A water-stopping method for well pipe diameter change

Abstract

The present invention relates to the technical field of well pipe construction, and in particular to a water-stopping method for a well pipe diameter change, comprising: determining the position of a gap at the well pipe diameter change, and determining it as a first gap and a second gap according to the width of the gap; filling the second gap with a water-stopping material using a multi-layer filling method, and using an ultrasonic flaw detector to ultrasonically detect each layer of the filled water-stopping material; determining whether the water-stopping effectiveness at the well pipe diameter change meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material; if the water-stopping effectiveness at the well pipe diameter change does not meet the requirements, determining whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time; if the applicability of the water-stopping process does not meet the requirements, determining whether it is necessary to increase the back pressure of the return oil pipeline in the grouting pump; and determining the switching frequency of the forward and reverse stirring based on the speed deviation rate of the stirring blade. The present invention improves the water-stopping effectiveness at the well pipe diameter change.

Description

Technical Field

[0001] The invention relates to the technical field of well pipe construction, and in particular to a water stopping method for a well pipe diameter change location. Background Art

[0002] In water conservancy projects, geological exploration, and underground resource development, well pipes serve as critical components for conveying fluids or isolating formations. The sudden change in diameter (i.e., the point where the pipe diameter changes suddenly) creates stress concentration and complex crack distribution, making it a weak link in the water-stop seal. According to statistics, over 60% of well pipe leakage incidents occur in this area. Especially when well pipes pass through aquifers, fractured rock formations, or high-pressure formations, failure of water-stopping at this point can lead to serious problems such as well pipe corrosion, formation collapse, and environmental pollution. Therefore, achieving efficient water-stopping at this point in the well pipe diameter change has become a pressing technical challenge in the engineering field.

[0003] Chinese Patent Publication No. CN104060634A discloses a water-stopping method and structure for reserved holes in a pipe jacking well. The method comprises the following steps: (1) after the pipe jacking construction is completed, a plurality of slow-expansion water-stopping strips are attached to the outer wall of the pipe jacking section and the inner wall of the reserved hole along the circumferential direction; (2) micro-expansion fine stone concrete is used to fill the gap between the outer wall of the pipe jacking section and the inner wall of the reserved hole; (3) a reinforced concrete slab is cast around the exposed pipe section of the pipe jacking well and close to the well wall to seal the micro-expansion fine stone concrete. It can be seen that the water-stopping method and structure for reserved holes in the pipe jacking well have the problem that the width of the gaps between the reserved holes is not differentiated and a unified water-stopping method is adopted. The gaps of different widths have great differences in the requirements for water-stopping materials and processes, resulting in a decrease in water-stopping effectiveness. Summary of the Invention

[0004] To this end, the present invention provides a water-stopping method for use at the diameter change point of the well pipe, so as to overcome the problem in the prior art that the width of the gaps between the reserved holes is not differentiated, a unified water-stopping method is adopted, and gaps of different widths have large differences in the requirements for water-stopping materials and processes, thereby resulting in a decrease in the effectiveness of water-stopping.

[0005] To achieve the above object, the present invention provides a water-stopping method for a well pipe with a variable diameter, comprising:

[0006] Determine the position of the gap at the well pipe diameter change, and determine it as a first gap and a second gap according to the width of the gap, use a mixer to mix the slurry, and use a grouting pump to inject the slurry into the first gap;

[0007] The second gap is filled with a water-stopping material using a multi-layer filling method, and each layer of the water-stopping material is ultrasonically inspected using an ultrasonic flaw detector. After the multi-layer filling is completed, a sealing strip is installed, and a waterproof coating is applied to the outside of the sealing strip. A water supply test is performed at the diameter change point of the well pipe;

[0008] During the test, the ultrasonic sound velocity at different positions of the water-stop material in the second gap is obtained, and the maximum difference in the ultrasonic sound velocity of the water-stop material is calculated;

[0009] Determining whether the water-stopping effectiveness at the well pipe diameter change location meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material;

[0010] If the water-stopping effectiveness at the well pipe diameter change does not meet the requirements, determine whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time; if it is not necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time, obtain the fluctuation amplitude of the grouting pressure of the grouting pump to determine whether the applicability of the water-stopping process meets the requirements;

[0011] If the applicability of the water-stopping process does not meet the requirements, determine whether it is necessary to increase the back pressure of the oil return line in the grouting pump;

[0012] If there is no need to increase the back pressure of the oil return line in the grouting pump, the switching frequency of the forward and reverse stirring is determined based on the speed deviation rate of the stirring blade.

[0013] Furthermore, determining whether the water-stopping effectiveness at the well pipe diameter change location meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material includes:

[0014] Comparing the maximum difference in ultrasonic sound velocity of the water-stop material with a preset first difference;

[0015] If the maximum difference in ultrasonic sound velocity of the water-stopping material is less than or equal to the preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change location meets the requirements;

[0016] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than a preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change does not meet the requirements.

[0017] Furthermore, determining whether it is necessary to reduce the layered filling thickness of the waterstop material and increase the filling interval time includes:

[0018] Comparing the maximum difference in ultrasonic sound velocity of the water-stopping material with the preset first difference and the preset second difference respectively;

[0019] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset second difference, it is determined that the layered filling thickness of the water-stopping material needs to be reduced and the filling interval time needs to be increased;

[0020] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to reduce the layered filling thickness of the water-stopping material and increase the filling interval time.

[0021] Furthermore, the reduction in the layered filling thickness of the water-stopping material is determined by the difference between the maximum difference in ultrasonic sound velocity of the water-stopping material and a preset second difference; the increase in the filling interval time is determined by the reduction in the layered filling thickness of the water-stopping material.

[0022] Furthermore, the applicability of the water-stopping process is determined to be in compliance with the requirements based on the fluctuation amplitude of the grouting pressure of the grouting pump, including:

[0023] Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with a preset first fluctuation amplitude;

[0024] If the fluctuation amplitude of the grouting pressure of the grouting pump is less than or equal to the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process meets the requirements, and whether the layered filling thickness and filling interval time of the water-stopping material meet the requirements;

[0025] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process does not meet the requirements.

[0026] Furthermore, it is determined whether the back pressure of the return oil line in the grouting pump needs to be increased, including:

[0027] Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with the preset first fluctuation amplitude and the preset second fluctuation amplitude respectively;

[0028] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude and less than or equal to the preset second fluctuation amplitude, it is determined that the back pressure of the oil return pipeline in the grouting pump needs to be increased, and the back pressure of the oil return pipeline in the grouting pump is increased;

[0029] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset second fluctuation amplitude, it is determined that there is no need to increase the back pressure of the return oil pipeline in the grouting pump.

[0030] Furthermore, the increase amplitude of the back pressure of the oil return pipeline in the grouting pump is determined by the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and a preset first fluctuation amplitude.

[0031] Furthermore, the switching frequency of the stirring forward and reverse rotation is determined based on the speed deviation rate of the stirring paddle, including:

[0032] Compare the speed deviation rate of the stirring blade with the preset deviation rate;

[0033] If the speed deviation rate of the agitator is less than or equal to the preset deviation rate, it is determined that the fluidity of the slurry meets the requirements and there is no need to increase the positive and negative time ratio of the stirring, and it is determined whether the back pressure of the return oil pipeline in the grouting pump meets the requirements.

[0034] Furthermore, if the rotation speed deviation rate of the stirring paddle is greater than the preset deviation rate, it is determined that the switching frequency of the stirring forward and reverse rotation needs to be increased, and the switching frequency of the stirring forward and reverse rotation is increased.

[0035] Furthermore, the increase range of the switching frequency of the stirring forward and reverse rotation is determined by the difference between the rotation speed deviation rate of the stirring paddle and the preset deviation rate.

[0036] Compared with the prior art, the beneficial effect of the present invention is that the method of the present invention adjusts the layered filling thickness and filling interval time of the water-stopping material according to the maximum difference in ultrasonic sound velocity of the water-stopping material. Since the filling speed is too fast during the filling process of the water-stopping material, the bubbles inside the material are not discharged in time, which will form cavities. By reducing the layered filling thickness of the water-stopping material and reducing the filling interval time, the time for the bubbles to rise to the surface can be shortened, the bubble discharge efficiency can be improved, and thus the risk of cavities can be reduced. The back pressure of the return oil pipeline in the grouting pump is adjusted according to the fluctuation amplitude of the grouting pressure of the grouting pump. Since the one-way valve at the outlet of the grouting pump is stuck by debris, indirect jamming occurs, resulting in pressure in The pressure is released inside the pump body, resulting in a decrease in the grouting pressure of the grouting pump. By increasing the back pressure of the return oil pipeline, the leakage resistance can be increased, the pressure relief volume can be reduced, the pressure loss inside the pump body can be reduced, the pressure difference fluctuation range can be narrowed, and the valve flap can be prevented from frequently opening and closing due to pressure imbalance and aggravated by stagnation. The switching frequency of the forward and reverse stirring is adjusted according to the speed deviation rate of the agitator. Since the bearings of the agitator for mixing the slurry are worn after long-term use, the speed fluctuates during operation, which reduces the stirring efficiency and causes the viscosity of the slurry to be too high. By increasing the switching frequency of the forward and reverse stirring, a turbulent effect can be generated, which increases the friction and collision between the materials, helps reduce the apparent viscosity, and improves the water-stopping effectiveness at the diameter change of the well pipe.

[0037] Furthermore, the method of the present invention adjusts the layered filling thickness and filling interval time of the water-stopping material by setting a preset first difference and a preset second difference. Since the filling speed is too fast during the filling process of the water-stopping material, the bubbles inside the material are not discharged in time, resulting in voids. By reducing the layered filling thickness of the water-stopping material and reducing the filling interval time, the time for bubbles to rise to the surface can be shortened, the bubble discharge efficiency can be improved, thereby reducing the risk of voids and further improving the effectiveness of water-stopping at the diameter change point of the well pipe.

[0038] Furthermore, the method of the present invention adjusts the back pressure of the return oil pipeline in the grouting pump by setting a preset first fluctuation amplitude and a preset second fluctuation amplitude. Since the one-way valve at the outlet of the grouting pump is stuck by debris, indirect jamming occurs, causing pressure to be released inside the pump body, thereby reducing the grouting pressure of the grouting pump. By increasing the back pressure of the return oil pipeline, the leakage resistance can be increased, the pressure relief amount can be reduced, the pressure loss inside the pump body can be reduced, the pressure difference fluctuation range can be narrowed, and the valve disc can be avoided from being frequently opened and closed due to pressure imbalance, which aggravates the jamming, thereby further improving the water-stopping effectiveness at the diameter change point of the well pipe.

[0039] Furthermore, the method of the present invention adjusts the switching frequency of the forward and reverse rotation of stirring by setting a preset deviation rate. Since the bearings of the mixer for mixing the slurry are worn after long-term use, the rotation speed fluctuates during operation, which reduces the stirring efficiency and causes the viscosity of the slurry to be too high. By increasing the switching frequency of the forward and reverse rotation of stirring, a turbulent effect can be generated, which increases the friction and collision between the materials, helps reduce the apparent viscosity, and further improves the water-stopping effectiveness at the diameter change point of the well pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is an overall flow chart of a water-stopping method for a well pipe diameter change according to an embodiment of the present invention;

[0041] Figure 2 A specific flow chart of the process of determining whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time for the water-stopping method at the diameter change of the well pipe according to an embodiment of the present invention;

[0042] Figure 3 A specific flow chart of the process of determining whether it is necessary to increase the back pressure of the oil return line in the grouting pump in the water stopping method at the diameter change of the well pipe according to an embodiment of the present invention;

[0043] Figure 4 This is a specific flow chart of the process of determining the switching frequency of forward and reverse stirring for the water-stopping method at the diameter change point of the well pipe according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0045] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0046] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0047] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0048] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of the water-stopping method for a well pipe diameter change according to an embodiment of the present invention, a specific flow chart of the process of determining whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time, a specific flow chart of the process of determining whether it is necessary to increase the back pressure of the return oil pipeline in the grouting pump, and a specific flow chart of the process of determining the switching frequency of the forward and reverse stirring. A water-stopping method for a well pipe diameter change according to the present invention comprises:

[0049] Step S1, determining the position of the gap at the diameter change of the well pipe, and determining it as a first gap and a second gap according to the width of the gap, using a mixer to mix the slurry, and using a grouting pump to inject the slurry into the first gap;

[0050] Step S2: Filling the second gap with a water-stopping material using a multi-layer filling method, and performing ultrasonic testing on each layer of the water-stopping material using an ultrasonic flaw detector. After the multi-layer filling is completed, a sealing strip is installed, and a waterproof coating is applied to the outside of the sealing strip. A water supply test is performed on the diameter change of the well pipe;

[0051] Step S3, during the test, obtaining the ultrasonic sound velocity of the water-stop material at different positions in the second gap, and calculating the maximum difference in the ultrasonic sound velocity of the water-stop material;

[0052] Step S4, determining whether the water-stopping effectiveness at the diameter change of the well pipe meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material;

[0053] Step S5: If the water-stopping effectiveness at the well pipe diameter change point does not meet the requirements, determine whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time; if it is not necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time, obtain the fluctuation amplitude of the grouting pressure of the grouting pump to determine whether the applicability of the water-stopping process meets the requirements;

[0054] Step S6: If the applicability of the water-stopping process does not meet the requirements, determine whether it is necessary to increase the back pressure of the oil return line in the grouting pump;

[0055] Step S7: If there is no need to increase the back pressure of the oil return line in the grouting pump, the switching frequency of the forward and reverse rotation of the stirring is determined based on the speed deviation rate of the stirring blade.

[0056] Specifically, the first gap is a gap with a width greater than 5 mm.

[0057] Specifically, the second gap is a gap with a width less than or equal to 5 mm.

[0058] Specifically, the slurry is cement slurry, bentonite slurry, and polymer grouting material.

[0059] Specifically, water-stopping materials include cement slurry, expansion rubber, and chemical water-stopping agents.

[0060] Specifically, the multi-layer filling method is to fill the cement slurry into the gap in multiple times and control the thickness of each layer. After a single layer of filling is completed, the next filling is carried out after a corresponding time interval.

[0061] Specifically, the layered filling thickness of the water-stopping material is the thickness of each single layer of water-stopping material filled in the multi-layer filling process.

[0062] Specifically, the back pressure of the oil return line in the grouting pump is the pressure formed by the reverse resistance when the oil in the oil return line in the hydraulic system of the grouting pump flows.

[0063] Specifically, the switching frequency of the stirring forward and reverse rotation is the number of complete cycles in a unit time during which the stirring paddle switches from forward rotation to reverse rotation and returns to forward rotation.

[0064] During implementation, the method of the present invention adjusts the layered filling thickness and filling interval time of the water-stop material according to the maximum difference in ultrasonic sound velocity of the water-stop material. Since the filling speed is too fast during the filling process of the water-stop material, the bubbles inside the material are not discharged in time, which will form voids. By reducing the layered filling thickness of the water-stop material and shortening the filling interval time, the time for the bubbles to rise to the surface can be shortened, the bubble discharge efficiency can be improved, and the risk of voids can be reduced. The back pressure of the return oil pipeline in the grouting pump is adjusted according to the fluctuation amplitude of the grouting pressure of the grouting pump. Since the one-way valve at the outlet of the grouting pump is stuck by debris, indirect jamming occurs, causing pressure relief inside the pump body. This results in a decrease in the grouting pressure of the grouting pump. By increasing the back pressure of the return oil pipeline, the leakage resistance can be increased, the pressure relief volume can be reduced, the pressure loss inside the pump body can be reduced, the pressure difference fluctuation range can be narrowed, and the valve flap can be prevented from frequently opening and closing due to pressure imbalance and aggravated by stagnation. The switching frequency of the forward and reverse stirring is adjusted according to the speed deviation rate of the agitator. Since the bearings of the agitator for mixing the slurry are worn after long-term use, the speed fluctuates during operation, which reduces the stirring efficiency and causes the viscosity of the slurry to be too high. By increasing the switching frequency of the forward and reverse stirring, a turbulent effect can be generated, which increases the friction and collision between the materials, helps reduce the apparent viscosity, and improves the water-stopping effectiveness at the diameter change of the well pipe.

[0065] Specifically, determining whether the water-stopping effectiveness at the well pipe diameter change location meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material includes:

[0066] Comparing the maximum difference in ultrasonic sound velocity of the water-stop material with a preset first difference;

[0067] If the maximum difference in ultrasonic sound velocity of the water-stopping material is less than or equal to the preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change location meets the requirements;

[0068] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than a preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change does not meet the requirements.

[0069] The reason for the waterstop effectiveness at the well pipe diameter change not meeting the requirements may be that the waterstop process is not suitable for the application requirements, or that the layered filling thickness and filling interval of the waterstop material do not meet the requirements. The next step is to determine which of these is the specific cause. This process also determines whether the layered filling thickness of the waterstop material needs to be reduced and the filling interval needs to be increased.

[0070] Specifically, determine whether it is necessary to reduce the layered fill thickness of the waterstop material and increase the fill interval time, including:

[0071] Comparing the maximum difference in ultrasonic sound velocity of the water-stopping material with the preset first difference and the preset second difference respectively;

[0072] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset second difference, it is determined that the layered filling thickness of the water-stopping material needs to be reduced and the filling interval time needs to be increased;

[0073] If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to reduce the layered filling thickness of the water-stopping material and increase the filling interval time.

[0074] Among them, when the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset second difference, it is determined that the reason why the water-stopping effectiveness at the well pipe diameter change does not meet the requirements is that the layered filling thickness and filling interval time of the water-stopping material do not meet the requirements, and therefore it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time. When the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset first difference and less than or equal to the preset second difference, it can be preliminarily determined that the applicability of the water-stopping process does not meet the requirements. Next, it is necessary to make a final determination of whether the applicability of the water-stopping process meets the requirements based on the fluctuation amplitude of the grouting pressure of the grouting pump, that is, to determine whether the reason why the water-stopping effectiveness at the well pipe diameter change does not meet the requirements is that the applicability of the water-stopping process does not meet the requirements.

[0075] It can be understood that the preset first difference is smaller than the preset second difference, and the three intervals divided by the preset first difference and the preset second difference correspond to three situations respectively:

[0076] The first interval is when the maximum difference in ultrasonic sound velocity of the water-stopping material is less than or equal to the preset first difference. This corresponds to the situation where the water-stopping effectiveness at the well pipe diameter change is determined to meet the requirements and no adjustment is required.

[0077] The second interval is when the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset first difference and less than or equal to the preset second difference. This corresponds to the situation where the one-way valve at the outlet of the grouting pump is stuck by debris, causing indirect jamming, resulting in pressure release inside the pump body, thereby reducing the grouting pressure of the grouting pump. In this case, it is necessary to further determine whether the applicability of the water-stopping process meets the requirements.

[0078] The third interval is that the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset second difference. The corresponding situation is: because the filling speed is too fast during the filling process of the water-stopping material, the bubbles inside the material are not discharged in time, resulting in voids. At this time, it is necessary to adjust the layered filling thickness and filling interval time of the water-stopping material.

[0079] It's understandable that using the first and second differentials to characterize the effectiveness of waterstops at pipe diameter changes essentially involves managing ultrasonic sound velocity differences through graded thresholds, enabling quantitative assessment of the uniformity and density of waterstop materials and precise control of construction processes. The first differential serves as a benchmark threshold for determining whether a waterstop meets standards, distinguishing between effective and ineffective waterstops. When ultrasonic waves propagate through uniform and dense waterstop materials, the speed of sound fluctuates minimally. If the speed difference exceeds the first differential, it indicates defects such as voids, delamination, or segregation within the material. When the speed difference exceeds the first differential but falls below the second differential, the waterstop hasn't completely failed, but potential risks exist. The second differential further determines whether construction parameters need to be optimized. If the speed difference falls between the first and second differentials, it indicates insufficient material uniformity but no through-hole defects have formed, which can be addressed by adjusting the layered filling process. If it exceeds the second differential, the defect is already severe. The preset first and second differentials can be set based on actual operating conditions. The purpose of setting the preset first and second differentials is to ensure the effectiveness and practicality of waterstops at pipe diameter changes. Optionally, the preset first and second differential amounts are determined by evaluating the water-stopping effect of different ultrasonic sound velocities on the well pipe diameter change through a limited number of tests. The predetermined first and second differential amounts should be neither too small nor excessively disruptive to the water-stopping process at the well pipe diameter change. For example, the preset first differential amount is generally selected from the range [250 m / s, 350 m / s], and the preset second differential amount is generally selected from the range [360 m / s, 460 m / s].

[0080] Preferably, the preferred embodiment of the preset first difference amount is 300 m / s, and the preferred embodiment of the preset second difference amount is 400 m / s.

[0081] Specifically, the maximum difference in ultrasonic sound velocity of the water-stopping material is the difference between the maximum ultrasonic sound velocity of the water-stopping material in the second gap and the minimum ultrasonic sound velocity of the water-stopping material in the second gap.

[0082] In implementation, the method of the present invention determines the water-stopping effectiveness at the well pipe diameter change point by setting a preset first difference and a preset second difference, thereby reducing the impact of the decreased water-stopping stability at the well pipe diameter change point due to inaccurate determination of the water-stopping effectiveness at the well pipe diameter change point, and further improving the water-stopping effectiveness at the well pipe diameter change point.

[0083] Specifically, the reduction in the layered filling thickness of the water-stopping material is determined by the difference between the maximum difference in ultrasonic sound velocity of the water-stopping material and a preset second difference; the increase in the filling interval time is determined by the reduction in the layered filling thickness of the water-stopping material.

[0084] Specifically, when the difference between the maximum difference in the ultrasonic sound velocity of the water-stop material and the preset second difference is within 100m / s, the layered filling thickness of the water-stop material is reduced to 0.9 times the original value; when the difference between the maximum difference in the ultrasonic sound velocity of the water-stop material and the preset second difference exceeds 100m / s, on the basis of being reduced to 0.9 times the original value, the layered filling thickness of the water-stop material is reduced by 1cm for every 50m / s that exceeds it. For example, the difference between the maximum difference in the ultrasonic sound velocity of the water-stop material and the preset second difference is 200m / s, the current layered filling thickness of the water-stop material is 10cm, and the layered filling thickness of the water-stop material is reduced by 10×0.9-1×2=7cm.

[0085] Specifically, for every 1 cm reduction in the layered filling thickness of the water-stop material, the filling interval time increases by 1 minute.

[0086] During implementation, the method of the present invention adjusts the layered filling thickness and filling interval time of the water-stop material by setting a preset first difference and a preset second difference. Since the filling speed is too fast during the filling process of the water-stop material, the bubbles inside the material are not discharged in time, resulting in voids. By reducing the layered filling thickness of the water-stop material and reducing the filling interval time, the time for bubbles to rise to the surface can be shortened, the bubble discharge efficiency can be improved, thereby reducing the risk of voids and further improving the effectiveness of water-stopping at the diameter change of the well pipe.

[0087] Specifically, the applicability of the water-stopping process is determined based on the fluctuation amplitude of the grouting pressure of the grouting pump, including:

[0088] Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with a preset first fluctuation amplitude;

[0089] If the fluctuation amplitude of the grouting pressure of the grouting pump is less than or equal to the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process meets the requirements, and whether the layered filling thickness and filling interval time of the water-stopping material meet the requirements;

[0090] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process does not meet the requirements.

[0091] Among them, when the fluctuation amplitude of the grouting pressure of the grouting pump is less than or equal to the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process meets the requirements, and it has been determined that the water-stopping effectiveness at the well pipe diameter change point does not meet the requirements, then it is necessary to further determine whether the layered filling thickness and filling interval time of the water-stopping material meet the requirements.

[0092] During implementation, whether the layered filling thickness and filling interval time of the water-stop material meet the requirements is determined based on the comparison between the actual layered filling thickness of the water-stop material and the predetermined thickness threshold and the comparison between the actual filling interval time and the predetermined interval time threshold. If the actual layered filling thickness of the water-stop material is greater than the predetermined thickness threshold or the actual filling interval time is less than the predetermined interval time threshold, it is determined that the layered filling thickness and filling interval time of the water-stop material do not meet the requirements, wherein the predetermined thickness threshold and the predetermined interval time threshold are both the average values ​​of the layered filling thickness and filling interval time of the water-stop material monitored within the first three months of the method.

[0093] If the layered filling thickness and filling interval time of the water-stop material do not meet the requirements, the layered filling thickness of the water-stop material shall be reduced and the filling interval time shall be increased; if the layered filling thickness and filling interval time of the water-stop material meet the requirements, the maximum difference in ultrasonic sound velocity of the water-stop material shall be recollected, and the effectiveness of the water-stop at the diameter change of the well pipe shall be re-evaluated.

[0094] When the grouting pump's grouting pressure fluctuates beyond a preset first fluctuation, it can be determined that the failure to achieve the required waterstop effectiveness at the wellbore taper is due to the unsuitable suitability of the waterstop process. This failure could be caused by unsuitable back pressure in the grouting pump's return line or unsuitable slurry fluidity. The next step is to determine the specific cause, which is the process of determining whether to increase the back pressure in the grouting pump's return line.

[0095] Specifically, determine whether the back pressure in the return line of the grouting pump needs to be increased, including:

[0096] Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with the preset first fluctuation amplitude and the preset second fluctuation amplitude respectively;

[0097] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude and less than or equal to the preset second fluctuation amplitude, it is determined that the back pressure of the oil return pipeline in the grouting pump needs to be increased, and the back pressure of the oil return pipeline in the grouting pump is increased;

[0098] If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset second fluctuation amplitude, it is determined that there is no need to increase the back pressure of the return oil pipeline in the grouting pump.

[0099] Among them, when the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude and less than or equal to the preset second fluctuation amplitude, it is determined that the reason for the non-compliance of the applicability of the water-stopping process is that the back pressure of the return oil pipeline in the grouting pump does not meet the requirements, and therefore it is necessary to increase the back pressure of the return oil pipeline in the grouting pump. When the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset second fluctuation amplitude, it can be preliminarily determined that the fluidity of the slurry does not meet the requirements. Next, it is necessary to make a final determination of whether the fluidity of the slurry meets the requirements based on the speed deviation rate of the stirring blade, that is, to determine whether the reason for the non-compliance of the applicability of the water-stopping process is that the fluidity of the slurry does not meet the requirements.

[0100] It can be understood that the preset first fluctuation amplitude is smaller than the preset second fluctuation amplitude, and the three intervals divided by the preset first fluctuation amplitude and the preset second fluctuation amplitude correspond to three situations respectively:

[0101] The first interval is when the fluctuation amplitude of the grouting pressure of the grouting pump is less than or equal to the preset first fluctuation amplitude. The corresponding situation is: it is determined that the applicability of the water-stopping process meets the requirements. In this case, it is necessary to further determine whether the layered filling thickness and filling interval time of the water-stopping material meet the requirements.

[0102] The second interval is when the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude and less than or equal to the preset second fluctuation amplitude. The corresponding situation is: the one-way valve at the outlet of the grouting pump is stuck by debris, resulting in indirect jamming, causing pressure to be released inside the pump body, thereby reducing the grouting pressure of the grouting pump. At this time, it is necessary to adjust the back pressure of the return oil pipeline in the grouting pump;

[0103] The third interval is when the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset second fluctuation amplitude. The corresponding situation is: since the bearings of the mixer for mixing the slurry are worn after long-term use, the speed fluctuates during operation, which reduces the mixing efficiency and causes the viscosity of the slurry to be too high. At this time, it is necessary to further judge whether the fluidity of the slurry meets the requirements.

[0104] It is understood that using the first and second fluctuation amplitudes as judgment indicators essentially reflects the process suitability through the stability of the grouting pressure. The first fluctuation amplitude serves as the minimum standard for determining process compliance. If the fluctuation amplitude is ≤ the first fluctuation amplitude, it indicates that the grouting pressure is stable, the waterstop material is evenly filled, and the process suitability meets the basic requirements. If the fluctuation amplitude is greater than the first fluctuation amplitude, the process suitability is directly determined to be unqualified and the cause must be immediately investigated. Within the range of unqualified process, the second fluctuation amplitude is used to further distinguish the degree of fluctuation and match different adjustment strategies. The preset first and second fluctuation amplitudes can be set according to actual working conditions. The setting of the preset first and second fluctuation amplitudes is intended to ensure the effectiveness and practicality of waterstopping at the well pipe diameter change. Optionally, the preset first and second fluctuation amplitudes are determined through a limited number of tests by evaluating the waterstopping effect of different pressure fluctuations at the well pipe diameter change. The preset first and second fluctuation amplitudes should be neither too small nor significantly interfere with the waterstopping process at the well pipe diameter change. Exemplarily, the preset first fluctuation amplitude is generally selected from the range of [0.3 MPa, 0.7 MPa], and the preset second fluctuation amplitude is generally selected from the range of [0.8 MPa, 1.2 MPa].

[0105] Preferably, the preferred embodiment of the preset first fluctuation amplitude is 0.5 MPa, and the preferred embodiment of the preset second fluctuation amplitude is 1 MPa.

[0106] Specifically, the fluctuation amplitude of the grouting pressure of the grouting pump is the difference between the maximum grouting pressure and the minimum grouting pressure of the grouting pump per unit time.

[0107] In implementation, the method of the present invention determines the applicability of the water-stopping process by setting a preset first fluctuation amplitude and a preset second fluctuation amplitude, thereby reducing the impact of the decreased water-stopping effectiveness at the well pipe diameter change point due to inaccurate determination of the applicability of the water-stopping process, and further improving the water-stopping effectiveness at the well pipe diameter change point.

[0108] Specifically, the increase amplitude of the back pressure of the oil return pipeline in the grouting pump is determined by the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and a preset first fluctuation amplitude.

[0109] Specifically, when the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and the preset first fluctuation amplitude is within 0.2MPa, the back pressure of the return oil pipeline in the grouting pump increases to 1.1 times the original value; when the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and the preset first fluctuation amplitude exceeds 0.2MPa, on the basis of increasing to 1.1 times the original value, the back pressure of the return oil pipeline in the grouting pump increases by 0.1MPa for every 0.1MPa exceeding it. For example, the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and the preset first fluctuation amplitude is 0.4MPa, the current back pressure of the return oil pipeline in the grouting pump is 0.5MPa, and the increased back pressure of the return oil pipeline in the grouting pump is 0.5×1.1+0.1×2=0.75MPa.

[0110] During implementation, the method of the present invention adjusts the back pressure of the return oil pipeline in the grouting pump by setting a preset first fluctuation amplitude and a preset second fluctuation amplitude. Since the one-way valve at the outlet of the grouting pump is stuck by debris, indirect jamming occurs, causing pressure to be released inside the pump body, thereby reducing the grouting pressure of the grouting pump. By increasing the back pressure of the return oil pipeline, the leakage resistance can be increased, the pressure relief amount can be reduced, the pressure loss inside the pump body can be reduced, the pressure difference fluctuation range can be narrowed, and the valve disc can be avoided from being frequently opened and closed due to pressure imbalance, which aggravates the jamming, thereby further improving the water-stopping effectiveness at the diameter change point of the well pipe.

[0111] Specifically, the switching frequency of the stirring forward and reverse rotation is determined based on the speed deviation rate of the stirring paddle, including:

[0112] Compare the speed deviation rate of the stirring blade with the preset deviation rate;

[0113] If the speed deviation rate of the agitator is less than or equal to the preset deviation rate, it is determined that the fluidity of the slurry meets the requirements and there is no need to increase the positive and negative time ratio of the stirring, and it is determined whether the back pressure of the return oil pipeline in the grouting pump meets the requirements.

[0114] Specifically, if the rotation speed deviation rate of the stirring paddle is greater than the preset deviation rate, it is determined that the switching frequency of the stirring forward and reverse rotation needs to be increased, and the switching frequency of the stirring forward and reverse rotation is increased.

[0115] Among them, when the speed deviation rate of the agitator is less than or equal to the preset deviation rate, it is determined that the fluidity of the slurry meets the requirements, and it has been determined that the applicability of the water-stopping process does not meet the requirements. Then it is necessary to further determine whether the back pressure of the return oil pipeline in the grouting pump meets the requirements.

[0116] During implementation, whether the back pressure of the return oil pipeline in the grouting pump meets the requirements is determined based on the comparison between the actual back pressure of the return oil pipeline in the grouting pump and the predetermined back pressure threshold value; if the actual back pressure of the return oil pipeline in the grouting pump is less than or equal to the back pressure threshold value, it is determined that the back pressure of the return oil pipeline in the grouting pump does not meet the requirements, wherein the predetermined back pressure threshold value is the average value of the back pressure of the return oil pipeline in the grouting pump monitored within the first three months of the historical period of the method.

[0117] If the back pressure of the return oil pipeline in the grouting pump does not meet the requirements, increase the back pressure of the return oil pipeline in the grouting pump; if the back pressure of the return oil pipeline in the grouting pump meets the requirements, re-collect the fluctuation amplitude of the grouting pressure of the grouting pump and re-evaluate the applicability of the water-stopping process.

[0118] When the speed deviation rate of the stirring blade is greater than the preset deviation rate, it can be determined that the reason why the applicability of the water-stopping process does not meet the requirements is that the fluidity of the slurry does not meet the requirements, so it is necessary to increase the switching frequency of the forward and reverse stirring.

[0119] It is understandable that the two intervals divided by the preset deviation rate correspond to two situations:

[0120] The first interval is when the speed deviation rate of the impeller is less than or equal to the preset deviation rate. This corresponds to the situation where the slurry fluidity is determined to meet the requirements. In this case, it is necessary to further determine whether the back pressure of the return oil pipeline in the grouting pump meets the requirements.

[0121] The second interval is when the speed deviation rate of the agitator is greater than the preset deviation rate. The corresponding situation is: due to the wear of the bearings of the agitator for mixing the slurry after long-term use, the speed fluctuates during operation, which reduces the stirring efficiency and causes the viscosity of the slurry to be too high. At this time, it is necessary to adjust the switching frequency of the forward and reverse stirring.

[0122] It is understandable that the core logic of using the agitator speed deviation rate to characterize the fluidity of the slurry in the water-stopping process at the well pipe diameter change is derived from the linkage relationship between viscosity, resistance and speed in fluid mechanics. The speed deviation rate essentially reflects the change in resistance encountered by the agitator in the slurry. The worse the slurry fluidity (the higher the viscosity), the greater the stirring resistance, the easier it is for the motor output speed to deviate from the set value, and the deviation rate increases accordingly. The preset deviation rate can be set according to actual working conditions. The setting of the preset deviation rate is intended to determine the effectiveness and practicality of water-stopping at the well pipe diameter change. Optionally, the preset deviation rate is determined by evaluating the water-stopping effect at the well pipe diameter change at different speeds through a limited number of tests. The determined preset deviation rate should be neither too small nor cause excessive interference to the water-stopping process at the well pipe diameter change. Exemplary, the range of the preset deviation rate is [9%, 11%].

[0123] Preferably, the preset deviation rate is 10%.

[0124] During implementation, the method of the present invention determines the fluidity of the slurry by setting a preset deviation rate, thereby reducing the impact of the decreased water-stopping effectiveness at the well pipe diameter change point due to inaccurate determination of the slurry fluidity, and further improving the water-stopping effectiveness at the well pipe diameter change point.

[0125] Specifically, the increase range of the switching frequency of the forward and reverse stirring is determined by the difference between the rotation speed deviation rate of the stirring paddle and the preset deviation rate.

[0126] Specifically, when the difference between the speed deviation rate of the stirring paddle and the preset deviation rate is within 2%, the switching frequency of the stirring forward and reverse rotation is increased to 1.2 times the original; when the difference between the speed deviation rate of the stirring paddle and the preset deviation rate exceeds 2%, on the basis of being increased to 1.2 times the original, the switching frequency of the stirring forward and reverse rotation is increased by 1 time / minute for every 1% exceeding it. For example, the difference between the speed deviation rate of the stirring paddle and the preset deviation rate is 4%, the current switching frequency of the stirring forward and reverse rotation is 5 times / minute, and the increased switching frequency of the stirring forward and reverse rotation is 5×1.2+1×2=8 times / minute.

[0127] During implementation, the method of the present invention adjusts the switching frequency of the forward and reverse rotation of stirring by setting a preset deviation rate. Since the bearings of the mixer for mixing the slurry are worn after long-term use, the rotation speed fluctuates during operation, which reduces the stirring efficiency and causes the viscosity of the slurry to be too high. By increasing the switching frequency of the forward and reverse rotation of stirring, a turbulent effect can be generated, which increases the friction and collision between the materials, helps reduce the apparent viscosity, and further improves the water-stopping effectiveness at the diameter change point of the well pipe.

[0128] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A water-stopping method for a well pipe with a variable diameter, characterized in that: include: Determine the position of the gap at the well pipe diameter change, and determine it as a first gap and a second gap according to the width of the gap, use a mixer to mix the slurry, and use a grouting pump to inject the slurry into the first gap; The second gap is filled with a water-stopping material using a multi-layer filling method, and each layer of the water-stopping material is ultrasonically inspected using an ultrasonic flaw detector. After the multi-layer filling is completed, a sealing strip is installed, and a waterproof coating is applied to the outside of the sealing strip. A water supply test is performed on the diameter change of the well pipe; During the test, the ultrasonic sound velocity at different positions of the water-stop material in the second gap is obtained, and the maximum difference in the ultrasonic sound velocity of the water-stop material is calculated; Determining whether the water-stopping effectiveness at the well pipe diameter change location meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material; If the water-stopping effectiveness at the well pipe diameter change does not meet the requirements, determine whether it is necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time; if it is not necessary to reduce the layered filling thickness of the water-stopping material and increase the filling interval time, obtain the fluctuation amplitude of the grouting pressure of the grouting pump to determine whether the applicability of the water-stopping process meets the requirements; If the applicability of the water-stopping process does not meet the requirements, determine whether it is necessary to increase the back pressure of the oil return line in the grouting pump; If there is no need to increase the back pressure of the oil return line in the grouting pump, the switching frequency of the forward and reverse stirring is determined based on the speed deviation rate of the stirring blade.

2. The water-stopping method for a well pipe with a variable diameter according to claim 1, characterized in that: Determining whether the water-stopping effectiveness at the well pipe diameter change location meets the requirements based on the maximum difference in ultrasonic sound velocity of the water-stopping material includes: Comparing the maximum difference in ultrasonic sound velocity of the water-stop material with a preset first difference; If the maximum difference in ultrasonic sound velocity of the water-stopping material is less than or equal to the preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change location meets the requirements; If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than a preset first difference, it is determined that the water-stopping effectiveness at the well pipe diameter change does not meet the requirements.

3. The water-stopping method for a well pipe with a variable diameter according to claim 2, characterized in that: Determine whether the layered fill thickness of the waterstop material needs to be reduced and the fill interval time needs to be increased, including: Comparing the maximum difference in ultrasonic sound velocity of the water-stopping material with the preset first difference and the preset second difference respectively; If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset second difference, it is determined that the layered filling thickness of the water-stopping material needs to be reduced and the filling interval time needs to be increased; If the maximum difference in ultrasonic sound velocity of the water-stopping material is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to reduce the layered filling thickness of the water-stopping material and increase the filling interval time.

4. The water-stopping method for a well pipe with a variable diameter according to claim 3, characterized in that: The reduction range of the layered filling thickness of the water-stopping material is determined by the difference between the maximum difference in ultrasonic sound velocity of the water-stopping material and a preset second difference; the increase range of the filling interval time is determined by the reduction range of the layered filling thickness of the water-stopping material.

5. The water-stopping method for a well pipe with a variable diameter according to claim 3, characterized in that: Determine whether the applicability of the water-stopping process meets the requirements based on the fluctuation amplitude of the grouting pump grouting pressure, including: Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with a preset first fluctuation amplitude; If the fluctuation amplitude of the grouting pressure of the grouting pump is less than or equal to the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process meets the requirements, and whether the layered filling thickness and filling interval time of the water-stopping material meet the requirements; If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude, it is determined that the applicability of the water-stopping process does not meet the requirements.

6. The water-stopping method for a well pipe with a variable diameter according to claim 5, characterized in that: Determine whether it is necessary to increase the back pressure of the return line in the grouting pump, including: Comparing the fluctuation amplitude of the grouting pressure of the grouting pump with the preset first fluctuation amplitude and the preset second fluctuation amplitude respectively; If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset first fluctuation amplitude and less than or equal to the preset second fluctuation amplitude, it is determined that the back pressure of the oil return pipeline in the grouting pump needs to be increased, and the back pressure of the oil return pipeline in the grouting pump is increased; If the fluctuation amplitude of the grouting pressure of the grouting pump is greater than the preset second fluctuation amplitude, it is determined that there is no need to increase the back pressure of the return oil pipeline in the grouting pump.

7. The water-stopping method for a well pipe with a variable diameter according to claim 6, characterized in that: The increase amplitude of the back pressure of the oil return pipeline in the grouting pump is determined by the difference between the fluctuation amplitude of the grouting pressure of the grouting pump and the preset first fluctuation amplitude.

8. The water-stopping method for a well pipe with a variable diameter according to claim 7, characterized in that: The switching frequency of the stirring forward and reverse rotation is determined based on the speed deviation rate of the stirring paddle, including: Compare the speed deviation rate of the stirring blade with the preset deviation rate; If the speed deviation rate of the agitator is less than or equal to the preset deviation rate, it is determined that the fluidity of the slurry meets the requirements and there is no need to increase the positive and negative stirring time ratio, and it is determined whether the back pressure of the return oil pipeline in the grouting pump meets the requirements.

9. The water-stopping method for a well pipe with a variable diameter according to claim 8, characterized in that: If the rotation speed deviation rate of the stirring paddle is greater than the preset deviation rate, it is determined that the switching frequency of the stirring forward and reverse rotation needs to be increased, and the switching frequency of the stirring forward and reverse rotation is increased.

10. The water stopping method for a well pipe diameter change according to claim 9, characterized in that: The increase range of the switching frequency of the forward and reverse stirring is determined by the difference between the rotation speed deviation rate of the stirring paddle and the preset deviation rate.

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