Method and system for evaluating the sealing capability of cement sheath in combined bond quality sections

Abstract

The present invention provides a method and system for evaluating the isolation capacity of cement sheaths in sections with varying cement quality combinations. This method, based on statistical experimental parameters and an established comprehensive simulation experimental device, conducts simulated logging experiments using different environmental data as test conditions for cement sheaths with all wellbore and wellbore parameters in a cementing parameter database. Based on the experimental data, a relationship between the isolation capacity of cement sheaths for different sealing section lengths and cementing quality conditions is fitted. The actual cementing sections are then segmented according to the cementing acoustic amplitude curve, resulting in accurate cement sheath isolation capacity data for sections with varying cement quality combinations. This approach overcomes the limitations of existing isolation capacity testing techniques, enabling comprehensive cement sheath isolation performance evaluation using a concise calculation strategy, providing technical guidance and optimization support for the formulation of oil and gas well development plans.

Description

Technical Field

[0001] The present invention relates to the technical field of cementing operations and optimization, and in particular to a method and system for evaluating the sealing capability of a cement sheath in a cementation quality combination section. Background Art

[0002] In oil and gas engineering, cementing refers to the process of running casing into a wellbore and injecting cement into the annular space between the wellbore and casing. It is an essential step in the drilling and completion process. Improving the quality of the cement sheath formed during cementing requires three key approaches: 1. Improving drilling fluid displacement efficiency; 2. Preventing oil, gas, and water from leaking out after cementing; and 3. Improving the bonding and sealing quality of the cement sheath interface. However, whether prior to implementation, during optimization experiments, or during execution, a precise understanding of the bonding and sealing qualities of the cement sheath itself is crucial.

[0003] The existing technology usually adopts CT scanning as an auxiliary observation method and tests the displacement or acoustic amplitude fluctuation of cement sheath samples through pressure experiments. However, in actual application, the service environment of cement sheaths in the well is very harsh. During actual on-site construction, casing eccentricity, pot-bellied wellbore, slurry mixing, uneven filling and other working conditions often occur, which inevitably form a variety of cement sheath combination sections with different bonding qualities. In this case, if the above-mentioned existing technology is used for measurement, it is often only possible to measure the sealing capacity evaluation information corresponding to the cement sheath of a certain fixed length or fixed bonding quality of the current cement sheath sample, and it is impossible to accurately measure the actual sealing performance data of cement sheaths with different bonding qualities in the combination section, resulting in poor on-site applicability.

[0004] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for evaluating the isolation capability of a cement sheath of a cement quality composite section. In one embodiment, the method comprises:

[0006] Simulate the data setup steps and collect historical cementing parameters of different types of oil and gas wells in different regions, including all wellbore data and cementing environment data involved in the cementing process. These data are stored in association with the oil and gas well type and region as labels to form a cementing parameter database.

[0007] Simulation experiment steps: Based on the established comprehensive simulation experiment device, simulated logging experiments are carried out for the cement sheath of all wellbore parameters in the cementing parameter database using different environmental data as test conditions;

[0008] Experimental data analysis steps: fitting the changing relationship between the logging acoustic amplitude data and isolation pressure data obtained under different experimental conditions according to the changing curves of the two under different experimental conditions;

[0009] Applying the segmentation steps, based on the set principles and the measured logging acoustic amplitude data, the actual cementing sections with different cementation quality combinations to be evaluated are divided to obtain multiple isolation sections;

[0010] The isolation pressure calculation steps are as follows: the isolation pressure data of the isolation section with different experimental lengths are calculated based on the fitted relationship between the logging acoustic amplitude data and the isolation pressure data; the relationship between the isolation pressure data and the isolation section length parameter under each logging acoustic amplitude data condition is fitted; the length data of each actual isolation section is then substituted into the corresponding segmented isolation pressure data and the isolation pressure data of the entire cementing section is generated by integration and calculation.

[0011] Preferably, in one embodiment, in the simulation experiment step, the configuration of the comprehensive simulation experiment device can meet the reproduction requirements of various parameters in the cementing parameter database.

[0012] Furthermore, in one embodiment, the process of performing the simulation experiment includes:

[0013] Place the pre-made simulated formation in the outer casing, then inject cement slurry into the annulus between the casing and the simulated formation to a preset height, and seal the wellbore with an upper cover;

[0014] After applying the curing temperature for 48 hours according to the preset environmental data, simulated logging was performed using the preset CBL logging instrument to measure the CBL simulated logging amplitude data of the cement sealing section;

[0015] According to the set test settings, gas / liquid is injected from the bottom of the annulus, and the isolation pressure of the cement sheath is measured at the same time.

[0016] Specifically, in one embodiment, the simulation experiment step includes:

[0017] Real-time recording of the logging acoustic amplitude of cement sheaths of different lengths under different curing temperature conditions, screening out records that differ by more than 15% from the average value of other measurement results as invalid experimental results, and performing additional experiments based on the experimental parameters corresponding to these experimental results;

[0018] The corresponding isolation pressure of each experimental sample with valid logging acoustic amplitude was tested respectively, and the records with a difference of more than 15% from the average value of other isolation pressure measurement results were screened as invalid experimental results. The experiments were then supplemented with the experimental parameters corresponding to the experimental results until the obtained logging acoustic amplitude and isolation pressure were both valid data.

[0019] In a preferred embodiment, in the experimental data analysis step, for cement sheath experimental samples of different lengths, curves of the change of the isolation pressure data with the logging acoustic amplitude under different curing temperature conditions are drawn, and the change relationship between the two is fitted as the corresponding relationship formula of the current length.

[0020] Optionally, in one embodiment, in the applying segmentation step, segmentation is achieved based on the principle that the absolute value of the difference between the CBL logging acoustic amplitude of all points in a segment and the average CBL logging acoustic amplitude of the segment is no more than 5%.

[0021] Furthermore, in one embodiment, the isolation pressure calculation step includes:

[0022] Based on the calculated cement sheath isolation pressure data and the isolation section length data used in the calculation, the relationship between the cement sheath isolation pressure y and the isolation section length x under the current actual logging acoustic amplitude is obtained: y = Gj(x);

[0023] The cement sheath isolation pressure of the current isolation section can be obtained by substituting the actual isolation section length of the cement sheath into the relationship between the cement sheath isolation pressure and the isolation section length.

[0024] Specifically, in one embodiment, in the isolation pressure calculation step, isolation pressure data of the entire cementing section is calculated and generated according to the following formula:

[0025]

[0026] Where, P z is the isolation pressure data of the entire cementing section, P j is the isolation pressure data of the ith isolation section, and m is the total number of sections currently divided by cementing.

[0027] Preferably, in the simulation data setting step, the wellbore data and cementing environment data in the cementing parameter database cover the ideal limit values ​​of construction parameters that may be encountered in the corresponding area and oil and gas well type, and the ideal limit values ​​are formed by assigning a set unidirectional offset based on the actual limit values.

[0028] Based on other aspects of the method described in any one or more of the above embodiments, the present invention also provides a system for evaluating the sealing ability of a cement sheath in a cementation quality combination section, which executes the method described in any one or more of the above embodiments.

[0029] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0030] The present invention provides a method and system for evaluating the isolation capability of cement sheaths in sections with combined cementing qualities. Based on a cement sheath isolation capability test and a CBL logging simulation experimental device, the method tests the isolation capability relationship of cement sheaths under conditions of different cementing section lengths and different cementing qualities. The method segments the actual cementing sections according to the cementing acoustic amplitude curve, thereby calculating and obtaining precise isolation capability data of cement sheaths in sections with different combined cementing qualities. The method overcomes the limitations of isolation capability testing in the prior art, utilizes concise calculations to achieve comprehensive cement sheath isolation performance evaluation, and provides technical guidance or reference for formulating oil and gas well development plans. The method has high engineering application value and scientific research value.

[0031] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0033] Figure 1 1 is a flow chart of a method for evaluating the sealing capability of a cement sheath of a cementation quality combination section provided by an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a comprehensive simulation experimental device used in the isolation capacity evaluation method provided in another embodiment of the present invention.

[0035] Figure 3 It is a structural schematic diagram of a system for evaluating the sealing capability of a cement sheath of a cementation quality combination section provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will describe in detail the implementation methods of the present invention in conjunction with the accompanying drawings and embodiments, so that practitioners of the present invention can fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects, and can implement the present invention in accordance with the above implementation process. It should be noted that as long as no conflict exists, the various embodiments and various features of each embodiment in the present invention can be combined with each other, and the resulting technical solutions are all within the scope of protection of the present invention.

[0037] Although the flowcharts depict the operations as sequential processes, many of the operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can be terminated when its operations are completed, but can also have additional steps not included in the figures. A process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0038] Computer devices include user devices and network devices. User devices or clients include, but are not limited to, computers, smartphones, PDAs, and the like; network devices include, but are not limited to, a single network server, a server group consisting of multiple network servers, or a cloud computing-based cloud consisting of a large number of computers or network servers. Computer devices can operate independently to implement the present invention, or they can connect to a network and interact with other computer devices in the network to implement the present invention. Networks in which computer devices reside include, but are not limited to, the Internet, wide area networks, metropolitan area networks, local area networks, VPN networks, and the like.

[0039] The terms "first," "second," and the like may be used herein to describe various elements, but these elements should not be limited by these terms, and these terms are used merely to distinguish one element from another. The term "and / or" as used herein includes any and all combinations of one or more of the listed associated items. When an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present.

[0040] The terms used herein are intended only to describe specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a", "an", "an item" used herein are also intended to include the plural. It should also be understood that the terms "comprise" and / or "include" used herein specify the presence of stated features, integers, steps, operations, units and / or components, and do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0041] In oil and gas engineering, cementing refers to the process of running casing into a wellbore and injecting cement into the annular space between the wellbore and casing. It is an essential step in the drilling and completion process. The resulting cement sheath not only isolates the formation but also plays an indispensable role in suspending and protecting the casing, extending the well's production cycle. Improving the quality of the cement sheath formed during cementing operations requires three key approaches: 1. Improving the efficiency of drilling fluid displacement; 2. Preventing oil, gas, and water from leaking out after cementing; and 3. Improving the bonding and sealing quality of the cement sheath interface. However, whether before optimization implementation, during experimentation, or during execution, a precise understanding of the bonding and sealing qualities of the cement sheath itself is essential.

[0042] The existing technology usually adopts CT scanning as auxiliary observation and tests the displacement or acoustic amplitude fluctuation of cement sheath samples through pressure experiments. Some researchers have also proposed using the well-bonded cumulative length method, the slurry band length method and the intersection method of the two methods to evaluate the sealing capacity of natural gas well cement sheaths. It is believed that using logging data to evaluate the sealing capacity of cement sheaths between gas layers is similar to the conventional cementing quality evaluation method. However, in actual application, the service environment of cement sheaths in the well is very harsh. During actual on-site construction, casing eccentricity, pot-bellied wellbore, slurry mixing, and uneven filling often occur, inevitably forming a variety of cement sheath combination sections with different bonding qualities. In this case, if the above-mentioned existing technologies are used for measurement, it is often only possible to measure the sealing capacity evaluation information corresponding to the cement sheath of a certain fixed length or fixed bonding quality of the current cement sheath sample, and it is impossible to accurately measure the actual sealing performance data of cement sheaths with different bonding qualities in the combination section, resulting in poor field applicability.

[0043] In summary, existing technologies can only evaluate the isolation capacity of cement at a fixed length or fixed bonding quality, and cannot consider the impact of different bonding quality combination sections. To solve the above problems, the present invention provides a flow chart and system for evaluating the isolation capacity of cement sheaths with different bonding quality combination sections. The present invention provides a set of isolation capacity experimental evaluation methods for cement sheaths with different bonding quality combination sections. The application of this scheme can accurately evaluate the isolation capacity of cement sheaths with different cement sheath isolation lengths and different bonding quality combination sections, and can more accurately evaluate the isolation capacity of actual cementing cement sheaths. It provides technical guidance or reference for formulating oil and gas well development plans, and has high engineering application value and scientific research value.

[0044] Next, the detailed process of the method according to the embodiment of the present invention is described in detail based on the accompanying drawings. The steps shown in the flowcharts of the accompanying drawings can be executed in a computer system including, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowcharts, in some cases, the steps shown or described can be executed in a different order than here.

[0045] Example 1

[0046] Figure 1 The flow chart of the method for evaluating the sealing capability of cement sheath of cement quality combination section provided by the first embodiment of the present invention is shown. Figure 1 It can be seen that the method includes the following steps.

[0047] Simulate the data setup steps and collect historical cementing parameters of different types of oil and gas wells in different regions, including all wellbore data and cementing environment data involved in the cementing process. These data are stored in association with the oil and gas well type and region as labels to form a cementing parameter database.

[0048] Simulation experiment steps: Based on the established comprehensive simulation experiment device, simulated logging experiments are carried out for the cement sheath of all wellbore parameters in the cementing parameter database using different environmental data as test conditions;

[0049] Experimental data analysis steps: fitting the changing relationship between the logging acoustic amplitude data and isolation pressure data obtained under different experimental conditions according to the changing curves of the two under different experimental conditions;

[0050] Applying the segmentation steps, based on the set principles and the measured logging acoustic amplitude data, the actual cementing sections with different cementation quality combinations to be evaluated are divided to obtain multiple isolation sections;

[0051] The isolation pressure calculation steps are as follows: the isolation pressure data of the isolation section with different experimental lengths are calculated based on the fitted relationship between the logging acoustic amplitude data and the isolation pressure data; the relationship between the isolation pressure data and the isolation section length parameter under each logging acoustic amplitude data condition is fitted; the length data of each actual isolation section is then substituted into the corresponding segmented isolation pressure data and the isolation pressure data of the entire cementing section is generated by integration and calculation.

[0052] The scheme logic in the above-mentioned embodiment of the present invention can be applied to accurately evaluate the sealing capacity of cement rings with different actual bonding quality combinations, so as to prevent oil, gas and water crossflow and annular space pressure, plan scientific oil and gas production, and formulate reasonable oil and gas production work systems. It has broad application and promotion prospects.

[0053] Furthermore, in one embodiment, in the simulation data setting step, the wellbore data and cementing environment data in the cementing parameter database cover the ideal limit values ​​of construction parameters that may be encountered in the corresponding area and oil and gas well type, and the ideal limit values ​​are formed by assigning a set unidirectional offset based on the actual limit values.

[0054] Specifically, in one embodiment, the wellbore data in the cementing parameter database includes all possible wellbore sizes and matching wellbore sizes involved in the construction, and the cementing environment data includes maintenance temperature data, covering downhole temperature data that may be used in the construction of all regions and oil and gas well types.

[0055] In actual application, professionals set the specific value of the same-direction offset. Based on the above embodiment, the comprehensiveness of various parameters in the cementing parameter database can be fundamentally guaranteed, which better guarantees the implementation of experiments and the reliability of experimental data.

[0056] Additionally, in an optional embodiment, the data content in the cementing parameter database can be updated according to actual cementing record data.

[0057] Furthermore, in one embodiment, in the simulation experiment step, the configuration of the comprehensive simulation experiment device can meet the reproduction requirements of various parameters in the cementing parameter database. Specifically, in actual application, the following can be established: Figure 2 The cement sheath isolation capability test and CBL logging simulation experiment device shown is 1.5 m high and can simulate the downhole temperature and wellbore conditions of the cement sheath to conduct cement sheath isolation capability test experiments for five wellbore sizes: 4-1 / 2 in casing × 6 in wellbore, 5-1 / 2 in casing × 8-1 / 2 in wellbore, 7 in casing × 8-1 / 2 in wellbore, 9-5 / 8 in casing × 12-1 / 4 in wellbore, and 13-3 / 8 in casing × 17-1 / 2 in wellbore.

[0058] In a preferred embodiment, the process of performing the simulation experiment includes:

[0059] Place the pre-made simulated formation in the outer casing, then inject cement slurry into the annulus between the casing and the simulated formation to a preset height, and seal the wellbore with an upper cover;

[0060] After applying the curing temperature for 48 hours according to the preset environmental data, simulated logging was performed using the preset CBL logging instrument to measure the CBL simulated logging amplitude data of the cement sealing section;

[0061] According to the set test settings, gas / liquid is injected from the bottom of the annulus, and the isolation pressure of the cement sheath is measured at the same time.

[0062] In actual application, combined with the Figure 2 To obtain the information in the simulation, you can first place the pre-made simulation layer as shown in the following figure. Figure 2 The outer tube shown is then filled with cement slurry into the annulus between the casing and the simulated formation to a preset height. The wellbore is then sealed with the upper cover and the curing temperature is applied. After curing for 48 hours, the CBL logging instrument is used to perform simulated logging and measure the CBL simulated logging acoustic amplitude of the cement sealing section. Finally, gas / liquid is injected from the bottom of the annulus to measure the isolation pressure of the cement sheath.

[0063] Furthermore, during the experiment, the Figure 1 The cement sheath isolation capability test and CBL logging simulation test device shown in the figure are based on the same cement slurry system formula and completely consistent standardized operation process to test different temperatures t i Under curing conditions (t0 is room temperature, t i =t0+i×△t, i=natural number from 0 to n, △t should be selected so that t i and t i+1 The CBL logging sound amplitudes under the two temperature curing conditions can be clearly distinguished or have a certain level difference, and n is not less than 9, t nCBL logging acoustic amplitude CBL under the conditions of the cement sheath isolation section length being 0.6m, 0.8m, 1.0m, 1.2m and 1.4m respectively ti1 、CBL ti2 、CBL ti3 、CBL ti4 、CBL ti5 , comparative analysis of CBL ti1 、CBL ti2 、CBL ti3 、CBL ti4 、CBL ti5 ;

[0064] Among them, if a certain value differs from the average value of other values ​​by more than 15%, it is considered to be invalid data and needs to be eliminated. Based on the same cement slurry system formula and completely consistent standardized operating procedures, a CBL logging simulation experiment under the conditions corresponding to this value is performed to obtain valid data.

[0065] After testing the CBL logging acoustic amplitude under a certain temperature ti curing condition in step 2, the cement sheath isolation pressures Pti1, Pti2, Pti3, Pti4, and Pti5 are tested under the conditions of cement sheath isolation lengths of 0.6 m, 0.8 m, 1.0 m, 1.2 m, and 1.4 m, respectively. A curve of cement sheath isolation pressure versus isolation section length is drawn based on the measured data. If a value is far from the curve, it is considered invalid data and needs to be eliminated. Based on the same cement slurry system formula and completely consistent standardized operating procedures, a cement sheath isolation pressure test experiment is performed under the conditions corresponding to the value to obtain valid data.

[0066] Therefore, in one embodiment, the simulation experiment step includes:

[0067] During the experiment, the logging acoustic amplitudes of cement sheaths of different lengths under different curing temperature conditions were recorded in real time. Records that differed from the average values ​​of other measurement results by more than 15% were selected as invalid experimental results, and additional experiments were performed based on the experimental parameters corresponding to these experimental results.

[0068] The corresponding isolation pressure of each experimental sample with valid logging acoustic amplitude was tested respectively, and the records with a difference of more than 15% from the average value of other isolation pressure measurement results were screened as invalid experimental results. The experiments were then supplemented with the experimental parameters corresponding to the experimental results until the obtained logging acoustic amplitude and isolation pressure were both valid data.

[0069] Furthermore, in a preferred embodiment, in the experimental data analysis step, for each cement sheath experimental sample of different lengths, a curve of the change of the isolation pressure data with the logging acoustic amplitude under different curing temperature conditions is drawn, and the change relationship between the two is fitted as the corresponding relationship formula of the current length.

[0070] In practical application, for example, the average logging amplitude CBL obtained under different temperature ti curing conditions for the experimental working condition with cement sheath isolation length of 0.6m ti and cement sheath isolation pressure P ti1 , plot cement sheath isolation pressure P ti1 Average value of the acoustic amplitude during logging CBL ti The change curve of cement sheath isolation pressure P is fitted ti1 Average value of the acoustic amplitude during logging CBL ti The relationship between the change of F1(x) is obtained; similarly, the cement sheath packing pressure P under the experimental conditions of cement sheath packing lengths of 0.8m, 1.0m, 1.2m, and 1.4m can be obtained. ti2 、P ti3 、P ti4 、P ti5 The average value of the logging sound amplitude CBL ti The changing relationships are F2(x), F3(x), F4(x), and F5(x) respectively.

[0071] Considering that cement sheaths of various bonding quality states need to be calculated separately, in one embodiment, segmentation is achieved in the segmentation step based on the principle that the absolute value of the difference between the CBL logging acoustic amplitude of all points in a segment and the average CBL logging acoustic amplitude of the segment is no more than 5%.

[0072] Specifically, in one embodiment, the isolation pressure calculation step includes:

[0073] Based on the calculated cement sheath isolation pressure data and the isolation section length data used in the calculation, the relationship between the cement sheath isolation pressure y and the isolation section length x under the current actual logging acoustic amplitude is obtained: y = G j (x);

[0074] The cement sheath isolation pressure of the current isolation section can be obtained by substituting the actual isolation section length of the cement sheath into the relationship between the cement sheath isolation pressure and the isolation section length.

[0075] In practical application, for the actual cementing sections with different cementing quality (CBL logging acoustic amplitude) combinations, firstly segment them based on the CBL logging acoustic amplitude (segmentation standard: the absolute value of the difference between the CBL logging acoustic amplitude of all points in the segment and the average CBL logging acoustic amplitude of the segment is not greater than 5%). Assuming that the actual cementing section is divided into m segments, the CBL logging acoustic amplitude of the jth segment is CBL j The corresponding packing length is L j , j is a natural number from 1 to m; CBL jSubstituting F1(x), F2(x), F3(x), F4(x), and F5(x) respectively, we can obtain the cement sheath isolation pressure P under the conditions of experimental lengths of 0.6m, 0.8m, 1.0m, 1.2m, and 1.4m. j1 、P j2 、P j3 、P j4 、P j5 , based on cement sheath isolation pressure data (P j1 、P j2 、P j3 、P j4 、P j5 ) and cement sheath interval length data (0.6m, 0.8m, 1.0m, 1.2m, 1.4m) to obtain the CBL logging acoustic amplitude value CBL j The cement sheath isolation pressure changes with the isolation section length when y=G j (x), the actual sealing length of cement sheath x=L j Substitute y = G j (x) can be used to calculate the actual sealing length of the cement sheath: L j And the CBL logging sound amplitude is CBL j The cement sheath isolation pressure in this section is P j .

[0076] Furthermore, in one embodiment, in the isolation pressure calculation step, isolation pressure data of the entire cementing section is calculated and generated according to the following formula:

[0077]

[0078] Where, P z is the isolation pressure data of the entire cementing section, P j is the isolation pressure data of the ith isolation section, and m is the total number of sections currently divided by cementing.

[0079] Based on the logic described in any one or more of the above embodiments of the present invention, it is possible to test the cement sheath isolation capacity relationship under different sealing section lengths and different cementing quality conditions based on the cement sheath isolation capacity test and CBL logging simulation experimental device, and to segment the cementing quality according to the actual cementing acoustic amplitude curve, thereby calculating the precise cement sheath isolation capacity of different cementing quality combination sections.

[0080] For simplicity of description, the aforementioned method embodiments are described as a series of actions. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions and modules involved are not necessarily required for the present invention.

[0081] It should be noted that, in other embodiments of the present invention, the method can also obtain a new cement sheath isolation capability evaluation method by combining one or more of the above embodiments, so as to achieve optimized guidance for cementing engineering.

[0082] It should be noted that, based on the method in any one or more of the above-mentioned embodiments of the present invention, the present invention also provides a storage medium, which stores program code that can implement the method described in any one or more of the above-mentioned embodiments. When the code is executed by the operating system, it can implement the above-mentioned method for evaluating the sealing capacity of the cement sheath of the bonding quality combination section.

[0083] Example 2

[0084] The methods disclosed in the above embodiments of the present invention are described in detail. The methods of the present invention can be implemented using various devices or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention further provides a system for evaluating the isolation capability of a cement sheath in a cementation quality combination section. This system is used to implement the method for evaluating the isolation capability of a cement sheath in a cementation quality combination section described in any one or more of the above embodiments. A specific embodiment is provided below for detailed description.

[0085] Specifically, Figure 3 FIG. 4 is a schematic diagram showing the structure of a system for evaluating the sealing capability of a cement sheath of a cementation quality combination section provided in an embodiment of the present invention. Figure 3 As shown, the system includes:

[0086] A simulation data setting module is configured to collect historical cementing parameters of different types of oil and gas wells in different regions, including all wellbore data and cementing environment data involved in the cementing process, and store them in association with oil and gas well type and region as labels to form a cementing parameter database;

[0087] A simulation device establishment module is used to establish a cement sheath isolation capability test and CBL logging simulation experimental device as a comprehensive simulation experimental device;

[0088] The simulation experiment module is configured to carry out simulation logging experiments based on the established comprehensive simulation experiment device for cement sheaths of all wellbore and wellbore parameters in the cementing parameter database using different environmental data as test conditions;

[0089] An experimental data analysis module is configured to fit the changing relationship between the well logging acoustic amplitude data and the isolation pressure data obtained under different experimental conditions according to the changing curves of the two data;

[0090] A segmentation module is applied, which is configured to divide the actual cementing sections of different cementation quality combinations to be evaluated based on the measured logging acoustic amplitude data according to the set principles, and obtain multiple isolation sections;

[0091] The isolation pressure calculation module is configured to calculate the isolation pressure data when the isolation section is of different experimental lengths based on the fitted relationship between the logging acoustic amplitude data and the isolation pressure data, and to obtain the relationship between the isolation pressure data and the isolation section length parameter under each logging acoustic amplitude data condition by fitting. Then, the length data of each actual isolation section is substituted into the module to calculate the corresponding segmented isolation pressure data and the integrated calculation is used to generate the isolation pressure data of the entire cementing section.

[0092] In one embodiment, the simulation data setting module is configured to set the wellbore data and cementing environment data in the cementing parameter database to cover the ideal limit values ​​of construction parameters that may be encountered in the corresponding area and oil and gas well type, and the ideal limit value is formed by assigning a set unidirectional offset based on the actual limit value.

[0093] Furthermore, in one embodiment, the configuration of the comprehensive simulation experimental device can meet the reproduction requirements of various parameters in the cementing parameter database.

[0094] In a preferred embodiment, the simulation experiment module performs the simulation experiment by:

[0095] Place the pre-made simulated formation in the outer casing, then inject cement slurry into the annulus between the casing and the simulated formation to a preset height, and seal the wellbore with an upper cover;

[0096] After applying the curing temperature for 48 hours according to the preset environmental data, simulated logging was performed using the preset CBL logging instrument to measure the CBL simulated logging amplitude data of the cement sealing section;

[0097] According to the set test settings, gas / liquid is injected from the bottom of the annulus, and the isolation pressure of the cement sheath is measured at the same time.

[0098] Furthermore, in one embodiment, the simulation experiment module further performs the following operations during the experiment:

[0099] Real-time recording of the logging acoustic amplitude of cement sheaths of different lengths under different curing temperature conditions, screening out records that differ by more than 15% from the average value of other measurement results as invalid experimental results, and performing additional experiments based on the experimental parameters corresponding to these experimental results;

[0100] The corresponding isolation pressure of each experimental sample with valid logging acoustic amplitude was tested respectively, and the records with a difference of more than 15% from the average value of other isolation pressure measurement results were screened as invalid experimental results. The experiments were then supplemented with the experimental parameters corresponding to the experimental results until the obtained logging acoustic amplitude and isolation pressure were both valid data.

[0101] In an optional embodiment, the experimental data analysis module is configured to: for each cement sheath experimental sample of different lengths, draw a curve of the change of the sealing pressure data with the logging sound amplitude under different curing temperature conditions, and fit the change relationship between the two as the corresponding relationship formula of the current length.

[0102] Specifically, in one embodiment, the application segmentation module is configured to implement segmentation based on the principle that the absolute value of the difference between the CBL logging acoustic amplitude of all points in a segment and the average CBL logging acoustic amplitude of the segment is no more than 5%.

[0103] Furthermore, the isolation pressure calculation module is configured to perform the following operations:

[0104] Based on the calculated cement sheath isolation pressure data and the isolation section length data used in the calculation, the relationship between the cement sheath isolation pressure y and the isolation section length x under the current actual logging acoustic amplitude is obtained: y = G j (x);

[0105] Substituting the actual isolation section length of the cement sheath into the relationship between the cement sheath isolation pressure and the isolation section length, the cement sheath isolation pressure of the current isolation section can be obtained.

[0106] The isolation pressure data of the entire cementing section is calculated according to the following formula:

[0107]

[0108] Where, P z is the isolation pressure data of the entire cementing section, P j is the isolation pressure data of the ith isolation section, and m is the total number of sections currently divided by cementing.

[0109] In the sealing capacity evaluation system for cement sheath of a cementation quality combined section provided by the embodiment of the present invention, each module or unit structure can be operated independently or in combination according to actual experimental and calculation requirements to achieve corresponding technical effects.

[0110] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0111] The phrase "one embodiment" mentioned in the specification means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "one embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0112] Although the embodiments disclosed herein are as described above, the contents described herein are merely embodiments for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A method for evaluating the sealing capacity of a cement sheath of a cementation quality composite section, characterized in that: The method comprises: Simulate the data setup steps and collect historical cementing parameters of different types of oil and gas wells in different regions, including all wellbore data and cementing environment data involved in the cementing process. These data are stored in association with the oil and gas well type and region as labels to form a cementing parameter database. Simulation experiment steps: Based on the established comprehensive simulation experiment device, simulated logging experiments are carried out for the cement sheath of all wellbore parameters in the cementing parameter database using different environmental data as test conditions; Experimental data analysis steps: fitting the changing relationship between the logging acoustic amplitude data and isolation pressure data obtained under different experimental conditions according to the changing curves of the two under different experimental conditions; Applying the segmentation steps, based on the set principles and the measured logging acoustic amplitude data, the actual cementing sections with different cementation quality combinations to be evaluated are divided to obtain multiple isolation sections; The isolation pressure calculation step is to calculate the isolation pressure data when the isolation section is of different experimental lengths based on the fitted relationship between the logging acoustic amplitude data and the isolation pressure data, and to obtain the relationship between the isolation pressure data and the isolation section length parameter under each logging acoustic amplitude data condition by fitting. Then, the length data of each actual isolation section is substituted into the calculation to calculate the corresponding segmented isolation pressure data, and the isolation pressure data of the entire cementing section is generated by integrating the calculation; In the experimental data analysis step, for each cement sheath test sample of different lengths, the curves of the change of the isolation pressure data with the logging acoustic amplitude under different curing temperature conditions are plotted, and the relationship between the two changes is fitted as the corresponding relationship formula of the current length; In the step of applying segmentation, segmentation is achieved based on the principle that the absolute value of the difference between the CBL logging acoustic amplitude of all points in the segment and the average CBL logging acoustic amplitude of the segment does not exceed a set threshold.

2. The method according to claim 1, characterized in that In the simulation experiment step, the configuration of the comprehensive simulation experiment device can meet the reproduction requirements of various parameters in the cementing parameter database.

3. The method according to claim 1, characterized in that The process of performing a simulation experiment includes: Place the pre-made simulated formation in the outer casing, inject cement slurry into the annulus between the casing and the simulated formation to a preset height, and seal the wellbore with an upper cover; After applying the curing temperature for 48 hours according to the preset environmental data, simulated logging was performed using the preset CBL logging instrument to measure the CBL simulated logging amplitude data of the cement sealing section; According to the set test settings, gas / liquid is injected from the bottom of the annulus, and the isolation pressure of the cement sheath is measured at the same time.

4. The method according to claim 1, wherein The simulation experiment steps include: Real-time recording of the logging acoustic amplitude of cement sheaths of different lengths under different curing temperature conditions. Records whose average values ​​differ from other measurement results by more than the set limit are selected as invalid experimental results, and additional experiments are performed based on the experimental parameters corresponding to the experimental results. The corresponding isolation pressure of each experimental sample with valid logging acoustic amplitude is tested respectively, and the records whose average value differs from other isolation pressure measurement results by more than the set limit are screened as invalid experimental results. The experiment is then supplemented with the experimental parameters corresponding to the experimental result until the obtained logging acoustic amplitude and isolation pressure are both valid data.

5. The method according to claim 1, characterized in that The isolation pressure calculation steps include: Based on the calculated cement sheath isolation pressure data and the isolation section length data used in the calculation, the relationship between the cement sheath isolation pressure y and the isolation section length x under the current actual logging acoustic amplitude is obtained: y = Gj(x); The cement sheath isolation pressure of the current isolation section can be obtained by substituting the actual isolation section length of the cement sheath into the relationship between the cement sheath isolation pressure and the isolation section length.

6. The method according to claim 5, characterized in that In the isolation pressure calculation step, the isolation pressure data of the entire cementing section is calculated according to the following formula: Where, P z is the isolation pressure data of the entire cementing section, P j is the isolation pressure data of the ith isolation section, and m is the total number of sections currently divided by cementing.

7. The method according to claim 1, characterized in that In the simulation data setting step, the wellbore data and cementing environment data in the cementing parameter database cover the ideal limit values ​​of construction parameters that may be encountered in the corresponding area and oil and gas well type. The ideal limit values ​​are formed by assigning a set same-direction offset based on the actual limit values.

8. A system for evaluating the sealing capacity of cement sheaths of bonded quality composite sections, characterized in that: The system executes the method according to any one of claims 1 to 7.

Images