Evaluation method and device for well cementation cement sheath acoustic cement well logging

Abstract

The invention relates to an evaluation method and device for well cementation cement sheath acoustic cement bond logging, and the method comprises the steps: S1, enabling an annular space to be formed between an outer pipe and a sleeve; a transmitting transducer and a receiving transducer are arranged in the sleeve; s2, preparing cement paste, and pouring the cement paste into the annular space; s3, the casing pipe is filled with liquid, and the pressure is increased to the set pressure in the casing pipe; s4, after the cement paste is solidified into a cement sheath for a preset time, at least part of pressure in the casing pipe is removed, so that a micro annular space is formed between the casing pipe and the cement sheath; s5, exciting the transmitting transducer to emit pulse sound signals at preset intervals, and receiving the pulse sound signals emitted by the transmitting transducer by the receiving transducer after the pulse sound signals are absorbed and reflected by the sleeve and the cement sheath; and S6, evaluating the well cementation quality of the cement sheath according to the sound wave signal received by the receiving transducer. According to the invention, a micro annular space can be formed between the sleeve and the cement sheath, and the sealing quality of the well cementation cement sheath can be reflected more truly.

Description

Technical Field

[0001] The present invention relates to the field of oil well cementing in petroleum engineering, and particularly to an evaluation method and device for acoustic cement bond logging of a cement sheath in a well. Background Art

[0002] Cementing is the most important link in the drilling engineering, and the quality of cementing is related to the normal production life of oil and gas wells. The cementing operation of oil and gas wells refers to designing corresponding cement slurries according to different well conditions and injecting them into the annular space between the downhole surrounding rock and the casing, and waiting for setting to form a cement sheath. The sealing quality of the cement sheath in a well is usually tested by acoustic cement bond logging, which is an important index of cementing technology, an important factor to prevent annular flow, and provides technical guarantee for a series of operations such as subsequent drilling, fracturing, acidizing, and production of oil and gas wells.

[0003] The results of acoustic cement bond logging are affected by various factors such as instruments, wellbore fluids, casings, cement sheaths, and formations. At present, the downhole conditions of oil and gas wells are complex and changeable, which has a great impact on the effectiveness of acoustic cement bond logging results, resulting in the inability to truly reflect the actual sealing quality of the downhole cement sheath. The existing devices mainly conduct simulated evaluations on the influence of acoustic cement bond logging for single or a small number of characteristics downhole, and there is no simulated evaluation device for the simultaneous influence of multiple parameters under downhole conditions. The invention patent with the publication number CN111827977A discloses an acoustic measuring device and an acoustic measuring method for indoor cementing quality evaluation. Through a heating device and a pressurizing device, simulated experiments for evaluating the cementing quality of cement sheaths with different densities can be carried out under different temperature and pressure conditions; the invention patent with the publication number CN112160742A discloses a simulated device and method for establishing cementing quality evaluation indexes. Using a completely cemented cement sheath as a simulated formation, the cementing state of the cement sheath in a sandstone formation can be evaluated, but only a single formation condition can be simulated. At present, there is no device that can comprehensively simulate various downhole complex situations and more truly reflect the influence of various factors, resulting in the incomplete exploration of the influence of each factor on acoustic cement bond logging, and the relationship between the electrical logging cementing quality and the actual downhole sealing quality of the cement sheath has not been fully explored. And measuring the cementing quality is the key to reflecting the actual sealing quality of the cement sheath in a well. Therefore, it is very necessary to carry out this research. Summary of the Invention

[0004] The purpose of the present invention is to provide an evaluation method and device for acoustic cement bond logging of a cement sheath in a well, which can form a micro-annulus between the casing and the cement sheath and can more truly reflect the sealing quality of the cement sheath in a well.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The present invention provides an evaluation method for acoustic cement bond logging of a cement sheath in well cementing, including:

[0007] S1. Assemble the outer pipe and the casing, and form an annular space between the outer pipe and the casing; install a transmitting transducer and a receiving transducer in the casing;

[0008] S2. Prepare cement slurry and pour the cement slurry into the annular space;

[0009] S3. Fill the casing with liquid and pressurize it to a set pipe pressure;

[0010] S4. After the cement slurry cures for a preset time and solidifies into a cement sheath, relieve at least part of the pressure in the casing to form a micro-annulus between the casing and the cement sheath;

[0011] S5. Excite the transmitting transducer to emit a pulsed acoustic signal at preset time intervals. The pulsed acoustic signal emitted by the transmitting transducer is absorbed and reflected by the casing and the cement sheath and then received by the receiving transducer;

[0012] S6. Evaluate the cementing quality of the cement sheath according to the acoustic signal received by the receiving transducer.

[0013] In a preferred embodiment of the present invention, in step S4, after forming the micro-annulus, the following steps are further included: injecting liquid into the micro-annulus, or injecting liquid into the micro-annulus and pressurizing it to a set pressure.

[0014] In a preferred embodiment of the present invention, in step S4, after forming the micro-annulus, the following steps are further included: injecting gas into the annular space and pressurizing it to a set pressure.

[0015] In a preferred embodiment of the present invention, step S1 further includes the following steps: sleeving a heating jacket outside the outer pipe; step S3 further includes the following steps: adjusting the temperature of the heating jacket to a set temperature.

[0016] The present invention also provides an evaluation device for acoustic cement bond logging of a cement sheath in well cementing, including a fixing frame, an outer pipe, a casing, a transmitting transducer and a receiving transducer; the outer pipe is sleeved outside the casing at intervals, the bottoms of the outer pipe and the casing are both connected to the fixing frame, and an annular top cover is detachably installed at the top of the outer pipe. A closed annular space is formed among the outer pipe, the casing, the fixing frame and the top cover. The casing can be filled with liquid and pressurized to a set pipe pressure, the annular space can be used to hold cement slurry, and the cement slurry can form a cement sheath after solidification. A micro-annulus can be formed between the cement sheath and the casing after relieving at least part of the pressure in the casing; the transmitting transducer and the receiving transducer are both arranged in the casing.

[0017] In a preferred embodiment of the present invention, an upper plug and a lower plug are respectively and sealingly installed at the upper port and the lower port of the casing. A pressurization hole is formed in the upper plug. The pressurization hole is connected to a pressurization pump through a corresponding pipeline in a switchable manner, and a first pressure valve is provided on the pipeline between the pressurization hole and the pressurization pump.

[0018] In a preferred embodiment of the present invention, a fluid inlet is communicated at the bottom of the annular space. An on-off inlet pipe is connected to the fluid inlet and can be used to inject fluid into the annular space.

[0019] In a preferred embodiment of the present invention, the inlet pipe can be connected to a delivery pump in a switchable manner, and a second pressure valve is provided on the pipeline between the inlet pipe and the delivery pump. The delivery pump can be used to inject liquid into the annular space; the inlet pipe can also be connected to a gas cylinder in a switchable manner, and a third pressure valve is provided on the pipeline between the gas cylinder and the inlet pipe. The gas cylinder can be used to inject gas into the annular space; a switchable fluid outlet is communicated at the top of the annular space.

[0020] In a preferred embodiment of the present invention, the fixing frame includes a top plate and a bottom bracket which are connected up and down. The bottom end of the outer pipe is inserted into the top plate. A through hole is formed in the top plate. After the casing passes through the through hole, it passes out of the top plate; an upper sealing ring and an upper filter screen ring are stacked and installed at the top of the annular space, and the top cover can be pressed on the upper sealing ring; a lower sealing ring and a lower filter screen ring are stacked and installed at the bottom of the annular space, and the lower sealing ring can abut against the top plate.

[0021] In a preferred embodiment of the present invention, a heating sleeve is sleeved outside the outer pipe, and the heating sleeve is electrically connected to a temperature control box.

[0022] In a preferred embodiment of the present invention, the evaluation device for cement sheath acoustic cementing logging also includes a control device, a pulse signal generator and an acoustic wave acquisition device; the transmitting transducer is electrically connected to the pulse signal generator, the receiving transducer is electrically connected to the acoustic wave acquisition device, and the control device is electrically connected to both the pulse signal generator and the acoustic wave acquisition device.

[0023] As described above, in the evaluation method and evaluation device of the present invention, due to the certain expansion and contraction property of the casing, when the cement slurry is poured into the annular space, and the casing is filled with liquid and pressurized, the casing will expand to a certain extent under the action of the internal pressure thereof; since the solidified cement sheath itself does not have the expansion and contraction property, when the cement slurry solidifies into a cement sheath and at least part of the pressure in the casing is removed according to the experimental requirements, the casing will contract, and thus a micro-annular gap with a smaller size will be formed between the casing and the cement sheath, which is more in line with the actual downhole cementing situation. On this basis, by adding other parameter conditions simulating the downhole situation, when the cementing quality is evaluated by the acoustic cementing logging method, the evaluation result can more truly reflect the sealing quality of the cement sheath. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following attached drawings are only intended to illustrate and explain the present invention schematically and do not limit the scope of the present invention.

[0025] Wherein:

[0026] Figure 1 : is a schematic structural diagram of an evaluation device for acoustic cement bond logging of a cement sheath in well cementing provided by the present invention.

[0027] Figure 2 : is Figure 1 A partial enlarged view at the second switching valve in

[0028] Figure 3 : is Figure 1 A partial enlarged view at the third switching valve in

[0029] Explanation of reference numerals in the attached drawings:

[0030] 1. Fixing frame; 11. Top plate; 111. Second switching valve; 112. Inlet pipe; 12. Bottom support; 13. Delivery pump; 131. Second pressure boosting valve; 14. Gas cylinder; 141. Third pressure boosting valve; 15. Pressure sensor;

[0031] 2. Outer pipe; 21. Top cover; 211. Third switching valve; 212. Flowmeter; 213. Bolt; 22. Upper sealing ring; 23. Upper filter screen ring; 24. Lower sealing ring; 25. Lower filter screen ring;

[0032] 3. Casing; 31. Upper plug; 311. First switching valve; 312. Lead wire device; 32. Lower plug; 33. Booster pump; 34. First pressure boosting valve;

[0033] 4. Cement sheath;

[0034] 5. Heating jacket; 51. Temperature control box;

[0035] 61. Transmitting transducer; 62. Receiving transducer; 63. Connecting rod;

[0036] 71. Pulse signal generator; 72. Acoustic wave acquisition device;

[0037] 8. Computer. Specific embodiments

[0038] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described with reference to the attached drawings.

[0039] As Figures 1 to 3 shown, the present application provides an evaluation method for acoustic cement bond logging of a cement sheath in well cementing, including:

[0040] S1. Assemble the outer pipe 2 and the casing 3 to form an annular space between the outer pipe 2 and the casing 3; install the transmitting transducer 61 and the receiving transducer 62 inside the casing 3;

[0041] S2. Prepare the cement slurry and pour it into the annular space;

[0042] S3. Fill the inside of the casing 3 with liquid and pressurize it to the set internal pipe pressure;

[0043] S4. After the cement slurry cures for a preset time to solidify into the cement sheath 4, relieve at least part of the pressure inside the casing 3 to form a micro-annulus between the casing 3 and the cement sheath 4;

[0044] S5. Excite the transmitting transducer 61 to emit pulsed acoustic signals at preset time intervals. The pulsed acoustic signals emitted by the transmitting transducer 61 are absorbed and reflected by the casing 3 and the cement sheath 4 and then received by the receiving transducer 62;

[0045] S6. Evaluate the cementing quality of the cement sheath 4 based on the acoustic signals received by the receiving transducer 62.

[0046] Specifically, the construction process of the actual cementing operation is roughly as follows:

[0047] After drilling is completed, the inside and outside of the casing 3 are all filled with drilling fluid. During cementing, in order to avoid the mutual influence between the drilling fluid and the cement slurry, a spacer fluid is first pumped in, and then the cement slurry is pumped in to displace the spacer fluid and the drilling fluid until the cement slurry fills the annulus between the casing 3 and the formation. After that, the cement slurry gradually solidifies over time to cure into the cement sheath 4, and the bonding quality between the cement sheath 4 and the casing 3 determines the quality of the cementing job.

[0048] However, due to the fact that the casing 3 itself has a certain degree of expansion and contraction, while the cement sheath 4 itself does not have expansion and contraction properties, during the cementing operation and subsequent production operations (such as fracturing operations, oil production operations, etc.), it is difficult to avoid generating small gaps between the casing 3 and the cement sheath 4 due to the expansion or contraction of the casing 3. It's just that the sizes of these gaps are different, and the degrees of influence on the cementing quality are also different. Of course, in actual working conditions, it is also difficult to avoid the existence of small gaps between the cement sheath 4 and the formation, but the gaps here have basically no impact on the cementing quality and generally do not need to be considered during experiments. Since the propagation speed of sound waves and the energy reflected after being absorbed are different in different media, the presence or absence of a micro-annulus between the casing 3 and the cement sheath 4 has a great impact on the propagation of sound waves, and the results of acoustic cement bond logging will also vary greatly. Therefore, the evaluation method in this embodiment makes a micro-annulus form between the casing 3 and the cement sheath 4 first, and then acoustic cement bond logging is carried out, which is more in line with the actual working conditions.

[0049] It should be noted that in step S4, when the cement slurry solidifies into the cement sheath 4, the cement sheath 4 is not completely hardened at this time. As time goes on, the cement sheath 4 will continue to harden, and its strength and hardness will also continuously increase. In step S5, the acoustic cement bond logging is carried out during the continuous hardening process of the cement sheath 4.

[0050] Thus, in the evaluation method of the present application, since the casing 3 has a certain expansion and contraction property, when the cement slurry is poured into the annular space, the casing 3 will expand to a certain extent under the action of the internal pressure after filling the casing 3 with liquid and pressurizing it; since the solidified cement sheath 4 itself does not have the property of expansion and contraction, when the cement slurry solidifies into the cement sheath 4 and at least part of the pressure in the casing 3 is removed (i.e., part of the pressure or all of the pressure) according to the experimental requirements, the casing 3 will contract, and then a micro-annulus with a smaller size will be formed between the casing 3 and the cement sheath 4, which is more in line with the actual downhole cementing situation. On this basis, by adding other parameter conditions simulating the downhole situation, the evaluation result can more truly reflect the cementing quality of the cement sheath 4 when using the acoustic cement bond logging method for cementing quality evaluation.

[0051] In a specific embodiment, in order to more comprehensively simulate various downhole complex situations and more truly reflect the influence of various factors on the acoustic cement bond logging of the cement sheath 4 of the well cementing, in one of the embodiments, after forming the micro-annulus in step S4, the following steps are further included: injecting liquid into the micro-annulus, or injecting liquid into the micro-annulus and pressurizing it to a set pressure, or injecting gas into the annular space and pressurizing it to a set pressure.

[0052] In some actual well cementing working conditions, during the process of the cement slurry displacing the spacer fluid and the drilling fluid, sometimes the displacement efficiency is not very high, and it is very difficult to completely displace the spacer fluid and the drilling fluid. Moreover, since the wellbore wall and the outer wall of the casing 3 are not absolutely smooth and flat, after the displacement is completed, there will still be liquids such as the spacer fluid and the drilling fluid that are not completely displaced remaining in the annulus in this working condition; after the micro-annulus is formed between the casing 3 and the cement sheath 4, due to the fluidity of the liquid, the micro-annulus will be filled with these liquids. Whether there is a micro-annulus between the casing 3 and the cement sheath 4 and whether there is liquid in the micro-annulus have a great influence on the propagation of sound waves, and the results of the acoustic cement bond logging will also vary greatly.

[0053] Therefore, when a micro-annulus is formed and no liquid is injected into the micro-annulus, some actual working conditions with good displacement effect (complete displacement) and no remaining liquid in the annulus can be simulated, and the micro-annulus is in a vacuum state at this time. When a micro-annulus is formed and liquid is injected into the micro-annulus, some actual working conditions with poor displacement effect and remaining liquid in the annulus can be simulated, and the micro-annulus is filled with liquid at this time; in this case, the injected liquid can be pressurized or not pressurized. Generally, in actual working conditions, the spacer fluid and the drilling fluid are in an unpressurized state, and in most cases, the injected liquid is simulated to be unpressurized during the experiment.

[0054] In another actual cementing operation, the displacement effect of the cement slurry is good, but gas may flow upward in the wellbore during the operation; after a micro-annulus is formed between the casing 3 and the cement sheath 4, due to the fluidity of the gas, the micro-annulus will be filled with this gas. The presence or absence of gas in the micro-annulus has a great influence on the propagation of acoustic waves, and the results of acoustic bond logging will also vary greatly.

[0055] Therefore, after the micro-annulus is formed, injecting gas into the micro-annulus can simulate some actual working conditions with good displacement effect but gas flowing upward in the wellbore. At this time, the micro-annulus is filled with gas.

[0056] Of course, in actual working conditions, there may also be a situation where both retained liquid and gas flowing upward in the wellbore exist in the micro-annulus. For the convenience of experimental testing, in this embodiment, only the situations where the micro-annulus is in a vacuum state, only retained liquid exists in the micro-annulus, and only gas exists in the micro-annulus are detected during the experiment. For the situation where both liquid and gas exist in the micro-annulus, it can be inferred based on the evaluation results of the two situations where only retained liquid exists in the micro-annulus and only gas exists in the micro-annulus. Of course, in a feasible embodiment, according to actual needs, the situation where both liquid and gas exist in the micro-annulus can also be simulated and tested.

[0057] Further preferably, step S1 further includes the following steps: sleeving a heating jacket 5 outside the outer tube 2; step S3 further includes the following steps: adjusting the temperature of the heating jacket 5 to a set temperature. By using the temperature of the heating jacket 5, the formation temperature can be simulated to better simulate the real downhole working conditions.

[0058] During the specific test, step S3 specifically includes the following steps:

[0059] Filling the casing 3 with liquid and pressurizing it to the initial pressure;

[0060] Adjusting the temperature of the heating jacket 5 to the set temperature;

[0061] After the temperature of the heating jacket 5 is stable, continue to pressurize the liquid in the casing 3 and pressurize it to the set internal pressure of the pipe. Among them, the initial pressure is less than the set internal pressure of the pipe.

[0062] This can facilitate heating the entire temperature inside the outer tube 2 to the preset temperature and maintaining the temperature stability, and also facilitate pressurizing the inside of the casing 3 to the set internal pressure of the pipe and maintaining the pressure stability. It also helps to ensure that the cement slurry remains in a liquid state and does not solidify before the pressure inside the casing 3 is pressurized to the set internal pressure of the pipe.

[0063] Further, as Figures 1 to 3As shown in the figure, the present application also provides an evaluation device for cement sheath acoustic cementing logging, including a fixing frame 1, an outer pipe 2, a casing 3, a transmitting transducer 61 and a receiving transducer 62; the outer pipe 2 is sleeved outside the casing 3 at intervals, and the bottoms of the outer pipe 2 and the casing 3 are both connected to the fixing frame 1. An annular top cover 21 is detachably installed at the top of the outer pipe 2. A closed annular space is formed among the outer pipe 2, the casing 3, the fixing frame 1 and the top cover 21. The inside of the casing 3 can be filled with liquid and pressurized to a set internal pipe pressure. The annular space can be used to hold cement slurry, and the cement slurry can form a cement sheath 4 after solidification. A micro-annulus can be formed between the cement sheath 4 and the casing 3 after at least part of the pressure inside the casing 3 is removed; both the transmitting transducer 61 and the receiving transducer 62 are arranged inside the casing 3.

[0064] This evaluation device specifically conducts experiments using the above evaluation method. During use, first install the fixing frame 1, the outer pipe 2, the casing 3, the transmitting transducer 61 and the receiving transducer 62. An annular space is formed between the outer pipe 2 and the casing 3. Pour the prepared cement slurry into the annular space, and cover the top cover 21 to make the annular space form a closed space; then fill the inside of the casing 3 with liquid (such as drilling fluid) and pressurize it to the set internal pipe pressure. After the cement slurry solidifies for a preset time (such as seven days) to form a cement sheath 4, at least part of the pressure inside the casing 3 is removed. Due to the certain expansion and contraction property of the casing 3 itself, a micro-annulus will be formed between the casing 3 and the cement sheath 4. Then, the transmitting transducer 61 is excited to emit pulsed acoustic signals at preset intervals. The pulsed acoustic signals emitted by the transmitting transducer 61 are absorbed and reflected by the casing 3 and the cement sheath 4 and then received by the receiving transducer 62. The cementing quality of the cement sheath 4 can be evaluated based on the acoustic signals received by the receiving transducer 62.

[0065] Therefore, the evaluation device in this embodiment has a simple structure and is easy to operate; after pouring the cement slurry into the annular space and filling the inside of the casing 3 with liquid and pressurizing it, the casing 3 will expand to a certain extent under the action of the internal pressure; when the cement slurry solidifies into a cement sheath 4 and part of the pressure inside the casing 3 is removed, the casing 3 will contract, and thus a micro-annulus with a smaller size will be formed between the casing 3 and the cement sheath 4, which is more in line with the actual downhole cementing situation. On this basis, by adding other parameter conditions simulating the downhole environment, the evaluation result can more truly reflect the sealing quality of the cement sheath 4 when using the acoustic cementing logging method to evaluate the cementing quality.

[0066] Further, in order to facilitate the formation of a micro-annulus between the cement sheath 4 and the casing 3, an upper plug 31 and a lower plug 32 are respectively and hermetically installed at the upper and lower ports of the casing 3. A pressurizing hole is opened on the upper plug 31, and the pressurizing hole is connected to a booster pump 33 through a corresponding pipeline (such as a metal pipe) in a switchable manner, and a first pressure valve 34 is arranged on the pipeline between the pressurizing hole and the booster pump 33.

[0067] Generally, both the upper plug 31 and the lower plug 32 are made of metal materials, and the gaps between the plugs and the casing 3 are sealed by corresponding sealing rings. The pressurizing hole can be opened, for example, at the center position of the upper plug 31, and a first switching valve 311 is provided at the pressurizing hole. Connect the booster pump 33 to the corresponding liquid storage tank, and corresponding liquid can be pumped into the casing 3. The booster pump 33 injects liquid into the interior of the casing 3 through a metal pipe, and has a constant pressure mode, a quantitative volume output, and a fixed volume back-drawing mode, and can apply casing pressure during the curing and measurement of the cement sheath 4, and the micro-gap between the casing 3 and the cement sheath 4 can be quantitatively created through the pressure change.

[0068] Specifically, after injecting cement slurry into the annular space and installing the top cover 21, fill the casing 3 with drilling fluid through the booster pump 33 and pressurize it to the set pipe pressure. After the cement slurry solidifies into the cement sheath 4, at least part of the pressure in the casing 3 is relieved, and a micro-annular gap can be formed between the casing 3 and the cement sheath 4. By adjusting the magnitude of the set pressure in the pipe and the specific amount of pressure relieved when relieving the pressure in the casing 3, the pressure in the casing 3 can also be adjusted when relieving the pressure in the casing 3.

[0069] Furthermore, in order to facilitate the simulation of the working conditions of annular space with annular stagnant fluid or annular pressure, a fluid inlet is connected to the bottom of the annular space, and an on-off inlet pipe 112 is connected to the fluid inlet, which can be used to inject fluid into the annular space. The fluid can be liquid or gas according to needs.

[0070] Refer to Figure 1 , the inlet pipe 112 can be connected to the delivery pump 13 in an on-off manner, and a second pressure valve 131 is provided on the pipeline between the inlet pipe 112 and the delivery pump 13, and the delivery pump 13 can be used to inject liquid into the annular space; the inlet pipe 112 can also be connected to the gas cylinder 14 in an on-off manner, and a third pressure valve 141 is provided on the pipeline between the gas cylinder 14 and the inlet pipe 112, and the gas cylinder 14 can be used to inject gas into the annular space.

[0071] Among them, a second switching valve 111 is provided at the fluid inlet; the delivery pump 13 can adopt a peristaltic pump, and the peristaltic pump can achieve fixed-volume pumping of liquid, and inject liquid into the annular space through the pressure valve, the inlet pipe 112 and the fluid inlet. The gas cylinder 14 can inject stable gases such as nitrogen into the annular space through the pressure valve, the inlet pipe 112 and the fluid inlet. During the experiment, after the micro-annular gap is formed, inject liquid into the annular space through the delivery pump 13 to fill the micro-annular gap with liquid, and the actual working condition of annular space with annular stagnant fluid can be simulated. After the micro-annular gap is formed, inject gas into the annular space through the gas cylinder 14, which can make the annular space pressurized and simulate the actual working condition of downhole annular pressure.

[0072] Generally, in order to more easily determine whether the annular space has been filled when injecting fluid into it, a fluid outlet that can be opened and closed is connected to the top of the annular space. Specifically, a third on-off valve 211 is provided at the fluid outlet to facilitate the opening and closing of the fluid outlet. When injecting liquid into the annular space using the transfer pump 13, the third on-off valve 211 is opened. When liquid flows out of the fluid outlet, it means that the annular space has been filled with liquid, and the fluid outlet can be closed. When injecting gas into the annular space using the gas cylinder 14, the third on-off valve 211 is opened. For safer operation, a flowmeter 212 is also connected to the fluid outlet, and the gas is judged whether it has been filled according to the flow rate detected by the flowmeter 212, and then the fluid outlet is closed. Generally, a pressure sensor 15 is also connected to the inlet pipe 112 to facilitate the detection of pressure data.

[0073] More specifically, the above-mentioned casing 3 can be cut from the casing used on site. The outer tube 2 can be a hollow cylinder made of stainless steel. The bottoms of the casing 3 and the outer tube 2 are both fixed by the fixing frame 1. The above-mentioned top cover 21 can be, for example, a flange plate, and the material can be stainless steel, and the size is matched with the casing 3. Specifically, the inner diameter of the flange plate is matched with the outer diameter of the casing 3, and the outer diameter of the flange plate should be larger than the outer diameter of the outer tube 2.

[0074] For easy installation, the fixing frame 1 includes a top plate 11 and a bottom bracket 12 connected up and down. The bottom end of the outer tube 2 is inserted into the top plate 11, and a perforation is provided on the top plate 11. The casing 3 passes through the perforation and then passes out of the top plate 11. For example, an annular slot is provided on the top plate 11, and the bottom end of the outer tube 2 is inserted into the annular slot for convenient fixing. The bottom end of the casing 3 passes through the perforation in a sealed manner, and a sealing ring can be clamped between the outer wall of the casing 3 and the hole wall of the perforation to ensure sealing.

[0075] Preferably, a stacked upper sealing ring 22 and an upper filter ring 23 are installed at the top of the annular space, and the top cover 21 can press on the upper sealing ring 22; a stacked lower sealing ring 24 and a lower filter ring 25 are installed at the bottom of the annular space, and the lower sealing ring 24 can abut against the top plate 11.

[0076] The above-mentioned closed annular space is formed between the upper sealing ring 22, the lower sealing ring 24, the outer tube 2 and the casing 3. The upper sealing ring 22 and the lower sealing ring 24 are both, for example, rubber rings, which can ensure the sealing of the annular space. The upper filter ring 23 and the lower filter ring 25 are both, for example, metal filters, which can prevent the cement slurry from blocking the fluid inlet and the fluid outlet.

[0077] The casing 3 is installed in the outer pipe 2, keeping the axes of both the casing 3 and the outer pipe 2 coincident. A temporarily top-open annular space is formed between them. The prepared cement slurry is poured into this annular space. Then, the upper filter ring 23, the upper sealing ring 22 and the flange are installed at the top of the outer pipe 2, and the flange is fixed to the fixing frame 1 through corresponding fasteners; for example, a plurality of bolts 213 are passed through the openings in the flange and the top plate 11 of the fixing frame 1, and nuts are screwed at both ends (the plurality of bolts 213 are circumferentially spaced outside the outer pipe 2). After installing the top cover 21, the annular space forms a sealed space, and the cement slurry inside will solidify into a cement ring 4 after curing for a set time.

[0078] Referring to Figure 2 and Figure 3 , the above-mentioned fluid inlet is specifically opened on the top plate 11 of the fixing frame 1, and the fluid outlet is opened on the top cover 21. To facilitate the inflow and outflow of the fluid more conveniently, gaps are left between the inner rings of the upper sealing ring 22 and the lower sealing ring 24 and the casing 3, and gaps are also left between the upper filter ring 23 and the lower filter ring 25 and the casing 3. Moreover, a gap is left between the bottom surface of the lower sealing ring 24 near its inner ring and the top surface of the top plate 11, and this gap is communicated with the gap between the lower sealing ring 24 and the casing 3 and the fluid inlet; a gap is left between the top surface of the upper sealing ring 22 near its inner ring and the bottom surface of the top cover 21, and this gap is communicated with the gap between the upper sealing ring 22 and the casing 3 and the fluid outlet.

[0079] Furthermore, to facilitate simulating the formation temperature, a heating sleeve 5 is sleeved outside the outer pipe 2, and the heating sleeve 5 is electrically connected to the temperature control box 51.

[0080] Referring to Figure 1 , the evaluation device for cement ring acoustic cement bond logging in well cementing further includes a control device, a pulse signal generator 71 and an acoustic wave acquisition device 72; the transmitting transducer 61 is electrically connected to the pulse signal generator 71, the receiving transducer 62 is electrically connected to the acoustic wave acquisition device 72, and the control device is electrically connected to both the pulse signal generator 71 and the acoustic wave acquisition device 72.

[0081] The control device is also electrically connected to the above-mentioned booster pump 33, temperature control box 51, pressure sensor 15, and flowmeter 212; the control device can be integrated in the computer 8, and the computer 8 is also equipped with a corresponding display screen to display data. For the convenience of wiring, generally, two mounting holes are provided on the upper plug 31 for installing two lead wire devices 312. The pulse signal generator 71 is connected to one of the lead wire devices 312 through an electric wire, and the transmitting transducer 61 is connected to this lead wire device 312 through an electric wire; the acoustic wave acquisition device 72 is connected to the other lead wire device 312 through an electric wire, and the receiving transducer 62 is connected to this lead wire device 312 through an electric wire. The transmitting transducer 61 can emit acoustic wave signals for well logging. After the acoustic wave signals pass through the casing 3 and the cement sheath 4, they are received by the receiving transducer 62, and the acoustic wave data is transmitted to the acoustic wave acquisition device 72 (also called an acoustic wave acquisition card) through the electric wire via the corresponding lead wire device 312, and then the data is transmitted to the computer 8 for recording and analysis. Specifically, the pulse signal generator 71, the acoustic wave acquisition device 72, and the temperature control box 51 themselves are all existing structures and will not be elaborated here.

[0082] All pressure manifolds in the evaluation device are high-pressure-resistant stainless steel pipelines. The evaluation device is equipped with connecting members and seals. The connecting members can be screws, bolts 213, threads, nuts, compression rings, etc.; the seals can be sealing rubber rings, and the material is tetrafluoroethylene.

[0083] More specifically, the evaluation device and the evaluation method can specifically simulate the effects of factors such as different cement slurry systems, different micro-annulus sizes, annular fluid stagnation, annular pressure, casing pressure, formation temperature (curing temperature), and cement slurry curing time on acoustic cement bond logging, providing more comprehensive guidance for the data processing of actual cementing quality acoustic logging. It has novelty in the field of cementing and also has a broad market prospect. Specifically as follows:

[0084] (1) Cement slurry system

[0085] The cement slurry system is configured according to the experimental requirements, specifically configured according to the API (American Petroleum Institute) standard. By changing the component ratio of the cement slurry, the effects of different cement slurry systems on acoustic cement bond logging can be simulated.

[0086] (2) Simulation calculation method for the micro-annulus between the cement sheath 4 and the casing 3:

[0087] Drain the air in the casing 3 and the booster pump 33, fill it with liquid, and operate the booster pump 33 in volume mode. The volume V of the liquid injected into the casing 3 after calibration of the compressibility coefficient is the volume of the expansion of the casing 3. Pressurize the fluid before the cement slurry solidifies and relieve the pressure after the cement slurry solidifies. The clearance calculation formula between the casing 3 and the cement sheath 4 is:

[0088] V = π × L × R 0 2 × [(1 + ε) 3 - 1]

[0089] where L is the height of the casing 3, R 0 is the initial inner hole radius of the casing 3, and ε is the strain of the casing 3. The size of the micro - annulus (i.e., the gap width between the collar and the cement sheath 4) can be expressed as 2 × R 0 × ε; this value is the calculated theoretical value. Generally, the final slit width (i.e., the gap width between the collar and the cement sheath 4) can also be verified by filling the gas cylinder 14 with gas and measuring the flow rate using the flowmeter 212.

[0090] Therefore, after selecting the casing, the slit width size of the micro - annulus is related to the size of the casing 3. By using casings 3 with different sizes, the influence on acoustic cement bond logging under different micro - annulus sizes can be simulated.

[0091] (3) The simulation method of annulus liquid holdup (which can also be called annulus fluid holdup) is as follows:

[0092] The peristaltic pump injects a fixed volume of liquid into the annulus in volume mode through the second pressure - regulating valve 131 to simulate different degrees of annulus liquid holdup. The pressure sensor 15 is installed on the inlet pipe 112 to monitor the fluid pressure entering the cement sheath 4 and transmit the monitored value to the computer 8 for recording.

[0093] Therefore, by changing the type of liquid injected into the annulus, the influence of different annulus liquid holdups on acoustic cement bond logging can be simulated. By pressurizing the liquid injected into the annulus, the influence of different pressured conditions of annulus liquid holdup on acoustic cement bond logging can also be simulated.

[0094] (4) The simulation method of annulus pressure is as follows:

[0095] Open the switch valve (the second switch valve 111) at the fluid inlet. The gas cylinder 14 injects gas into the annulus through the third pressure - regulating valve 141 to simulate annulus pressure.

[0096] Therefore, by changing the pressure of the gas injected into the annulus, the influence of different pressured conditions in the annulus on acoustic cement bond logging can be simulated.

[0097] (5) The simulation method of casing pressure is as follows:

[0098] Inject liquid into the casing 3 through the booster pump 33 and pressurize it to the set pressure inside the pipe. After the cement slurry solidifies into the cement sheath 4, at least part of the pressure inside the casing 3 is relieved, and the pressure inside the casing 3 can be adjusted.

[0099] Therefore, by setting different pressures in the setting pipe and / or discharging different pressures, after discharging the pressure in the casing 3, the pressure in the casing 3 can be adjusted to simulate the influence of different casing pressures on acoustic cement bond logging.

[0100] (6) The method for simulating formation temperature is as follows:

[0101] Wrap a heating sleeve 5 around the outer wall of the outer pipe 2. Its material can be flexible silica gel, which contains heating wires and temperature sensors. Connect the heating sleeve 5 to a temperature control box 51 through a cable. The temperature control box 51 is mainly composed of a PID intelligent regulator, a temperature sensor, and a solid-state relay, and is used to control the heating sleeve 5 to heat the entire device. Heat the outer pipe 2 to a fixed value through the temperature control box 51 to simulate the formation temperature.

[0102] Therefore, by changing the heating temperature of the heating sleeve 5, the influence of different formation temperatures on acoustic cement bond logging can be simulated.

[0103] (7) The method for simulating the curing time of cement slurry:

[0104] After the cement slurry is injected into the annular space between the casing 3 and the outer pipe 2, set different intervals for acoustic wave emission and acquisition through the computer 8 to simulate different setting times of the cement sheath 4.

[0105] Therefore, after the cement slurry is cured into the cement sheath 4, by controlling the intervals for acoustic wave emission and acquisition set in the device, the transmitting transducer 61 can be excited to emit pulse signals every preset time, and the acoustic wave data received by the receiving transducer 62 can be collected. By changing this preset time, the influence of the cement sheath 4 on acoustic cement bond logging at different setting times can be simulated.

[0106] For the variable factors mentioned above, generally for more convenient experimental testing, either neither of the two factors of annular gap liquid retention and annulus pressure is selected, or only one of them is selected. When neither is selected, the micro-annular gap is in a vacuum state, mainly used to simulate the actual working condition where the initial contact quality between the cement sheath 4 and the casing 3 is good, but during the later operation process, the casing 3 shrinks, resulting in the formation of a micro-annular gap between the casing 3 and the cement sheath 4; when only annular gap liquid retention is selected, it is mainly used to simulate the actual working condition where the displacement of drilling fluid and spacer fluid by cement slurry is not clean, resulting in the presence of retained liquid in the annular space; when only annulus pressure is selected, it is mainly used to simulate the actual working condition where the initial contact quality between the cement sheath 4 and the casing 3 is good, but during the later operation process, the gas at the bottom of the well surges up, resulting in the presence of pressurized gas in the annular space.

[0107] In addition, for the seven variable simulation factors mentioned above, for the same set of evaluation devices, only after determining the specific parameter values of each simulation factor can a simulation experiment be carried out. If at least some of the parameters need to be changed, another set of evaluation devices needs to be used for the experiment, or after the experiment of this set of evaluation devices is completed, the casing 3 is replaced and then the experiment is carried out. For each component in the evaluation device, generally, the casing 3 is only used for one experiment and then replaced without being reused; of course, according to needs, the casing 3 can also be cleaned and reused; the outer tube 2, the heating sleeve 5, the flange, the fixing frame 1, the transducer, etc. can all be reused.

[0108] The following takes a specific embodiment to illustrate the experimental method of the evaluation device. The evaluation method for evaluating the influence of different downhole conditions on the acoustic cement bond logging of the cement sheath by using the above-mentioned evaluation device specifically includes the following steps in sequence:

[0109] (1) Install a lower plug 32 at the lower part of the casing 3 and fix it to the outer tube 2 on the fixing frame 1 to form an annular space.

[0110] (2) The transmitting transducer 61 and the receiving transducer 62 are arranged vertically, and the two are connected by a connecting rod 63 and placed inside the casing 3. An upper plug 31 and two lead wire devices 312 are installed at the upper part of the casing 3, and a pulse signal generator 71, an acoustic wave acquisition device 72 and a computer 8 are connected.

[0111] (3) Prepare the cement slurry required for the experiment as required, pour it from the upper part into the annular space between the casing 3 and the outer tube 2, and place a metal filter screen, a rubber pad and a flange, and fix them with bolts 213.

[0112] (4) Fill the casing 3 with drilling fluid through a booster pump 33 and pressurize it to a preset initial pressure.

[0113] (5) Set the temperature control box 51 to the set experimental temperature, the heating sleeve 5 starts to work, and after the temperature is stable, continue to pressurize the inside of the casing 3 until the set pressure inside the pipe is reached.

[0114] (6) Cure the cement slurry into the cement sheath 4 for the set experimental curing time. After the cement slurry solidifies into the cement sheath 4, release part of the pressure inside the casing 3 to create a micro-annulus between the cement sheath 4 and the casing 3.

[0115] (7) Open the second switch valve 111 at the fluid inlet and the gas cylinder 14, inject gas into the micro-annulus, and verify the situation of the micro-annulus between the cement sheath 4 and the casing 3 through the flowmeter 212 at the fluid outlet.

[0116] (8) Close the third switching valve 211 at the fluid outlet, and inject gas into the micro-annulus through the gas cylinder 14 to simulate the situation of annulus pressure; or inject liquids such as drilling fluid or spacer fluid into the micro-annulus through a positive displacement pump. The pressure data is transmitted to the computer 8 through the pressure sensor 15. When the liquid flows out of the fluid outlet, close the third switching valve 211 at the fluid outlet to simulate the situation of annulus stagnant liquid.

[0117] (9) Set the acoustic wave emission data through the computer 8, and record the situation of acoustic wave collection where the pulse acoustic wave signal is emitted by the transmitting transducer 61 excited by the pulse signal transmitter, absorbed and reflected by the casing 3 and the cement sheath 4, and then received by the receiving transducer 62 and transmitted to the acoustic wave acquisition device 72 and the computer 8.

[0118] The whole experimental process includes two processes: cement sheath curing and acoustic bond logging evaluation. During the cement sheath curing process, cement slurry is injected into the annular space between the casing 3 and the outer pipe 2, the pressure inside the casing 3 is pressurized by the booster pump 33, and the curing temperature of the cement slurry is controlled by the temperature control box 51. After the set experimental curing time, the cement slurry solidifies into the cement sheath 4. During the acoustic bond logging evaluation process, after at least partially relieving the pressure inside the casing 3, a micro-annulus is formed between the casing 3 and the cement sheath 4; by changing the pressure inside the casing 3 when relieving the pressure inside the casing 3, fluids such as gas, drilling fluid or spacer fluid are injected into the interface gap between the casing 3 and the cement sheath 4. The pulse signal generator 71 is used to excite the transmitting transducer 61 to emit a pulse acoustic signal, which is absorbed and reflected by the casing 3 and the cement sheath 4 and then received by the receiving transducer 62. The data is stored in the computer 8 through the acoustic wave acquisition device 72, and the influence of factors such as different cement slurry systems, different micro-annulus sizes, annulus stagnant liquid, annulus pressure, casing pressure, curing temperature and cement slurry curing time on acoustic bond logging can be simulated and tested.

[0119] In summary, the evaluation device and method in this embodiment can more realistically simulate the influence of various downhole conditions on the acoustic bond logging of the cement sheath 4 of the well cementing. This device can simulate different downhole conditions, which helps to find out the well cementing quality and wellbore integrity of the cement sheath 4 of the well cementing under the actual downhole conditions, and make up for the deficiencies of the current testing methods and devices in the field of well cementing. Using the above experimental device to form an evaluation method for the influence of different downhole conditions on the acoustic bond logging of the cement sheath 4 of the well cementing, this method has a reliable principle, is easy to operate, and has broad prospects for market application research.

[0120] The above is only a schematic specific embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for evaluating acoustic bonding logging of cement rings for cementing, characterized in that: include: S1, assembling an outer tube and a casing to form an annular space between the outer tube and the casing; installing a transmitting transducer and a receiving transducer in the casing; S2, preparing cement slurry, and pouring the cement slurry into the annular space; S3, filling the casing with liquid and pressurizing it to a set pressure inside the casing; S4, after the cement slurry solidifies into a cement ring for a preset time, at least part of the pressure in the casing is released to form a micro-annular gap between the casing and the cement ring; S5, stimulating the transmitting transducer to emit a pulse sound signal at a preset time interval, wherein the pulse sound signal emitted by the transmitting transducer is absorbed and reflected by the casing and the cement ring and then received by the receiving transducer; S6. Evaluate the cementing quality of the cement sheath according to the acoustic wave signal received by the receiving transducer.

2. The evaluation method for cement ring acoustic bonding logging as claimed in claim 1, characterized in that: In step S4, after the micro-annular gap is formed, the following steps are further included: injecting liquid into the micro-annular gap, or injecting liquid into the micro-annular gap and pressurizing it to a set pressure.

3. The evaluation method for cement ring acoustic bonding logging of cementing as claimed in claim 1, characterized in that: In step S4, after the micro-annular gap is formed, the following steps are also included: injecting gas into the annular space and pressurizing it to a set pressure.

4. The evaluation method for cement ring acoustic bonding logging as claimed in claim 1, characterized in that: Step S1 also includes the following steps: installing a heating jacket outside the outer tube; Step S3 also includes the following steps: adjusting the temperature of the heating jacket to a set temperature.

5. An evaluation device for cement ring acoustic bonding logging, characterized in that: It includes a fixing frame, an outer tube, a sleeve, a transmitting transducer and a receiving transducer; The outer tube is sleeved on the outside of the casing, the bottoms of the outer tube and the casing are connected to the fixing frame, an annular top cover is detachably installed on the top of the outer tube, and a closed annular space is formed between the outer tube, the casing, the fixing frame and the top cover. The casing can be filled with liquid and pressurized to a set internal pressure of the tube, and the annular space can be used to contain cement slurry. The cement slurry can form a cement ring after solidification, and a micro-annular gap can be formed between the cement ring and the casing after at least part of the pressure in the casing is released; the transmitting transducer and the receiving transducer are both arranged in the casing.

6. The evaluation device for cement ring acoustic bonding logging according to claim 5, characterized in that: The upper port and the lower port of the sleeve are respectively sealed with an upper plug and a lower plug, and a boosting hole is opened on the upper plug. The boosting hole is connected to the boosting pump through a corresponding pipeline so as to be on and off, and a first pressurizing valve is provided on the pipeline between the boosting hole and the boosting pump.

7. The evaluation device for cement ring acoustic bonding logging according to claim 5, characterized in that: A fluid inlet is connected to the bottom of the annular space, and a switchable inlet pipe is connected to the fluid inlet, which can be used to inject fluid into the annular space.

8. The evaluation device for cement ring acoustic bonding logging according to claim 7, characterized in that: The inlet pipe can be connected to the delivery pump in an on-off manner, and a second pressure valve is provided on the pipeline between the inlet pipe and the delivery pump, and the delivery pump can be used to inject liquid into the annular space; The inlet pipe can also be connected to the gas cylinder in an on-off manner, and a third pressurizing valve is provided on the pipeline between the gas cylinder and the inlet pipe. The gas cylinder can be used to inject gas into the annular space; a fluid outlet that can be opened and closed is connected to the top of the annular space.

9. The evaluation device for cement ring acoustic bonding logging according to claim 5, characterized in that: The fixing frame comprises a top plate and a bottom bracket connected up and down, the bottom end of the outer tube is inserted into the top plate, a through hole is formed on the top plate, and the sleeve passes through the through hole and then passes out of the top plate; An upper sealing ring and an upper filter ring are stacked on the top of the annular space, and the top cover can be pressed on the upper sealing ring; A stacked lower sealing ring and a lower filter ring are installed at the bottom of the annular space, and the lower sealing ring can abut against the top plate.

10. The evaluation device for cement ring acoustic bonding logging according to claim 5, characterized in that: A heating jacket is provided on the outer sleeve of the outer tube, and the heating jacket is electrically connected to the temperature control box.

11. The evaluation device for cement ring acoustic bonding logging according to claim 5, characterized in that: The evaluation device for cement ring acoustic bonding logging also includes a control device, a pulse signal generator and an acoustic wave collection device; The transmitting transducer is electrically connected to the pulse signal generator, the receiving transducer is electrically connected to the sound wave collection device, and the control device is electrically connected to both the pulse signal generator and the sound wave collection device.

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