0030] Figure 3 A schematic diagram of a process for detecting ground stress in a fracturing well according to an embodiment of the present application is shown;

[0031] Figure 4 A schematic diagram of a standard geostress chart according to an embodiment of the present application is schematically shown.

[0032] Figure 5 A schematic diagram of a process of another method for detecting ground stress in a fracturing well according to an embodiment of the present application is schematically shown;

[0033] Figure 6 A schematic diagram showing a comparison between an acoustic wave response curve of a fractured layer section to be measured and a standard plate of in-situ stress of a fractured well according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] If there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0036] As described in the background art, in the process of oil and gas production, understanding the in-situ stress of the fractured well is crucial to determine the appropriate fracturing operation and optimize the well pattern design. However, the commonly used in-situ stress measurement methods for fractured wells have problems such as high measurement difficulty, short measurement time, long measurement time and low measurement accuracy in actual application.

[0037] In view of this, in one embodiment of the present application, a composite material for detecting ground stress in a fracturing well is provided, wherein the composite material may include metal particles and an elastic material coated on the surface of the metal particles; the density of the metal particles is 5 g / cm 3 -10g / cm 3 , the elastic modulus of the elastic material is less than or equal to 0.1 GPa.

[0038] The metal particles may be made of metals with a relatively high density such as iron or copper. The elastic material may include rubber, specifically rubber with a melting temperature above 180°C.

[0039] The particle size of the composite material can be 20 mesh to 40 mesh. Mesh is a unit used to describe the size of the mesh size of a sieve, indicating the number of mesh holes per inch. 20 mesh to 40 mesh means that the particle size of the composite material varies within this range. 20 mesh means that larger particles in the composite material can pass through a sieve with 20 pinhole meshes per square inch, and 40 mesh means that smaller particles in the composite material can pass through a sieve with 40 pinhole meshes per square inch.

[0040] In the embodiment of the present application, the principle of detecting the ground stress of the fractured well based on the composite material is as follows: during the fracturing process, the composite material is squeezed into the formation along with the fracturing fluid, and the formation cracks close and squeeze the composite material, causing it to deform, resulting in changes in the structural parameters of the composite material, thereby affecting its acoustic properties. Therefore, an acoustic logging instrument can be used to transmit sound waves to the formation, and receive the frequency and sound intensity characteristics of the reflected sound waves in a specific frequency band, and the frequency and sound intensity characteristics of the reflected sound waves in the specific frequency band can be analyzed to achieve the measurement of the ground stress of the fractured well.

[0041] It can be understood that the composite material for detecting the ground stress of a fracturing well provided in the embodiment of the present application comprises metal particles and an elastic material coated on the surface of the metal particles; wherein the density of the metal particles is 5 g / cm 3 -10g / cm 3, the elastic modulus of the elastic material is less than or equal to 0.1GPa. Since the ground stress of the fractured well can be measured by using the composite material and the acoustic logging instrument, the difficulty of measuring the ground stress of the fractured well is greatly reduced. In addition, since the composite material can be input into the formation with the fracturing fluid and is located in the formation for a long time, after the oil and gas well is produced for a period of time, the ground stress of the fractured well can still be detected by measuring the reflected sound waves of the composite material of the fracturing section; that is, long-term detection can be achieved. In addition, by adopting the composite material provided in the embodiment of the present application, the ground stress of the fractured well can be obtained based on the analysis of the reflected sound waves of the composite material, and the process is relatively simple, thereby greatly shortening the time consumed for the detection of the ground stress of the fractured well. In addition, by adopting the composite material provided in the embodiment of the present application, the ground stress of the fractured well can be obtained based on the change of the reflected sound waves caused by the deformation of the composite material, and the sound wave response is generally more sensitive, so the measurement accuracy of the ground stress of the fractured well can be improved.

[0042] In practical applications, in order to enable the composite material to undergo an appropriate degree of deformation when squeezed by formation fractures, in one embodiment, the ratio of the radius of the metal particles to the coating thickness of the elastic material can be 1:1 to 1:2.

[0043] In order to further improve the measurement accuracy of the in-situ stress of the fracturing well, in one embodiment, the shape of the composite material is spherical or quasi-spherical, such as Figure 1 As shown. Therefore, when the composite material is squeezed by the formation cracks, the deformation is more uniform, so that the reflected sound waves can more truly reflect the ground stress of the fracturing well. Figure 2 A photograph of the composite material is shown, and the composite material shown in the photograph has a particle size of 20 to 40 meshes.

[0044] Based on the composite material for detecting ground stress in a fracturing well provided in the above embodiment of the present application, the embodiment of the present application also provides a method for detecting ground stress in a fracturing well using the above composite material. Figure 3 As shown, the method for detecting the in-situ stress of a fractured well may include the following steps:

[0045] Step 101, inputting the composite material into the formation for fracturing.

[0046] In the embodiment of the present application, the composite material can be added to the fracturing fluid during the sand adding stage to obtain the target fracturing fluid; the target fracturing fluid is introduced into the formation for fracturing; thereby implementing the introduction of the composite material into the formation.

[0047] In specific implementation, the composite material is added to the fracturing fluid in the sand adding stage, and more than 1 ton of 20-40 mesh composite materials can be prepared, and the composite material is mixed and added in the last sand adding stage in the fracturing process.

[0048] Step 102, transmitting sound waves to the formation, and obtaining the in-situ stress of the fracturing well based on the reflected sound waves of the composite material.

[0049] After the fracturing is completed, an acoustic logging instrument may be used to emit acoustic waves to the formation, and then the acoustic logging instrument may be dragged along the wellbore to measure the acoustic wave response of the fracturing layer section to be measured.

[0050] In an embodiment of the present application, obtaining the in-situ stress of the fractured well based on the reflected sound wave of the composite material may include: obtaining a corresponding sound wave response curve according to the reflected sound wave; and obtaining the in-situ stress of the fractured well based on the sound wave response curve and a standard in-situ stress plate. The sound wave response curve may specifically be a sound wave response curve of the fractured layer section to be measured.

[0051] Wherein, obtaining the in-situ stress of the fracturing well based on the acoustic wave response curve and the in-situ stress standard chart may include: comparing the acoustic wave response curve with the in-situ stress standard chart; and calculating the in-situ stress of the fracturing well based on the interpolation method. The in-situ stress standard chart based on the composite material provided in the embodiment of the present application may be as follows: Figure 4 As shown in Figure 3, with the increase of ground stress, the frequency corresponding to the maximum penetration loss of the composite material shifts to high frequency.

[0052] In the embodiments of the present application, the in-situ stress of the fracturing well is calculated based on the interpolation method, and the numerical value of the in-situ stress of the fracturing well can be quantitatively explained.

[0053] It can be understood that the method for detecting the in-situ stress of a fracturing well provided by the embodiment of the present application includes: inputting a composite material into a formation for fracturing; emitting an acoustic wave to the formation, and obtaining the in-situ stress of the fracturing well based on the reflected acoustic wave of the composite material. Since the in-situ stress of the fracturing well can be measured by using a composite material and an acoustic logging instrument, the difficulty of measuring the in-situ stress of the fracturing well is greatly reduced. In addition, since the composite material can be input into the formation with the fracturing fluid and is located in the formation for a long time, after the oil and gas well is produced for a period of time, the in-situ stress of the fracturing well can still be detected by measuring the reflected acoustic wave of the composite material in the fracturing section; that is, long-term detection can be achieved. Moreover, by using the composite material provided by the embodiment of the present application, the in-situ stress of the fracturing well can be obtained based on the analysis of the reflected acoustic wave of the composite material, and the process is relatively simple, thereby greatly shortening the time consumed for the detection of the in-situ stress of the fracturing well. In addition, by using the composite material provided by the embodiment of the present application, the in-situ stress of the fracturing well can be obtained based on the change of the reflected acoustic wave caused by the deformation of the composite material, and the acoustic wave response is generally more sensitive, so the measurement accuracy of the in-situ stress of the fracturing well can be improved.

[0054] Based on the method for detecting ground stress in a fracturing well provided in the above-mentioned embodiment of the present application, the embodiment of the present application also provides a more specific method for detecting ground stress in a fracturing well. Figure 5As shown, the method may include the following steps:

[0055] Step 201 , preparing more than 1 ton of 20-40 mesh composite materials.

[0056] Step 202, mixing and adding the composite material in the last sand adding stage of the fracturing process.

[0057] Step 203, after the fracturing is completed, the sonic logging instrument is dragged along the wellbore to measure the sonic response of the fracturing layer to be tested.

[0058] Step 204, comparing the acoustic wave response curve of the to-be-tested fractured layer segment with the standard in-situ stress chart.

[0059] Step 205, quantitatively interpreting the in-situ stress of the fractured well.

[0060] The relevant interpretations of steps 201 to 205 can be found in the previous text and will not be repeated here.

[0061] It can be understood that the method for detecting the in-situ stress of a fracturing well provided by the embodiment of the present application can be used to measure the in-situ stress of a fracturing well by using a composite material and an acoustic logging instrument, thereby greatly reducing the difficulty of measuring the in-situ stress of a fracturing well. In addition, since the composite material can be input into the formation with the fracturing fluid and is located in the formation for a long time, after the oil and gas well is produced for a period of time, the in-situ stress of the fracturing well can still be detected by measuring the reflected acoustic waves of the composite material of the fracturing section; that is, long-term detection can be achieved. In addition, by using the composite material provided by the embodiment of the present application, the in-situ stress of the fracturing well can be obtained based on the analysis of the reflected acoustic waves of the composite material, and the process is relatively simple, thereby greatly shortening the time consumed by the in-situ stress detection of the fracturing well. In addition, by using the composite material provided by the embodiment of the present application, the in-situ stress of the fracturing well can be obtained based on the change of the reflected acoustic waves caused by the deformation of the composite material, and the acoustic wave response is generally more sensitive, so the measurement accuracy of the in-situ stress of the fracturing well can be improved.

[0062] The composite material for detecting ground stress in a fracturing well and the method for detecting ground stress in a fracturing well provided in the embodiments of the present application are described below in combination with specific embodiments:

[0063] In the composite material used to detect ground stress in fracturing wells, the metal particles are made of iron, and the elastic material coated on the surface of the metal particles is rubber with an elastic modulus of 0.07 GPa; the ratio of the radius of the metal particles to the coating thickness of the elastic material is 1:1; the particle size of the composite material is 20 to 40 meshes.

[0064] The composite material is mixed and added in the last sand adding stage of the fracturing process. After the fracturing is completed, the acoustic logging instrument is dragged along the wellbore to measure the acoustic response of the fracturing layer to be tested. The acoustic response curve of the fracturing layer to be tested is compared with the standard plate of ground stress, such as Figure 6 As shown, Figure 6 The solid black line in the middle is the acoustic response curve of the fractured layer to be tested.

[0065] Depend on Figure 6 It can be seen that the acoustic wave response curve of the tested fracturing layer is between 60MPa and 80MPa in the standard plate of ground stress, and the ground stress at the tested position is 68MPa obtained by interpolation calculation.

[0066] It can be seen that the present application can measure the ground stress of the fractured well by using the composite material and the acoustic logging instrument, which greatly reduces the difficulty of measuring the ground stress of the fractured well. By using the composite material provided in the embodiment of the present application, the ground stress of the fractured well can be obtained based on the analysis of the acoustic waves reflected by the composite material, and the process is relatively simple, thus greatly shortening the time consumed for the detection of the ground stress of the fractured well.

[0067] It should also be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0068] The terms "include", "comprising" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or apparatus. In the absence of more restrictions, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, commodity or apparatus comprising the element.

[0069] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A composite material for detecting ground stress in a fracturing well, characterized in that: The composite material comprises metal particles and an elastic material coated on the surface of the metal particles; Wherein, the density of the metal particles is 5g / cm 3 -10g / cm 3 , the elastic modulus of the elastic material is less than or equal to 0.1 GPa.

2. The composite material for detecting ground stress in a fracturing well according to claim 1, characterized in that: The ratio of the radius of the metal particles to the coating thickness of the elastic material is 1:1 to 1:

2.

3. The composite material for detecting ground stress in a fracturing well according to claim 1, characterized in that: The composite material is in a spherical or quasi-spherical shape.

4. The composite material for detecting ground stress in a fracturing well according to claim 1, characterized in that: The metal particles are made of iron or copper.

5. The composite material for detecting ground stress in a fracturing well according to claim 1, characterized in that: The elastic material includes rubber.

6. The composite material for detecting in-situ stress in a fracturing well according to claim 1, characterized in that: The particle size of the composite material is 20-40 meshes.

7. A method for detecting in-situ stress in a fracturing well using the composite material for detecting in-situ stress in a fracturing well according to any one of claims 1 to 6, characterized in that: The method comprises: The composite material is introduced into the formation for fracturing; Acoustic waves are emitted to the formation, and the in-situ stress of the fractured well is obtained based on the reflected acoustic waves of the composite material.

8. The method according to claim 7, characterized in that The step of inputting the composite material into the formation for fracturing comprises: In the sand adding stage, the composite material is added to the fracturing fluid to obtain the target fracturing fluid; The target fracturing fluid is introduced into the formation for fracturing.

9. The method according to claim 7, characterized in that: The method of obtaining the in-situ stress of the fracturing well based on the reflected sound wave of the composite material comprises: Obtaining a corresponding sound wave response curve according to the reflected sound wave; Based on the acoustic wave response curve and the standard plate of ground stress, the ground stress of the fracturing well is obtained.

10. The method according to claim 9, characterized in that The method of obtaining the in-situ stress of the fracturing well based on the acoustic wave response curve and the in-situ stress standard plate includes: comparing the acoustic wave response curve with a standard plate of ground stress; Calculate the ground stress of fractured wells based on the interpolation method.

Images