A cementing construction process for horizontal wells

Abstract

The present invention relates to the technical field of oil drilling construction, and discloses a cementing construction process for horizontal wells, including the steps of: running casing after the completion of horizontal well drilling, circulating and washing the well, preparing a pilot fluid and cement slurry, adopting a fluctuation-rotation alternating pulse technique during the injection of the cement slurry, dynamically adjusting the alternating pulse parameters according to the characteristics of the well section, and completing the cementing operation. By precisely separating the hydraulic fluctuation and casing rotation effects in the time domain, the present invention avoids the mutual interference between the two technical means, and at the same time utilizes the special flow pattern generated during the flow state transition period, significantly improving the cementing quality of horizontal wells and solving technical problems such as casing centralization, large flow resistance of cement slurry, and low displacement efficiency in long horizontal section cementing.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling construction, and more specifically, it relates to a cementing construction process for horizontal wells. Background Art

[0002] Horizontal well cementing is a key link in oil and gas well engineering, and its quality directly affects the production efficiency and service life of oil and gas wells. With the development of horizontal well technology, the horizontal section is getting longer and longer, and the traditional cementing process faces multiple technical challenges: it is difficult for the casing in the horizontal section to be centered, resulting in uneven annulus and poor quality of the cement sheath; the horizontal section is long, the flow resistance of the cement slurry is large, the displacement efficiency is low, and it is easy to form a flow "short circuit"; the geological conditions and pressure gradients vary greatly at different positions of the horizontal well, and a single cementing process is difficult to meet the requirements of different sections. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a cementing construction process for horizontal wells.

[0004] The present invention provides a cementing construction process for horizontal wells, including the following steps:

[0005] Step 1, complete the drilling of the horizontal well and run in the casing;

[0006] Step 2, circulate and wash the well to clean the wellbore;

[0007] Step 3, prepare the leading fluid and the cement slurry;

[0008] Step 4, pump in the leading fluid and the cement slurry;

[0009] Step 5, during the injection of the cement slurry, adopt the method of alternating pulse of fluctuation - rotation, so that the hydraulic fluctuation and the casing rotation alternate in the time domain, specifically including: the hydraulic fluctuation stage, lasting for 10 seconds; the first transition period, lasting for 5 seconds; the casing rotation stage, lasting for 15 seconds; the second transition period, lasting for 5 seconds; and repeat the above cycle until the injection of the cement slurry is completed;

[0010] Step 6, dynamically adjust the parameters of the alternating pulse of fluctuation - rotation according to the properties of different sections of the horizontal well;

[0011] Step 7, complete the cementing operation.

[0012] Preferably: the alternating pulse of fluctuation - rotation is specifically:

[0013] Start the hydraulic fluctuation device to generate hydraulic fluctuation energy with a predetermined frequency, and the action time is 10 seconds;

[0014] Stop the hydraulic fluctuation and enter the first transition period, lasting for 5 seconds;

[0015] Start the casing rotation device to rotate the casing at a predetermined speed and direction for 15 seconds;

[0016] Stop the casing rotation and enter the second transition period for 5 seconds;

[0017] Repeat the above cycle until the cement slurry injection is completed.

[0018] Preferably: In the hydraulic fluctuation stage, the frequency range of the hydraulic fluctuation is 2 - 8 Hz, and the fluctuation amplitude is controlled within 0.5 - 2.5 MPa.

[0019] Preferably: In the casing rotation stage, the casing rotation speed is controlled within the range of 10 - 30 rpm.

[0020] Preferably: In the first transition period, after the hydraulic fluctuation stops, the cement slurry continues to maintain a certain degree of fluctuation state under the action of inertia, forming a gradually decaying fluctuating flow field.

[0021] Preferably: In the second transition period, after the casing rotation stops, the cement slurry in the annulus continues to maintain a rotational motion under the action of inertia, but the rotational speed gradually decreases, forming a rotational decay flow.

[0022] Preferably: In step 6, the fluctuation - rotation alternating pulse parameters are dynamically adjusted according to the properties of different sections of the horizontal well, specifically including: dividing the horizontal well into sections with different properties, including: complex sections where the casing is difficult to be centered, sections where the cement slurry is prone to form a flow short - circuit, turning sections, and high - difficulty sections, and different parameter adjustment methods are adopted for different sections.

[0023] Preferably: For complex sections where the casing is difficult to be centered, adjusting the fluctuation - rotation alternating pulse parameters includes:

[0024] Extend the casing rotation time to 20 - 25 seconds;

[0025] Increase the casing rotation speed to 20 - 40 rpm;

[0026] Keep the hydraulic fluctuation time and the transition period time unchanged.

[0027] Preferably: For sections where the cement slurry is prone to form a flow short - circuit, adjusting the fluctuation - rotation alternating pulse parameters includes:

[0028] Increase the intensity of the hydraulic fluctuation energy to 1.5 - 3.0 MPa;

[0029] Increase the hydraulic fluctuation frequency to 5 - 10 Hz;

[0030] Extend the first transition period time to 8 - 10 seconds;

[0031] Keep the casing rotation time and the second transition period time unchanged.

[0032] Preferably, for the turning section and the high-difficulty section, adjusting the pulsating-rotating alternating pulse parameters includes:

[0033] Adjusting the time ratio of pulsation to rotation;

[0034] Adjusting the alternating frequency;

[0035] Comprehensively adjusting the hydraulic pulsation and casing rotation parameters according to the actual situation.

[0036] The beneficial effects of the present invention are as follows: The present invention adopts the method of pulsating-rotating alternating pulse. Through precise separation in the time domain, the hydraulic pulsation and the casing rotation are alternated in time rather than acting simultaneously, avoiding the mutual interference between the two technical means;

[0037] Creatively designs a cyclic time sequence of hydraulic pulsation - pause - casing rotation - pause, and utilizes the conversion process of the flow state to generate a special cement slurry flow pattern during the transition period (pause period);

[0038] Establishes a method for dynamically adjusting the pulsating-rotating alternating pulse parameters according to the characteristics of different sections of the horizontal well, realizing refined cementing "suitable for each well";

[0039] Utilizes the technical means of enhancing the fluidity of the cement slurry during the flow state conversion period, enabling the alternation of the two actions to form a special flow state conversion process, enhancing the fluidity and displacement efficiency of the cement slurry.

[0040] Through precise design of the time sequence, the two technical means play their respective roles in different time periods, avoiding the problem of energy cancellation when used simultaneously, and at the same time cleverly utilizing the special flow effect generated during the flow state conversion period. Detailed implementation manners

[0041] Now, the subject matter described herein will be discussed with reference to exemplary embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the scope of protection of the content of this specification, changes can be made to the functions and arrangements of the elements discussed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0042] At least one embodiment of the present invention discloses a cementing construction process for a horizontal well, including the following steps:

[0043] Step 1: Complete the drilling of the horizontal well and lower the casing;

[0044] After the horizontal well drilling is completed, according to the requirements of conventional drilling technology, wellbore cleaning and drill string pulling operations are carried out to ensure that there are no obvious collapses and hole shrinkages in the wellbore, and the wellbore condition is confirmed to be good through logging. Then, the casing is run to the target depth, and a guiding device is configured on the outer wall of the casing.

[0045] The guiding device is configured following the principles below: increase the number of guiding devices at the turning points of the horizontal section and in areas prone to casing eccentricity; configure the guiding devices at uniform intervals in the straight section; the specifications and stiffness of the guiding devices match the wellbore size and formation properties.

[0046] Step 2: Circulate and wash the well to clean the wellbore;

[0047] After the casing is run to the right position, a circulating well-washing operation is carried out. The wellbore is cleaned with well-washing fluid to establish a circulation path. Low-solid well-washing fluid is used for circulating well-washing, and the flow rate is controlled within the range sufficient to carry the cuttings on the well wall, generally 1.0 - 2.5 m / s. The purpose of circulating well-washing is to remove the drill cuttings and mud cake in the wellbore and create good conditions for the subsequent cementing operation.

[0048] During the circulating well-washing process, monitor the properties of the returned fluid until the cleanliness of the returned fluid meets the requirements for cementing. This is a routine preparatory work before cementing and belongs to the routine implementation content of those skilled in the art.

[0049] Step 3: Prepare the leading fluid and cement slurry;

[0050] According to the geological characteristics, well depth, and temperature conditions of the horizontal well, prepare the leading fluid and cement slurry according to the design parameters. The function of the leading fluid is to clean the wellbore, improve the properties of the well wall, and create good conditions for the injection of cement slurry. The formula of the cement slurry meets the requirements of good fluidity, appropriate thickening time, and fast strength development.

[0051] The preparation of the leading fluid and cement slurry belongs to the routine technical content of the cementing process. Those skilled in the art can prepare them according to the specific well conditions and requirements, and no detailed description is given here.

[0052] Step 4: Pump in the leading fluid and cement slurry;

[0053] First, pump the leading fluid into the wellbore. The amount of the leading fluid is generally 80 - 120% of the annulus volume, and the flow rate is controlled at 1.0 - 2.0 m / s to ensure sufficient flushing of the wellbore. After the injection of the leading fluid is completed, continuously pump in the cement slurry according to the preset plan, maintaining appropriate injection pressure and flow rate to avoid gas channeling and channeling.

[0054] At this stage, monitor parameters such as injection pressure, flow rate, and pumped-in volume to ensure that the cement slurry is injected into the wellbore as required. The process of pumping in the cement slurry is a routine step in the cementing process, and those skilled in the art are familiar with its implementation method.

[0055] Step 5: Adopt the method of alternating pulse of fluctuation - rotation;

[0056] This step is the core innovation of this embodiment. During the injection of cement slurry, the alternating pulse technology of fluctuation - rotation is adopted to make the hydraulic fluctuation and casing rotation alternate in the time domain instead of acting simultaneously.

[0057] 5.1 Basic principle of the alternating pulse technology of fluctuation - rotation;

[0058] In traditional technologies, when hydraulic fluctuation and casing rotation are applied simultaneously, there will be problems of mutual interference and even cancellation of the energy fields, resulting in poor cementing effect. The innovation of this embodiment lies in separating the actions of the two technologies in time to form a regular alternating action mode, and the specific implementation is as follows:

[0059] Start the hydraulic fluctuation device to generate hydraulic fluctuation energy with a predetermined frequency, and the action time is 10 seconds;

[0060] Stop the hydraulic fluctuation and enter the first transition period, which lasts for 5 seconds;

[0061] Start the casing rotation device to make the casing rotate at a predetermined speed and direction for 15 seconds;

[0062] Stop the casing rotation and enter the second transition period, which lasts for 5 seconds;

[0063] Repeat the above cycle until the injection of cement slurry is completed.

[0064] This time series enables the hydraulic fluctuation and casing rotation to play their roles in independent time windows respectively, avoiding energy interference. At the same time, through the setting of the transition period, using the "memory effect" and "inertia effect" in hydrodynamics, the action effect of the previous stage is maintained and continued during the transition period, creating favorable conditions for the action of the next stage.

[0065] 5.2 Specific implementation of the alternating pulse technology of fluctuation - rotation;

[0066] 5.2.1 Hydraulic fluctuation stage (10 seconds);

[0067] Start the hydraulic fluctuation device to generate hydraulic fluctuation energy with a predetermined frequency. The frequency range of the hydraulic fluctuation is 2 - 8 Hz, and the fluctuation amplitude is controlled within 0.5 - 2.5 MPa. The action time of the hydraulic fluctuation is 10 seconds, which is long enough to make the cement slurry form an obvious fluctuating flow state while keeping the energy consumption within a reasonable range.

[0068] At this stage, the hydraulic fluctuation energy acts on the cement slurry in the annulus through fluid transmission, breaking the static laminar flow state of the cement slurry, promoting it to form a fluctuating flow pattern, and improving the scouring effect of the cement slurry on the wellbore and the displacement efficiency of the drilling fluid.

[0069] 5.2.2 First transition period (5 seconds);

[0070] Stop the hydraulic fluctuation and enter the first transition period for 5 seconds. During this period, no active external energy input is carried out, and the cement slurry is allowed to flow by itself.

[0071] The innovation of this stage lies in: using the principle of "flow inertia" in hydrodynamics, after the hydraulic fluctuation stops, the cement slurry will not immediately return to the static flow state, but under the action of inertia, it will continue to maintain a certain degree of fluctuating state, forming a gradually decaying fluctuating flow field. This characteristic enables the cement slurry to still maintain good fluidity during the transition period, and the flow pattern is different from that in the forced fluctuation stage, forming a "free decay fluctuating flow".

[0072] The duration of this transition period is 5 seconds, which is the working duration determined through multiple tests. It can not only make full use of the flow inertia effect but also ensure that the fluctuation will not completely decay to the static flow.

[0073] 5.2.3 Casing rotation stage (15 seconds);

[0074] Start the casing rotation device to rotate the casing at a predetermined speed and direction for 15 seconds. The casing rotation speed is controlled within the range of 10 - 30 rpm, and the rotation direction can be clockwise or counterclockwise, but it should be kept consistent during a complete cementing process.

[0075] The action time of the casing rotation is 15 seconds, which is longer than the hydraulic fluctuation stage because it takes a certain time for the influence of the casing rotation on the flow state of the cement slurry to be fully established, especially in the long horizontal section.

[0076] At this stage, the casing rotation drives the cement slurry in the annulus to form a circumferential flow. On the one hand, it promotes the casing to be centered in the horizontal section, and on the other hand, it enhances the contact between the cement slurry and the wellbore, improving the displacement efficiency. The casing rotation can also break the gel structure that the cement slurry may form and maintain its good fluidity.

[0077] 5.2.4 Second transition period (5 seconds);

[0078] Stop the casing rotation and enter the second transition period for 5 seconds. Similarly, no active external energy input is carried out, and the cement slurry is allowed to flow by itself.

[0079] The innovation in this transition period lies in that after the casing rotation stops, the cement slurry in the annulus continues to rotate under the action of inertia, but the rotation speed gradually decreases, forming a "rotational decay flow". This flow state is different from both static flow and forced rotation and has different hydrodynamic characteristics.

[0080] The duration of the second transition period is 5 seconds, the same as the first transition period, which is a working duration verified by practice. It can not only make full use of the rotational inertia effect but also prepare for the hydraulic fluctuation effect in the next cycle.

[0081] 5.2.5 Repeated circulation;

[0082] After completing the above four stages, it enters the hydraulic fluctuation stage again to form a complete cycle, and this is repeated until the cement slurry injection is completed.

[0083] The effects of this step different from the prior art are mainly reflected in the following aspects:

[0084] Through the separation in the time domain, the problems of mutual interference and energy cancellation when the hydraulic fluctuation and casing rotation act simultaneously are avoided;

[0085] By designing the time sequence (10 s - 5 s - 15 s - 5 s), the two technical means can play their roles within the appropriate time window, and the requirements for cementing horizontal wells are also considered;

[0086] Two transition periods are introduced. Using the principle of "flow inertia" in fluid dynamics, two different flow states of "free decay fluctuation flow" and "rotational decay flow" are formed. These two flow states are different from the flow states generated by forced fluctuation and forced rotation and can act on the cement slurry and the wellbore in different ways;

[0087] Through the cyclic conversion of four different flow states (forced fluctuation flow - free decay fluctuation flow - forced rotation flow - rotational decay flow), a diverse flow field structure is created, breaking the limitation of radial symmetric flow in traditional cementing and forming a multi-dimensional and multi-mode flow system, which improves the fluidity and displacement efficiency of the cement slurry.

[0088] Step 6: Dynamically adjust the fluctuation-rotation alternating pulse parameters;

[0089] This step is to dynamically adjust the fluctuation-rotation alternating pulse parameters according to the characteristics of different sections of the horizontal well to achieve refined cementing "suitable for the well".

[0090] 6.1 Section identification and parameter adjustment principle;

[0091] First of all, according to the logging data, drilling data and geological data, the horizontal well is divided into sections of different properties, mainly including:

[0092] Complex sections where it is difficult for the casing to be centered: usually the sections with enlarged boreholes, reduced-diameter boreholes, or large formation undulations;

[0093] Sections where the cement slurry is prone to form a flow short circuit: usually the sections with large borehole ovality and high borehole wall roughness;

[0094] Turning sections and high-difficulty sections: usually the transition areas between horizontal sections and vertical sections, or the sections with complex geological conditions.

[0095] For different sections, different parameter adjustment methods are adopted:

[0096] 6.2 Specific adjustment methods;

[0097] 6.2.1 Complex sections where it is difficult for the casing to be centered;

[0098] In such sections, the main problem is the uneven annulus caused by casing eccentricity. To address this issue, the pulsating-rotating alternating pulse parameters are adjusted as follows:

[0099] Prolong the casing rotation time: extend the standard 15 seconds to 20 - 25 seconds to enhance the casing centering effect;

[0100] Increase the casing rotation speed: increase the standard 10 - 30 rpm to 20 - 40 rpm to increase the centrifugal force of the casing rotation;

[0101] Keep the hydraulic pulsation time and the transition period time unchanged to ensure the stability of the basic circulation mode.

[0102] This adjustment method enhances the effect of casing rotation on casing centering while maintaining the basic characteristics of the pulsating-rotating alternating pulse technology.

[0103] 6.2.2 Sections where the cement slurry is prone to form a flow short circuit;

[0104] In such sections, the main problem is the uneven flow of the cement slurry and insufficient displacement in some areas. To address this issue, the pulsating-rotating alternating pulse parameters are adjusted as follows:

[0105] Increase the intensity of the hydraulic pulsation energy: increase the standard 0.5 - 2.5 MPa to 1.5 - 3.0 MPa to enhance the disturbing effect of the hydraulic pulsation on the flow of the cement slurry;

[0106] Increase the hydraulic pulsation frequency: increase the standard 2 - 8 Hz to 5 - 10 Hz to enhance the penetration power of the hydraulic pulsation;

[0107] Prolong the first transition period time: extend the standard 5 seconds to 8 - 10 seconds to allow the "free decay pulsating flow" to act on the annulus for a more sufficient time;

[0108] Keep the casing rotation time and the second transition period time unchanged.

[0109] This adjustment method enhances the effect of hydraulic fluctuations on changing the flow pattern of the cement slurry and improves the flow uniformity of the cement slurry in the complex annulus.

[0110] 6.2.3 Bend sections and difficult sections;

[0111] In such sections, multiple technical problems coexist, and it is necessary to comprehensively adjust the parameters of the alternating pulse of fluctuation-rotation:

[0112] Adjust the time ratio of fluctuation to rotation: According to the specific situation, different time ratios such as "10 seconds of fluctuation - 5 seconds of transition - 20 seconds of rotation - 5 seconds of transition" or "15 seconds of fluctuation - 5 seconds of transition - 15 seconds of rotation - 5 seconds of transition" can be adopted;

[0113] Adjust the alternating frequency: By shortening the total time of the whole cycle (such as 30 seconds for one cycle), the number of times of the fluctuation-rotation alternation per unit time can be increased;

[0114] The parameters of hydraulic fluctuations and casing rotation are comprehensively adjusted according to the actual situation.

[0115] This comprehensive parameter adjustment method can provide a more accurate technical solution for the complex situation in difficult sections.

[0116] 6.3 Implementation and monitoring of parameter adjustment;

[0117] The parameter adjustment is carried out according to the pre-established cementing plan. At the same time, during the cementing process, the adjustment effect is evaluated by real-time monitoring of parameters such as injection pressure, flow rate, and casing torque, and fine-tuning is carried out if necessary.

[0118] The innovation of the parameter adjustment lies in the realization of the refinement of the cementing process, "constructing according to the well" based on the actual situation of the horizontal well, and improving the cementing success rate and the quality of the cement sheath.

[0119] Step 7: Complete the cementing operation;

[0120] After the cement slurry injection is completed, maintain an appropriate displacement pressure to ensure the stable position of the cement slurry in the annulus. After the cement slurry begins to set, gradually release the pressure to complete the cementing operation.

[0121] This step is a conventional final step of the cementing process, and those skilled in the art are familiar with its implementation method, so it will not be described in detail here.

[0122] The horizontal well cementing construction process provided by this embodiment has achieved the following technical effects through the fluctuation-rotation alternating pulse technology and the dynamic parameter adjustment method:

[0123] The technical interference problem is solved: In traditional technologies, when hydraulic fluctuations and casing rotation are applied simultaneously, there will be problems of mutual interference and even cancellation of energy fields. In this embodiment, through separation in the time domain, the two technical means play independent roles within appropriate time windows respectively, thus solving this technical problem.

[0124] The fluidity and displacement efficiency of the cement slurry are improved: In this embodiment, the flow patterns generated during the flow state transition period are utilized to form a cyclic conversion of four different flow states, namely "forced fluctuation flow - free decay fluctuation flow - forced rotation flow - rotational decay flow", creating diverse flow field structures and improving the fluidity and displacement efficiency of the cement slurry.

[0125] Fine cementing is achieved: In this embodiment, by dynamically adjusting the wave - rotation alternating pulse parameters, fine cementing for different well sections is realized, solving multiple problems such as casing centralization, short - circuit flow of cement slurry, and poor cementing quality in complex sections.

[0126] The integrity of the cement sheath is improved: In this embodiment, through the alternating action of four different flow states, the limitation of radial symmetric flow in traditional cementing is broken, improving the adhesion of the cement slurry to the wellbore wall and the integrity of the annulus cement sheath.

[0127] Wide applicability and strong operability: This embodiment does not require additional equipment. Only by using existing hydraulic fluctuation equipment and casing rotation devices and improving the technological process and operation timing sequence can a technical breakthrough be achieved, with good engineering applicability and operability.

[0128] In summary, through the improvement of the technological process, especially the application of the wave - rotation alternating pulse technology, this embodiment solves multiple technical problems in horizontal well cementing, improves the cementing quality of horizontal wells, and has important engineering application value.

[0129] To verify the technical effects of the horizontal well cementing construction process proposed in this embodiment, the following series of experimental tests were carried out.

[0130] Experiment 1: Experiment on solving the technical interference problem

[0131] I. Experiment purpose: To verify whether the wave - rotation alternating pulse technology can effectively solve the problem of mutual interference of energy fields generated when hydraulic fluctuations and casing rotation are applied simultaneously.

[0132] II. Experimental device

[0133] Laboratory simulation wellbore device, with an inner diameter of 150 mm and a length of 15 m, of which the horizontal section length is 10 m; hydraulic fluctuation generating device, with adjustable frequency (0 - 10 Hz) and adjustable fluctuation amplitude (0 - 3 MPa); casing rotation simulation device, with adjustable rotation speed (0 - 50 rpm); cement slurry circulation system; pressure, flow rate, and temperature sensor group; data acquisition system.

[0134] III. Experimental steps

[0135] Prepare three groups of experiments:

[0136] Group A: Only use hydraulic fluctuation technology;

[0137] Group B: Only use casing rotation technology;

[0138] Group C: Simultaneously use hydraulic fluctuation and casing rotation technologies;

[0139] Group D: Use the fluctuation-rotation alternating pulse technology;

[0140] For Group A, set the hydraulic fluctuation frequency to 5 Hz and the fluctuation amplitude to 1.5 MPa;

[0141] For Group B, set the casing rotation speed to 20 rpm;

[0142] For Group C, simultaneously apply hydraulic fluctuation (5 Hz, 1.5 MPa) and casing rotation (20 rpm);

[0143] For Group D, implement the fluctuation-rotation alternating pulse technology according to the time sequence of "10 seconds of fluctuation (5 Hz, 1.5 MPa) - 5 seconds of transition - 15 seconds of rotation (20 rpm) - 5 seconds of transition";

[0144] In each group of experiments, use the same cement slurry and leading fluid formulations, with the same injection volume and operating conditions;

[0145] Record parameters such as pressure fluctuations, casing torque, and cement slurry flow rate during the experiment through sensors;

[0146] After the experiment is completed, measure the cement sheath quality indicators, including cement sheath density, uniformity, and bond strength with the wellbore wall, etc.

[0147] IV. Experimental results

[0148] By comparing and analyzing the experimental data of the four groups, the following results are obtained, as shown in Table 1:

[0149] Table 1: Comparison of energy transfer efficiency of different cementing technologies

[0150]

[0151] In the table: The energy transfer efficiency refers to the proportion of the input energy effectively transferred in the wellbore; the comprehensive energy utilization rate refers to the proportion of the input energy that actually contributes to the cementing quality; the cement sheath quality score adopts a 100-point system and is comprehensively evaluated according to the density, uniformity, bond strength, etc. of the cement sheath.

[0152] V. Experimental Analysis

[0153] When hydraulic fluctuations and casing rotation are applied simultaneously (Group C), the two energy forms interfere with each other, resulting in the energy transfer efficiencies of the two decreasing to 52% and 55% respectively, and the comprehensive energy utilization rate is only 53.5%, which is lower than the effect of using either technology alone. After adopting the fluctuating-rotating alternating pulse technology (Group D), the energy transfer efficiencies of hydraulic fluctuations and casing rotation reach 65% and 69% respectively, approaching the levels when used alone, but the comprehensive energy utilization rate is significantly increased to 85%, and the cement sheath quality score reaches 91 points, 16 - 23 points higher than other groups. This proves that the fluctuating-rotating alternating pulse technology effectively solves the problem of energy interference when the two technologies are applied simultaneously.

[0154] Experiment 2: Experiment on Improving the Fluidity and Displacement Efficiency of Cement Slurry

[0155] I. Experimental Purpose

[0156] Verify whether the fluctuating-rotating alternating pulse technology can effectively improve the fluidity and displacement efficiency of cement slurry, especially its performance in long horizontal sections.

[0157] II. Experimental Equipment

[0158] Simulated wellbore with a long horizontal section, inner diameter 120 mm, total length 30 m, of which the horizontal section length is 25 m; transparent observation windows, one set every 5 m along the horizontal section, used to observe the flow state of cement slurry; wellbore mud cake simulation device, which can evenly coat the inner surface of the wellbore with simulated mud cake; hydraulic fluctuation generating device and casing rotation device; tracer detection system; high-precision flowmeter and pressure sensor array.

[0159] III. Experimental Procedures

[0160] Prepare four groups of experiments:

[0161] Group A: Conventional cementing process (no fluctuations, no rotation);

[0162] Group B: Only use the hydraulic fluctuation technology (frequency 5 Hz, fluctuation amplitude 1.5 MPa);

[0163] Group C: Only use the casing rotation technology (20 rpm);

[0164] Group D: Fluctuating-rotating alternating pulse technology;

[0165] Uniformly coat the inner wall of the wellbore with simulated mud cake, with a thickness of about 2 mm;

[0166] Add a fluorescent tracer to the drilling fluid and inject it into the wellbore;

[0167] Sequentially inject the leading fluid and cement slurry to simulate the cementing process;

[0168] Record the process of cement slurry displacing drilling fluid at each position through a transparent observation window;

[0169] Real-time monitor the pressure and flow rate changes at each measuring point;

[0170] After completion, measure the mud cake removal rate and cement slurry filling rate at each position in the wellbore.

[0171] IV. Experimental Results

[0172] By comparing the four groups of experimental data, the following results are obtained, as shown in Tables 2 and 3:

[0173] Table 2: Comparison of Cement Slurry Fluidity of Different Cementing Technologies

[0174]

[0175] In the table: The dynamic-plasticity ratio of the cement slurry refers to the percentage reduction in dynamic plasticity relative to the conventional process (Group A); the flow resistance reduction rate refers to the percentage reduction in flow resistance relative to the conventional process; the pulsation intensity of the cement slurry refers to the pressure pulsation amplitude during the flow of the cement slurry.

[0176] Table 3: Comparison of Displacement Efficiency of Different Cementing Technologies

[0177]

[0178] V. Experimental Analysis

[0179] Compared with the conventional process, the fluctuation-rotation alternating pulse technology (Group D) reduces the dynamic plasticity of the cement slurry by 38% and the flow resistance by 35%, showing a significant improvement in fluidity. At the same time, the pulsation intensity of the cement slurry in Group D reaches 7800 Pa, much higher than that in Group B and Group C, indicating that the alternating conversion of four different flow states generates a stronger flow disturbance effect.

[0180] The average displacement efficiency of the fluctuation-rotation alternating pulse technology reaches 89%, which is about 16 percentage points higher than that of using hydraulic fluctuation or casing rotation technology alone and 30 percentage points higher than that of the conventional process. Especially at the end of the horizontal section, the displacement rate of Group D reaches 86%, much higher than that of other groups, indicating that the alternating pulse technology has a significant effect on improving the displacement efficiency of long horizontal sections. At the same time, the mud cake removal rate of Group D is also significantly higher than that of other groups, reaching 89%, proving that this technology can effectively improve the wellbore wall cleanliness.

[0181] These results fully prove that the fluctuation-rotation alternating pulse technology creates diverse flow field structures by forming a cyclic conversion of four different flow states: "forced fluctuation flow - free decay fluctuation flow - forced rotation flow - rotational decay flow", effectively improving the fluidity and displacement efficiency of the cement slurry.

[0182] Experiment Three: Experiment on Fine Cementing

[0183] I. Experiment Purpose

[0184] Verify whether the method of dynamically adjusting the fluctuation-rotation alternating pulse parameters according to the characteristics of different sections of the horizontal well can effectively solve the cementing quality problems in different well sections and achieve fine cementing.

[0185] II. Experiment Apparatus

[0186] Complex well type simulation device, including the following characteristic sections:

[0187] Elliptical wellbore section (5 m long) simulating difficult casing centralization;

[0188] High-roughness wellbore section (5 m long) simulating easy formation of flow short-circuit of cement slurry;

[0189] Simulated turning section (3 m long, with a curvature radius of 15 m);

[0190] Hydraulic fluctuation and casing rotation control system capable of real-time parameter adjustment;

[0191] Multi-point logging simulation system capable of monitoring casing eccentricity and cement slurry circulation state in each section;

[0192] Neutron logging simulation system for evaluating the quality of the cement sheath;

[0193] Data acquisition and analysis system.

[0194] III. Experiment Steps

[0195] Prepare two groups of experiments:

[0196] Group A: Use the fluctuation-rotation alternating pulse technology with fixed parameters (without adjusting parameters according to well section characteristics);

[0197] Group B: Use the fluctuation-rotation alternating pulse technology with dynamically adjusted parameters;

[0198] For the experiments in Group B, set parameters according to the characteristics of different sections:

[0199] Elliptical wellbore section with difficult casing centralization: Extend the casing rotation time to 25 seconds and increase the casing rotation speed to 35 rpm;

[0200] High-roughness wellbore section prone to flow short-circuit: Increase the intensity of hydraulic fluctuation energy to 2.5 MPa, the frequency to 8 Hz, and extend the first transition period to 10 seconds;

[0201] Turning section: Adopt a time series of "15-second fluctuation - 5-second transition - 15-second rotation - 5-second transition", with a fluctuation frequency of 6 Hz and a rotation speed of 25 rpm;

[0202] Perform cementing operations and monitor the cementing parameters of each section throughout the process;

[0203] After completion, evaluate the cementing quality indicators of each section.

[0204] IV. Experimental Results

[0205] By comparing the data of the two groups of experiments, the following results are obtained, as shown in Table 4:

[0206] Table 4: Comparison of Cementing Quality between Fixed Parameters and Dynamically Adjusted Parameters

[0207]

[0208] In the table: The casing eccentricity refers to the degree of deviation between the center of the casing and the center of the wellbore. The lower the value, the better the centering effect; the micro-annulus index is an index indicating the proportion of small gaps in the cement sheath. The lower the value, the more complete the cement sheath.

[0209] V. Experimental Analysis

[0210] Compared with the fluctuation-rotation alternating pulse technology with fixed parameters, the method of dynamically adjusting parameters has achieved obvious quality improvement in each characteristic section:

[0211] In the elliptical wellbore section, by extending the casing rotation time and increasing the rotation speed, the casing eccentricity is reduced from 42% to 18%, and the uniformity score of the cement sheath is increased by 34.9%, effectively solving the problem of casing centering.

[0212] In the high-roughness wellbore section, by increasing the intensity and frequency of hydraulic fluctuation energy and extending the first transition period, the displacement efficiency is increased from 76% to 92%, and the wellbore bonding strength is increased by 50%, effectively solving the problem of cement slurry flow short-circuit.

[0213] In the turning section, by adjusting the time ratio and parameters of fluctuation and rotation, the integrity score of the cement sheath is increased by 23.6%, and the micro-annulus index is reduced by 75%, effectively solving the cementing problem in this section.

[0214] Overall, the method of dynamically adjusting parameters increases the average cementing quality score from 71 to 88, an increase of 23.9%, proving the effectiveness of this method for achieving refined cementing.

[0215] The experimental results show that the method of dynamically adjusting the pulsation-rotation alternating pulse parameters according to the characteristics of different sections of horizontal wells can provide accurate technical solutions for the cementing problems in different well sections, realizing refined cementing of "adapting to the well conditions", and significantly improving the overall cementing quality.

[0216] Experiment 4: Experiment on improving the integrity of the cement sheath

[0217] I. Experimental purpose

[0218] Verify whether the pulsation-rotation alternating pulse technology can effectively improve the integrity of the cement sheath and reduce the occurrence rate of cement sheath channels and micro-annuli.

[0219] II. Experimental device

[0220] Large-scale horizontal well simulation device with an inner diameter of 180 mm and a length of 20 m;

[0221] Cross-section sampling device, which can sample along the wellbore direction after cementing;

[0222] Acoustic logging simulation system for measuring the acoustic propagation parameters of the cement sheath;

[0223] Pressure cycle test system, which can simulate the pressure changes during the production process;

[0224] CT scanning system for three-dimensional imaging analysis of the cement sheath structure;

[0225] Hydraulic pulsation and casing rotation device.

[0226] III. Experimental steps

[0227] Prepare three groups of experiments:

[0228] Group A: Conventional cementing technology;

[0229] Group B: Apply hydraulic pulsation and casing rotation technologies simultaneously;

[0230] Group C: Pulsation-rotation alternating pulse technology;

[0231] Conduct cementing operations under the same conditions;

[0232] After the cement slurry has solidified, use the acoustic logging system to evaluate the acoustic parameters of the cement sheath;

[0233] Conduct a pressure cycle test on the wellbore to simulate the pressure changes during the production process;

[0234] After the pressure cycle, conduct acoustic logging evaluation again;

[0235] Take samples at different positions in the wellbore for CT scanning analysis;

[0236] Measure and record parameters such as the density, porosity, and microcrack distribution of the cement sheath;

[0237] IV. Experimental Results

[0238] By comparing the three groups of experimental data, the following results are obtained, as shown in Tables 5 and 6:

[0239] Table 5: Comparison of Cement Sheath Integrity of Different Cementing Technologies

[0240]

[0241] In the table: The cement sheath uniformity coefficient refers to the consistency of the circumferential thickness of the cement sheath. The closer the value is to 1, the better the uniformity; the microcrack index refers to the comprehensive evaluation of the number and length of microcracks per unit volume. The lower the value, the fewer the microcracks.

[0242] Table 6: Change Rates of Cement Sheath Performance after Pressure Cycling Tests

[0243]

[0244] In the table: The acoustic wave attenuation change rate refers to the percentage change in the acoustic wave attenuation degree before and after pressure cycling. A negative value indicates an increase in attenuation; the cement sheath thickness change rate refers to the percentage reduction in the cement sheath thickness caused by pressure cycling; the micro-annulus growth rate refers to the percentage increase in the micro-annulus area caused by pressure cycling; the seal integrity retention rate refers to the percentage of the cement sheath maintaining its original sealing performance after pressure cycling.

[0245] V. Experimental Analysis

[0246] The cement sheath formed by the pulsating-rotating alternating pulse technology (Group C) has significantly better physical properties than the other groups: the cement sheath uniformity coefficient is as high as 0.92, close to the ideal value of 1; the cement sheath density reaches 1.94 g / cm³, higher than that of Group A and Group B; the porosity is only 3.5%, about 40% of the conventional process; the microcrack index is 0.08, only 23% of the conventional process. This indicates that the cement sheath formed by the alternating pulse technology has a more dense and uniform structure, and significantly fewer micro-defects.

[0247] After the pressure cycling test simulating the production process, the performance of the cement sheath in Group C remains the most stable: the acoustic wave attenuation change rate is only -7%, while that of Group A is -26%; the cement sheath thickness change rate is only -1.2%, much lower than the other groups; the micro-annulus growth rate is only 6%, while that of Group A is as high as 42%; the seal integrity retention rate is as high as 93%, 32 percentage points higher than the conventional process. This indicates that the cement sheath formed by the alternating pulse technology not only has high initial quality but also significantly improved stability during the production process.

[0248] CT scan analysis further showed that the microstructure of the cement sheath in Group C was more uniform, the crystal arrangement was more compact, and the interfacial bonding was stronger. This was because the alternating action of four different flow states broke the limitation of radial symmetric flow in traditional cementing, allowing the cement slurry to penetrate and bond more fully at the microscopic level.

[0249] In summary, the pulsating-rotating alternating pulse technology significantly improves the integrity and durability of the cement sheath by optimizing the flow and displacement process of the cement slurry, providing a more reliable guarantee for the long-term safe production of horizontal wells.

[0250] Experiment 5: Applicability and operability verification experiment

[0251] I. Experiment purpose

[0252] Verify the engineering applicability and operation convenience of the pulsating-rotating alternating pulse technology, and evaluate its implementation difficulty and economy under different working conditions.

[0253] II. Experiment equipment

[0254] On-site cementing operation simulation system;

[0255] Conventional cementing equipment combination, including cement truck, mixing tank, pump truck, etc.;

[0256] Hydraulic pulsation equipment and casing rotation device;

[0257] Automation control system;

[0258] Energy consumption monitoring system;

[0259] Operation complexity evaluation system.

[0260] III. Experiment steps

[0261] Design three different working conditions:

[0262] Condition A: Shallow well (1500m), standard wellbore size;

[0263] Condition B: Medium-deep well (3000m), long horizontal section (1500m);

[0264] Condition C: Deep well (4500m), high-temperature and high-pressure environment;

[0265] Under each working condition, conduct construction simulations of the conventional cementing process and the pulsating-rotating alternating pulse technology respectively;

[0266] Record parameters such as equipment requirements, personnel allocation, operation process complexity, construction risk points, etc. of the two processes under each working condition;

[0267] Record the resource usage such as energy consumption, time consumption, and material consumption of the two processes under various working conditions;

[0268] Invite 10 experienced cementing engineers to rate the operation convenience;

[0269] Comprehensively analyze the applicability and economic differences of the two processes under different working conditions.

[0270] IV. Experimental Results

[0271] By comparing and analyzing various data, the following results are obtained, as shown in Table 7 and Table 8:

[0272] Table 7: Comparison of the operability between the fluctuation-rotation alternating pulse technology and the conventional process under different working conditions

[0273]

[0274] In the table: The difference ratio represents the percentage increase of the alternating pulse technology relative to the conventional process; the operation complexity score is based on a 100-point system, and the lower the score, the simpler the operation.

[0275] Table 8: Comparison of the economy between the fluctuation-rotation alternating pulse technology and the conventional process under different working conditions

[0276]

[0277] V. Experimental Analysis

[0278] Compared with the conventional process, the fluctuation-rotation alternating pulse technology requires slightly more equipment and operation steps, and the operation complexity is slightly higher. However, as the well depth increases and the well conditions become more complex, the difference in operation complexity between the two processes gradually decreases, and the difference is only 7% in Working Condition C. This shows that although the alternating pulse technology is slightly more complex than the conventional process, it will not significantly increase the operation difficulty, especially in high-difficulty well conditions.

[0279] In terms of economy, the energy consumption and construction time of the alternating pulse technology are slightly higher than those of the conventional process, but as the well condition complexity increases, this difference gradually decreases, and the energy consumption difference is only 3.8% and the time difference is only 2.6% in Working Condition C. More significantly, the alternating pulse technology reduces the amount of cement slurry used in all working conditions, with a saving range of 8% - 13.7%, and at the same time, the cementing success rate is greatly improved, with an increase range of 25% - 29.4% in complex well conditions.

[0280] Based on the comprehensive analysis of operability and economy, the applicability of the fluctuation-rotation alternating pulse technology is reflected in the following aspects:

[0281] The technical implementation threshold is not high, and only a hydraulic fluctuation control system and a casing rotation parameter optimization system need to be added on the basis of conventional cementing equipment;

[0282] The operation complexity is moderate, and the difference from the conventional process is smaller under high-difficulty well conditions;

[0283] Although the initial investment is slightly higher, the overall construction cost can be actually reduced by reducing the amount of cement slurry and increasing the success rate of cementing;

[0284] The technical effect becomes more significant as the well condition complexity increases, and it is especially suitable for cementing long horizontal sections and high-difficulty wells.

[0285] The evaluation by cementing engineers shows that after short-term training, the operators can quickly master the key points of implementing the alternating pulse technology. The operability has obtained an average score of 82 (out of 100), indicating that this technology has good engineering practicability.

[0286] Summary of experimental tests

[0287] Through the above five groups of systematic experimental tests, the technical effects of the horizontal well cementing construction process proposed in this embodiment have been fully verified:

[0288] The fluctuation-rotation alternating pulse technology effectively solves the problem of mutual interference of the energy fields when hydraulic fluctuation and casing rotation are applied simultaneously through separation in the time domain, and the energy utilization rate is increased by 31.5 percentage points;

[0289] The cyclic conversion of the four flow states forms a diverse flow field structure, reducing the dynamic plasticity of the cement slurry by 38%, reducing the flow resistance by 35%, and the average displacement efficiency reaching 89%, which is 30 percentage points higher than the conventional process;

[0290] The method of dynamically adjusting parameters according to the characteristics of different sections of the horizontal well realizes refined cementing, increasing the average cementing quality score by 23.9% and effectively solving the cementing problems in different well sections;

[0291] The cement ring structure formed by the fluctuation-rotation alternating pulse technology is more dense and uniform. The uniformity coefficient of the cement ring reaches 0.92, and the porosity is only 3.5%. It shows excellent stability in the pressure cycle test;

[0292] This technology has good engineering applicability and operability, and has more advantages especially under high-difficulty well conditions, which can reduce the amount of cement slurry by 8% - 13.7% and increase the success rate of cementing by 11.8% - 29.4%.

[0293] The above describes the embodiments of the present invention, but these embodiments are not limited to the above specific implementation manners. The above specific implementation manners are only illustrative and not restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make more equivalent embodiments in various forms, all of which fall within the protection scope of this embodiment.

Claims

1. A cementing construction process for horizontal wells, characterized in that, It includes the following steps: Step 1: Complete the horizontal well drilling and run in the casing. Step 2: Circulate and wash the well to clean the wellbore. Step 3: Prepare the leading fluid and cement slurry. Step 4: Pump in the leading fluid and cement slurry. Step 5: During the injection of the cement slurry, adopt the method of alternating pulsed wave - rotation, so that the hydraulic wave and the casing rotation alternate in the time domain, specifically including: Hydraulic wave stage: Start the hydraulic wave equipment to generate hydraulic wave energy with a given frequency for 10 seconds. The hydraulic wave energy acts on the cement slurry in the annulus through fluid transmission, breaking the static laminar flow state of the cement slurry and promoting it to form a fluctuating flow pattern. The first transition period: Last for 5 seconds. After the hydraulic wave stops, the cement slurry will not immediately return to the static flow state, but continue to maintain a certain degree of fluctuating state under the action of inertia, forming a gradually decaying fluctuating flow field. Casing rotation stage: Last for 15 seconds. The casing rotation drives the cement slurry in the annulus to form a circumferential flow. On the one hand, it promotes the centering of the casing in the horizontal section. On the other hand, it enhances the contact between the cement slurry and the wellbore wall, improving the displacement efficiency. The casing rotation can also break the gel structure that the cement slurry may form and maintain its good fluidity. The second transition period: Last for 5 seconds. After the casing rotation stops, the cement slurry in the annulus continues to maintain a rotational motion under the action of inertia, but the rotational speed gradually decreases, forming a "rotational decay flow". And repeat the above cycle until the injection of the cement slurry is completed. Step 6: Dynamically adjust the alternating pulsed wave - rotation parameters according to the properties of different sections of the horizontal well. Step 7: Complete the cementing operation.

2. The cementing construction process of a horizontal well according to claim 1, characterized in that, During the hydraulic wave stage, the frequency range of the hydraulic wave is 2 - 8 Hz, and the fluctuation amplitude is controlled within 0.5 - 2.5 MPa.

3. The cementing construction process of a horizontal well according to claim 1, characterized in that, During the casing rotation stage, the casing rotation speed is controlled within the range of 10 - 30 rpm.

4. The cementing construction process of a horizontal well according to claim 1, characterized in that, During the first transition period, after the hydraulic wave stops, the cement slurry continues to maintain a certain degree of fluctuating state under the action of inertia, forming a gradually decaying fluctuating flow field.

5. The cementing construction process of a horizontal well according to claim 1, characterized in that, During the second transition period, after the casing rotation stops, the cement slurry in the annulus continues to maintain a rotational motion under the action of inertia, but the rotational speed gradually decreases, forming a rotational decay flow.

6. The cementing construction process of a horizontal well according to claim 1, characterized in that, In step 6, dynamically adjust the alternating pulsed wave - rotation parameters according to the properties of different sections of the horizontal well, specifically including: Divide the horizontal well into sections with different properties, including: complex sections where it is difficult for the casing to be centered, sections where the cement slurry is prone to form flow short - circuits, turning sections, and high - difficulty sections, and adopt different parameter adjustment methods for different sections.

7. The cementing construction process of a horizontal well according to claim 6, characterized in that, For complex sections where it is difficult for the casing to be centered, adjusting the alternating pulsed wave - rotation parameters includes: Extend the casing rotation time to 20 - 25 seconds; Increase the casing rotation speed to 20 - 40 rpm; Keep the hydraulic wave time and the transition period time unchanged.

8. The cementing construction process of a horizontal well according to claim 6, characterized in that, For sections where the cement slurry is prone to form flow short - circuits, adjusting the alternating pulsed wave - rotation parameters includes: Increase the intensity of the hydraulic wave energy to 1.5 - 3.0 MPa; Increase the hydraulic wave frequency to 5 - 10 Hz; Extend the first transition period time to 8 - 10 seconds; Keep the casing rotation time and the second transition period time unchanged.

9. A cementing construction process for a horizontal well according to claim 6, characterized in that, For turning sections and high - difficulty sections, adjusting the alternating pulsed wave - rotation parameters includes: Adjust the time ratio of fluctuation and rotation; Adjust the alternating frequency; Comprehensively adjust the hydraulic fluctuation and casing rotation parameters according to the actual situation.

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