Unconventional oil and gas well casing deformation management method

Abstract

The application discloses a method for controlling and managing casing deformation of an unconventional oil and gas well, which comprises the following steps: evaluating casing deformation risks existing in a single section of a gas well, and determining which casing deformation risks exist in the single section of the gas well, wherein the casing deformation risks include fault development, natural fracture development, microstructure development, frequent layer crossing, poor cementing quality and hole diameter expansion; and corresponding control methods are performed according to different types of risks. The application realizes effective control and management of casing deformation without carrying out geological modeling and fracturing simulation and without lowering high-cost monitoring instruments.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of unconventional oil and gas stimulation and reconstruction, and particularly relates to a casing deformation control method for unconventional oil and gas wells. BACKGROUND

[0002] From the geological point of view, the main geological medium causing casing deformation is a large number of natural fractures and faults in the reservoir. During the process of horizontal well staged multi-cluster fracturing, a large amount of fracturing fluid enters the formation, activates the fractures and faults to reach a critical state, and the formation slips along the natural fractures, bedding planes and faults, resulting in shear deformation of the casing and the fact that the conventional bridge plug cannot pass. The change rule of the influence degree of the approaching angle and length of the natural fractures on casing deformation is further demonstrated. From the engineering point of view, the sudden pressure relief in the pipe at the end of the large-volume fracturing will make the casing be in the most dangerous working condition of anti-external extrusion failure; the change of annulus pressure caused by cold fracturing fluid will increase the risk of casing deformation; the non-uniform fractures produced by fracturing are easy to cause the imbalance of formation rock deformation and the asymmetry of casing stress, and the formation slips along the weak interface and the broken surface, and the extrusion load or the stress deficiency around the casing causes casing deformation; the eccentricity of the casing or the cementing quality problems such as the loss of the cement sheath will make the casing bear asymmetric load, and under the differential influence of the fracturing fluid on the temperature difference from the heel end to the toe end of the horizontal wellbore, the risk of damage to the heel end casing is increased.

[0003] In the prior art, patent ZL201610497331.X proposes a method and device for determining the fracturing casing deformation area, but it needs to carry out regional seismic interpretation, which has huge workload and extremely high cost; patent ZL202010078842.4 proposes a method for determining the casing deformation risk area, but it needs to fully understand the formation and carry out fine geological modeling, fracturing simulation and other work, which has a long work flow and is difficult to catch up with the development progress; patent ZL202011170898.9 proposes a real-time monitoring and evaluation method for reservoir fracturing reconstruction induced downhole casing deformation, which needs to lower a magnetic positioning instrument to receive downhole abnormal signals for judgment, but it needs to increase equipment cost and has high downhole damage rate, and cannot realize batch prediction for hundreds of wells. SUMMARY

[0004] The present application aims to overcome the defects of the prior art and provides a casing deformation control method for unconventional oil and gas wells, which establishes casing deformation prediction before fracturing by evaluating the development of faults around the well, the development of natural fractures around the well, the development of micro-amplitude structures around the well, the well trajectory crossing the layer, the well cementing quality, the well diameter expansion condition and the real-time net pressure curve, realizes low-cost and high-efficiency casing deformation prediction, and guarantees the smooth implementation of subsequent construction.

[0005] The object of the present application is achieved by the following technical solutions:

[0006] An unconventional oil and gas well casing deformation management method, the method comprises:

[0007] The casing deformation risk existing in the single section of the gas well is evaluated, and it is judged which casing deformation risks exist in the single section of the gas well, the casing deformation risks include fault development, natural fracture development, micro-structure development, frequent layer crossing, poor cementing quality and hole diameter expansion;

[0008] When there is only one casing deformation risk:

[0009] The corresponding position of the developed fault adopts the measure of non-fracturing construction;

[0010] The corresponding position of the developed natural fracture adopts the measure of reducing the scale of fracturing construction;

[0011] The corresponding position of the developed micro-structure adopts the measure of non-fracturing construction;

[0012] The corresponding position of the frequent layer crossing adopts the measure of reducing the scale of fracturing construction, the frequent layer crossing is positioned as the number of passing through different layers in a preset length section exceeding a preset threshold;

[0013] For the corresponding position of the well section with medium cementing quality, the single section fracturing fluid volume and the single section construction discharge volume are controlled within the preset threshold, for the corresponding position of the poor well section, the measure of non-fracturing construction is adopted, the cementing quality evaluation result includes excellent, medium and poor, and the cementing quality evaluation result is determined according to the one-interface cementing quality and the two-interface cementing quality of different depths and different well sections;

[0014] The corresponding position of the hole diameter expansion adopts the measure of reducing the scale of fracturing construction;

[0015] When there are any two to three casing deformation risks, the single section fracturing fluid volume and the single section construction discharge volume of the corresponding position are controlled within the preset threshold range;

[0016] When there are any four to six casing deformation risks, the measure of non-fracturing construction is adopted.

[0017] Further, the method further comprises:

[0018] In the process of implementing fracturing, the real-time net pressure of the fracturing section is monitored, the net pressure curve is established, and the construction measures are adjusted in real time according to the shape of the curve:

[0019] When the curve as a whole shows an upward trend, the corresponding section does not have casing deformation risk, and the operation is continuously carried out according to the original fracturing construction parameters;

[0020] When the curve as a whole shows a horizontal trend, the curve shape of the subsequent fracturing section needs to be monitored in real time, the casing deformation risk is low, and the single section fracturing fluid volume and the construction discharge volume are reduced according to the preset value.

[0021] When the curve as a whole presents a downward trend, the corresponding section has a risk of casing deformation, if two consecutive sections present a downward trend, it is determined that the third sequence section will have casing deformation, and the single-section fracturing fluid volume and the construction discharge volume are controlled within a preset threshold.

[0022] Further, the monitoring method of the net pressure comprises:

[0023] The minimum horizontal principal stress, static liquid column pressure, real-time construction pressure, real-time frictional resistance along the path and real-time hole friction of each fracturing section are collected, and the net pressure calculation formula is net pressure = static liquid column pressure + real-time construction pressure - real-time frictional resistance along the path - real-time hole friction - small horizontal principal stress.

[0024] Further, the measures of reducing the fracturing scale for the corresponding positions of the developed natural fractures specifically comprise:

[0025] The natural fractures around the well are classified by length, and the natural fractures of each grade section are controlled according to a preset threshold to control the single-section fracturing fluid volume and the single-section construction discharge volume.

[0026] Further, the measures of reducing the fracturing scale for the corresponding positions of the frequent layer penetrations specifically comprise:

[0027] The layer penetrations are classified by times, and the layer penetrations of each grade section are controlled according to a preset threshold to control the single-section fracturing fluid volume and the single-section construction discharge volume.

[0028] Further, the measures of reducing the fracturing scale for the corresponding positions of the well diameter expansion specifically comprise controlling the single-section fracturing fluid volume and the single-section construction discharge volume within a preset threshold.

[0029] Further, the fault development judgment method comprises:

[0030] A fault delineation map within a preset range of the gas well is obtained, the well circumference is defined as an area within a preset radius range from any point on the horizontal wellbore, it is judged whether there is a fault in the well circumference, and if there is a fault in the well circumference, there is a risk of casing deformation caused by the fault.

[0031] Further, the natural fracture development judgment method comprises:

[0032] A natural fracture delineation map within a preset range of the gas well is obtained, the well circumference is defined as an area within a preset radius range from any point on the horizontal wellbore, it is judged whether there is a natural fracture in the well circumference, and if there is a natural fracture in the well circumference, there is a risk of casing deformation caused by the natural fracture.

[0033] Further, the micro-amplitude structure development judgment method comprises:

[0034] The seismic profile along the gas well trajectory is acquired, the well circumference is defined as the area within the preset radius range from any point on the horizontal wellbore, if the variation range of the stratum dip angle of each preset length on the profile within the well circumference range is greater than the amplitude threshold, then it is determined that there is microstructure development, and if there is microstructure development within the well circumference range, then there is a casing deformation risk caused by microstructure.

[0035] Further, the judgment method of the well diameter expansion includes:

[0036] The well diameter logging curve and result of the horizontal section of the gas well are acquired, the average value of the well diameter of the horizontal section is denoted as x, and it is defined that if the average value of the well diameter value deviation within the preset length range on the horizontal section reaches the preset threshold, then it is judged that the well diameter expansion is abnormal, and then there is a casing deformation risk caused by the well diameter expansion.

[0037] The beneficial effects of the present application are that:

[0038] The present application fully utilizes the test results of unconventional oil and gas wells, fully combines the related parameters of geology, drilling and fracturing, maximizes the prediction speed and prediction accuracy, and maximizes the prediction cost, without the need to carry out tedious work such as geological modeling and numerical simulation during the period, greatly reducing the workload of scientific researchers, and after completing the risk prediction, different control measures are adopted for different types of risks, which can ensure that the casing deformation of the gas well is effectively controlled. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is the multi-stage fracture drawing of the gas well of the embodiment of the present application;

[0040] Figure 2 is the gas well completion model and microstructure and frequent layer-penetrating position schematic diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied through other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0043] In the prior art, a method and device for determining the deformation region of a fracturing casing are proposed in patent ZL201610497331.X, but regional seismic interpretation needs to be carried out, which is of huge workload and extremely high cost; a method for determining the deformation risk region of a casing is proposed in patent ZL202010078842.4, but full understanding of the stratum and fine geological modeling, fracturing simulation and other work need to be carried out, which is of a long work flow and difficult to catch up with the development progress; a real-time monitoring and evaluation method for reservoir fracturing reconstruction induced casing deformation is proposed in patent ZL202011170898.9, which needs to lower a magnetic positioning instrument to receive an abnormal signal for judgment, but the equipment cost needs to be increased, the downhole damage rate is high, and batch prediction for hundreds of wells cannot be realized.

[0044] In order to solve the above technical problems, the present application provides the following embodiments of a method for controlling casing deformation in unconventional oil and gas wells.

[0045] Embodiment 1

[0046] The present embodiment provides a method for controlling casing deformation in unconventional oil and gas wells, which aims to establish a casing deformation prediction method before fracturing by combining the evaluation of the development of faults around the well, the development of natural fractures around the well, the development of micro-faults around the well, the well trajectory crossing the layer, the well cementing quality, the well diameter expansion, the real-time net pressure curve, etc., to realize low-cost and high-efficiency casing deformation prediction and control, and to ensure the smooth implementation of subsequent construction.

[0047] The method specifically comprises:

[0048] 1. Evaluate the development of faults around the well:

[0049] Obtain the fault delineation map near the well to determine whether there are faults around the well. The well circumference is defined as a range of 300 meters from any point on the horizontal wellbore with a radius of 300 meters.

[0050] If there is no fault in the well circumference, it is determined that the casing deformation risk caused by the fault does not exist.

[0051] If the well circumference develops faults, it is determined that the casing deformation risk caused by the fault exists. For the corresponding position of the developed fault, measures such as non-fracturing construction are taken.

[0052] 2. Evaluate the development of natural fractures around the well:

[0053] Obtain the natural fracture delineation map near the well to determine whether there are natural fractures around the well. The well circumference is defined as a range of 150 meters from any point on the horizontal wellbore with a radius of 150 meters.

[0054] If there is no natural fracture development in the well circumference, it is determined that the casing deformation risk caused by the natural fracture does not exist.

[0055] If there are natural fractures developed in the wellbore range, it is determined that the well has the risk of casing deformation caused by natural fractures. For the corresponding position of the developed natural fractures, measures of reducing the scale of fracturing are taken. When the distance of the wellbore natural fractures is between 0-50m, the single-stage fracturing fluid volume needs to be controlled within 1400m 3 , and the single-stage construction discharge rate is controlled below 12m 3 / min; when the distance of the wellbore natural fractures is between 50-100m, the single-stage fracturing fluid volume needs to be controlled within 1600m 3 , and the single-stage construction discharge rate is controlled below 14m 3 / min; when the distance of the wellbore natural fractures is between 100-150m, the single-stage fracturing fluid volume needs to be controlled within 1800m 3 , and the single-stage construction discharge rate is controlled below 16m 3 / min.

[0056] 3. Evaluate the development of micro-amplitude structure around the well:

[0057] Obtain the seismic profile along the well trajectory to determine whether there is micro-amplitude structure around the well. The wellbore is defined as the change in the inclination of the stratum on the profile being greater than 10 degrees per 100 meters;

[0058] If there is no micro-amplitude structure developed in the wellbore range, it is determined that the well has no risk of casing deformation caused by micro-amplitude structure;

[0059] If there are micro-amplitude structures developed in the wellbore range, it is determined that the well has the risk of casing deformation caused by micro-amplitude structure. For the corresponding position of the developed micro-amplitude structure, measures of non-fracturing construction are taken.

[0060] 4. Evaluate the well trajectory through the layer:

[0061] Obtain the well trajectory diagram of the horizontal section of the well to determine the trajectory through different strata. The trajectory is defined as passing through 3 or more different layers within 200 meters, and repeatedly passing through the same layer is counted as multiple times.

[0062] If the horizontal well trajectory basically passes through the same layer, or only passes through 2 layers within 200 meters, it is determined that the well has no risk of casing deformation caused by frequent layering;

[0063] If the horizontal well trajectory has frequent layering, it is determined that the well has the risk of casing deformation caused by frequent layering. For the corresponding position of the frequent layering, measures of reducing the scale of fracturing are taken. When the number of layering is between 3-5 times, the single-stage fracturing fluid volume needs to be controlled within 1800m 3 , and the single-stage construction discharge rate is controlled below 16m 3 / min; when the number of layering is between 6-8 times, the single-stage fracturing fluid volume needs to be controlled within 1600m 3Within 14 m 3 / min, when the number of times of crossing the layer is more than 8, the single-stage fracturing fluid volume needs to be controlled within 1400 m 3 Within 12 m 3 / min.

[0064] 5. Evaluate the well cementing quality:

[0065] Obtain the cementing quality evaluation results of the horizontal section of the well, and determine the interface cementing quality and the two-interface cementing quality at different depths and different well sections. Define the well section with both the interface and the two-interface being excellent cementing quality as a high-quality well section, define the well section with either the interface or the two-interface being excellent cementing quality and the other being medium cementing quality as a medium-quality well section, and define the well section with either the interface or the two-interface being poor cementing quality as a poor-quality well section.

[0066] If the cementing quality of the horizontal section is all excellent, it is determined that the well has no casing deformation risk caused by cementing quality.

[0067] If the cementing quality of the horizontal section contains no poor-quality well section but contains a medium-quality well section, the single-stage fracturing fluid volume needs to be controlled within 1400 m 3 Within 12 m 3 / min at the corresponding position of the medium-quality well section.

[0068] If the cementing quality of the horizontal section contains a poor-quality well section, it is determined that the well has a casing deformation risk caused by poor cementing quality, and measures of no fracturing construction are taken at the corresponding position of the poor-quality well section.

[0069] 6. Evaluate the well diameter expansion:

[0070] Obtain the well diameter logging curve and results of the horizontal section of the well, determine the average value of the well diameter of the horizontal section, denoted as x inches, and define that if there is an average deviation of 3 inches or more in the well diameter value within 10 meters of the horizontal section, i.e., not within the x+3 inch interval, it is determined that the well diameter expansion is abnormal.

[0071] If the well diameter logging values at each position of the horizontal section of the well are within x+3 inches, it is determined that the well has no casing deformation risk caused by well diameter abnormality.

[0072] If there is well diameter abnormality in the horizontal section of the well, it is determined that the well has a casing deformation risk caused by well diameter abnormality, and measures of reducing the construction scale of fracturing are taken at the corresponding position of the well diameter abnormality, and the single-stage fracturing fluid volume needs to be controlled within 1400 m 3 Within 12 m 3 / min.

[0073] In the process of implementing fracturing, the casing deformation prediction method and control method during fracturing are established according to the real-time net pressure curve shape:

[0074] Collect the minimum horizontal principal stress corresponding to each fracturing section, denoted as σ min ;

[0075] Collect the static liquid column pressure corresponding to each fracturing section, denoted as P o ;

[0076] Collect the real-time construction pressure of each fracturing section during fracturing, denoted as P1, which should be recorded in real time during the construction process;

[0077] Collect the real-time friction along the way of each fracturing section during fracturing, denoted as P2, which should be recorded in real time during the construction process;

[0078] Collect the real-time hole friction of each fracturing section during fracturing, denoted as P3, which should be recorded in real time during the construction process;

[0079] According to the situation during the construction process, the net pressure P net is calculated in real time, and the calculation formula is as follows:

[0080] P net = P o + P1-P2-P3-σ min

[0081] Read the shape of the net pressure curve, judge the three shapes of the curve: when the overall curve shows an upward trend, there is no casing deformation risk in this section; when the overall curve shows a horizontal trend, the curve shape of the subsequent fracturing section needs to be monitored in real time, and the casing deformation risk is low; when the overall curve shows a downward trend, the casing deformation risk exists in this section, and if two consecutive sections exist, it is determined that the third sequence section will occur casing deformation.

[0082] The real-time control measures formulated according to the curve shape include:

[0083] When the overall curve shows an upward trend, there is no casing deformation risk in this section, and the original fracturing construction parameters are continued to carry out the construction operation;

[0084] When the overall curve shows a horizontal trend, the curve shape of the subsequent fracturing section needs to be monitored in real time, and the casing deformation risk is low, at this time the single-section fracturing fluid volume is reduced by 200m 3 , and the construction discharge is reduced by 1-2m 3 / min;

[0085] When the curve shows a downward trend as a whole, there is a risk of casing deformation in this section. If this situation occurs in two consecutive sections, it is determined that casing deformation will occur in the third sequence section, and the single-stage fracturing fluid volume is controlled at 1000m 3 , the construction displacement shall not exceed 12m 3 / min.

[0086] This embodiment makes full use of the test results that must be carried out on unconventional oil and gas wells, fully combines the relevant parameters of geology, drilling, and fracturing, maximizes the prediction speed and prediction accuracy, and minimizes the prediction cost. During this period, there is no need to carry out tedious work such as geological modeling and numerical simulation, which greatly reduces the workload of scientific researchers. After completing the risk prediction, different control measures are adopted for different numbers of risk types to ensure that the deformation of the gas well casing is effectively controlled.

[0087] Example 2

[0088] Well X was used as an example to predict casing deformation. Well X has 20 sections, and by analyzing the characteristics of different fracturing operations, we were able to predict casing deformation risks in advance.

[0089] Reference Figure 1 ,like Figure 1 Shown is a depiction of multi-stage fractures in a gas well according to this embodiment.

[0090] As can be seen from the figure, there are no faults around Well X, so it is determined that there is no risk of casing deformation caused by faults.

[0091] It can also be seen from the figure that there are natural fractures around Well X. There is a risk of casing deformation caused by natural fractures at sections 3, 8, 10, and 18. Figure 1 Different fracturing scales are formulated based on the distance between natural fractures.

[0092] Reference Figure 2 ,like Figure 2 Shown is a schematic diagram of the gas well completion model and micro-structure and frequent penetration locations in this embodiment.

[0093] As can be seen from the figure, there are micro-structures around Well X, and there is a risk of casing deformation caused by micro-structures at sections 4 and 18. Figure 2 Different fracturing scales are formulated at locations where medium and micro structures are developed.

[0094] It can also be seen from the figure that Well X has frequent penetrations, and there is a risk of casing deformation at the 4th and 18th sections due to frequent penetrations. Figure 2 Different fracturing scales are formulated for locations with frequent penetration.

[0095] According to the cementing quality table, the X well has the medium and poor cementing quality at the 18th section position, and the casing deformation risk caused by the cementing quality, and different fracturing scales need to be formulated according to the cementing quality.

[0096] According to the well diameter logging interpretation result, the X well has the well diameter abnormal phenomenon at the 9th, 10th and 20th section positions, and different fracturing scales are formulated according to the well diameter abnormal positions.

[0097] The foregoing analysis results can be obtained before the management method provided by the foregoing embodiment is implemented.

[0098] According to the foregoing analysis results, the parameter design before fracturing is formulated, so as to achieve the comprehensive prediction, and see Table 1.

[0099] Table 1: X well fracturing parameter design table before fracturing

[0100]

[0101]

[0102] The X well has the construction net pressure drop when fracturing the 9th and 10th sections, and the real-time adjustment measures need to be carried out.

[0103] By further reducing the construction liquid volume of the 11th section from 1800m 3 to 1600m 3 , the construction curve form is stably in the continuous rising trend, and the casing deformation in the 11th section position is effectively controlled.

[0104] The foregoing merely describes the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for controlling deformation of casing in unconventional oil and gas wells, characterized in that: The method comprises: Assess the casing deformation risk in a single section of a gas well and determine which casing deformation risks exist in the single section of the gas well. The casing deformation risks include fault development, natural fracture development, micro-structure development, frequent layer penetration, poor cementing quality, and wellbore expansion. When there is only one risk of casing deformation: Take measures not to perform fracturing at the corresponding locations of developed faults; Take measures to reduce the scale of fracturing at corresponding locations where natural fractures have developed; Take measures not to perform fracturing at the corresponding locations where micro-structures are developed; Taking measures to reduce the scale of fracturing at locations with frequent fracturing, where frequent fracturing is defined as the number of times fracturing different layers within a preset length exceeds a preset threshold; For the corresponding positions of well sections with medium cementing quality, the single-stage fracturing fluid volume and single-stage construction displacement need to be controlled within the preset thresholds. For the corresponding positions of well sections with poor cementing quality, no fracturing is adopted. The cementing quality evaluation results include excellent, medium and poor. The cementing quality evaluation results are determined based on the first interface cementing quality and the second interface cementing quality at different cementing depths and well sections. Take measures to reduce the scale of fracturing at the corresponding locations of well diameter expansion; When there are any two or three casing deformation risks, the single-stage fracturing fluid volume and single-stage construction displacement at the corresponding location are controlled within the preset threshold range; When there are any four to six casing deformation risks, measures such as no fracturing construction shall be taken.

2. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, characterized in that: The method further comprises: During the fracturing process, monitor the real-time net pressure of the fracturing section, establish a net pressure curve, and adjust the construction measures in real time according to the shape of the curve: When the curve shows an overall upward trend, there is no risk of casing deformation in the corresponding section, and the fracturing operation can be continued according to the original fracturing operation parameters; When the curve shows a horizontal trend as a whole, the corresponding section needs to monitor the curve shape of the subsequent fracturing section in real time. If the risk of casing deformation is low, the single-stage fracturing fluid volume and operation displacement should be reduced to the preset values. When the curve shows a downward trend as a whole, there is a risk of casing deformation in the corresponding section. If two consecutive sections show a downward trend, it is determined that casing deformation will occur in the third sequence section, and the single-stage fracturing fluid volume and construction displacement are controlled within the preset thresholds.

3. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 2, characterized in that: The method for monitoring the net pressure includes: The minimum horizontal principal stress, hydrostatic column pressure, real-time operation pressure, real-time friction along the fracturing stage, and real-time perforation friction resistance are collected for each fracturing stage. The net pressure is calculated as follows: net pressure = hydrostatic column pressure + real-time operation pressure - real-time friction along the fracturing stage - real-time perforation friction resistance - minimum horizontal principal stress.

4. The method for controlling casing deformation in unconventional oil and gas wells according to claim 1, wherein: The measures to reduce the scale of fracturing at the corresponding locations where natural fractures develop specifically include: The natural fractures around the well are graded by length, and the single-stage fracturing fluid volume and single-stage construction displacement of the natural fractures in each grade section are controlled according to the preset threshold.

5. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, wherein: The measures to reduce the scale of fracturing at locations with frequent penetration specifically include: The penetration layers are graded according to the number of times, and the single-stage fracturing fluid volume and single-stage construction displacement are controlled according to the preset threshold value for the penetration layers of each grade section.

6. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, characterized in that: The measures to reduce the scale of fracturing at the corresponding position of the well diameter expansion specifically include controlling the single-stage fracturing fluid volume and the single-stage construction displacement within a preset threshold value.

7. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, characterized in that: Methods for determining the development of the fault include: Obtain a fault map within a preset range of the gas well. The wellbore perimeter is defined as the area within a preset radius from any point on the horizontal wellbore. Determine whether there are faults around the wellbore. If faults develop within the wellbore perimeter, there is a risk of casing deformation caused by the faults.

8. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, wherein: Methods for determining the development of natural fractures include: Obtain a natural fracture profile within a preset range of the gas well. The wellbore perimeter is defined as the area within a preset radius from any point on the horizontal wellbore. Determine whether natural fractures exist around the wellbore. If natural fractures develop around the wellbore perimeter, there is a risk of casing deformation caused by natural fractures.

9. The method for controlling deformation of casing of unconventional oil and gas wells according to claim 1, wherein: Methods for determining the microstructural development include: A seismic profile is obtained along the trajectory of the gas well. The wellbore perimeter is defined as the area within a preset radius from any point on the horizontal wellbore. If the change in the formation dip angle for each preset length on the profile within the wellbore perimeter is greater than the amplitude threshold, it is determined that micro-structures are developed. If micro-structures are developed within the wellbore perimeter, there is a risk of casing deformation caused by the micro-structures.

10. The method for controlling casing deformation in unconventional oil and gas wells according to claim 1, wherein: The method for determining the well diameter expansion includes: Obtain the caliper logging curve and results of the horizontal section of the gas well. The average caliper value of the horizontal section is recorded as x. If the average caliper value deviation within a preset length range on the horizontal section reaches a preset threshold, it is judged as abnormal caliper expansion, and there is a risk of casing deformation caused by caliper expansion.

Images